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From the collection of the 

j f 

o Prelinger h 
v Ijibrary 



San Francisco, California 

Released from 
Cr^nbrook htsHtute of oden 





Director, Department of Tropical Research 
New York Zoological Society 


Smithsonian Institution 


Chairman, Department of Birds, 
American Museum of Natural History 


President, New York Zoological Society 
President, Conservation Foundation 





Associate Curator, Department of Insects and Spiders, 
American Museum of Natural History 



D. Van Nostrand Company, Inc., 250 Fourth Avenue, New York 3 

D. Van Nostrand Company (Canada), Ltd., 228 Bloor Street, Toronto 8 

Macmillan & Company, Ltd., St. Martin's Street, London, W.C. 2 



Published simultaneously in Canada by 

All Rights Reserved 

This book, or any parts thereof, may not be 
reproduced in any form without written per- 
mission from the author and the publishers. 

Produced in collaboration with Chanticleer Press, Inc. 




portion of the animal life of the vast and diversified land that is 
North America. That general knowledge of them is relatively 
meager must be attributed to the circumstance of size, rather than 
to inferiority in either importance or genuine interest. By means of 
size, and also of sound, birds, mammals, and vertebrate animals mo- 
nopolize the stage and divert attention. Yet only a slight change in 
perspective will bring into view a microcosm of tiny creatures that, 
hidden away in leafy jungles or unseen in miniature forests under 
foot, live lives of unbelievable strangeness and complexity. To bring 
this microcosm into sharp focus for the general reader is the prime 
purpose of this book. 

Our American spider heritage is a large and diversified fauna 
commensurate in importance with the age and size of the continent 
itself. Proclaiming this heritage is a large and rewarding body of 
literature created by students during more than one hundred and 
fifty years of enthusiastic devotion. At the beginning one would 
mention the name of John Abbot, who, as early as 1776, began the 
study of spiders and other animals in the region around Savannah, 
Georgia. It is to be regretted that his fine paintings and accompany- 
ing notes were never published, as were those of the birds, butter- 
flies, and moths for which he became justly famous. Thereafter, 
with Nicholas Marcellus Hentz, whose first contribution appeared 
in 1821, began a line of investigators (H. C. McCook, T. H. Mont- 
gomery, G. W. and E. G. Peckham, J. H. Comstock, and J. H. 
Emerton, to mention only a few) which has terminated in that out- 
standing living American devotee of Arachne, Alexander Petrunke- 
vitch, and in a growing circle of younger workers. The contribution 
of Americans to world araneology has been a striking one, but we 
have profited in even greater measure by the energy and genius of 
students from other lands, foreigners in language only. 


Our debt to the past is a very great one, and credit for our (often 
presumed) deeper insight into the Araneae must to a considerable 
extent go to the accumulation of information marshaled by the 
pioneers. The facts brought together in this book are borrowed 
largely from a fund of information available to all arachnologists, 
and, while they reflect commendable knowledge, at the same time 
they reveal comparative ignorance of much in the lives of the spin- 
ning creatures. It is therefore the author's hope that this book will, 
in addition to its other purposes, act as a stimulus to those eager to 
unearth the many details still unknown. 

Most spiders are difficult subjects that try the patience and tech- 
niques of photographers. It is thus particularly gratifying that an 
excellent and representative collection of photographs was available 
for use in this book. On the many colored and black-and-white 
plates are depicted graphically the forms, patterns, and handiwork 
of some of our commonest and most interesting spiders, almost all 
from living subjects. To those who have offered their photographs, 
many of them associates and personal friends, I extend my sincere 
thanks and further express my admiration for their splendid work. 
One of the contributors, George Elwood Jenks of Los Angeles, 
died before the completion of this book, leaving behind distin- 
guished pictorial explorations of the lives of spiders and their 
enemies as a monument to his enthusiasm. To my friend and col- 
league, Walker Van Riper of the Denver Museum of Natural His- 
tory, I offer my special gratitude. In addition to placing his valuable 
albums in my hands for use without reservation, he has aided ma- 
terially in securing photographs of the subjects most needed. Fi- 
nally, it is a privilege to acknowledge the contribution made by 
Dr. B. J. Kaston of Connecticut State Teachers College at New 
Britain, who, in spite of preoccupation with other work, found time 
to read and criticize a large portion of this book. All the sugges- 
tions he has made, which reflect his broad training in biology, have 
resulted in material improvement of the manuscript. 






1. Introducing Spiders i 

2. The Place of Spiders in Nature 1 1 
The Life of the Spider 28 

4. Silk Spinning and Handiwork 52 

5. Courtship and Mating 68 

6. The Evolution of Spiders 99 

7. The Tarantulas 107 

8. The Cribellate Spiders 137 

9. The Aerial Web Spinners 157 
7 The Hunting Spiders 193 

11. Economic and Medical Importance 236 

12. The North American Spider Fauna 255 

INDEX 273 


List of Illustrations 



1. Orb web covered with dew 2 

2. Orange Argiope, Argiope aurantia, in web 3 

3. Crab spider, Misumena calycina, dropping on dragline 16 

4. Spider Relatives 

a Solpugids of the family Eremobatidae 17 
b Scorpion, Hadmrus hirsutus, stinging tarantula, 

Aphonopelma . 17 

5. A humped orb weaver, Aranea gemmoides, on egg sac 32 

6. Black Widows 

a Black widow, Latrodectus mactans, in web 33 

b Black widow, Latrodectus mactans, ventral view 33 

7. Egg Sacs 

a Opened egg sac of orange Argiope, Argiope aurantia 48 

b Egg sac of shamrock orb weaver, Aranea trifolium 48 

8. Cluster of baby orb weavers, Aranea, preparing to disperse 49 

9. Crab spider, Misumenoides aleatonus, on flower 64 

10. Southern Spiders 

a Huntsman spider, Heteropoda venatoria 65 

b Silk spider, Nephila clavipes 65 

11. Black Widow, Latrodectus mactans, with prey 80 

12. Tarantulas 

a Tarantula, Aphonopelma, and tarantula hawk 81 

b Tarantula, Aphonopelma, and tarantula hawk 81 

13. Tarantulas 

a Portrait of a tarantula, Aphonopelma 94 

b Side view of a tarantula, Aphonopelma 94 

14. Orb Weavers 

a Banded Argiope, Argiope trifasciata, in web 95 
b Spiny-bodied spider, Gasteracantha cancriformis, on 

leaf 95 

15. Purse web of Atypus abboti against tree 1 10 

1 6. Burrow of Folding-Door Tarantula, Antrodiaetus 1 1 1 

a Door open 1 1 1 




b Door half open 1 1 1 

c Door closed 1 1 1 

17. Black widow, Latrodectus mactans, with egg sac 124 

1 8. Shamrock orb weaver, Aranea trifolium, on flower 125 

19. Banded Argiope, Argiope trifasciata, with swathed prey, 

dorsal view FIG. 4 

20. Banded Argiope, Argiope trifasciata, ventral view 139 

21. Orange Argiope, Argiope aurantia, in web, side view 154 

22. Spiny-bodied spider, Micrathena gracilis, spinning 155 

23. Orb Weavers 

a Shamrock orb weaver, Aranea trtfolium 170 

b The garden spider, Aranea diadema 170 

c Orb weaver, Neoscona 170 

d Orb weaver, Neoscona, on leaf 170 

24. Wolf spider, Geolycosa missouriensis, at mouth of burrow FIG. 5 

25. Wolf Spiders 

a Wolf spider, Geolycosa turricola, side view 182 

b Burrow of wolf spider, Geolycosa, in grass 182 

26. Grass spider, Agelenopsis, on egg sac 183 

27. Crab spider, Misumena calycina, on flower 198 

28. Crab spider, Xysticus gulosus, with prey 199 

29. Jumping spider, Phidippus mineatus, side view 214 

30. Jumping spider, Phidippus cardinalis, on flower 2 1 5 

31. Green lynx spider, Peucetia viridans, and nest 230 

32. Jumping spider, Phidippus, dorsal view 231 


I. Banded Argiope, Argiope trifasciata, swathing a 

grasshopper 20 

II. Orange Argiope, Argiope aurantia, with swathed 

prey 2 1 

III. Female bolas spider, Mastophora cornigera, with re- 
cently emerged brood, including some adult 
males 28 

A symmetrical orb web of a mountain orb weaver, 

Aranea aculeata 28 

Meshed web of Dictyna on dried weed 28 



IV. A Jumping Spider, Phidippus audax, and its Dragline 

a Preparing to leap 29 

b Leaping 29 

V. A Juvenile Jumping Spider, Phidippus, On A Thin 

Toothpick, Prepares To Fly 
a Orienting in response to breeze, secured by 

dragline 52 

b Ballooning threads stream from spinnerets 52 

VI. Courtship and Mating In The Black Widows, La- 

trodectus mactans 53 

a The cautious approach of the small male 53 

b The mating 53 

VII. Black Widows, Latrodectus mactans 

a The male after mating is occasionally, as here, 

killed and eaten by the female 60 

b A female in her tangled snare with long-legged 

spiders, P silo chorus 60 

VIII. Relatives of Spiders 

a A desert solpugid (Eremobates) 61 

b A giant-tailed whip scorpion, Matigoproctus 

giganteus 61 

IX. Spider Relatives: Harvestmen on aphis-covered rose 

shoots 84 

X. Trap-Door Spider, Bothriocyrtum calif ornicum 

a Molting. Carapace and chelicerae freed FIG. 2 

b Molting. The shed skin FIG. 2 

c Cradle of eggs in burrow FIG. 2 

XI. California Trap-Door Spider, Bothriocyrtum call- 


a Exposed burrow 90 

b Male 90 

c Cork-door nest held open 90 

XII. California Trap-Door Spider, Bothriocyrtum cali- 


a Capturing a ground beetle 91 

b Lifting the cork lid 91 

XIII. Female purse web spider, Atypus bicolor 114 

XIV. A Western Trap-Door Spider, Aptostichus, Dorsal 

View of Male FIG. 3 

A Mexican Trap-Door Spider, Eucteniza 



a Surprised in its burrow FIG. 3 

b Exposed burrow FIG. 3 

XV. Male Tarantula, Aphonopelma 

a Clambering over stone 120 

b Portrait 1 20 

XVI. Tarantula, Aphonopelma 

a Female on desert soil 1 2 1 

b Web-covered entrance to burrow 121 

c Female and egg sac in exposed burrow 1 2 1 

XVII. Tarantula, Aphonopelma, and Tarantula Hawk 

a The tarantula assumes a defensive attitude 142 

b The wasp inserts its sting 142 

c Pulling the bulky prey to prepared burrow 142 
XVIII. Silver Argiope, Argiope argentata 

a Female and pygmy male 143 

b-Egg sac 143 

Egg Sac of Orb Weavers 

a Banded Argiope, Argiope trifasciata 143 

b Humped orb weaver, Aranea gemmoides 143 

XIX. Long-Legged Cellar Spiders, Pholcus phalangioides 

a Male and female, with eggs, in tangled web 150 
b Female holding mass of recently hatched 

young 1 50 

XX. A Comb-Footed Spider, The Black Widow, La- 
trodectus mactans. Captures A Jerusalem 
a The spider approaches as the cricket touches 

the capture threads 151 

b Nooses of swathing film are combed over the 

leg 151 

XXI. A Comb-Footed Spider, The Black Widow, La- 
trodectus mactans, Captures A Jerusalem 

c Tiny fangs inject the venom 172 

d The bulky insect is lifted above the floor 172 

XXII. A female humped orb weaver, Aranea gemmoides % 

clinging to a plant 173 

A female humped orb weaver, Aranea gemmoides, 

hanging in the hub of her orb web 173 

A fisher spider, Pisaurina mira, with egg sac 173 



XXIII. Mud Dauber, Mud Nest and Spider Prey 180 
The Bolas Spider, Mastophora cornigera 

a Portrait 180 

b The pendent egg sac, opened to show young 1 80 

XXIV. Feather-foot spider, Uloborus americanus, with egg 

sac FIG. 6 

A symmetrical orb web of banded Argiope, Ar- 

giope trifasciata FIG. 6 

Female of tuberculate Cyclosa, Cyclosa turbinata, 

on egg string FIG. 6 

XXV. Wolf Spiders 

a A female Lycosa covered with young 202 

b Portrait of male, Pardosa milvina 202 

c Turret of burrow of Lycosa carolinensis 202 
XXVI. Wolf Spiders, Lycosa 

a With captured fly 203 

b With attached egg sac 203 
XXVII. The Green Lynx Spider, Peucetia viridans 

a Female and egg sac 210 

b Male . 210 

XXVIII. A Fisher Spider, Dolomedes scriptus 2 1 1 
Grass Spider, Agelenopsis. An immature male sits in 

its tunnel 2 1 1 

Web of a grass spider, Agelenopsis, blankets the soil 2 1 1 
XXIX. Hunting Spiders 

a A giant crab spider, Olios fasciculatus 246 

b A crab spider, Misumenoides aleatorius 246 
XXX. Hunting Spiders 

a Male and female running spiders, Trachelas, in 

silken cell 247 
b Running spider, Chirac anthium incluswn, with 

egg sac 247 

XXXI. Portrait of wandering spider, Cupiennius 262 

A wandering spider, Ctenus, with egg sac 262 

Portrait of jumping spider, Phidippus 262 

XXXII. Jumping Spiders 

a Phidippus formosus stalks a fly 263 

b Phidippus audax with bee fly 263 


Introducing Spiders 



of the United States and Canada and is concerned almost wholly 
with their habits and life histories, their morphology and peculiarities, 
and also with their numbers and kinds. Most of us know something 
about spiders, but few of us are aware of the vast numbers that 
exist and of the great diversity in appearance and habits of the spin- 
ning creatures. Yet even a limited acquaintance soon makes it evi- 
dent that spiders in many ways far outshine insects and lesser 
animals of much greater reputation. Thus it seems desirable that, 
at the very outset, a few of the striking peculiarities of the maligned 
spiders be enumerated. 

Insects have developed wings and on them have attained the most 
exalted place among the arthropods. Although a wingless creature 
of the earth and its plant cover, the spiderling can float its threads 
on the breezes and fly through the air, often reaching tremendous 
heights and sailing for long distances. This "ballooning" of spiders 
has been instrumental in distributing them into new colonizing areas 
at a rate not possible even for insects with their wings. The rigging 
of ships two hundred miles from the nearest land has been showered 
with tiny aeronauts riding on silken streamers. The spider can spin 
a line one-millionth of an inch in thickness, but most of its single 
lines are ten or twenty times as thick. This strand of silk is a line 
of great elasticity that will stretch one-fifth its length before break- 
ing, and of a tensile strength second only to fused quartz fibers. It 
is a line of such fineness that it is impossible to duplicate; it serves 
admirably as a marker in various surveying and laboratory instru- 
ments. An inveterate spinner during all of its life, the spider uses 
silk for so many different purposes that this material is the most 


important thing in its life, the factor that has largely determined 
its physical form and dominant place in nature. 

Almost alone among the lesser creatures the spider prepares a 
trap to capture its prey. By their structure these traps are identified 
as tube webs, purse webs, sheet webs, tangled webs, and orb webs. 
Sometimes they are complex structures of very curious form. 

The orb web (PI. I and PL III) has long been a symbol of the 
spider in the mind of man, who sees in its shimmering lightness and 
intricate, symmetrical design a thing of wonder and beauty. Such 
esteem is well merited, for the orb web is the most highly evolved 
of all the space webs developed by the sedentary spiders. It repre- 
sents a triumph in engineering worthy of great mechanical inge- 
nuity and learning; yet it was arrived at by lowly spiders, which 
even by their most ardent supporters are credited with hardly a 
gleam of what is called intelligence. The ingredients of almost un- 
limited time, of moderate compulsion to irresistible change, and the 
stimulus of real advantages gained have contrived to produce the 
two-dimensional orb web from the seemingly wasteful tangle of 
threads that is its origin. Instinctively and blindly the spider has 
followed the long path leading to its symmetrical masterpiece. The 
orb weavers are virtually slaves of their webs and have wagered 
their future on the tenuous lines. Within the limits of their circum- 
scribed world they are supreme autocrats, but when brushed from 
their snares, many are clumsy, vulnerable creatures. 

In accomplishing the purpose of entangling flying insects, the 
web has served the needs of the spider admirably and at remarkably 
small cost. Only about an hour is consumed in spinning the average 
orb web, which, because of great damage to the lines, frequently is 
replaced every suitable night by the methodical spider. Yet within 
the orb- weaving group there are some members that have broken so 
completely with the past that they do not spin orb webs at all but 
have substituted an entirely different method of securing their prey. 
Instead of relying on the static but dependable round web, they 
spin a line, weight the end with a sticky drop of liquid silk, and hurl 
it much as the gaucho throws his bolas or the angler casts his line. 
One need not travel to the exotic tropics to find these bolas spiders; 
they live over most of the United States and even within large 
cities, seeming to prefer the trees of our formal parks. Close rela- 
tives of the bolas spiders live in Australia and Africa; one of these 
African cousins varies the casting procedure by spinning its line 
around like a whirligig. 


Richard L. Cassell 

Orb web covered with dew 


Orange Argiope, Argiope aurantia, in web 


The female bolas spider (Pis. Ill and XXIII) is a plump creature, 
about one-half inch long and equally wide, which sits placidly on 
a twig, simulating with considerable faithfulness a bud, a nut, a 
snail, or even a bit of bird dung. What about her mate? He is an 
insignificant atom no larger than the head of an ordinary pin. Pre- 
cociously developed, he walks out of the egg sac fully mature, along 
with sisters his own size who are just beginning their life and must 
wait weeks and increase tremendously in size before they become 
sexually mature. 

Spiders and their relatives are ancient animals; they were among 
the first creatures to leave the waters for a life on land. Some mod- 
ern spiders seem to be only thinly masked replicas of creatures that 
were living in the northern hemisphere during the remote Paleozoic 
Era, when the coal measures were still in infancy. Although more 
generalized than the commoner true spiders, the tarantulas and their 
kin have become specialists in their own fashion, and have devised 
new and extraordinary ways of living in a world of competition. 
The purse-web spiders live in a long silken tube closed at both ends, 
and have developed long fangs with which they impale insects that 
walk over their cylinder by biting through it. The burrowing taran- 
tulas of the genus Antrodiaetus ensure privacy in their burrow home 
by pulling two flaps of silk, which fit like folding doors, over the 
entrance. The trap-door spiders are accomplished burrowers and 
cap the opening to their chamber with a hinged trap-door. One of 
the strangest trap-door spiders is Cyclocosmia, which has an ab- 
domen hardened and rounded behind to form a plug with which it 
at one time was reputed to close its burrow. 

Among the vagrant tarantulas are some that have become verita- 
ble giants far exceeding most insects in bulk and rivaling in size even 
the great black scorpions of Africa. Armed with long, strong fangs, 
they are able to kill with ease and feed on frogs, toads, and lizards, 
and also to subdue and eat rattlesnakes and other larger animals. 
Some of the arboreal tarantulas are known to kill small birds, and 
have gained one of their common names of "bird spiders" from this 
activity. Longer-lived than any terrestrial invertebrate are some of 
the great hairy tarantulas, which do not become sexually adult until 
eight or nine years old and are known to live thirty years. 

Among the true spiders are the diurnal jumping spiders; these 
actively pursue their prey over the ground and on plants. Special 
tufts of adhesive hairs on the tarsi allow them great freedom of 
movement on precipitous surfaces, and, aided by the keenest eye- 


sight of all spiders, they emulate the carnivores in stalking their 
prey. Their stout bodies and legs are gaily colored and bedecked 
with tufts of bright hairs, pendant scales, and curious spines. Gleam- 
ing with their iridescent scales like jewels in the sun, they rival the 
gaudiest insects. During courtship dances, the little males caper and 
posture before the females in such manner as to display their bril- 
liant ornaments to best advantage. 

In the petals of many kinds of flowers hide stubby little crab 
spiders which, simulating the assasin bugs, seize flying insects that 
visit the blossoms for nectar. In keeping with their role of decep- 
tion, they change from white to yellow, or vice versa, to conform 
with their background. 

All spiders breathe air through orifices on the ventral side of 
the abdomen. In spite of their air requirements, many have adopted 
an amphibious life and stay under water for periods of variable 
length. Some live in little waterproof chambers spun in holes in 
coral rock that are covered over during high tide. Most extraordi- 
nary of all is the water spider, Argyroneta of Eurasia, which is able 
to swim about and live for weeks in the fresh water of streams and 
ponds in a domicile that resembles a small diving bell. This spider 
carries air bubbles beneath the surface to its retreat, which is an- 
chored to aquatic plants by silk lines, and keeps a supply of air 
imprisoned in the silken chamber. Its prey consists of small aquatic 
animals, which it captures in the stream. Even the eggs are laid and 
the family hatched out under water in the security of the nest. 
Among American amphibious spiders are some of the fisher and 
wolf spiders, which run over the surface freely and dive into its 
depths where they stay for long periods. Occasionally small fish or 
amphibians are caught by the large fisher spiders of the genus Dolo- 

The sexual characteristics of spiders are especially interesting. 
In both sexes the genital opening is a simple pore beneath the base 
of the abdomen through which emerge the spermatozoa or eggs. 
One would expect that during mating the male products would be 
transferred directly to the female by contact between these orifices 
or by means of an eversible intromittent organ. Instead, the male 
spider has transformed the claws on the ends of the pedipalpi (the 
leglike appendages lying on each side of the head in both sexes), 
into a complicated intromittent organ, comparable to a syringe or 
a hypodermic needle, and has modified and greatly enlarged the 
distal segments of the pedipalp to protect the organ and facilitate 


the pairing. These organs of the male, called palpi, have no internal 
connection with the gonads of the abdomen, so the semen must be 
transferred from the genital orifice to the palpi. To accomplish this 
the male spins a little sperm web, deposits a small globule of semen 
upon it, and then sucks it into the syringe in each of the palpi. The 
female has developed in front of the genital pore paired pouches for 
the storage of the semen, each unit of which is shaped to receive 
the corresponding palpus of the male. 

Since spiders are solitary, predaceous creatures, the male runs 
considerable risk in approaching his usually much larger mate, who 
may be only hungry and not ready for mating. Some males are 
killed because of early failure to diagnose the attitude of the female, 
or, after being successful in their suit, of not leaving the premises 
before the normal predatory instincts of the female again dominate 
her. Various routines have been devised by different groups of 
spiders to gain the recognition of the female and make possible a 
transfer of the semen in relative safety. 

In the bodies of spiders are found clues that give considerable 
insight into the racial history of the group. From lumbering ground 
creatures have come fleet runners on soil and vegetation, and trapeze 
artists that hang in midair on silken lines. In the variety and strange- 
ness of their forms, spiders surpass all comparable invertebrate 
groups. In color pattern, ornamentation, and brilliance they are on 
a par with any of the insects. Indeed, the vaunted brilliance of the 
morpho butterflies and of the birds of paradise is excelled by the 
iridescent variety of the jumping spiders of the tropics. Only the 
small size of spiders conceals their beauty and keeps them largely 

Finally, it should be noted that spiders have attained their pres- 
ent position without benefit of so-called intelligence. Endowed 
with incredibly complicated instincts, the spinning creatures per- 
form their marvels largely as automatons, and show only moderate 
ability to break the bonds of their behavior patterns. The baby 
orb weaver spins a perfect orb web soon after it leaves the egg sac, 
and thereafter scarcely changes it, except in size, during its whole 
lifetime. The mother spider encloses her eggs in a sac which, often 
beautifully designed, advertises the species to which she belongs, 
and then defends her precious burden against any assailant. Instinct 
plays a large role in every action of the spider and is the guiding 
principle throughout its life. 



Spiders are seen in different lights by different peoples. Primitive 
men regard some spiders as bad, others as good, and most as having 
little importance or significance in their lives. To those that become 
important because of venomous or presumed dangerous character, 
they give special names. The chintatlahua of the Oaxaca Indians, 
the po-ko-moo of the Mewan tribe of California, and the katipo of 
the Maoris, all refer to similar spiders of the genus Latrodectus, 
which have long been notorious over much of the temperate and 
tropical world. Each people has a distinctive name for the brightly 
marked spiders known as "black widows." In addition, species re- 
sembling the virulent ones are regarded with suspicion and often 
endowed with the same venomous powers. This is a practical ap- 
proach, learned by trial and error, and tested in time by peoples 
who have close contact with the lesser creatures about them. There- 
fore it is not surprising that the beliefs of primitive peoples often 
have a firm foundation in fact. 

In the second category are some spiders that are good because 
their presence at certain hours, on specific occasions, in particular 
places, constitutes a good omen. A few are eaten with keen relish. 
Others are seen as wonderful creatures that produce marvelous 
webs overnight and have magical powers. 

To the American Indians the spider is a creature of mystery and 
power, which, though capable of trickery, duplicity, and even great 
evil, plays a benevolent and often potent role in many of their le- 
gends. The prowess of spiders in this folklore is based largely on 
their great skill as spinners, and to a lesser extent on the deadliness 
of their bite. To the Dakotah the orb web is a symbol of the 
heavens; the corners of the foundation lines point in the four direc- 
tions from which come the thunders, while from the spirals of the 
orb emanate the mystery and power of the Great Spirit. In Indian 
legend spiders are venerated for spinning silken lines of great 
strength on which some unfortunate is able to escape from des- 
truction. A youth, betrayed into sleep by the seduction of a woman, 
awakes on a precipitous cliff but lowers himself to safety on a line 
furnished by a spider friend. This same silken cord may also be a 
rope to the sky on which the dead mount to the new hunting 
ground, or the brave climb to wreak vengeance on the sky people. 
But more often it is a line from the sky to the earth on which the 


pursued can descend; it is on such a "sky rope" that the Algonkin 
maiden, fallen from grace as wife of the Morning Star, is sent back 
to earth. 

In many interesting myths of the Pueblos the main role in the 
Creation is assigned to the spider. According to the Sia Indians, in 
the beginning there was only one personage, a spider, living in a 
world sterile of life and lacking many material things. From each 
of two little packages possessed by the spider was conjured, in re- 
sponse to its magical singing, a woman. From the first woman thus 
created have descended all the Indians, and from the second all the 
other races of men. 

Some of the virtues attributed to spiders are industry, patience, 
and persistence. Well known is the legend of Robert Bruce who 
gained new courage by watching a spider finally reach its cobweb 
home after many unsuccessful attempts. In a delightful Cherokee 
myth the little spider appears as a successful agent when all other 
animals fail. In the beginning the world was cold. Then fire ap- 
peared on the earth, having been placed in a hollow tree on an 
island by thunder and lightning. The shivering animals gazed across 
the waters and resolved to secure the warmth of the fire for their 
own purposes. After consultation, the raven was dispatched to 
secure the bright embers, but was unsuccessful and soon returned 
with blackened feathers, which it wears to this day. One by one 
the birds, snakes, and other animals risked a trial, but all brought 
back only scars from the fiery furnace in the tree. Finally, the 
spider alone was left to brave the waters. She prepared herself by 
spinning a little tusti-bovsl of her silk, which was then fastened to 
her back. Skating across the surface of the water, she crept through 
the grasses to the site of the fire, caught a little ember in the tusti- 
bowl, and delivered the priceless jewel to the waiting animals. This 
successful venture is usually attributed to one of the amphibious 
wolf spiders, which drags its egg sac behind it, attached to the 

A legend of great antiquity is that of the Spider Woman of the 
American Southwest, who is credited with being the inventor of 
weaving and the teacher of all textile art to the various Indian tribes. 
She is an earth goddess and usually lives in a burrow deep in the 
soil with the Spider Man, her husband. According to Navajo legend, 
the art of blanket- and basket-weaving was brought to them by an 
unhappy Pueblo girl from Blue House, near Pueblo Bonito, who 
came to the hogans of the Navajos to earn her living. One day the 


girl wandered far from the hogan and, attracted by a thin wisp of 
smoke, discovered a small hole in the earth at the bottom of which 
was an old woman spinning a web. It was the Spider Woman, who 
quickly invited the girl to enter her house and blew up the hole 
until it was large enough to accommodate her guest. Befriended by 
the kindly Spider Woman, the girl stayed several days and learned 
to weave the blankets and baskets that now distinguish the Navajo. 
The Pueblo girl then transmitted this weaving art to her adopted 
people, and along with it an admonition from the Spider Woman 
that to forestall bad luck a hole must be left in the middle of each 
article. In compliance with this request, the Navajo women left a 
spider hole in the middle of each blanket, like the entrance to the 
burrow of the Spider Woman. Even to this day the spider hole 
may still be found in the blankets and baskets of the Navajo. Its 
position and form are greatly changed and masked in deference to 
the wishes of persons who pay a better price for flawless examples. 
Needless to say, it is always present in the blankets of the old 
women, who do not care to risk the anger of the mythical Spider 
Woman and the threat she made to spin silken threads in their 

In a number of legends, spiders are placed in an unfavorable 
light and are pictured as villains and murderers. Thus the Win- 
nebagos tell of the eight blind men who snared and killed people 
with long cords strung among the trees. Wash-Ching-Geka, the 
Little Hare, went among the evil creatures, incited them to quarrel- 
ing, and then poisoned the meat they were cooking. They ate of 
the meat and were soon dead, whereupon Wash-Ching-Geka dis- 
covered that they were in reality spiders. 

The duplicity of the spider is dwelt upon in the rhyme of the 
Spider and the Fly, and that theme also occurs in the Indian legends. 
Here the spider is often a rascal and excels as a trickster. The Zuni 
tell a very pleasing story of how "old tarantula" dupes a handsomely 
dressed youth and finally absconds with his prizes. The youth is 
persuaded to allow "old tarantula" to don his fine clothes so that 
he can appreciate how handsome he appears in the eyes of others. 

"Look at me now. How do I look?" asks the spider as he dis- 
plays the garments. The youth, finding the ugliness of the 
wearer somewhat detrimental to the appearance of the clothes, 
is not greatly impressed. The spider moves off a bit, and as dis- 
tance lends enchantment, or at least makes repulsiveness less 


obtrusive, the youth notes an improvement. Still a little farther 
off moves the spider, pretending that his only object is to gain 
the youth's approbation, but really intent on getting nearer and 
nearer to his burrow. At last he arrives at the entrance. "How 
do I look now?" asks the wily creature. "Perfectly handsome," 
replies the youth; but as he speaks the spider dives into the earth 
with the stolen finery. 1 

Many curious beliefs are current in various parts of the United 
States regarding spiders, and often they are contradictory. It is 
rather generally believed that killing a spider or a daddy-long-legs 
will bring rain, and that many cobwebs on the grass in the morning 
foretell clear weather. The color of a spider is frequently of much 
significance in these superstitions. Black ones are almost invariably 
bad, just as white ones almost certainly signify good luck, but oc- 
casionally the colors are reversed and assume the opposite attribute. 
Although in some cases they are thought to be unlucky, the appear- 
ance of spiders is usually supposed to signify good luck, bringing 
to the observer new clothes, gifts, money, or visitors. 

Spiders have gained notoriety by smaller effort than any other 
animals. The bad reputation of a few species has been magnified 
beyond reason and is now attached to all of them. There is a gen- 
eral belief throughout the United States, and probably over much 
of Europe, that the bite of any spider is poisonous. Public opinion 
has been influenced by tall stories from far places, by sensationalism 
in the newspapers, and by the natural prejudices of housewives who 
can be forgiven for wanting their rooms completely free of all 
crawling creatures. Spiders are for the most part small, and, because 
of their nocturnal habits, rarely intrude upon our notice. Much of 
the general aversion for them can be traced to teachings from par- 
ents and grandparents who early instill the young child with mis- 
information. The popular prejudice, which even finds expression in 
nursery rhymes, often amounts to a phobia. The squeamishness of 
grown men who "can't stand" spiders of whatever size contrasts 
most unfavorably with the nonchalance of small Indian boys who 
keep pet tarantulas on a string. 

A frank dislike of spiders because of their predaceous habits 
would put the whole business on a rational basis. The spectacle of 
insects being pounced upon, trussed up, crushed, and sucked dry is 

1 H. F. Schwarz, "Spider Myths of the American Indian," Natural History, 
Journal of the American Museum of Natural History, Vol. 21 (1921), pp. 382-5. 


one that prejudices us in favor of the underdog. But we have little 
dislike for other creatures, such as the ladybugs, which are quite 
as voracious. It is doubtful that people give sufficient heed to 
spiders to be affected by their rapacious methods; they are labeled 
nasty, crawly creatures in a completely irrational manner. 


The Place of Spiders 
in Nature 




comprising the phylum Arthropoda includes such familiar creatures 
as the crabs and lobsters, centipedes, millipedes, and insects, as well 
as the spiders and their multitudinous kin. Indeed, three fourths of 
the known animals of the world are arthropods and attest by their 
numbers, their variety, and their occupancy of every conceivable 
place in nature a degree of success not even closely approached by 
any other group of animals. Present in numbers conservatively esti- 
mated as beyond a million different species, they make up in vast 
populations what they concede to the vertebrates in size. Most of 
them are small, and because seven out of every ten kinds are insects, 
the average size is perhaps as small as a quarter of an inch. Indeed, 
it is perhaps to this small size, and to superior armament in the form 
of a tough but light external covering, that they owe their domi- 
nance in the world. 

The arthropods have their bodies encased in a stiffened outer 
covering, or exoskeleton, and completely lack the type of internal 
skeleton present in the vertebrates. The integument is made imper- 
meable to liquids and gases and kept hard and tough by the presence 
of amber-colored substances called sclerotin and chitin. Between 
the body segments and the joints of the appendages the cuticle is 
not so strongly impregnated with sclerotin and remains soft and 
pliable, allowing movement of the legs and other articulated seg- 
ments of the body. The problem of growth in size has been solved 
in the arthropods by their shedding the rigid outer skeleton at 
rather definite intervals, a process called molting. All the increase 



in size of the carapace and appendages, and often of the abdomen 
as well, must take place immediately following molting when the 
integument is still soft. 

One characteristic of all the arthropods is the fact that their 
bodies are divided transversely into numerous well-marked rings or 
segments (in some cases most indications of segmentation are lost). 
The segments in front, which go to form the guiding center of the 
animal, are usually dissimilar and so greatly modified and fused that 
their exact limits are obscured. Thus, the head in one group is not 
necessarily the same as the head in another; it may be composed of 
more segments or carry more appendages, and the appendages of 
the same segment may be vastly different. From primitive append- 
ages have been derived mouth parts, swimmerets, legs, spinnerets, 
antennae, and many other organs. They are used for feeding, swim- 
ming, running, silk-spinning, mating, and for sensory perception. 
The hind portion of the animal, which is called the abdomen, is like- 
wise not the same in all the arthropods. In the centipedes and milli- 
pedes it is a multisegmented trunk, provided with numerous jointed 
legs, in some instances nearly two hundred pairs. In the insects the 
abdomen completely lacks appendages except at the caudal end. In 
spiders the only abdominal appendages are the spinnerets. 

With such marked difference in the external form of the Arthro- 
poda as compared with vertebrates, it is not surprising that the 
internal anatomy should also be quite distinct. The various systems 
for carrying on living, such as those for digestion, respiration, excre- 
tion, and reproduction, show marked differences. 

In the horseshoe crabs and most of the crustaceans, the respira- 
tory organs are external gills, which aerate the blood by absorbing 
through their delicate walls the oxygen and other gases dissolved 
in the water. Whereas most of the other arthropods long ago aban- 
doned an aquatic life, some individualists among the insects have 
secondarily returned to its security during parts of their life, but 
not before they devised new means of living. Respiration in the 
land arthropods is effected by means of internal aerating chambers 
called book lungs and tracheae, or, less frequently, by breathing 
directly through a soft outer covering. The book lungs of the 
arachnids are closely packed sheets of body surface bound together 
like the leaves of a book, to give the maximum surface for aeration. 
The tracheae in the arachnids are small tubes that lead into the 
body and sometimes ramify to form complex systems. In the myri- 
apods and insects, the air is conducted directly to the tissues by 


means of tracheae which, however, are dissimilar to those of the 
arachnids and develop in a different way. Although simple diffu- 
sion through the skin or into the body by means of the tracheae 
often is sufficient in small, inactive arthropods, in large and more 
active forms some sort of breathing takes place, usually through 
rhythmical movements of parts of the body by special muscles of 
the abdomen. 

The type of circulatory system in the arthropods is a specialized 
one, seemingly highly efficient within the size limits of these crea- 
tures. Instead of closed tubes that carry the blood to every part 
of the body and ramify in great profusion to reach all the tissues, 
the system is at least in part an "open" one. The place of the veins 
is taken by expansive channels, or sinuses, filled with blood, in which 
the organs and tissues are bathed. In a large pericardial sinus lies 
the heart, which expands to allow the blood to enter the pumping 
vessel through paired lateral openings, and contracts to send the 
blood coursing through the arteries to all parts of the body. The 
blood is ordinarily a clear liquid in which are suspended numerous 
pale blood cells. A disadvantage of having the internal organs 
bathed in blood is the seriousness of accidental rupture of the outer 
covering. Any breaking of the body wall might prove fatal to the 
creature, since the blood would quickly drain from the body, but 
the tough exoskeleton guards against this. Injury to an appendage 
could also be fatal, but in many arthropods the injured member is 
removed by breaking it off (a process called autotomy) at a point 
where healing is rapidly accomplished. 

The digestive system is a tube that extends from one end of the 
body to the other, and is often subjected to various types of elabora- 
tion by coiling and compounding to increase the amount of absorp- 
tive surface. In the spiders and their relatives, this is accomplished 
by extending arms in many directions from the main tube. A con- 
siderable diversity exists among the arthropods as regards the de- 
tails of the digestive system, but all are alike in having a foregut 
and hindgut derived from the infolding ectoderm, and an expansive 
midgut, in which absorption is accomplished by means of the en- 
zyme-producing epithelium. 

The foregut in spiders is modified to pull in the liquid food. It 
consists of a pharynx into which the small mouth opens, an esopha- 
gus, and a so-called sucking stomach. The former are rather simple 
tubes, but the sucking stomach is an enlargement behind the esopha- 
gus supplied with powerful muscles on its four sides. When these 


contract, they increase the size of the stomach and there results a 
strong sucking action that pulls the predigested food into the mid- 
gut. All the absorption occurs in the midgut, which is notable for 
a series of large blind sacs in the cephalothorax extending as four 
thick arms on each side, and voluminous glandular extensions from 
the main digestive tube in the abdomen. The hindgut provides a 
channel of egress for the fecal material, a thick, whitish liquid that 
is accumulated in a large bladderlike sac called the stercoral pocket, 
and voided through the anus. 

In addition to the tubular Malpighian vessels opening into the 
hindgut, which serve as excretory organs, spiders have a pair of 
coxal glands located opposite the coxae of the first and third legs, 
and these discharge their products through tiny openings behind 
the coxae. It is believed that the coxal glands are modified nephridia, 
the primitive excretory organs of earthworms and other animals, 
and that from similar glands in other parts of the animal have de- 
veloped the various silk glands and perhaps the poison glands as well. 

The activities of the arthropods are governed by a nervous 
system quite different from that found in the vertebrates. In the 
simpler forms it consists of a double nerve cord lying below the 
alimentary tract, which is enlarged in each segment to form a center 
or ganglion, from which lesser nerves arise. The most anterior pair 
of ganglia lie above the pharynx, and, joined to the pair immediately 
behind and below the pharynx by nerve connections, is called the 
brain. A very considerable modification of this generalized condi- 
tion is to be seen in most of the spiders, which have contained 
within the cephalothorax all the central nervous system. The 
ganglia in the cephalothorax have been consolidated into a single 
mass around the esophagus and below the digestive system. From 
the dorsal brain arise the nerves for the eyes and the chelicerae, and 
from the lower mass large nerves go to the appendages and back 
into the abdomen through the narrow pedicel. 

Sensation from the external environment is communicated to the 
central nervous system by means of structures called receptors. 
The most obvious ones are the eyes, which are remarkable organs 
in some insects but by comparison very feebly developed in spiders. 
Also very poorly represented in the arachnids are receptors for 
chemical stimuli, such as smell and taste, and perhaps the former 
sensation, as it is understood in vertebrates, is not even present in 
spiders. The receptors for touch are numerous and varied in the 


Arachnida, and it is through their stimulation that these animals 
are best able to know their environment. 


The spiders and spiderlike animals belong to the class Arachnida, 
one of the major divisions of the Arthropoda. They differ at sight 
from most other arthropods in completely lacking visible antennae, 
the sensory appendages on the heads often appropriately called 
"feelers." Although frequently confused with insects because of 
similar size and general superficial appearance, the arachnids are 
not close relatives of these creatures, which have only three pairs 
of legs and have developed wings. All adult arachnids have four 
pairs of legs, except in rare instances, and they never have wings. 

Important and interesting in their own right are the arachnid 
relatives of spiders, such as the scorpions, harvestmen, and mites, 
which in this book can be mentioned only briefly in passing. Some 
were among the first animals to crawl out upon the land and adjust 
themselves to a terrestrial existence. And, rinding the land a most 
suitable zone for their development, almost none have returned to 
the water to live even part of their lives, as have many insects. A 
few of the mites have invaded both fresh and salt water, where they 
largely live parasitically on the bodies of aquatic animals. 

Each of the major groups, or orders, of the Arachnida has de- 
veloped a distinctive form, and the various types are quite familiar 
to most people. The members of the following four orders have 
the abdomen broadly joined to the cephalothorax by a thick waist: 

Order Scorpiones the Scorpions 

Order Pseudoscorpiones the Pseudoscorpions 

Order Opiliones the Harvestmen 

Order Acari the Mites 

The remaining orders of the Arachnida have the abdomen narrowed 
and attenuated in front to join the cephalothorax by a narrow 

Order Solpugida the Solpugids 
Order Ricinulei the Ricinuleids 
Order Pedipalpi the Whip Scorpions 
Order Palpigradi the Micro- Whip Scorpions 
Order Araneae the Spiders 


Every one of these living orders of arachnids occurs within 
the limits of the United States. A few interesting peculiarities of 
each should be noted. 

Scorpions. The scorpions are the most primitive members of 
the land arachnids, and also the oldest, being known from Silurian 
fossils that have an age of about four hundred million years. Among 
the oldest is a species from fossil beds at Waterville, New York, 
which was named Proscorpio osborni, and which was perhaps the 
first animal to adjust itself to a land life in North America. This 
ancient creature had no tarsal claws, and perhaps had not completely 
divested itself of the external gills that characterize the related, 
extinct eurypterids. 

The most obvious characteristic of the scorpion (Plate 4) is 
the invariable presence of a poisonous sting on the end of the ab- 
domen, which is narrowed to form an elongate tail. In life, the tail 
is curved over the back, and the spinelike sting is directed forward, 
always in position to attack its prey. The sting is generally used in 
conjunction with the great pedipalpi, which are developed as pin- 
cers to grasp and hold the victim. The venom of most scorpions 
is capable of causing mild to severe local reactions. A few species 
are known to cause pronounced neurotoxic reaction in man and 
warm-blooded animals. Two species of Centruroides occur in Ari- 
zona and are more notorious than the black widow for the virulent 
nature of their sting, which often is serious or fatal in children. 

Scorpions produce living young that mount the back of the 
mother and stay there until after their first molt, usually for a week 
or more. During this time they do not feed, but rely for sustenance 
upon the food stored in their bodies. The story that these little 
creatures, weakly armed with tiny chelicerae, feed upon the body 
juices of the mother, is a figment of some fertile imagination. An- 
other fable is the belief that scorpions commit suicide by stinging 
themselves when they are helplessly cornered or surrounded by a 
ring of fire. 

Pseudoscorpions. The pseudoscorpions are so named because of 
their superficial resemblance to true scorpions. They have the same 
enlarged pedipalpi terminating in pinching chelae, but the seg- 
mented abdomen is broadly rounded behind and is without trace 
of whip or tail. The largest species are scarcely more than one 
fourth inch in length, and most of the others are much smaller. 


Walker Van Riper, Colorado Museum of Natural History 

Crab spider, Misumena calycina, dropping on dragline 

> > 

a. Solpugids of the family Eremobatidae 


Richard L. Cassell 

rtr^fc -T,r ** 

* * W*fc,j| 


A 4 


Richard L. Cassell 

b. Scorpion, Hadrurus hirsulus, stinging tarantula, Aphonopelma 


They live under stones, in moss, leaves, or debris on the ground, 
under the bark of trees, in the nests of bees, ants, and termites, and 
often in the dwellings of man. Many are found only in caves. One 
of the better-known species, the large, cosmopolitan Chelifer can- 
croides, lives in houses and shelters of man all over the world. 

The food of pseudoscorpions is believed to consist of mites, 
psocids, springtails, and other tiny insects, which are grasped with 
strong claws and perhaps anesthetized by venom from tiny glands 
in the chelicerae. Along with the spiders and some of the mites, 
the pseudoscorpions share the ability to produce a kind of silk. It 
comes from glands that are probably homologous with those that 
in spiders produce the venom to subdue prey. During periods when 
they are relatively helpless, such as when the female is distended 
with eggs, or when molting, they spin silk copiously and enclose 
themselves in wonderfully constructed nests or retreats. As is true 
of most arachnids, the pseudoscorpions have very poor vision, and 
frequently eyes are lacking altogether. The numerous sensory hairs 
on the pedipalpi and on other parts of the body take the place 
of eyes. 

The pseudoscorpions frequently attach themselves to the bodies 
of such insects as flies and bettles, and are thus transported quickly 
from one locality to another. 

Harvestmen. Familiar to most people because of the great length 
and thinness of their legs, the harvestmen, or daddy-long-legs, 
scarcely need introduction. Though often confused with spiders, 
to which they have a certain resemblance, they can always be dis- 
tinguished from their spinning relatives by the body, which has the 
cephalothorax and abdomen broadly joined to form a single unit. 
In this respect they are similar to the mites but differ from them in 
having the abdominal portion with well-marked segments. 

Most of the harvestmen (Plate IX) found in the temperate zone 
are active creatures that run rapidly on stilt-like legs, which they 
shed readily when in danger of being caught. They often congre- 
gate in considerable numbers on vegetation or on the trunks of 
trees, and are especially noticeable during the harvesting season, a 
fact that has inspired the common name. The harvestmen seem to 
feed largely on dead insects, but are also known to kill small ones 
for food, and to suck juices from various soft fruits and vegetables. 

The long-legged harvestmen are partially replaced in the warmer 
parts of the United States and in the tropics by shorter-legged spe~ 


cies, which tend to be less active and frequently are quite sluggish. 
Many of these are bizarre animals that have beautifull sculptured 
bodies, often set with strangely shaped spines, and short legs, fre- 
quently armed with spines and processes. Many of them occur in 
caves in our southern states, where they have developed some un- 
usual types. 

Mites. Mites far surpass the other arachnids in numbers and 
economic importance. Most are minute reddish creatures with un- 
segmented, ovoid bodies fused into a single piece. The tiniest mites 
are wormlike and suck plant juices, thereby causing galls, spots, and 
blemishes on the foliage of trees and plants. Other pygmies live in 
the tracheal tubes of bees and in the hair follicles of mammals, in- 
cluding man. Some of the most gaily colored species have taken 
to living in water and swim with the aid of long hairs on their legs. 
The free living forms abound in detritus, where they prey on tiny 
animals or eat decaying animals or vegetable matter. About half 
the mites are parasitic and live on the bodies of animals all or a part 
of their lives. 

Mites hatch from eggs as six-legged "larvae," an unusual physi- 
cal phase for which we still have no adequate explanation. After a 
period of feeding, the larvae change into eight-legged nymphs, which 
undergo one or more nymphal stages before becoming the sexually 
mature adults. 

Most pestiferous of all are the larvae of the harvest mites, known 
to Americans as redbugs and chiggers, which attach to the skin and 
cause violent itching and irritation. Some redbugs transmit Rickett- 
sial organisms, which cause tsutsugamushi disease, or scrub typhus, 
which is frequently fatal to man. The nymphs and adults of the 
redbugs are innocuous creatures content to live on vegetable matter. 

Largest of all the mites are the ticks, whose leathery bodies are 
capable of becoming greatly distended with blood, to nearly an 
inch long in some females. Following engorgement, which is ac- 
complished by forcing the beaklike mouth parts deep into the skin 
of the host, the mature females fall to the ground and lay several 
thousands of eggs. From them hatch six-legged larvae, called "seed 
ticks," which climb on the body of a new host when opportunity 
arrives. Some ticks use the same host during all their feeding, but 
others require two or even three different kinds of hosts in order 
to complete their life cycle. Many ticks attack man and are a great 
source of annoyance because of their irritating bite. Among tick- 


borne diseases are Texas Fever of cattle and Rocky Mountain 
Spotted Fever, a serious illness of man. 

Solpugids. The curious arachnids know as solpugids (Plate 4 
and Plate VIII) are commonly encountered in the American South- 
west, as well as in some of the northern states in the West. The 
outstanding characteristic of these creatures is the great size of their 
chelicerae, which are proportionately larger than in any of their 
relatives. While feeding on their insect prey, they work the cheli- 
cerae with a sawing motion, holding fast with one while they drive 
the other in deeper. It is believed that they take only liquid food 
from their prey and cannot eat pieces of any size. 

Most species live in arid regions, where they hide under stones 
and debris, and come out at night to do their hunting. They are 
swift creatures and for that reason have been called "wind scor- 
pions" in the Near East and in Africa, where a great many large 
species abound. Most American species are about an inch long, but 
two or three are nearly double that size; with their long legs clothed 
with reddish hairs, they have a formidable appearance. But, since 
they possess no poison glands and cannot effectively use their tre- 
mendous chelicerae on large objects, they need not be feared by 

Ricinuleids. The curious, enigmatic arachnids of this group are 
the rarest of all arthropods. They resemble ticks superficially in 
general appearance, and further simulate the sluggish, deliberate 
movements of the latter. The ricinuleids possess various peculiarities 
of structure that set them apart from all other living arachnids, and 
represent a group that was probably far more abundant in Car- 
boniferous times than they are today. No true eyes are present in 
the ricinuleids, but vague, pale spots on each side of the carapace 
may well represent vestigial eyes. Appended to the frontal edge 
of the carapace is a hood, the cucullus, which fits down tightly over 
the chelicerae. The cephalothorax is narrowly joined to the abdomen 
by a pedicel, but this is hidden from view by expansions of the 
base of the abdomen, which fits very closely with the cephalothorax, 
the juncture forming a coupling device. The living animal is able 
to disengage the carapace from the abdomen so that the genital 
orifice is exposed, and this action is necessary during egg-laying and 
mating. In the males, the third leg is provided with a complicated 
copulatory apparatus. It is presumed by analogy that the apparatus 


aids in the transfer of the spermatophore to the female during 
mating. However, the exact use of this unique structure has never 
been observed. 

A single species of this curious rare group is known from 
southern Texas. A few other species occur in tropical America 
and in Africa, but the appearance of even a single example of this 
order is an event. 

Whip Scorpions. The whip scorpions resemble the true scorpions 
in a general way, but are readily distinguished by the absence of a 
caudal sting and by important differences in the other appendages. 
The pedipalpi are enlarged into formidable grasping organs, which 
bear, along their inner edges, numerous teeth or sharp spines that 
aid in crushing prey. The long, slender first pair of legs is special- 
ized as organs of touch. 

The tailed whip scorpions have a slender, jointed, whiplike tail, 
which is responsible for their common name. In this group the 
carapace is longer than it is broad, the pedipalpi are very stout, and 
the first pair of legs is of only moderate length. Essentially noc- 
turnal in habit, these creatures spend the day in crevices in trees or 
under objects on the ground, and are active burro wers into sand 
and debris. Although greatly feared by uninformed peoples, the 
whip scorpions are without poison glands and incapable of causing 
more than slight mechanical injury with their clumsy, raptorial 
pedipalps. At least some of them are known to emit an odor re- 
sembling' acetic acid from glands located in the base of the tail, a 
fact that finds expression in the name of "vinegaroon" given by 
some Americans to Mastigoproctus giganteus (Plate VIII), the giant 
whip scorpion, which often measures three inches long. 

The tailless whip scorpions are flattened creatures, which again 
have the carapace longer than broad, but are without any trace of 
a tail. The first pair of legs is modified into very long, lashlike 
whips, the tips of which are flexible. These animals live in dark, 
sheltered places, such as fissures in the rocks and under the bark 
of trees. They frequently occur in great numbers in caves, and 
many of them enter houses. They run with great speed when 
disturbed. Two or three species occur in the southern part of the 
United States. 

Micro-Whip Scorpions. As their common name suggests, these 
tiny arachnids resemble the tailed whip scorpions, but they are far 


Walker. Van Riper 

Banded Argiope, Argiope trifasciata, swathing a grasshopper 

Orange Argiope, Argiope aurantia, with swathed prey 


more generalized in thek structure. The largest examples so far 
discovered are only about one tenth of an inch long, and half of 
this length is made up of the slender tail. The micro-whip scorpions 
have no eyes, and their mouth parts are extremely simple. All ap- 
pendages are leglike and none have become specialized for grasping, 
cutting the prey, or otherwise aiding in feeding. 

These minute arachnids are found in Texas and California and 
in warm areas in other parts of the world. They live under stones 
and probably feed on tiny insects. 


To understand more fully the accomplishments and limitations 
of spiders, it is essential to have a brief resume of their most obvious 
physical features (Text Fig. i). In common with most Arachnida, 
they have the body divided into two principal regions, the cephalo- 
thorax and the abdomen, and each of the sections is provided with 
certain types of appendages. In spiders the division between these 
two units is a very narrow pedicel; whereas in such relatives as the 
scorpions, ticks, and mites the waist is thick. From the several nar- 
row-waisted arachnids the spiders are immediately differentiated by 
their possession of ventral spinning organs, or spinnerets, on an ab- 
domen that is completely unsegmented, except in rare instances. 
Furthermore, it can be noted that the males of all spiders have a 
complicated copulatory organ on the end of the pedipalp, a structure 
never found in this position in the other arachnids. 

Cephalothorax. As the name implies, the cephalothorax repre- 
sents those segments commonly called head and thorax, but they are 
intimately fused into a single piece. It must be remembered that 
several distinct segments have formed this region; their number is 
indicated by the number of pairs of appendages (in spiders only 
six) and sometimes by vague indications. The dorsal part of the 
cephalothorax is provided with a hardened shield or carapace, ordi- 
narily convex and bearing the eyes at the front end. The head 
portion is usually more elevated, and may be strongly marked off 
by a V-shaped groove. On the rounded, flatter thoracic portion are 
usually evident a median groove and radiating depressions that mark 
the internal attachments of the muscles of the stomach and of 
the legs. 


The cephalothorax is subject to considerable variation in shape 
and armature. In long spiders it is usually long, and in short species 
may be wider than its length. Various spines, humps, and promi- 
nences of many kinds often surmount it; frequently some of the 
eyes sit on weirdly designed elevations. In the dwarf spiders the 
carapace of certain males is grotesquely formed, and has deep pits 
into which the chelicerae of the females are fitted during copula- 
tion. In most instances the reason for the presence of such special- 
ized innovations is not clear. 

On the front of the head are the eyes, which are simple and 
resemble the ocelli of insects. Most spiders have eight eyes, appar- 
ently the original number, but various lines have lost some, so that 
there are in existence six-eyed, four-eyed, and two-eyed spiders. 
In one tiny spider from the jungle floor of Panama only a single 
median eye is present, probably representing the fusion of one pair. 
Some of the cave spiders and others that live in dark situations have 
completely lost their eyes, or retain only vestiges. The size and 
position of the eyes vary considerably. Some of the hunting spiders 
have large eyes and relatively keen vision, this being one of the 
necessities for their foraging activities. In many, a tapetum, which 
causes the eyes to shine in the dark when struck by light rays, con- 
tributes to the efficiency of this night vision. Most spiders, how- 
ever, are shortsighted animals that rely on their sense of touch, 
which they have sharpened at the expense of their eyes. 

Immediately below the carapace on the ventral surface of the 
cephalothorax is a median plate, frequently heart-shaped, called the 
sternum. In front of it is the much smaller lower lip, or labium, 
which forms the floor of the mouth. Around each side of the 
sternum are the coxae of the legs and the pedipalpi, which fit snugly 
against the sternum and lie in the space between it and the carapace. 
The coxa of the pedipalp in most spiders is fitted with an enlarged, 
sharp plate, the maxilla or endite, which aids in the breaking of 
the prey. 

Directly beneath the cephalothorax at the front end are located 
the two chelicerae, or jaws, which are the offensive weapons of the 
spider. It is believed that the chelicerae are derived from the same 
pair of primitive appendages that became the second antennae in 
the crustaceans, and this fact illustrates the quite distinct use to 
which the same generalized appendages are put by a different crea- 
tures. Each chelicera is composed of two segments, a basal one, 
which is stout and ordinarily margined by a toothed groove at the 


distal end, and a shorter, movable fang, which lies in the groove 
when at rest. The sharp fang is the part that is thrust into the prey. 
Near its end is a tiny opening through which venom flows into the 
wound. The poison glands, present in all but two small groups of 
spiders, are associated with the chelicerae, sometimes being entirely 
contained within the basal segment, but in most true spiders extend- 
ing farther back into the head as more or less voluminous pouches. 

All spiders are predaceous, subsist on the body juices of living 
animals, and only rarely can be duped to accept dead food. The 
bulk of their food is made up of insects, which are subdued by 
their venom. Their method of feeding is a most unusual one. The 
sharp edges of the maxillae and the chelicerae are used to crush and 
break the fresh body of the prey, which at the same time is bathed 
with quantities of digestive fluid from the maxillary glands. The 
softer parts of the animal are broken down and predigested to a 
liquid state, and this liquid is sucked into the stomach by means of 
powerful muscles. As the prey is rolled and chewed, it gradually 
becomes smaller and smaller until only a little ball of indigestible 
matter remains. This is finally cast aside, or, in some instances, is 
hung up on the egg sac or in some section of the web, a trophy 
of the chase. In some hard-bodied insects the juices are sucked 
through holes made by the chelicerae, and the shell of the drained 
insect is then discarded. Some spiders require several hours of nearly 
continuous effort to digest completely an ordinary fly. It is doubt- 
ful that spiders ever actually imbibe solid food material through the 
small mouth, and probable that even small snakes, birds, and mam- 
mal prey are first reduced by the powerful digestive juices. 

The remaining appendages of the cephalothorax are the pair of 
pedipalpi and the four pairs of walking legs. The former are situ- 
ated on each side of the mouth and resemble the legs closely except 
for size and for lack of the metatarsal segment. In the female, the 
pedipalp is a simple appendage terminated ordinarily with a single 
tarsal claw, but in the male the distal end is the seat of the special 
copulatory organ of that sex. The role of the palpi in mating will 
be mentioned later. 

Four pairs of legs are always present, as in typical arachnids. 
Each leg consists of seven segments, called beginning with the one 
that fits snugly into the sternal space coxa, trochanter, femur, pat- 
ella, tibia, metatarsus, and tarsus. At the end of the tarsus are to be 
found two or three claws. The legs vary tremendously in length 


among different spiders, some of them being long, fine stilts on 
which the spider hangs, and others stubby props. 

With so many walking appendages, the means of synchronizing 
all of them is of some interest. In order to take a step, the spider 
moves the first and third leg of one side in conjunction with the 
second and fourth legs of the other side of the body. The remain- 
ing legs of both sides go into action while the other series is at rest, 
and thus the creature advances step by step. 

The appendages and other parts of the body are usually covered 
with hairs and spines of different kinds. Some of these lie flat against 
the integument and serve as a covering blanket. Others are heavier 
or longer or more erect, and are used in many ways by the spider 
to perform important functions during the spinning of silk, for the 
preening of the body, preceding and during the mating, and as 
aids in capturing and holding the prey. Many of these setae are 
extremely sensitive to touch and vibration, and some may be re- 
ceptors for various chemical stimuli. By means of its sensory hairs 
the spider has a keen knowledge of its surroundings. 

Abdomen. The juncture between the cephalothorax and the 
abdomen is made by a narrow waist or pedicel, which represents 
the first true abdominal segment. In the antlike spiders the pedicel 
is visible from above as a small tubular connection armed above and 
below by hard plates, but in most other spiders it is not evident, 
its presence being largely masked by the overhanging abdomen. 
Through the tiny channel of the pedicel must pass the several struc- 
tures essential to maintenance of life in both body parts: the ventral 
nerve cord, a large artery, part of the midgut, and, frequently, 
numerous tiny tracheal tubes. 

Ordinarily the abdomen is a saclike structure without visible 
segmentation and, though covered by a sclerotized cuticle, is usu- 
ally much softer than the cephalothorax. In the primitive liphistiids 
and their relatives, the dorsum of the abdomen is armed with a 
series of hard transverse plates, or tergites, each set with erect black 
spines. In a few of the primitive true spiders there are evidences 
of dorsal segmentation, especially in the spiderlings, but in some 
well-known cases this segmentation may have been acquired sec- 

The abdomen frequently exhibits on its upper surface a series 
of small, rounded depressions that mark the internal attachments 
of muscles. Often brightly painted, and variegated with contrasting 


colors, the abdomen in many groups of spiders is accorded more 
than its share of elegance and elaboration. In some spiders the 
dorsum is covered in whole or part by a hard plate, and in others 
it is armed with curious spines and processes, some of them of great 
length. The reasons for the possession of such curious structures 
are no more apparent than are the reasons for those on the cephalo- 
thorax. Perhaps, because of its many sharp projections, this armor 
discourages birds from attack. In some of our sedentary spiders the 
abdomen is drawn out into a long tail, which gives the creature a 
worm-like appearance. 

The under side of the abdomen is much like the upper in many 
spiders, and rarely bears conspicuous prominences. Near the base 
are usually to be seen the two openings to the book lungs, and 
between them the genital opening. The copulatory organ of the 
mature female, the epigynum, is located just in front of the genital 
opening and takes one of many forms. Farther back may be present 
a second pair of book lungs, a pair of tracheal spiracles, or, near the 
spinnerets, a single median spiracle. In most spiders of the northern 
hemisphere is found the single spiracle. At the tip of the abdomen 
is the anal tubercle or postabdomen, which has the anal opening at 
its tip. 

Both book lungs and tracheae are found in spiders. The open- 
ing to the former is a rather conspicuous transverse spiracle, and 
the area of the lung itself is usually evident externally as a paler 
patch. In all the tarantulas and their allies, and in one small family 
of true spiders, two pairs of book lungs are present, the front pair 
near the base of the abdomen at each side of the genital pore, and 
the hind pair much farther back near the center of the abdomen. 
The possession of four lungs is usually considered to be a primitive 
condition, since higher spiders have the posterior pair changed into 
tracheal tubes. The tracheae always replace the book lungs when 
the latter are lost, and probably are not new creations at all but only 
modified and expanded book lungs without the leaves that ramify 
beyond the original space limits. In most of the true spiders there 
is a tracheal spiracle just in front of the spinnerets. In a few tiny 
spiders all the book lungs have been replaced by tracheal tubes. 

Because in the higher spiders the book lungs have been replaced, 
at least in part, by tracheae, it can perhaps be concluded that these 
latter are more efficient respiratory organs. The true spiders are 
more vigorous creatures of much smaller average size than the four- 
lunged spiders, and require superior respiratory as well as other 


equipment to maintain their place in the extremely diversified hab- 
itats they occupy. 

The spinning organs of spiders are the spinnerets, fingerlike 
appendages usually located near the end of the abdomen on the 
lower surface. They are believed to have been derived from two- 
branched abdominal appendages of ancient spiders, or their pre- 
cursors, which were originally put to some other use than that of 
spinning, perhaps being used as swimming or ambulatory organs. 
Associated with each of these appendages was a coxal gland in the 
abdomen that voided its excretory products through a pore on some 
part of the appendage. From the two pairs of two-branched ap- 
pendages of the third and fourth abdominal segments have come 
the four pairs of spinnerets of contemporary spiders. Their devel- 
opment, modification, and elaboration have gone hand-in-hand with 
a metamorphosis of the lowly coxal glands into a series of abdominal 
receptacles for production and storage of distinct types of liquid 
silk. Originally an excretory product, silk has been put to varied 
and distinct uses, and it has largely charted the course spiders have 
followed through their racial history. 

The spinnerets were originally located much nearer the base of 
the abdomen than their position in most modern spiders now indi- 
cates, and there was a considerable open space between them and 
the anal tubercle. The trend has been toward reduction of the num- 
ber of abdominal segments, and the simplification of the systems 
inside the abdomen, as well as the segmentation of the outer integu- 
ment. As the posterior segments became superfluous and were lost 
or incorporated into the anal tubercle, the relative position of the 
spinnerets changed also. Ancestral spiders had a long interval of 
segmented abdomen between the spinnerets and the anal tubercle. 
In Liphistius this space has been greatly reduced by partial reduc- 
tion of the size of the segments. In Atypus and Antrodiaetus the 
space interval has been still further reduced, and in almost all other 
spiders the spinnerets are immediately adjacent to the anal tubercle. 

Only in the most primitive spiders are eight spinnerets still 
present as fingerlike projections. The liphistiid spiders have re- 
tained all of the projections, but both the anterior and posterior 
median spinnerets are greatly reduced in size, and perhaps figure 
little or not at all in spinning. In Heptathela only six spinnerets are 
present, and the so-called seventh one is the fused remnant of the 
posterior median pair, a "colulus" in an advanced stage of obso- 
lescence. In the other mygalomorph spiders, the anterior median 


pair has been lost, and in only a few are there vestiges of the anterior 
lateral spinnerets. Thus the four spinnerets of the tarantulas and 
most of their allies represent the single, small, posterior median pair 
and the longer, posterior, lateral, segmented pair. The loss of the 
spinning function seemingly has preceded the degeneration and 
obliteration of the spinning organs. 

Most true spiders have retained the eight spinnerets in one form 
or another, and in only a few instances have they reduced their 
number below three pairs. In all the cribellate spiders the anterior 
median pair is still retained as the cribellum, a flat spinning field 
which is used in conjunction with a comb of hairs on the fourth 
metatarsus, the calamistrum, to produce characteristic threads. The 
cribellum probably existed before the anterior median spinnerets 
had lost their spinning function, and became greatly changed and 
important because of its special function. Whether the cribellum 
is a new development from the ancient anterior median spinnerets, 
or represents the ancestral condition of all true spiders, is still a 
debatable question. At any rate, in almost all higher spiders a vestige 
of variable size evidences the former presence of an anterior median 
pair of spinnerets. In some it is a fingerlike colulus; in others, a 
pair of flat plates, connate plates, or a single sclerotized plate, all 
set with covering hairs; and in still others, a tiny point or blister 
bearing one or two erect setae. In some groups of true spiders the 
hind spinnerets are greatly reduced in size and become obsolete to 
a considerable extent, but their former location is marked by some 
sort of vestige. 

The ordinary true spider has three pairs of well-developed spin- 
nerets set closely together in a single group. The anterior pair is 
two-segmented, and the apical segment is bountifully supplied with 
many spools and a fewer number of spigots 'on the spinning field. 
The posterior pair is likewise segmented, most commonly with two 
but frequently with three or even more segments, and is also well 
supplied with spinning equipment. Between the latter are the me- 
dian spinnerets, each of a single segment and ordinarily less well 
provided with spinning openings. 

In the sedentary orb weavers and comb-footed spiders, which 
are the finest spinners, the spinnerets are relatively short, with small 
apical segments, and are set closely together in a small field. In 
many other spiders whose spinning is less noted the spinnerets are 
sometimes long and conspicuous, frequently many-segmented, and 
arranged in different ways. 


The Life of the Spider 




life of the spider is crowded into the first few days of freedom 
when the young spiderlings, having just broken through the egg 
sac, strike out for themselves in a world completely new to them. 
It is spring and the warmth of the sun has changed the inertia of 
earlier life in the egg sac to one of intense activity. Hundreds of 
brothers and sisters, still closely packed together and indistinguish- 
able one from the other, move about within the narrow confines. 
Finally the actions of a few vigorous leaders result in the opening 
of a small aperture at some point in the sac, and a little body 
squeezes through it to greet the open air. One by one the tiny 
creatures emerge through the round opening, until the sac is covered 
with them. They do not tarry long but climb all over the dried 
leaves and the stems on which the sac is placed, stringing their 
threads as they go. Soon we see a tangle of webs (Plate 8), strung 
on every available support, crisscrossing in all directions, and invad- 
ing space like a living thing. Many of the spiderlings hang motion- 
less once they have gained their particular station, but others press 
on with undiminished activity. Up and up they move, to the tips 
of the tall grass stems and the summits of the leafless shrubs which 
mark the meadow site of the egg sac. Straight toward the sun they 
climb until they can climb no higher, impelled by a strange urge 
to throw silken threads out upon the soft breezes. 

This is the urge toward ballooning, one of the most extraordi- 
nary accomplishments of the spider. 

Once the spiderling has reached the summit of the nearest pro- 
montory, a weed, a spike of grass, or a fence rail, it turns its face 
in the direction of the wind, extends its legs to their fullest, and 



George Elwood Jenks 

Female bolas spider, Mastophora cornigera, with recently emerged brood, 
including some adult males 

Walker Van Riper 

A symmetrical orb web of a mountain 
orb weaver, Aranea aculeata 

Walker Van Riper 

Meshed web of Dictyna 
on dried weed 


a. Preparing to leap 

Walker Van Riper 

b. Leaping 

Walker Van Ripa 


tilts its abdomen upward (Plate V). The threads from the spin- 
nerets are seized and drawn out by the air currents. Although the 
dragline threads are often used, those from several spinnerets may 
stream out in long filaments. When the pull on the threads is suffi- 
ciently strong to support the weight of the aeronaut, it lets go of 
the substratum and is pulled into the air. Spider lings balloon in 
different ways, and some of them when afloat climb on their threads 
like little acrobats, pulling in and winding up or streaming out more 
filaments, and in this way exercising some control of the ship they 
are flying. 

Not the exclusive habit of a single species, as was once supposed, 
or limited to part of any season, ballooning goes on during much of 
the year and is easy to observe. In the spring and during the fall 
months, when immense quantities hatch from the egg, emerge from 
their egg sacs and fly, the ballooning spiders by their very numbers 
force themselves upon our attention. Small spiders can be inspired 
to take off if one blows steadily against them; they tilt up their 
abdomens, assume a ludicrous pose, and then bound into the air. 
Because they are so tiny and weigh an insignificant amount, spider- 
lings are sometimes at the mercy of the air currents and are lifted 
into the air when they least expect it. Even larger spiders, caught 
while dropping on their threads, are blown some distance. The 
small aeronauts seem to float on streamers only a yard or two in 
length, but the lines may actually be several times as long. In the 
days of Aristotle, it was commonly believed that the spider could 
shoot out its silk as the porcupine does its quills. We know now 
that the spider must depend on breezes to pull the threads from its 
spinnerets and to bear it aloft after the volume of silk is great 
enough to support its weight on the air currents. 

How far do spiders fly on their silken filaments? Darwin recorded 
the arrival on the Beagle of "vast numbers of a small spider, about 
one tenth inch in length, and of a dusky red color," when the ship 
was sixty miles from the coast of South America. He watched them 
and observed that the slightest breeze was sufficient to prompt them 
to sail rapidly away, after letting out new lines to catch the wind. 
Even greater distances have been covered by these tiny aeronauts, 
which have been known to alight upon the rigging of ships more 
than two hundred miles from the nearest land. Because they move 
upward and forward at a substantial pace, and because of their tiny 
size, the spiderlings are quickly lost to sight. The average distance 
they span can only be conjectured. The spider may be dropped to 


the earth near the site of its departure, but it can fly again and 
again, and thus accumulate a substantial dispersal distance. 

Most ballooning goes on at reasonable heights, probably less 
than two hundred feet, as was noted by McCook; but sometimes 
powerful air currents carry the creatures to great heights. During 
an aerial survey in Louisiana, B. R. Goad found spiders and mites 
well represented in samples of aerial fauna at 10,000 feet, and they 
were even more frequent in the catches of from 20 feet up to 5000. 

Ballooning has made possible the distribution of spider species 
over the world. Species have been enabled to send pioneers in num- 
bers into new areas of all kinds. Oceanic islands have received their 
spider population almost exclusively through this colonizing mech- 
anism. On the bleak cliffs of Mt. Everest, at an elevation of 22,000 
feet, Kingston found tiny jumping spiders hopping about on the 
surface and hiding underneath stones. These could easily have been 
carried upward by the air current. On the other hand there is a pos- 
sibility that they were permanent residents living at an elevation 
too high for almost any other creature, and undoubtedly existing on 
small insects unnoticed by Hingston. 

In the temperate zone aeronautic spiders are most numerous 
during Indian summer, when balmy days follow cool nights. In 
1918, J. H. Emerton studied the aerial fauna in Massachusetts and 
listed sixty-nine species that took to the air during the days of his 
observation. A considerable number of these spiders were fully 
mature, others were advanced in their age, but all were of rather 
small species. It is now well known that many adult and half-grown 
spiders fly, and that this curious activity is not confined to spider- 
lings just emerging from their egg sacs. Emerton characterized the 
males of Zygoballus terrestris, a stocky little jumping spider, as be- 
ing "a regular autumn flyer." Males of some of the smaller orb 
weavers, such as Aranea pegnia and A. displicata, may be seen 
ballooning on sunny afternoons, floating a few feet above the 
ground on long filaments. 

It is probable that almost all groups of true spiders use this 
interesting dispersal device during at least some part of their life. 
Those that shun the light during all their life may not resort to 
flying; and only a few of the mygalomorph spiders are credited 
with this activity. The tarantulas are not known to balloon at all, 
and the large size of their young would seemingly preclude such 
activity. The purse- web spiders, notably the European Atypus 
piceus, disperse by taking to the air for short distances, so it is prob- 


able that many of the smaller four-lunged spiders also have this 
singular habit. A few years ago Dr. W. J. Baerg described the 
flying activities of one of the trap-door spiders, Pachylomerus cara- 
bivorus. The young leave the parental burrow and walk in single 
file toward and up a tree of considerable size, leaving behind them 
as a record of their march a silken band that can be traced back to 
the trap door. From the tree the plump little creatures "spin out 
a thread of silk, which, when having sufficient buoyancy, carries 
the spiders off and out into the world." Dr. Baerg did not see 
the babies fly, so we know nothing of the distance they covered or 
of their flying behavior. However, this activity may be limited to 
certain species or only indulged in occasionally. The young of 
some Mexican species of Pachylomerus remain in the burrow with 
the mother until they are much too large to balloon. 

The drifting threads of spider silk are known in prose and 
poetry as gossamer, a name of uncertain derivation but possibly 
from "goose summer" in "reference to the fanciful resemblance of 
the fragile skeins of silk to the down of geese, which the thrifty 
housewife causes to fly when she renovates her feather beds and 
pillows." The gossamer season is known in France as fils de la 
Vierge, and in Germany as Marienjaden or "Our Lady's threads." 
The reference here regards gossamer as being "the remnant of Our 
Lady's winding sheet which fell away in these lightest fragments as 
she was assumed into heaven." 

Great showers of gossamer have fallen in many places in the 
world, and their origin has been subject to fantastic interpretations. 
The true explanation is a very simple one. During the autumn 
months, spiders become greatly active and cover the meadows and 
shrubbery with innumerable filaments, which soon form a thin web- 
bing over everything. Many of these threads are put out by spiders 
in unsuccessful attempts to fly, and remain hanging on the vegeta- 
tion. The matted gossamer is then picked up by the wind and 
showered down in spots often far from where the cobweb orig- 

In the Yosemite valley of California is located a series of arches 
which form natural traps for spider threads carried upward by the 
air currents and deposited in vast sheets. In these areas "all the 
shrubs, bushes and trees are webbed about in such a manner that 
the trunks of the largest trees are but faint shadows, while limbs 
and foliage resemble a glistening mass of crystal. In the midst of 
this mass are bunches of rolled-up webs that are as white as cotton 


and quite thick. When the mass is disturbed by a gentle breeze, it 
moves throughout its entire length with a graceful undulating mo- 
tion." 2 The gossamer that falls during rainstorms in California 
may well have its origin in some such concentrated area of silk. 

It is generally believed that ballooning and its resultant dispersal 
is an instinctive impulse based on necessity, and that it constitutes 
a protective device. The scattering of the many babies from the 
site of the egg sac apparently works against overcrowding and 
fratricide, and improves the chances of survival for each tiny aero- 
naut. However, we must remember that flying is not the province 
solely of the spiderling, and that spiders of all ages indulge in it, 
limited only by size and weight. During their babyhood spiders 
eat very little and probably represent no great menace to each other. 
On the other hand, a high percentage of aeronauts may drown or 
be dropped in situations where they have little chance of survival. 


The life of the spider begins at the time when a zygote is 
formed by the uniting of the male spermatozoon with the ovum of 
the female. It is believed that this occurs soon after the eggs are 
laid by the female. The mother spider prepares a silken sheet on 
which the eggs are placed. They issue one by one from the genital 
opening beneath the base of the abdomen, and are bathed with a 
syrupy fluid in which quantities of sperm from the stores in the 
spermathecae have been discharged. At this time the eggs have a 
very soft chorion, which is easily penetrated by the sperm at any 

Spiders have long been listed among animals that are able to 
reproduce parthenogenetically, that is, without having the eggs 
fertilized by the male gamete. This belief has been perpetuated on 
the basis of a few records, which are now completely discredited. 
It has become well known that females can store the sperms of 
males for weeks or months, and that they are thus able to fertilize 
several masses of eggs in succession at distant time intervals from 
the product of the initial fertilization. This curious fact has prob- 
ably misled the few workers who have recorded parthenogenesis in 
spiders, a phenomenon for which there is no unassailable evidence. 

2 L. O. Howard, "On Gossamer Spider's Web," Proc. Ent. Soc. Washington, 
Vol. 3, pp. 191-2. 

Walker Van Riper, Colorado Museum of Natural History 

A humped orb weaver, Aranea gemmoides, on egg sac 


Walker Van Riper, Colorado Museum of Natural History 

a. Black widow, Latrodectus mactans, in web 

J. M. Hollisler 

b. Black widow, Latrodectus mactans, ventral view 


After laying a mass of eggs, the female covers them with a silken 
sheet and molds the mass into the egg sac characteristic of her spe- 
cies. The eggs (Plate X) are ordinarily spherical, or broadly oval, 
but their shape may be largely determined by their position in the 
egg mass. A great many spiders cover the eggs with a viscid secre- 
tion, which hardens and agglutinates the mass into a single body. 
In some cases the eggs are only lightly agglutinated, held together 
in a mass by a few threads, and thus retain nearly a spherical form. 
Frequently, the weight of the mass is so great that the eggs assume 
the shape forced upon them by the available space, and thus are 
irregular in outline. The size of the eggs varies within rather wide 
limits, being 0.4 mm. in some of the smallest true spiders, but at- 
taining 4.00 mm. in the large tarantulas. 

The number of eggs laid by different spiders varies enormously. 
The largest of all spiders, Theraphosa blondi, is reputed to lay as 
many as 3000, and the large orb weavers and pisaurids, which fre- 
quently spin more than a single egg sac, are credited with 2200 in 
a single sac. At the other extreme we find many tiny spiders that 
habitually lay only one, two, or very few eggs at a time, and per- 
haps no more than a dozen during their lifetime. The average num- 
ber for average spiders is in the neighborhood of one hundred. 
Those habitually producing more than a single sac usually place 
fewer eggs in each, so that the average is not greatly increased. 

There is a considerable correlation between the size of spiders 
and the number of eggs they are physically capable of producing at 
any one time. We expect the large tarantulas to be large egg pro- 
ducers, and find it true, as is well shown by Baerg's average of 812 
eggs per sac for one of the large southwestern American species. 
The contents of five sacs varied from 631 to 1018. The sacs of these 
creatures are tremendous flabby bags often 2 or 3 inches in diameter. 
An unopened sac of Hapalopus pentaloris, a brightly colored and 
curiously marked tarantula of moderate size, from Mexico, con- 
tained 986 young and each of the babies measured about 3 mm. in 
length. Only 288 eggs were found in a sac of Phormictopus can- 
ceroides, a very large West Indian tarantula. Another unopened sac 
of this same species was 2% inches in diameter and contained 252 
eggs in the deutovum or second egg stage. The eggs of the first sac 
measured about 4 mm. in diameter, and the deutova of the second 
were about 7 mm. in length. 

Larger eggs are produced by spiders of greater size. The eggs 
of Phormictopus are as large as small peas and exceed by several 


times the bulk of those of any true spider. The young of these 
spiders after the first true molt are quite large, 7 mm., even before 
they have left the egg sac. It is small wonder that ballooning is not 
a characteristic of this group of spiders. Some true spiders produce 
a greater number of eggs during a single year, but female tarantulas 
live several years, and in total number of eggs produced probably 
far outdistance all spiders. 

True spiders may produce few or many eggs and may place 
them in one or in several separate cocoons. A tiny cave spider, 
Telema tenella, lays one egg at a time. The blind spider of Mam- 
moth Cave in Kentucky is said to lay from 2 to 5 eggs. Among 
the more generalized true spiders those of the family Oonopidae 
lay few eggs, and Oonops pulcher of Europe is known to place only 
two in a cocoon. The Peckhams state that Peckhamia picata, a small, 
antlike spider, produces 3 eggs. They assumed that ants had few 
enemies a supposition for which there seems to be good evidence 
and that creatures resembling them would not have to produce so 
many offspring to maintain their normal population. Likewise in 
many other families, small spiders produce few simply because the 
abdomen is too small to accommodate many eggs, each of which 
must provide sufficient food for the growing embryo. They mul- 
tiply their low production by maturing eggs for several distinct 

Medium-sized spiders produce moderate numbers of eggs. Tra- 
chelas tranquillus, a common eastern American species often found 
in houses, lays 30 or 40. Many small wolf spiders produce 100 or 
even less. The common labyrinth spider, Metepeira labyrinthea, 
spins 5 or 6 cocoons and places about 30 eggs in each. Uloborus 
americanus also places a string of cocoons in her orb web and leaves 
about 50 eggs in each. A species from the high mountains of Ari- 
zona, Uloborus arizonicuSj is a social spider and spins several sacs 
in each of which are about 60 eggs. And finally, the gregarious 
Uloborus republicanus of the American tropics, somewhat larger 
in size than the other two species, spins larger cocoons, in which 
are as many as 163 eggs. The eggs of these three species are essen- 
tially the same in size, measuring from .6 to .7 mm. 

The large orb weavers produce several hundred eggs. The 
Peckhams state that the orange garden spider lays from 500 to 2200 
in its cocoon, but McCook believed that 1000 was about the aver- 
age number for the species. The cocoon of one of the large fisher 
spiders from Oklahoma, Dolomedes triton, contained 1537 eggs in 


its large brown egg sac. The smaller Pisaurina mira had 518 in a 
sac of average size. Bonnet records a total of 2292 eggs in the four 
cocoons of the European Dolomedes fimbriatus, a species much 
smaller in size than several American members of the genus. 

When multiple cocoons are spun by a single female, the number 
of eggs is less in the later ones. A female of Aranea cornuta, which 
made 10 sacs, laid a total of 1210 eggs, deposited in the following 
order: 234, 218, 182, 140, 112, 87, 81, 72, 51, and 33. In instances 
of this kind, some of the later eggs may be infertile, owing no doubt 
to the exhaustion of the semen stored in the receptacles, and perhaps 
also to its gradual loss of viability. In the later cocoons, the exhaus- 
tion of the female is apparent in her spinning ability, which becomes 
progressively less perfect. In order to maintain the normal popula- 
tion of a species, spiders produce a sufficient number of eggs to cope 
with all the factors of the environmental resistance, and emerge 
with a pair for each one in the normal population. The female 
Argiope aurantia lays 1000 eggs, covers them with a tough cocoon, 
and yet has an average survival from the large number of only one 
pair. Peckhamia picata lays a few eggs, placing them at different 
places in 3 or 4 cocoons, and still maintains an average population. 


The essential work of the female is completed when she has laid 
her eggs and enclosed them in some kind of silken sac. This act 
frequently represents the last effort of the mother in behalf of a 
new generation she may never see. But though early death is the 
lot for many, it may be delayed long enough for the mother to 
guard the cocoon for a limited period and even to aid in some way 
the emergence of her brood. In some species, the female spins more 
than one sac and must then dispose of the others in her web or hide 
them away, in order to give her time to the newest sac. 

In the contents of the sac rest the hopes of the whole species 
for survival, so it is not surprising that considerable attention may 
be given to the fabrication of the covering. Many egg sacs are 
strongly made, beautifully designed creations, often pleasingly tinted 
with colored silk. Especially constructed for her eggs by the female 
spider, the egg case is fundamentally different from an insect co- 
coon, which is the covering the larval insect spins around itself and 
in which it transforms. The degree of perfection of the sac is cor- 


related to some extent with the danger of destruction to which it 
is subjected. When the mother spider remains with her eggs until 
the young hatch, the need for a tough sac is not so great. Similarly, 
a sac hidden away in the depths of a burrow or surrounded by 
barriers of dry web or viscid strands is usually not strongly made. 
The situation in which the sac is placed and the length of time it 
must remain there before the young desert it are the important con- 
siderations. Probably in response to such stimuli, spiders have devel- 
oped different means of achieving a normal hatching of progeny 
under varied circumstances. 

Most spiders are provided with a set of glands especially used 
for the building of egg sacs. Known as cylindrical glands because 
of their form, they feed their products through spigots on the out- 
side of the posterior spinnerets. The silk spun from these glands is 
frequently different in color from the dry silk, and from that pro- 
duced by other glands. In addition, the silk of the egg sac is differ- 
ent in its physical properties, being less elastic and not as strong as 
the dragline silk. It is apparently never viscid. The outer, varnished 
layers of some sacs suggest that the outer envelope is different in 
origin from the silk of most of the sac, or differs at least in the 
manner of being carded and applied as a layer. 

The egg sac is generally a spherical or lenticular object, resem- 
bling a little ball, a biscuit, or a flat disc. The manner in which 
these sacs are produced illustrates the fact that even in realizing such 
commonplace structures, the spider must give considerable time and 
exercise great instinctive ingenuity. Take for example the small 
wolf spiders, whose sac-making can be conveniently observed. Or- 
dinarily, Pardosa spins a light scaffolding of lines attached to adja- 
cent objects, and between them lays down a flat sheet of silk. This 
sheet usually takes the form of a circular disc approximating in 
diameter the length of the female. It is a closely woven fabric made 
by brushing the hind spinnerets from side to side and rotating the 
abdomen and body. The finished base may be nearly flat, but fre- 
quently it is a shallow basin, a veritable cradle for the eggs. 

The actual deposition of the yellowish eggs requires only a 
minute or two. The gravid female stands over the sheet and ex- 
trudes through the oviduct a viscid fluid that forms a pool on the 
silk into which the eggs, singly or in small groups, are laid. The vis- 
cosity of the fluid is such that the egg mass largely retains its 
globular shape. In this fluid are sperms from the seminal recepta- 
cles. The female next spins, over the mass, a somewhat smaller 


covering similar in texture to the base, and then cuts the biscuit- 
shaped object loose from the floor and the scaffolding. This she 
now seizes and holds beneath her cephalothorax and revolves slowly 
by means of her palpi and legs. At first the spinnerets sew up the 
edges between the two circular sheets until the break is scarcely 
apparent. Then the mass is revolved in all directions and the spin- 
nerets put down additional layers of silk until, as the sac is molded 
and shaped, a nearly spherical object results. Soon after completion 
of the sac, its white silk takes on a tinge varying from gray to 
yellow, blue, or green; and the spider attaches the bag to her spin- 

Many spiders spin this type of sac. The great flabby egg purses 
of the tarantulas are prepared in the burrow and are guarded by 
the mother until long after the young emerge. The delicate silken 
bags of the trap-door spiders often hang from the side of their 
burrow. The large lens-shaped bag of the huntsman spider is held 
beneath the body by the female, who will not relinquish it without 
a struggle. Many of the vagrant gnaphosids guard their eggs, but 
others place their tough little sacs colored a shiny yellow, pink, or 
red close against a rock or a chip of wood and leave them. 

The simplest type of egg sacs are those of the long-legged 
pholcids and other primitive spiders, which use only a few threads 
of silk to hold the mass together. The cosmopolitan Pholcus (Plate 
XIX) glues her few eggs lightly and carries the mass in her cheli- 
cerae. The tiny funnel-web tarantulas of the genus Microhexura 
also carry their eggs in this manner, and thus minimize the need 
for a strong sac. 

Some of the most marvelous and elaborate egg sacs are spun by 
the sedentary spiders, which put their web-spinning superiority to 
good use in constructing the coziest of egg cradles. The sac may 
hang in plain view among the threads the central theme of the 
web or it may be tied nearby to herbs or similar objects. Along 
with the special attention accorded the precious egg mass goes a 
somewhat different method of realizing the finished cradle. For 

The large, pear-shaped sac of the orange Argiope (Plate 7), 
which hangs near her web, is constructed in a most unusual manner. 
Argiope always hangs downward from the threads of her slightly 
inclined web, and her spinning activities are profoundly influenced 
by this posture. A series of cross lines attached at several points 
prepares a firm scaffold for the sac, which itself is a compound 


structure. First, yellowish threads are laid down to form a roughly 
rectangular roof, and on this the female spins a thick tuft of fluffy 
yellowish silk, which forms an irregular mass above her. Into this 
yielding feather bed she next spins a firmer sheet of dark brown 
silk, comparable to the base in which Pardosa places her eggs, and 
which serves the same purpose for Argiope. She lays the eggs up- 
ward against this brownish sheet by forcing the viscid liquid and 
the many hundreds of eggs through the genital orifice. (Most of the 
sedentary spiders that hang downward from webs, and even some 
of the vagrants that run upright, defy gravity by depositing their 
eggs in this strange manner.) The egg mass hangs as a yellow 
spherical ball, and over it Argiope spins a thin but tough covering 
of whitish or yellowish silk, which is joined to the brown silk disc. 
Around the whole mass the eggs, their covering, and the rectan- 
gular roof she then spins a fluffy covering of rusty brown or yel- 
lowish brown silk, very loosely packed, which forms a voluminous 
blanket around the egg mass. These lines are spun with the aid 
of the spider's hind legs, which comb them out of the hind spin- 
nerets in loose loops and pat them down into the mass. Over the 
spongy padding Argiope now puts down a more finely spun cover- 
ing of white or yellow silk, largely made by using the hind spin- 
nerets alone. Smooth and closely spun, this outer covering hardens, 
becoming a dry yellowish or brownish cover that crackles like 

The orange Argiope thus produces, after several hours of tireless 
spinning, six different sheets, tufts, or covers and from them makes 
three envelopes for her eggs a thin white inner fabric, a thick 
woolly or flossy blanket, and a tough outer cover. The innermost 
layer is essentially the same as that spun by Pardosa and many other 
spiders, and is composed of two parts, the sheet that receives the 
egg mass and the cover. 

In some orb weavers, the sac is drawn out into a short or long 
neck or stalk. Mastophora hangs her sac (Plates III and XXIII), a 
globular bag with a thick stalk once or twice its length, on twigs 
and leaves near her nest. It is doubtful that the stalk contributes in 
any way to the security of the eggs, since the sac is easily available 
to any insects that can reach the twigs. In many instances, Masto- 
phora lashes the base of her sac directly to the twig. In some other 
spiders, however, the ball of eggs is suspended in midair by a thread 
of silk. The pale brown bag of Ero, with its irregular covering of 
brownish silk, hangs on an inch-long pedicel in a cavity beneath 


a stone or under boards. The golden brown balls of Theridiosoma 
frequently are found hanging to vegetation, suspended by a fine 
long thread. Very likely such a pendant sac offers difficulties to 
predators that might destroy it if it were nearer at hand. 

The use of silk coverings to give the eggs a relative security 
from depredation must have been discovered early in the history of 
spiders. Even a superficial silken covering would be a deterrent, 
since many insects cannot penetrate it and might even become en- 
tangled in the threads. Spiders have, in the course of time, added 
many refinements to their sacs and thus gained greater protection 
from predators. The covering has been toughened, thickened, vari- 
egated with tufted and woolly silks, and, in many cases, several 
blankets envelop the egg mass. Often the sac is plastered with 
layers of mud, or embellished with bits of wood, leaves, stones, and 
other debris, rendering it less conspicuous. Some are glued to stones, 
tied to twigs, enclosed in folded leaves, or suspended at the end of 
fine threads. Others sit in the center of the web or lie behind a 
tangle of threads in a retreat. 

Some spiders have divided the risk by putting their eggs in 
several baskets. They spin a series of sacs, which hang as a string in 
the center of their snare or are left singly here and there. It is 
uncommon to find every sac in a string parasitized, whereas the 
whole effort of a mother spider may be lost in a single bag. 

In addition to this type of protection, the spider often plays an 
active role in seeing her eggs through to hatching and babyhood. 
The crab spiders and many hunting spiders guard the egg sac and 
strenuously resist effort to pilfer the contents. Wolf spiders drag 
their sac attached to their spinnerets, and, later, carry the young 
around on their backs until the spiderlings are able to fend for 
themselves. The varied efforts made by mother spiders to provide 
for the welfare of their eggs or young are remarkable and complex, 
and especially noteworthy because they are largely instinctive 


Spiders undergo a development within the egg that is compara- 
ble to that of other arachnids and also of insects. The embryo 
spider gradually takes form on the outside of the vast sphere of 
yolk that makes up most of the egg. On the generalized part, which 
will become the cephalothorax, appear little buds, which gradually 


become differentiated into the chelicerae, palpi, and the legs. A 
similar series appears on the abdominal portion, associated with a 
rather definite segmentation of eight to twelve segments, but all 
those behind the sixth true segment disappear as development pro- 
ceeds. The basal pairs of buds persist for some time, and those of 
the fourth and fifth segments develop into the paired spinnerets. 
The buds on the second and third segments become invaginated 
and go to form the book lungs. Finally, the embryo nearly encircles 
the outside of the egg and the ventral surface is outside, unnaturally 
bent and convex so it can lie within the stiff chorion. At this point 
occurs what is called "reversion," a process by which the position 
is reversed and the cephalothoracic portion becomes free. At about 
this time too, with the pressure against the chorion of the expanding 
embryo, and with the aid of a sharp egg tooth at the base of the 
pedipalpi, the egg covering is broken. 

With the shedding of the chorion of the egg there is revealed a 
creature somewhat spiderlike and yet obviously different from the 
well-known spiderling. (The term "larva" has been applied to this 
stage, but since that term more commonly describes insects at an 
active feeding stage and has quite a different sense, it will not be 
used here.) It is not unreasonable to suppose that this imperfect 
creature is prematurely hatched, and that it actually represents part 
of the egg stage. In order to gain space for fuller development and 
more freedom, the tough chorion is broken but the creature is still 
swathed in embryonal membranes. In mites an analogous stage is 
called the deutovum, and is so similar to what exists in spiders that 
the term may be applied to the latter also. 

This period in the spider's growth is not nearly so simple as 
was once supposed. Dr. Ake Holm has discovered and described 
in various Swedish spiders two or even more incomplete stadia (the 
intervals between molts), each marked by the shedding of a mem- 
brane. Some spiders hatch from the egg at a more advanced stage 
than do others, the degree of development being roughly approxi- 
mated by the specialization of the family. In Segestria, the first 
postembryonal stadium brings to light a very primitive creature, 
whereas in a more highly developed spider, such as Pardosa, the 
deutovum is far more advanced. 

The deutovum is without dark coloration of any kind, the cara- 
pace usually being milky white and the abdomen somewhat duller. 
Tarsal claws are completely lacking on the pudgy legs. The crea- 
ture is unable to feed or spin, for only parts of the important struc- 


tures are developed. No setae or hairs are present on any part 
of the body. The shape and size of the eyes are sometimes indi- 
cated even at this stage, but they are colorless and without func- 
tion. In the abdomen is an abundant yolk material on which the 
creature can subsist until able to feed. The deutovum grows 
quickly after emerging from the egg covering, and soon is twice 
as large as the space occupied by the egg. The duration of the 
deutovum stage is usually quite short, and toward the end of it 
we begin to see the darker coloration of the growing spiderling 
beneath the cuticle. 

The first true molt, always undergone while in the egg sac, 
brings to light the creature that we all recognize as a spider, and 
which is truly a miniature of the adult. During a rather indefinite 
period of its life, perhaps for several stadia, it is referred to as a 
spiderling because of its small size. The legs are now longer, 
much more slender, and clothed with darker spines and hairs. At 
the tip of the tarsi are found tarsal claws, two or three depending 
on the family to which the spiderling belongs. The spiderling is 
now able to spin but it uses little silk until after it leaves the 
egg sac. The digestive system is more perfectly developed, and 
the spiderling is probably able to feed, but its food requirements 
are still being met by unused yolk material in the abdomen. 

What happens next is largely dependent upon the tempera- 
ture. If the weather is favorable, the spiderlings become active 
and move about in the sac, their actions dependent upon the de- 
gree of warmth that penetrates through the silken covering of their 
domicile. Some female spiders guard the egg sac until they die, and 
others are reputed to aid their babies to escape from the sac by 
tearing it open. In most cases, however, the female has long since 
died and the escape must be effected by the spiderlings themselves. 
In tough sacs they usually cut a neat round hole, through which 
they emerge one by one, or, in weaker sacs, they will force a large 
rent. Following emergence comes the dispersal of the family, usu- 
ally by ballooning. 

If the weather is cold, the spiderlings in the cocoon are inac- 
tive. They often stay in the egg sac through the whole winter, 
awaiting the proper temperature in the spring before dispersing. 
This is particularly true of those species that lay their eggs late 
in the fall, when not enough time and warmth are available to 
allow the spiderlings to develop and disperse. 



At rather definite intervals in its development the spider casts 
off the bonds of its stiff outer covering and readjusts itself for 
life in a more advanced stadium. This molting, or ecdysis, is 
characteristic of all the arthropods and is ordinarily their method 
of providing for increase of size when the old cuticle becomes 
too tight. They emerge from their transformation with shiny new 
armor, fully set with new hairs and spines, and often even with new 
structures not represented in their previous condition. In the spiders, 
metamorphosis brings with it a rather gradual change from the 
spiderling to the adult, and is comparable for the most part to the 
changes undergone by grasshoppers and other lower insects. During 
each molt the epidermis formed under the old cuticle is capable of 
considerable increase in size before it becomes hardened. A much 
greater change occurs at the last molt, for it brings to light the fully 
developed, sexually mature adult. Only some of the more primitive 
spiders resort to molting after sexual maturity; they are the females 
that are long-lived and perhaps require a periodical change of rai- 
ment for other reasons. Apparently postnuptial molts are not neces- 
sary for growth, inasmuch as the creatures have reached their 
maximum and may even decrease in size thereafter. Perhaps they 
are required in order to provide a new and complete covering of 
spines and hairs, which are the prime sensory equipment of spiders, 
and without which they remain at a distinct disadvantage. 

Molting is ordinarily preceded by various symptoms that indi- 
cate the approach of the ordeal. This is particularly true of the 
later molts, which are of longer duration and more difficult of suc- 
cessful completion. For hours, days, or even weeks, the spider re- 
fuses to feed and becomes more and more lethargic. Certain changes 
in color have been noted, in some instances a darkening of the legs, 
in others a lightening or darkening of the whole body, owing no 
doubt to the changes going on under the old integument. Burrow- 
ing spiders often spin up the entrance of their burrows or block the 
opening with a plug of earth. Those that normally live in silken 
nests or leaf retreats use these for molting quarters. Some of the 
orb weavers hang exposed in their webs and are thus in an especially 
vulnerable position. 

The details of molting (Plate X) vary little among groups of 
spiders, but they are of considerable interest. The large American 


tarantulas are fine performers and their molting activities have been 
described a number of times. During the late summer they usually 
show evidences of an impending change and refuse to accept food 
for days or even weeks. The dorsum of the abdomen has by this 
time usually been rubbed completely bare, as a result of the normal 
scraping characteristic of these creatures; and because they have 
worn their covering of hairs for a full year, their bodies are dull 
and quite bleached as compared with their fresh condition. 

Tarantulas ordinarily have their quarters liberally covered with 
silk, but on this occasion they spin an expansive, closely woven 
sheet of silk, appropriately termed the molting bed, which requires 
several hours of intensive work. On this soft cover the spider lies, 
turned completely over on its back and with legs outstretched, the 
front and hind ones with tarsi affixed to the silken bed. To all 
appearances it is dead, but if one watches the prone figure closely, 
occasional slight movements can be detected. After two or three 
hours, the old skin splits along the sides of the carapace, and the 
old shield comes loose from the new integument. Splitting continues 
over the pedicel and the sides of the abdomen until the dorsum of 
the whole spider is partially freed, the old skin adhering more or 
less closely for some time. At this stage, the spider has changed its 
position so that it is lying on one side, and it now begins the labori- 
ous process of pulling the appendages from their old casings. The 
spider extracts its chelicerae first, and then starts a series of rhythmi- 
cal contractions which gradually bring to light the femora, patellae, 
and successively the rest of the legs. The first legs and the palpi are 
freed initially, then come the posterior legs. After about an 
hour, the cephalothorax and the legs are completely freed; where- 
upon the spider easily extracts the abdomen and moves away from 
the cast skin. For three or four hours it lies on its back or side 
while the new skin hardens; then it resumes its normal upright posi- 
tion. The freshly cast skin of the tarantula is moist inside, and the 
new cuticle also shows traces of moisture. The molting fluid be- 
tween the old and the new skins perhaps aids the progress of the 
molt by loosening the old skin. 

Essentially the same picture is presented in the molting of true 
spiders. The sedentary spiders hang in their webs or in their re- 
treats. Many of the vagrants spin a few threads in a favorable nook 
and hang downward, their tarsi fixed in the silken lines and their 
abdomen supported by a thread from the spinnerets. The cuticle 
splits around the sides of the carapace and around the abdomen. 


Then the legs are freed in slow stages by the usual rhythmical con- 
tractions, the front ones coming out first and finally the posterior 
pair. By the time this is accomplished, the abdomen is virtually 
freed and the spider is suspended in the air by the thread from its 
spinnerets. The whole process requires ten or fifteen minutes, the 
length of time apparently being governed by the size of the spider. 
Young spiderlings suspend themselves, molt, and lengthen their legs 
in less than half an hour, the molting itself often taking only three 
or four minutes. Half-grown spiderlings require about an hour, and 
young males and females in the last molt about two hours. Molting 
may proceed during either day or night, and seems not to be lim- 
ited by time as are many other activities of spiders. 

The freshly molted spider is much paler and softer than in the 
previous instar, and only gradually hardens and darkens its new 
integument. During this relatively brief period occurs all the in- 
crease in size of the carapace and appendages until the next molt. 
Size increase is usually progressive and is determined by the instar 
and the sex of the spider. In some species the legs increase tre- 
mendously in length between the instars. Growth commences as 
the legs are pulled out of the old integument much as fingers are 
pulled from a glove. It continues during the time the spider is free 
of the cast skin and hangs suspended. The appendages are bent back 
and forth in a regular ritual. Pierre Bonnet has demonstrated with 
some very ingenious experiments the necessity of these calisthenics 
following the molting. Without such bending movements the ap- 
pendages become sclerotized even at the joints and remain stiff. 

The number of molts necessary to attain maturity varies widely 
in spiders. Bonnet has shown rather conclusively that size is the de- 
ciding factor in most species. Tiny species molt few times, whereas 
large ones molt a greater number of times. Bonnet noted that small 
species of 5 or 6 mm. in length (Pholcus phalangioides, Uloborus 
plumipes, etc.) molted four or five times. Species of medium size, 
measuring about 8 to 1 1 mm. (Aranea diadema, Pirata piraticus, 
etc.), molted seven or eight times. The larger spiders, 15 to 30 mm. 
in length, molt ten to thirteen times (Dolomedes plantarius, Nephila 
madagascariensiSy etc.). The largest of all spiders, the tarantulas, 
molt even more often: according to Dr. Baerg, twenty-two times 
for the male of Eurypelma californica. Further, in these spiders 
various postnuptial molts make it probable that the females molt 
between thirty or forty times before they die. At the lower limits, 
only four molts are credited by Bonnet to the male of Nephila 


madagascariensis; and I have discovered that the male of Mastophora 
cornigera undergoes only two molts before becoming mature. 

Even within the same species there is variation in the number of 
molts. Bonnet found that to become mature, females of Dolomedes 
plantarius molted as few as nine or as many as thirteen times. The 
number of molts was to some extent correlated with size, the larger 
examples requiring more molts, but various other factors were im- 
portant, the amount of nourishment being one. The males of this 
same species became adults after nine, ten, or eleven molts, a number 
similar in the lower limits to that of the female that they resembled 
in size. In the northern United States the egg sacs of the species of 
Mastophora are broken open early in the spring and the young 
disperse. The males emerge either in the penultimate stadium or 
fully mature, in the latter case having molted only twice. The fe- 
males are of the same size, and presumably have likewise undergone 
one or two molts, but they must molt seven or eight times before 
they are sexually adult. The difference between molts is probably 
five or six, and reflects an enormous disparity between the size of 
the sexes, a difference greater than in any other spiders known to 
me. Time is also important, and whenever maturity is reached 
quickly for the species, the molts are near the minimum for the 
species. When maturity is retarded for some reason, more molts 
are undergone. Abundant food diminishes the number of molts, 
whereas starving increases the number. 

For very few North American spiders is the number of molts 
known. The black widow, Latrodectus mactans, has been studied 
rather carefully by several investigators, and we find the usual con- 
siderable differences between the sexes as regards molting behavior. 
The males become adult after the fifth, sixth, or seventh molt, 
whereas females are adult after the seventh, eighth, or ninth molt. 
In the related spider Teutana grossa the males become adult at the 
sixth or seventh, the females at the seventh or eighth molt. This 
number of molts is about average for spiders of this general size, and 
the males almost invariably molt at least one less time than the fe- 
male. In 1927 Gabritschevsky recorded the time intervals between 
molts for Misumena vatia as a part of his paper on the change in 
pigmentation of that species. The synopsis is as follows: Deposition 
of eggs, July 28; hatching, August 8 (my estimate); first molt, about 
August 12; emergence from the egg sac, August 14; second molt, 
August 24; third molt, September 5; fourth molt, September 23; 


fifth molt, October 17; sixth molt, January 5; final molt, a time after 
January 5 that was not indicated. 

Various morphological changes accompany molting; some of 
them being very significant. The presence of a third claw on the 
tarsi of very young spiders that are two-clawed as adults indicates 
that the three-clawed condition is the primitive one. Young wolf 
spiders have the eye formula of the Pisauridae, a fact which cor- 
roborates our belief that the former were derived from an ancestor 
very much like recent pisaurids. The young of Tibellus oblongus, 
a greatly elongated species, have the general body form and the 
eye relations of species of the more conservative Thanatus. 

Each molt represents a crisis in the life of the spider, and brings 
with it dangers of many kinds. During the transformation the 
spider is completely helpless, trussed up in old worn clothing and 
exposed to attack from many enemies. Crickets, sowbugs, meal- 
worms, and other omnivorous animals, not serious adversaries under 
normal conditions, are liable to nibble and kill it; it lies vulnerable 
to attack from the meanest foe. Normal enemies find it completely 
unable to fight back. Furthermore, the mechanical difficulty of 
extracting its appendages may prove insurmountable, and the im- 
prisoned creature will perish, or so mutilate its legs that its chance 
for life in a hostile world is much diminished. G. and E. Deevey 
found that nearly half the deaths before maturity (thirteen out of 
thirty-one) among the black widow spiders they reared were the 
result of failure to complete a molt. One out of every twelve 
spiders in the total of one hundred fifty-eight that were studied 
from hatching to death died from this cause. 


The spider shares with many other arthropods the ability to 
drop an appendage without great inconvenience called "autotomy" 
and the ability to replace it in a more or less perfect form by sub- 
sequent regeneration. This latter power of replacing lost or muti- 
lated organs is a very old one, and, most strongly developed in 
lower animals, serves as a device of great importance from the 
viewpoint of protection and survival. Often the spider is able to 
escape the clutches of an enemy without greater loss than the 
shedding of one or two of its appendages. Whereas autotomy oc- 
curs in spiders of all ages, the regeneration of new appendages is 


limited to young spiders that have not stopped molting, or to those 
few primitive spiders which molt after sexual maturity. 

It is now known that autotomy in the strictest sense that is, 
the act of reflex self-mutilationdoes not occur in the Arachnida. 
An appendage is dropped only after a visible effort on the part of 
the spider, which struggles with such violence that the tension on 
the member snaps it off at its weakest point. This action was termed 
"autospasy" by Pieron in 1907; it involves the breaking of the 
appendage at a predetermined locus of weakness when pulled by 
an outside force. This locus is between the coxa and the trochanter 
in the legs in most spiders: a point found by Wood to resist only 
7 per cent of the stress that the next weakest juncture, that between 
the metatarsus and the tarsus, could withstand. In harvestmen, the 
weakest point is between the trochanter and the femur, and in other 
animals the break may occur in quite different locations. 

The reaction of the spider to the loss of appendages varies con- 
siderably. The loss of one, two, or even three legs in some of the 
active crab spiders seems to result in little inconvenience to the 
animal, which runs away without crippling effects. Stocky crab 
spiders that have lost the first two pairs of legs take up a position 
in which the short third legs are directed forward as in normal 
posture, and are able to move about with relative ease. The stout 
front legs of the crab spiders are at the same time organs of touch 
and offensive weapons, and when they are lost, the ability to cap- 
ture flies is seriously impaired. Mature males that have lost some 
of their long front legs are at a distinct disadvantage during court- 
ship, and fall easy prey to females not willing to meet them. 

Autotomy is easy to observe. If a spider is grasped by one of 
the legs and the animal has a good hold on the substratum, the leg 
will break loose at the usual locus between coxa and trochanter. On 
the other hand, if the spider is held in the air and is unable to exert 
some countering force by grasping an object, it is unable to drop 
a leg. When held in a pair of forceps, the animal usually twists 
around, grasps the forceps, and literally pulls its body loose from 
the leg. The speed with which this is accomplished varies with the 
species and with the thickness of its appendages, but it is practically 
instantaneous once the spider begins to effect an escape. If two legs 
are held firmly, some spiders break both of them easily, but some 
of the stocky crab spiders are unable to exert enough force to free 

Sometimes the spider is seized by a predator that is able only 


to break the cuticle of the leg, with the result that blood begins 
to flow through the break. Although the spider may escape other- 
wise unscathed, this is a most serious situation, inasmuch as an open 
venous system allows the gradual draining of blood from the body 
until death occurs. The instinct of the spider is immediately di- 
rected to a preventive device. The leg is pulled out, and the flow 
of blood is quickly halted at the normal breaking point between 
coxa and trochanter. This amputation is accomplished with the 
help of the remaining legs and the mouth parts. In some instances 
the spider spins threads and ties the appendage to them, and is able 
to amputate a whole leg or even a small stump and thus save itself 
from almost certain death. 

Autotomy can be put to use by the spider to rid itself of an 
appendage that is unwelcome for some reason other than injury. 
The known males of the species of Tidarren have long been ob- 
served to carry only one palpus, a great bulbous affair held in front 
of the head. In the antepenultimate stadium, the palpi are only 
slightly swollen, but after molting the creatures have two tumorous 
enlargements resembling boxing gloves. So large are these new 
members that the spider is handicapped by them, and is able to 
manipulate them only clumsily. The obvious solution to the prob- 
lem is the amputation of one of these palpi, and this is exactly what 
the spider does, by a most interesting process. It spins a scaffold 
of silk, similar to the molting sheet, and, suspended from it by its 
legs, fixes one of its palpi in the threads. The spider now twists 
around and around and, aided by pressure from its hind legs, twists 
off the unwelcome palpus. The spider now has a single palpus, 
which is held in front of the head and occupies much of the avail- 
able space. At the next molt it becomes sexually mature, and the 
vital parts of the palpus are revealed. A second palpus is never 
regenerated to replace the old one. 

The spider's instinct to rid itself of an injured or inconveniencing 
appendage takes precedence over all others, but once autotomy is 
accomplished, the spider almost invariably does a most curious 
thing. It picks up the bleeding member and sucks the juices from 
it, usually discarding it only after it is sucked dry. This autophagy 
is perhaps as old a habit as autotomy itself, but may not have any 
especial significance beyond its general interest. Spiders often attack 
each other, or other prey, and if successful only in securing a leg, 
will stop and suck it dry in the same manner. The instinct asso- 


J. M. Hollisler 

a. Opened egg sac of orange Argiope, Argiope aurantia 

J. M. Hollister 

b. Egg sac of shamrock orb weaver, Aranea trifolium 


Cluster of baby orb weavers, Aranea, preparing to disperse 


ciated with bleeding prey and the taste of the blood prompts the 

If a leg is lost by an immature spider, it is replaced by a smaller, 
imperfect replica at the next molt, provided a sufficient time has 
elapsed between the loss and the molt. The regenerated appendage 
increases in size with successive molts but never quite attains the 
full perfection of the normal appendage. The same leg can be 
regenerated repeatedly, so long as the spider is still immature, but 
at least three successive molts are necessary to attain a size com- 
parable to that of the normal appendage. 

The regeneration of a leg takes a definite course. A good illus- 
tration is the crab spider, Misumena calycina. The females of this 
species have white legs, and when one is lost, the appendage that 
replaces it is shorter, unmarked (as is to be expected), and deficient 
in the number of spines, as compared with the normal appendages. 
In the male, however, the first two pairs of legs are banded after 
the third or fourth molt, and in each successive molt the amount 
of pigment in the dark annulae increases. If the male loses a leg 
during the third instar, when it is still white, after the next molt 
the regenerated leg is wholly white, but the normal front legs 
continue to increase their annular pigmental areas. After the fourth 
molt, the regenerated leg becomes annulate, but the depth of the 
chromation is much less than in the normal leg. In other words, in 
Misumena calycina a regenerated leg takes on the normal coloration 
of the leg at the previous instar, and never quite approximates the 
normal leg in size and color. 


Most spiders that inhabit the temperate zones live only one year. 
The yearly population may be divided very roughly into two 
faunas, one identified with the spring and the second with the fall. 
Over-wintered or recently matured males of many vagrant spiders 
are abundant in early spring and are on hand when their females 
become mature. The crab spiders are found on the ground, in the 
corollas of spring flowers, or running over the stems of shrubs and 
the bark of trees. The grassland teems with jumping spiders, wolf 
spiders, clubionids, and many other wandering types. The sedentary 
web spinners are likewise well represented by many species that 
spin inconspicuous orb webs or tangled webs on the vegetation. In 


a few weeks most of the males disappear and gravid females are 
found on all sides, some spinning up domiciles for egg-laying, while 
others, having already made their first sac, carry it attached to their 
spinnerets or held in their jaws. By midsummer the possibility of 
finding males of the spring spiders is not very good, but the females 
carry on far into the year, often laying several egg masses. Thus, 
in the spring and early summer we have the males and females of 
the spring fauna, and the juvenile and growing representatives of 
the fall fauna. 

In the fall, the sedentary spiders advertise their presence in a 
conspicuous manner by great sheet webs and expansive orbs. The 
males appear in midsummer and early fall and attend the females 
on the outskirts of their modest webs. In August we find the webs 
of the grass spiders on grass and shrubs, and can surprise the adults 
pairing in the funnels. The orb weavers now are attaining maturity 
in great numbers, and every suitable situation is filled by a web 
of variable dimensions. Having vastly increased in size, they spin 
correspondingly larger webs. As the season progresses, the males 
dwindle rapidly; soon all are gone, having lived the shorter, intenser 
life identified with their sex. The females lay their eggs and enclose 
them in sacs of various kinds, which tend to be more substantially 
built and more heavily insulated than those of the spring spiders. 
After the killing frosts of November, most adults of the fall fauna 
are gone, but already the growing young of the spring spiders have 
attained nearly their full development. During October and Nov- 
ember, the partially developed spring spiders engage in ballooning 
activities in company with many precocious fall spiderlings. The 
fall spiders produce their eggs in the fall, and their young either 
spend the cold winter months in their cocoons, or, having deserted 
them, live under debris or in protected places until warmer days 
allow them to begin their march to full maturity. 

It must not be thought that the two faunas are discretely sep- 
arated one from the other. Actually they are bridged by species 
that mature during the midsummer. Because of multiple cocooning 
and precocity, or tardiness, of some species, there is a considerable 
overlapping of the faunas. Further, some species do not seem to 
conform to any definite pattern, and mature males and females may 
be found during almost any month of the year. In the American 
South it is possible to have two full generations during the year. 
For the most part, however, even in warmer areas we find only 
one generation each year. Over much of Canada there is only one 


generation per year, while in the colder northern reaches some of 
the species probably require two or more years to attain complete 

The life of the male is invariably shorter than that of the female. 
Males of the spring spiders die in early summer after having lived 
about ten months. The same longevity holds true of the fall species, 
and the females outlive the males by several weeks. Under laboratory 
conditions, G. and E. Deevey found that average male black widows 
matured in about 70 days and lived a total of about 100 days; 
whereas females matured in 90 days and lived about 271 days. The 
greatest life span for the males was 160 days, and for the females 
550 days. Such data show that mating between brothers and sisters 
of the egg masses is quite improbable. 

A number of spiders are known to live more than one year. 
In the northern United States almost the only ones to do so are the 
large wolf spiders, which burrow into the soil and probably live 
several years. Occasionally other spiders live about 1 8 months, such 
as the large water spiders and the black widows, even though their 
normal life span is only a year. 

The more primitive true spiders often live more than a single 
year. Some of the segestriids and scytodids are said to be peren- 
nials, and Dr. Lucien Berland kept a female filistatid for ten years. 
It is probable that all ancestral spiders were longer-lived, and that 
one of the sacrifices of the modern true spider for the many advan- 
tages it enjoys is a drastic reduction in life span. 

It is generally believed that all mygalomorph spiders live several 
years. The purse-web spiders are reported to live as much as seven 
years, and the true trap-door spiders are also perennials. Exceeding 
all other spiders in length of life are the large tarantulas. Dr. Baerg 
has kept a female tarantula for more than 20 years and believes that 
25 or even 30 years probably represents the normal age for females. 
The males mature in 8 or 9 years, but ordinarily die a few months 


Silk Spinning and Handiwork 



of Idmon of Colophon in Lydia, became widely known for the 
excellence of her work at the loom. Indeed, her art was so superb 
that the nymphs from the woods and streams came to gaze upon it. 
Many wondered whether even Athene, Goddess of Weaving and 
the Handicrafts, could surpass this maiden, who seemed to have 
been tutored by the Gods themselves. So confident became Arachne 
in her amazing skill that she challenged Athene to compete with 
her. Although affronted by the presumption of the girl, Athene 
accepted the challenge and wove a tapestry showing the warfare of 
the Gods and the fate of those who conspire against them. Arachne 
depicted the love adventure of the Gods with such exceeding per- 
fection that the Goddess, unwilling to admit that so high a degree 
of excellence could be attained by a mere mortal, became enraged 
and destroyed it with a blow from her spinning shuttle. The rash 
and humiliated Arachne attempted to hang herself, but the noose 
was loosened and became a cobweb, and the maiden was changed 
into a spider. Thus disgraced, lying on the rent pieces of her 
tapestry, Arachne was condemned to perpetual spinning. 

The Greek word for spider is arachne, commemorating the 
weaving skill and mythical fate of the imprudent maiden. From it 
we derive the group name Arachnida, which embraces all the arach- 
nids or spider like creatures, and also the ordinal names of Araneae 
or Araneida, exclusively used for spiders. 

The English word "spider" is a corruption of "spinder," one who 
spins, and is similar in form to other Teutonic words derived from 
the same root, such as the Spinne of the Germans. This root per- 
sists in different form in the words "spinstress" and "spinster," both 

5 2 


a. Orienting in response to breeze, secured by dragline 

Walker Van Riper 

b. Ballooning threads stream from spinnerets 

Walker Van Riper 



a. The cautious approach of the small male 

Walker Van Riper 

b. The mating 


having reference to women who spin as a profession, but the latter 
has acquired a quite different connotation. 

While most people associate spiders with a silken web of some 
sort, few are aware of the dependence of these creatures on silk. 
The ability to spin is an early gift to the spiderling, and is developed 
after the first molt and before emergence from the egg sac. Imme- 
diately upon leaving the sac, the spiderling strings out its dragline 
threads and attaches them at intervals to the substratum. There- 
after it is never free of this securing band through its whole life, 
except by an accidental breaking of the cord. 

The degree of reliance on silk varies considerably among the 
spiders. The very oldest ones, the precursors of those few we 
know from Carboniferous rocks, probably had clumsy appendages 
that were only beginning to be used to comb out a liquid silk. The 
most primitive of recent spiders are said not to spin a dragline, 
although they are otherwise probably as well equipped for spin- 
ning as most spiders, from the evidence of their well-made egg sacs 
and silken tubes closed with a trap door. The familiar jumping 
spiders and wolf spiders, so often seen running over the ground or 
climbing on plants, are vagrant types in which the use of silk is lim- 
ited. They employ it chiefly for their draglines, for covering their 
eggs, and for lining their retreats. On the other hand, a vast multi- 
tude of sedentary spiders are strongly dependent on silk. Some of 
them have become slaves of elaborate webs and are nearly helpless 
when not in contact with them. For spiders of this type silk is of 
paramount importance during the whole life span. 

The majority of spiders are inveterate spinners and far surpass 
all other animals in the variety and excellence of their weaving. 
Some of the other arachnids produce silk, but they use it in a very 
limited way. The pseudoscorpions have cephalic glands and spin 
silk through a tiny spinneret located on the tip of the movable fin- 
ger of the chelicera. Before laying their eggs, these tiny animals 
build an ingenious little domicile made of small particles cemented 
together with silk, and lined inside by a covering of silk. A few of 
the mites also have silk glands and are said to spin threads so fine 
they are invisible to the naked eye. The so-called "red spiders" are 
mites of the family Tetranychidae, which cover the leaves of trees 
with silk and use it as a protecting blanket for their eggs and young. 

Many insects spin silk and in such profusion that they rival the 
work of even the sedentary spiders. The unsightly webs of the 
tent caterpillars are familiar and despised objects to most people but, 


looked at objectively, they are quite wonderful fabrications. Their 
tent nests are not far different from some made by gregarious 
spiders. Many other moths spin silk, but its use is largely restricted 
to making the cocoon. The most noted insect spinner is the silk- 
worm, the larva of the moth Bombyx mori, which has been domes- 
ticated for so long that it cannot now maintain itself in the wild 
state. It produces cocoons that are easily unwound, and supplies 
the bulk of commercial silk. The silk of moths, caddis flies, and 
sawflies is produced in cephalic glands, which pour their contents 
through a single opening in the lower lip. The threads are usually 
much thicker than those of spiders. The silk is probably of only 
one kind. 

The spider's reliance on silk is well illustrated by the many dif- 
ferent uses to which it is put. A list of some of these is given be- 
low, without any attempt at other than a general classification: 

Protection and Retreats 

The dragline; the bridge line; the trap line of the orb weavers; 

the warning threads of Ariadna 
The ballooning line 
Attachment discs to anchor the lines 
The cells and retreats of all spiders 
Hibernating chambers 
Molting threads, beds, and chambers 
Trap-door covers; spinning up of burrows and open retreats 

Protection of Eggs and Spiderlings 

The egg sacs 

The nursery webs of the Pisauridae 

Web Structures Associated ivith Mating 

The sperm web of the males 

The bridal veil of the crab spiders and other vagrants 
The courtship and mating bowers of the black widow and sed- 
entary spiders 
The mating chambers of the vagrant spiders 

Structures for Stopping and Ensnaring Prey 

Sheet webs 

The stopping tangle webs of the grass spiders and the aerial sheet 
weavers (Linyphiidae) 


The viscid or entangling webs of the orb weavers and certain 

other spiders 
The viscid ball and pendulum line of Mastophora, Dichrostichus, 

and Cladomelea 
The viscid hackled band in the diverse capturing webs of the 

cribellate spiders 

The catching thread of Miagrammopes 
The retiarius of the Dinopidae 

Bands for Binding the Prey 

The swathing band of the orb weavers 

The swathing film of the comb-footed spiders 

The swathing band of Hyptiotes 

The entangling ribbon of the Hersiliidae 

The capturing band of Drassodes and other vagrant species 

The above requirements and others not listed are met by the 
production of different kinds of silk, which are used, seemingly at 
the will of the spider, either separately or in combination to pro- 
vide the special threads, desired bands, or drops for a particular 


The silk of spiders is a scleroprotein which is produced as a 
liquid in varied and voluminous abdominal glands. When drawn 
out of the spinnerets, the liquid ordinarily hardens to form the 
familiar silken threads. It is believed that the mechanical stretching 
of the silk during the drawing of the lines is responsible for the 
hardening, rather than exposure to air or any chemical process. 
Viscid silk is produced in some of the glands and remains sticky 
for long periods. An analysis of the silk has shown that it is a com- 
plex albuminoid protein quite similar to that produced by the silk- 
worm, although this similarity is denied by some investigators. The 
silk of the silkworm comes from modified salivary glands located 
in the head, whereas that of the spider is derived from transformed 
coxal glands in the abdomen. 

Spider silk is noted for its strength and elasticity. The tension 
necessary to bring a compound thread .01 cm. in diameter to the 
breaking point was once found to be eighty grams. This consid- 
erable tensile strength, which is said to be second only to fused 


quartz fibers and far greater than steel, goes hand in hand with great 
elasticity. The threads will stretch one fifth their length before they 

The strength of the threads is to some extent dependent on the 
manner in which the spider draws them out, greater speed increas- 
ing it. When they are drawn speedily, the fibroin chains attain a 
maximum orientation, which contributes greater strength to the 
lines. The cocoon silk of the silkworm is essentially equal in strength 
to that of the orb-weaving spider. However, spiders produce sev- 
eral varieties of silk, and some differences are found among them 
in strength and elasticity. The viscid line of the orb-weaver snare 
is not very strong but extremely elastic; whereas the foundation 
lines of these webs are of great strength, exceeding even that of 
the cocoon silk. 

Most spider threads are not single fibers, although they may 
appear so to the naked eye. The dragline thread readily separates 
into two rods of equal thickness, but often elements from other 
glands lie parallel to these elementary strands and mar the uniform- 
ity. Under ordinary magnification, single fibers are rather uniform 
rods, but when photographed by the electron microscope at 35,000 
diameters even the finest threads are not completely uniform, and 
show tiny enlargements and irregularities. Not much detail of the 
internal structure of the silk can be seen even at this great magnifi- 
cation. The finest single fibers attain a thinness of 0.03 micron, or 
about one millionth of an inch, and are invisible to the naked eye. 
Much thicker threads are relatively large, being o.i micron, or one 
quarter-millionth of an inch in thickness. Many molecules are larger 
than the width of these spider threads. It is possible that the spider 
can draw out its filaments to a degree equal to the thickness of its 
protein molecule, and that the finest threads represent a single chain 
of molecules. 


The silk glands of spiders are secreting organs located within 
the abdomen. Differing in size, form, and location, these organs are 
classified largely on the basis of their physical characters. Thus, 
the pyriform glands are pear-shaped, the aciniform are berry-shaped, 
and the other kinds are similarly identified by their contour. At 
least seven distinct kinds of glands are known to occur in the whole 
group of spiders, but not all of them are found in any single family. 


The cribellar glands are found only in spiders that have a cribellum 
a flat spinning plate and are used in conjunction with the calamis- 
trum, a comb of hairs on the hind metatarsi. The comb-footed 
spiders of the family Theridiidae possess all six of the remaining 
types of glands, and are the only ones having lobed glands, which 
secrete the material of the swathing film. These spiders thus are 
provided with one more set of glands than their close relatives, the 
sedentary orb weavers and the linyphiid spiders. 

Even the oversimplified classifications of Apstein and others 
demonstrate conclusively that the spinning organs and glands of 
spiders are the most complicated structures known for the produc- 
tion and utilization of silk. The several types of glands and the 
uses of their silk products are enumerated below: 

/. The aciniform, or berry-shaped glands. These glands are 
found in all spiders and are characterized by their nearly spherical 
shape and resemblance to various berry fruits, such as a raspberry. 
Four clusters, each containing from a few to as many as a hundred 
glands, send the silk through each of the posterior and median 
spinnerets. The swathing band is a product of these glands. Ac- 
cording to Apstein, they also produce the ground lines for the 
viscid drops. 

2. The pyriform, or pear-shaped glands. Also found in all 
spiders, these glands occur in two clusters of a few to one hundred 
or more, and communicate with the front spinnerets. The making 
of the attachment disks is one of their functions, but they some- 
times contribute wild threads to the thicker draglines. 

3. The ampullate, or bellied glands. Known in all spiders, these 
usually are present as four large, long, cylindrical glands, but fre- 
quently there are six, eight, or even twelve. They open through 
spigots which, when four glands are present, are located on the 
inner side of each of the front and middle spinnerets. Most of the 
dry silk of spiders, the dragline being the chief agent, is produced 
in the ampullate glands. Comstock has suggested that the ground 
line of elastic silk in the orb weavers is produced by these glands, 
two of which have been modified for the production of this impor- 
tant element. The fact that the yellow silk of Nephila is spun from 
the anterior spinnerets partially confirms this opinion. 

4. The cylindrical glands. These long, cylinder-shaped glands 
are often wanting in males, and are lacking in the Dysderidae and 
the Salticidae. They number six or more, and open on the inside 


of each posterior spinneret through a spigot. They produce the 
silk for the egg sac. 

j. The aggregate, or tree-form glands. There are six of these 
irregularly branched, compound glands, opening on the inner sur- 
face of each posterior spinneret through spigots. From these glands, 
which are found only in the Argiopidae, Linyphiidae, and Theri- 
diidae, are produced the viscid drops for the viscid threads of 
the web. 

6. The lobed glands. Found only in the Theridiidae, these are 
irregular in shape and lobed, opening on the posterior spinnerets 
through spigots. The swathing film of the family is produced in 
these glands, which are developed largely at the expense of the 
aciniform glands. 

7. The cribellum glands. These numerous, spherical glands open 
on the cribellum through many tiny pores. They occur only in the 
cribellate spiders, and secrete the woof of the hackled band. 

As is to be expected, those spiders that use many types of silk 
have the greatest number and volume of glands. The abdomen of 
the sedentary orb weavers is largely filled by glands; whereas the 
vagrants are less bountifully supplied. In some males the cylindrical 
glands are missing, and in many males the other glands are less well 
developed than in females. Inasmuch as the male's need for some 
types of silk virtually ceases when he becomes adult, the lack of 
specific glands is of no great importance. 

The spider has at its command these various types of silk glands 
and can call upon them for its many needs. Flexible fingers are the 
spinnerets: they can be extended, withdrawn, compressed, and 
manipulated like human hands. The filaments produced are some- 
times simple threads in multiples of two, but frequently they are 
composite lines and are drawn from different glands. The viscid 
spiral of the orb-weaver snare, for example, is composed of a double 
ground line, possibly coming from the aciniform glands, on which 
is superimposed a thin coating of viscid silk from the aggregate 
glands. Only when this line is spun in a particular way does it take 
on the characteristic form of a beaded necklace. The spiral is spun 
rather slowly, and the spider pulls out the coated line and lets it 
go with a jerk. As a result, the fluid is arranged in globules, spaced 
along the line and far more sticky than a thin, uniform covering. 
The rate of pull and the degree of the tension determine the finished 
product. The spider spins leisurely or swiftly, according to its need. 



No better illustration of the dependence of spiders on silk is 
afFored than the habit of laying down a dragline or securing thread. 
Wherever the spider goes, it always plays out behind from its spin- 
nerets a silken line, which is anchored at intervals (by means of the 
attachment disks) to the substratum, as the climber lets out a rope 
when he enters the recesses of a deep cave or moves down the slope 
of a precipitous mountain. The dragline is a constant companion 
of spiders of all ages and all kinds, excepting a small group of 
primitive forms of the family Liphistiidae. It is the fundamental 
thread of most spinning. 

The sedentary orb weaver, committed largely to an aerial life 
in the confines of its web, outlines the zones of its snare with this 
thread. Long strands floated in the air form bridge lines from tree 
to tree or across streams. On draglines, the spider balloons for 
long distances. Great sheets and flakes of gossamer are mostly the 
discarded draglines from many spiders. The orb weaver again, hid- 
den in its leafy retreat, holds a trap line and uses it to detect the 
presence of an insect in the web. 

The dragline is the lifeline of the spider. It is an aid in prevent- 
ing falls from precipitous surfaces, and may also serve as a means 
of escaping enemies. Web spiders often drop from their webs on 
these lines and hide in the vegetation. Or they drop down and hang 
suspended in midair until the danger is past, whereupon they climb 
up hand over hand to their original position. The hunting spiders 
jump headlong over cliffs or leap from the sides of buildings to 
escape capture, and float down gently on their silken ropes. Most 
of the spinning in our houses is dragline silk, which the house spiders 
lay down in great profusion and which soon is transformed into 
the familiar cobweb, heavy with air debris. Even the framework of 
the retreats is put up with dragline silk, and on this base other types 
of silk laid. 

Not a single filament, as the name implies, the dragline in its 
simplest form is composed of two relatively large threads that ad- 
here so closely together that only one line is apparent. On occa- 
sion, the dragline may be made of four strands, or even of a great 
many threads drawn from several spinnerets. 



The use of spider silk for reticules in various optical instruments 
is a direct consequence of the fineness of the fibers and of their 
great strength and ability to withstand extremes of weather. Prior 
to World War I, spider silk was very extensively used for cross 
hairs and sighting marks in a great variety of engineering, labora- 
tory, and fire-control instruments. For transits, levels, theodolites, 
astronomical telescopes, and many other optical devices there is 
nothing much superior to spider silk. Most people who use such 
instruments are familiar with the fibers, and often replace them in 
the field, using old spider silk or drawing a supply from living 

Since World War I there has been a slackening in the use of 
this material. The finest threads are useless for cross hairs because 
of their fragility and the difficulty of installation. Because dragline 
silk is most often used, the joined fibers must first be separated 
so that the primary line will be a single uniform thread. This can 
be easily done, since the two or four threads are discrete, and the 
resultant single strand, averaging 1/20,000 of an inch in diameter, 
is usable. Even finer fibers can sometimes be used. But the lines 
spun by spiderlings and small spiders, as well as the finer fibers of 
larger ones, are usually quite useless. 

The cocoon silk of the large Argiopes can often be employed 
for telescopes. The floss beneath the tough outer covering is pulled 
out easily, and single strands of considerable length procured. This 
cocoon silk is spun from different glands and is not quite as strong 
as the dragline silk, which is the most commonly used fiber. The 
silks of many spiders are suitable for reticules. In Europe the 
favorite species are large orb weavers such as Aranea diadema and 
Zilla atrica. Many other spiders provide suitable silk, even those 
belonging to quite different families. In the United States most silk 
comes from the common house orb weavers, Aranea foliata and 
dumetorum, from the numerous humped araneas, from the argio- 
pids, particularly Argiope aurantia, and many others. The silk of 
the black widow has also been used extensively. 

Silk is usually reeled from the spinnerets of living spiders and 
placed upon suitable frames for storage. It is easy to secure and 
retains its properties for many years. During World War II there 
was an increased demand for spider fiber for laboratory and sur- 



Walker Van Riper 

a. The male after mating is occasionally, as here, killed and eaten 

by the female 

Walker Van Riper 

b. A female in her tangled snare with long-legged spiders, Psilochorus 
BLACK WIDOWS, Latrodectus mactans 


Lee Passmore 

. A desert solpugid (Eremobates) 

A giant-tailed whip scorpion, Mastigoproctus giganteus 


veying instruments. Although few of the optical instruments re- 
quiring spider silk were directly concerned with war in the field, 
some newspaper publicity gave the impression that the silk was in 
great demand as a critical war material. The truth of the matter is 
that all needs were satisfied by a few individuals who only devoted 
part of their time to the securing of the web. 

The importance of spider silk in industry has decreased progres- 
sively during the past thirty years. Its place has been taken by 
platinum filaments and by engraving on glass plates. Where an 
aerial reticule is desired, drawn filaments of silver-coated platinum 
wire are frequently used. These filaments, usually 1/10,000 of an 
inch in diameter, are mounted in a heavy metal ring to form the 
desired pattern. They are said to be superior to spider web since 
they show an even black line and do not sag in a humid atmosphere. 
For all instruments requiring a complicated pattern, etched glass 
reticules are usually used. In bomb sights, range finders, periscopes, 
and most gun sights, in fact in virtually all optical fire-control in- 
struments, the width of the line has to be carefully adapted to the 
optical purposes and characteristics of the instrument. Etched glass 
is obviously necessary in most such instances; it would be impossible 
to accomplish the desired results with spider silk. 


It has for centuries been the ardent desire of araneologists to find 
some way of exploiting for commercial purposes the tremendous 
supply of spider silk available in nature. As long ago as 1709, a 
Frenchman, Bon de Saint-Hilaire, demonstrated that spider silk was 
usable for fabrics in the same way as the silk of the silkworm. A 
large number of egg sacs were washed, boiled, and cleansed of all 
extraneous matter, then allowed to dry out. With fine combs the 
sacs were carded and worked into slender thread of a pleasing gray 
color. Two or three pairs of stockings and gloves were made from 
the natural silk, and were presented to the French Academy. So 
sensational was this accomplishment that in 1710 the Academy of 
Sciences of Paris commissioned R. A. de Reaumur to investigate 
the possibility of an extensive utilization of spider silk. After a thor- 
ough study, this eminent entomologist (and inventor) concluded 
there was little likelihood that spider silk, at least such as was avail- 
able in Europe, could become a profitable industry. 


The difficulties he enumerated are inherent in the spiders them- 
selves and in their silk, and are still those that rule out the silk of 
spiders as a potential material for commerce. In the first place, 
spiders are solitary, predaceous animals that feed only on living 
invertebrates. Each spider must be segregated and maintained apart 
from its neighbor, for cannibalism is the rule when the larger 
spiders come together, and the population is soon decimated. Space 
requirements are considerable; the difficulties of providing suitable 
food are almost insurmountable. Only the egg-sac silk was con- 
sidered at that time to be usable, and, although many sacs are pro- 
duced by the females, it would require, as de Reaumur estimated, 
663,522 spiders to produce a pound of silk. On such terms, compe- 
tition with the silkworm was impossible. 

The silk itself was considered inferior in strength to that of the 
silkworm, owing to its far finer threads, which lacked the luster 
of insect silk and were difficult to work satisfactorily. The silk- 
worm produces a single line of silk, which is usually between four 
and seven hundred yards long a production representing the total 
output, the whole lifework, of the larval moth. Even with the 
relatively thick lines of the silkworm, their joining together to form 
commercially usable threads is an exacting process, which, because 
no mechanical solutions have been successful, must be done by 
hand. Strands of spider silk do vary in thickness, and the large silk 
spiders of the genus Nephila, which abound in the East Indies and 
in the Orient, produce a silk noted for its strength. However, state- 
ments that the lines in the webs of Nephila sometimes attain the 
thickness of darning wool are exaggerations. Their thickest line is 
very much finer than that of the silkworm. 

In Madagascar an attempt was made to take silk from the local 
spiders by drawing it directly from their bodies. The natives 
brought the animals into cleared areas and established them in great 
numbers near the site of the reeling apparatus. At intervals, the 
mature spiders were removed from their webs and imprisoned in 
a most curious device consisting of little stocks that held them 
firmly between cephalothorax and abdomen. Then small revolving 
mills were touched to each spinneret, and, as the filaments were 
pulled out, they were rolled into a single thread by a hand-operated 
mill. The silk so produced was of a beautiful golden color and quite 
as good as that of the silkworm, but the project had to be aban- 
doned because of the practical difficulties. 

In the United States, Dr. B. G. Wilder drew attention to the 


possibility of using the silk of the big American Nephila. In 1866 
he extracted silk directly from the body of this spider unaware, at 
the time, of the earlier European experiments. Wilder was amazed 
by the ease with which it was possible to reel off the golden silk, 
and intrigued by the possibility of producing quantities of it for 
textiles. From one spider he reeled off silk for an hour and a quarter, 
at the rate of six feet per minute, taking a total of one hundred and 
fifty yards. Later he devised an ingenious little apparatus to hold 
the spider during the reeling, and was able to obtain quickly the 
full quota of available silk. In addition to holding the creature 
firmly in stocks, the device had a round piece of cork on which the 
spider could rest its legs, thus being prevented from interfering with 
the flow of silk from its spinnerets. 

Dr. Wilder found that one female would yield at successive reel- 
ings one grain of silk, and that four hundred and fifteen spiders 
would be required to yield one square yard of commercial silk. 
For an ordinary dress requiring twelve yards of material, therefore, 
nearly five thousand spiders would be required. This was quite 
bountiful production for spiders, yet it is still only half the amount 
obtainable from an equal number of silkworms. 

Today we are no nearer than Saint-Hilaire and Wilder to a 
realization of spider silk as a practical commercial textile. The 
basic obstacles remain, inherent in the characteristic differences be- 
tween the silk spider and the silkworm. 


A material of such abundance and strength as spider silk could 
scarcely have failed to be used by primitive peoples for some of 
their needs. Indeed, it is surprising that we do not have more 
records of its use in the Americas, where the same types of spiders 
abound that have supplied the Papuan and Oriental natives for gen- 
erations. From the great Nephila spiders comes silk to supply cer- 
tain New Guinea natives with gill nets, kite nets, dip nets, and va- 
rious lures for their fishing activities, silk with which to weave bags, 
caps, and headdresses, and silk for other purposes. Strength resides 
not in a single strand of silk but rather in the twisted and matted 
threads, which form a tough fabric. The large aerial webs of Ne- 
phila are made with a very strong silk, and are capable on occasion 
of ensnaring birds in their viscid and elastic lines. 


In the New Hebrides, the natives use spider silk to fabricate 
small bags in which they carry arrowheads, tobacco, and even the 
dried poison used on their arrowheads. Some New Guinea natives 
of the Aroa River district make a headdress of insect or spider 
silk to keep out the rain. To more sinister uses are put the smoth- 
ering cap and the dooming bag, both made by the New Hebrideans. 
The former is a strong, conical cap which is pulled down tightly 
over the heads of victims, usually adultresses, and causes death by 
suffocation. The dooming bag, a purse filled with various bric-a- 
brac, is said to have magical properties. According to the stories, 
it is rubbed over the forehead of a sleeping victim with a rhythmic 
motion and with muttered magical words, causing him to remain 
in a deep hypnotic sleep from which there is no awakening. The 
soporific effect of the dooming bag is assured by the victim's exe- 
cutioners, who administer a coup de grace after they have carried 
him into the jungle. 

Of more interest are the fishing nets of the Papuans, which show 
varied and ingenious use of spider fiber. Several accounts illus- 
trating primitive man's ability to seize upon common materials and 
suit them to his purposes are well worth mentioning. 

The North Queensland black boy entangles one end of a thin 
switch in the web of Nephila and, by adroit weaving motions, 
twists the coarse lines into a strand a foot or more long. The frayed 
ends of the line are moistened in the crushed body of the large 
olive-green silk spider (known to these aborigines as "karan-jam- 
ara") and the remaining morsels are thrown into the stream, imme- 
diately attracting shoals of small fishes. As the silken lure is trailed 
through the shallow water, a fish rises to sample the tidbits on the 
invisible strand. Lines of gossamer become entangled in its teeth, 
and the smiling angler lands the two-inch long prize with a careless 
flourish. This method of fly fishing, and other engaging fishing 
techniques of the Australian aborigines, may be found described in 
detail in E. J. Banfield's book Tropic Days. 

That the catch is limited to small fishes does not detract from 
the efficiency of the method. Many are caught in a relatively short 
time, seventeen fingerlings in ten minutes according to one account, 
and make up in numbers what they lack in size. It is said that these 
lures, as generally made, are capable of holding fish weighing nearly 
three-quarters of a pound. 

A similar lure is used as part of a novel method of catching fish 
on the east coast and adjacent islands of New Guinea, and in the 


Richard L. Cassell 

Crab spider, Misumenoides aleatorius, on flower 


a. Huntsman spider, Heteropoda venaloria 

J. M. Hollister 

b. Silk spider, Nephila clavipes 


Solomon Islands. The natives make a kite of the large flat leaves 
of one of the local trees, sewing them together and stiffening them 
with tough strips to produce an object about two and a half feet 
long and nearly a foot in width. The completed kite is embellished 
with five wings of pandanus leaf. A flying line is made of fiber 
twine, ordinarily about one-third of a mile long, while the tail is 
another length of twine from one to three hundred yards in length, 
at the end of which is tied a tassel made from the web of silk spiders. 
The kites are then flown over the seas either from the shore or 
from canoes in such a way that the spider tassel skips along the 
water and entices fish to strike. The golden-yellow silk entangles 
the teeth of the fish, and, after some maneuvering with kite and 
boat, it is lifted into the canoe by means of a dip net. 

Still another intriguing method of capturing small fish is prac- 
ticed by certain Solomon Island natives. This account by H. B. 
Guppy is from The Solomon Islands and Their Natives: 

The following ingenious snare was employed on one occasion 
by my natives in Treasury, when I was anxious to obtain for 
Dr. Gunther some small fish that frequented the streams on the 
north side of the island. I was very desirous to have some of 
these fish, and my natives were equally anxious to display their 
ingenuity in catching them. They first bent a pliant switch into 
an oval hoop about a foot in length, over which they spread a 
covering of stout spider-web which was found in a wood hard 
by. Having placed the hoop on the surface of the water, buoy- 
ing it up with two light sticks, they shook over it a portion of 
a nest of ants, which formed a large kind of tumour on the 
trunk of a neighboring tree, thus covering the web with a num- 
ber of struggling young insects. This snare was allowed to float 
down the stream, when the little fish, which were between two 
and three inches long, commenced jumping up at the white 
bodies of the ants from underneath the hoop, apparently not 
seeing the intervening web on which they lay, as it appeared 
nearly transparent in the water. In a short time, one of the small 
fish succeeded in getting its snout and gills entangled in the web, 
when a native at once waded in, and placing his hand under the 
entangled fish, secured the prize. With two or three of these 
web hoops we caught nine or ten of these little fish in a quarter 
of an hour. 3 

8 H. B. Guppy, The Solomon Islands and Their Natives, London, 1887, p. 157. 


The Papuan natives make landing nets from the orb webs of 
Nephila. A. E. Pratt describes this practice as follows: 

One of the curiosities of Waley (near Yule Bay), and, in- 
deed, one of the greatest curiosities that I noted during my stay 
in New Guinea, was the spiders' web fishing-net. 

In the forest at this point huge spiders' webs, 6 feet in diam- 
eter, abounded. These are woven in a large mesh, varying from 
i inch square at the outside of the web to about Y 8 th inch at the 
centre. The web was most substantial, and had great resisting 
power, a fact of which the natives were not slow to avail them- 
selves, for they have pressed into the service of man this spider, 
which is about the size of a small hazel-nut, with hairy, dark- 
brown legs, spreading to about 2 inches. This diligent creature 
they have beguiled into weaving their fishing-nets. At the place 
where the webs are thickest they set up long bamboos, bent over 
into a loop at the end. In a very short time the spider weaves 
a web on this most convenient frame, and the Papuan has his 
fishing-net ready to his hand. He goes down to the stream and 
uses it with great dexterity to catch fish of about i Ib. weight, 
neither the water nor the fish sufficing to break the mesh. The 
usual practice is to stand on a rock in a backwater, where there 
is an eddy. There they watch for a fish and then dexterously 
dip it up and throw it on the land. Several men would set up 
bamboos so as to have the nets ready all together, and would 
then arrange little fishing parties. It seems to me that the web 
resisted water as readily as a duck's back. 4 

Although Pratt's account has not been verified, there is never- 
theless more reason to believe that it could be true of Nephila webs 
rather than of the garden variety of orb web. It is not difficult to 
persuade the spider to use a bamboo hoop, since it is a most suitable 
framework for a web, and we know that American orb weavers 
sometimes oblige by spinning a web on a frame supplied them. It 
is also true that the radii of the Nephila webs are more numerous, 
and that the many closely set spirals would contribute to the 
strength of the web. The spiral line becomes a permanent part of 
the web and thus multiplies its strength. Finally, it is possible that 
immersion in water contributes in a mechanical way to the strength, 
making the struggles of the fish less liable to rupture the lines. 

*E. A. Pratt, Two Years Among New Guinea Cannibals, London, 1906, 
p. 268. 


In other reports of spider-silk landing nets, the spiders are not 
said to spin their webs upon the hoops, but instead the latter are 
twisted and turned through a number of large webs until there 
results a many-layered covering of fiber. When drawn through the 
water, these nets are stretched to the shape of a shallow bag. In 
the Trobriand Islands, the frame is only the fork of a shrub on 
which the web is twisted. Apparently, these homemade landing 
nets are quite durable objects and can be used over and over again, 
ordinarily requiring only a limited amount of patching. Their haul 
is made up of prawn, shrimps, and various kinds of fish sometimes 
weighing as much as three or four pounds. 

Thus the wiles of the modern angler, with his casting fly, his 
trolling lines, and his gill nets, are duplicated by natives of a single 
region, and the important element of all these snares is spider silk. 


Courtship and Mating 


lengths to ensure that the chain of life continues strong and un- 
broken. The bringing-together of the sex cells is accomplished by 
these arachnids in a manner so extraordinary that the various strange 
details almost transcend belief. Completely lacking a primary in- 
tromittent organ at the site of the genital opening, the male spider 
has developed a secondary one of wonderful complexity at the end 
of each of the pedipalpi. The female has also developed, in comple- 
ment to the palpi of the male, an organ called the epigynum, which 
lies immediately in front of the genital opening and which is spe- 
cialized to receive the male palpus, to store the sperms, and to com- 
municate them to the liquid body of the egg mass 'at the time of 
egg laying. 

The roles of the male and female preparatory to and during the 
mating are quite distinctive. Soon after the male become mature, 
following the last molt, when the palpal organ is completely de- 
veloped, he transfers to the palpi the sperm produced in the testes. 
This step is termed sperm induction. Next he must find a female 
and overpower her, or must elicit through characteristic actions an 
acquiescence to his desire for mating. The series of actions that 
mark the period during which he is endeavoring to gain her recog- 
nition is called courtship. The mating itself is accomplished by 
means of a series of accessory apophyses on the palpi, on the legs, 
or on other parts of the body, which seize and orient the bodies of 
both sexes in such a way that the palpal organ can come in contact 
with the apparatus of the epigynum. On the other hand, the role 
of the female is a more passive one; she needs only to ascertain 
through instinctive means that the presence of the male is to be 
welcomed and to conform to the distinct pattern that makes possible 
a successful mating. 




Spiders are to all intents sexless until they arrive at maturity. 
There is nothing in the general appearance of immature specimens 
that indicates with certainty femaleness or maleness, and nothing 
in their early-life activities of digging, hunting, or web spinning that 
marks either sex. Many people think of immature spiders as being 
female, and there is good reason for this since they usually more 
closely approximate the mature female in general appearance. It is 
probable that ancestral spiders exhibited little sexual dimorphism, 
and we note that this is true for some (but by no means all) of the 
more primitive types. Changes in the sexes have occurred both in 
the female and male, but they have been far greater in the male. 

The female is specialized for a particular function, and, if we 
presume to evaluate the sexes in finite terms, is a far greater con- 
tributor to the race than the male. Whereas the male has completed 
his assignment when he transfers the sperms to the female recepta- 
cles, the female maintains the eggs in her body until they are ready 
to be delivered and fertilized, encases them in a silken sac, guards 
them in various ways, and often is on hand to protect the young 
spiderlings for a considerable period. Her body has been molded 
as a receptacle for nurturing a variable number of developing eggs, 
and it responds to this need by maintaining a greater size than the 
male. Perhaps in response to her protective role, she is less con- 
spicuously colored and far less of an extrovert than her male. On 
the other hand, because of greater size, she is much more powerful; 
and she is dominated most of the time by predatory instincts inten- 
sified by her solitary habits. 

Among spiders, the male is a luxury item, developed for the 
single purpose of transferring the sperm. He offers no protection 
to the female or the offspring, as do many other animals, and is 
usually dead before the eggs are laid. He has changed in various 
ways to become a specialist, and is modified in many ways to play 
his part more expertly. The force that sends him into the arms of 
the female ogre is a very strong one, but he has become conditioned 
to preserve himself by taking flight should he be unwelcome. He 
has also become conditioned to overpower the female on certain 

The specialization of the male has proceeded in several direc- 
tions, and we find a considerable variety of types. In many of the 


hunting spiders the sexes are quite similar in size and seemingly 
nearly equal in strength. But even with these there are noticeable 
differences. The abdomen of the male is slimmer, and frequently 
clothed with somewhat different hairs and patches of setae. The 
color pattern of the males is almost always somewhat brighter, even 
though the species be classified as drab. In these spiders of nearly 
equal size (the Lycosidae, Oxyopidae, Gnaphosidae, Clubionidae, 
and others), the outstanding feature of the male is his somewhat 
longer legs, which give him a greater range of sensory perception 
and are thus important in evading and overpowering the female. 
This disparity in leg length is presumably maintained because of 
and correlative to the quite different modes of life of the sexes, and 
the dedication of the whole adult life of the male to sex. Among 
the spiders that have quite similar sexes except for the longer legs 
of the males are the trap-door spiders. We can interpret in various 
ways the difference in leg length. In addition to the advantages 
enjoyed during the courtship and mating, it may mean that the male 
is better fitted to wander about in search of the female. On the 
other hand, the longer legs may represent the more generalized 
condition, and the shortening of the legs of the female a response 
to the burrowing habit. 

Sexual dimorphism manifests itself in pronounced difference in 
size in many of the higher web spiders. Among the orb weavers 
exist all intergrades between a near equality of the sexes and a reduc- 
tion of the male size to an infinitesimal portion of the female bulk. 
The large humped orb weavers have males that are nearly equal to 
their females, but in other members of the same genus Aranea the 
male may be one fourth her size. In Argiope (Plate XVIII), Cy- 
closa, and many other genera, the male is much smaller than the 
female, in the first genus being about one fourth as long. The dis- 
parity is far greater in Nephila, where the female of the American 
species weighs more than one hundred times as much as the male, 
and in some exotic species is said to be over one thousand times 
larger than the male. The male is also a pygmy among such spiders 
as Mastophora (Plate III), Gasteracantha, and Micrathena. A re- 
markable sexual dimorphism exists also among the comb-footed 
aerial spiders, the Theridiidae, and the vagrant crab spiders of the 
family Thomisidae. 

The smaller size of the male gives it certain advantages during 
courtship and mating, and perhaps is used to counterbalance the 
physical superiority of the female. In Mastophora and Nephila it 


has been carried to a ridiculous extreme. These tiny males are vir- 
tually immune to the attacks of the great females, being far beneath 
the usual size of the latter's prey. Tiny insects have much the same 
immunity, and are tolerated when they crawl over a spider's body 
and left untouched when they are caught in its web. Great reduc- 
tion in size doubtless represents an orthogenetic development that 
has nothing to do with the needs of the sex itself, but persists once 
it has started. It also brings with it other problems, since the males 
become sexually mature weeks in advance of the females and must 
live until the females mature. 

The males possess the two pedipalps with the complex sexual 
organs at the end; these organs have become wonderfully specialized 
to aid in the pairing. The legs are also frequently armed with spurs 
or with rows of modified and enlarged spines that aid in clasping 
the female or in holding her chelicerae or appendages. The taran- 
tulas, trap-door spiders, and many of the primitive true spiders have 
two prominent processes on the front legs to catch the appendages 
of the female. The elongated chelicerae of Tetragnatha and Pachy- 
gnatha are used to grasp those of the female. Among aerial sheet 
weavers, the Linyphiidae, we find a tremendous group of species in 
which the heads of the males are specialized in divers peculiar ways. 
There are pointed or rounded spurs armed with curious setae, great 
rounded lobes, long, thin processes, prolongations of the clypeus or 
front; and the eyes are often carried to the tops or sides of these 
eminences. There is little doubt that these spurs are of significance 
in the mating of the species. In some of these spiders, it is known 
that the female fixes her chelicerae in the tiny pits on each side of 
the head lobe, and thus orients the male for mating. 

Sexual dimorphism also manifests itself in profound differences 
in color pattern and intensity. The carmine legs and shining black 
body of At y pus bicolor, the large purse-web spider, far outshine 
the pleasant brown tones of the female. The male tarantulas have a 
darker body and often have the abdomen set with long golden or 
reddish hairs. Among the true spiders, the males are much more 
varied and usually more handsome than their mates. This is espe- 
cially true of the jumping spiders, which in the tropics display a 
spectrum of color, the most brilliant hues of which are restricted to 
the males. In many instances, the sexes are so different in appearance 
that they were formerly regarded as being of distant species. 
Among certain of the sedentary spiders the sexes are somewhat 
more equal from the color standpoint; and of the spiny-bodied 


spiders, Gasteracantha and Micrathena, the females even have beau- 
tifully painted and sculptured bodies. 


The strange process by which the male spider transfers semen 
from the primary genital organs into the receptacles of the palpi is 
called "sperm induction." It was observed for the first time in 1843, 
by Anton Menge, who described how the male constructed a little 
web of silk, desposited a droplet of sperm upon it, and then applied 
his palpi to the drop until it was entirely absorbed into these latter 
organs. It is not at all surprising that this extraordinary action was 
doubted at first by many people, among them several eminent 
arachnologists, who insisted that there must be an internal connec- 
tion between the testes, deep in the abdomen, and the tips of the 
palpi. Now we recognize sperm induction as only the first step in 
a series of strange acts that mark the sexual life of spiders. 

Sperm induction is of necessity a very common phenomenon, but 
one must be on hand at the right time to observe it. Soon after the 
male becomes sexually mature, he charges his palpi and is then 
ready to wander about in search of a mate. This is an act which is 
not part of the previous experience of the male, but' is initiated by 
internal changes in the body associated with the arrival of maturity. 
He performs it instinctively and perfectly at the outset, because it 
is fixed in his behavior as a racial memory. Thereafter, he fills his 
palpi frequently, usually immediately following copulation, which 
is the best time to see this interesting spectacle. A few spiders are 
able to mate more than once without exhausting their semen; others 
have to pause during their mating to refill the bulbs. 

There is considerable diversity in the manner in which different 
types of spiders accomplish sperm induction. In no known instance 
is the sperm taken directly from the genital opening at the base of 
the abdomen, which would appear to be a logical means of solving 
the problem, and would be physically possible in many spiders with 
long palpi. Some spiders spin very simple, loose webs and absorb 
the semen by placing the palpi directly against it. In Pholcus a 
single silk line between the third legs is drawn across the genital 
opening until the spermatic globule adheres to it, whereupon it is 
taken up by the chelicerae and held there for direct absorption by 
the palpi. Some of the other primitive spiders do essentially the 


same, but hold the globule and the tiny web between the palpi or 
front legs until it is absorbed. A great many spiders spin a tiny 
sheet of very fine web, usually quadrangular or triangular in outline, 
place a drop upon the surface, and then take the semen indirectly 
by applying their palpi on the opposite side of the sheet. 

Among the tarantulas sperm induction is a long operation that 
sometimes requires three or four hours. The male spins a large flat 
sheet of silk, attached to adjacent objects, in which are left a large 
oval opening and a much smaller one, the two separated by a nar- 
row band of strongly woven silk. He then crawls through the large 
opening, and, lying on his back, strengthens the silk around the 
holes. After rubbing his palpi through his chelicerae and stroking 
his genital opening against the reinforced silk band between the 
holes, a drop of spermatic fluid appears and is deposited on the 
underside. The male now clambers back, and, sitting upright on the 
web over the globule, reaches around the edge of the narrow band 
to touch the sperm directly. The process of absorption takes an 
hour or more, and consists of a rhythmical alternate tapping of the 
palpi in the globule, usually at the fast rate of one hundred to one 
hundred fifty per minute. Afterward the web is destroyed or de- 

Most spiders are able to recharge their palpi much more quickly, 
usually within half an hour. T. H. Montgomery has described how 
one of the small American wolf spiders, Schizocosa crassipes, spun a 
triangular sheet attached to the floor and walls of its cage, and stood 
on the upper side of this web. A small globule of yellowish semen 
was ejaculated upon the surface of the sheet at about the middle. 
The male "then reached his palpi downward and backward, below 
the sheet, and applied the concave portion of the palpal organ of 
each against that part of the sheet which carried the drop of sperm. 
Each palpus was then rubbed against the lower surface of this drop 
several times, then withdrawn and slowly shaken in the air, while 
the other was similarly applied to the drop." 5 This process con- 
tinued for seven minutes, during which time all the sperm was taken 
up into the palpal organ, and soon afterward the male left the sperm 

The male seems to derive considerable gratification from the 
process of sperm induction. Before the act, the genital region is 
rubbed against the strands of webbing to incite the ejaculation of 

$ T. H. Montgomery, "Studies on the Habits of Spiders, Particularly Those 
of the Mating Period," Proc. Acad. Nat. Set., Philadelphia, 1903, p. 65. 


the semen. The presence of the female is not a necessary adjunct 
of the act, which is implemented by internal factors, whereas later 
on she, or her threads, become the stimuli which result in the 


Inasmuch as the young male leads the same kind of life as the fe- 
male, and lives in similar webs on plants or hides in similar places on 
the ground, maturity finds him not far distant from female neigh- 
bors. After he has prepared himself for mating by charging his 
palpi, a new impulse sends him in search of a female of his species, 
and he moves about in a random manner until he is able to detect 
his mate. 

Since spiders are largely creatures of touch, it is not surprising 
that to find the female he relies mainly on the fine sensory hairs 
that clothe his body and appendages. Contact with the substratum 
brings him something more than the mere mechanical sensation of 
touch or tension or vibration. Accompanying it is an ability to dis- 
tinguish certain chemical substances with which his hairs come in 
contact; this combined sense is called chemotactic. The receptors 
for it have not been recognized, but it seems reasonably certain that 
some of the hairs on the appendages are sensillae that respond to this 
type of stimulation. Since the sensation comes to the spider only 
when in actual contact with chemical substances, it is nearer that 
of "taste" than "smell," but it remains a quite different sense from 
any possessed by man. The male spider thus becames keenly aware 
of the presence of a mate through the touch of her threads, or of 
the trail she leaves on the substratum, or of her actual body. 

There is still another way in which some spiders are able to dis- 
cover their mates. The vagrant spiders have developed eyes of such 
acuity that they can see moving objects at a considerable distance 
for a spider and can identify the other sex when still several inches 
away. In these relatively long-sighted types, and especially in the 
jumping spiders, recognition of the female may be possible by sight 
alone, without any aid from the chemotactic sense. On the other 
hand, certain of the wolf spiders, having vision nearly on a par with 
the jumpers, nevertheless appear to require both sight and touch to 
incite pairing. 

Once the male has dicovered the female, he is on the threshold 
of realizing the racial instinct for which he has become specialized 


the transfer of the semen. But there are difficulties. The object of 
his attention may not be of the same mind as he is, and she usually 
exceeds him in size and strength. Further, since virtually all of her 
life has been devoted to capturing and feeding on animals of suit- 
able size, her first instinct is predatory. That the interloper is a male 
of her own kind is immaterial, if she is not conditioned to distin- 
guish him from any other suitable prey. There consequently ensue 
certain more or less marked preliminary activities before the actual 
mating, which constitute the spiders' courtship. Most of the initia- 
tive is taken by the male, who being the less valuable sex is con- 
ditioned to make the first advances and brave the danger. Upon him 
rests the burden of announcing himself in a convincing manner, and 
of stimulating the female to a point where sexual union is possible. 

Among the aerial spiders and other web spinners, courtship usu- 
ally consists first of some kind of vibration of the threads of the 
web, and later of stroking the body of the female. Among the 
hunting spiders there is a considerable diversity in methods of 
courting. The species blessed with good eyesight have developed 
a relatively complicated prenuptial procedure in the course of 
which the male advertises his presence by movements of the legs 
and body. Correlated with this behavior to some degree are various 
epigamic structures such as brushes or ornaments on the legs and 
tufts of hair on the head. Spiders with poorer eyesight are ordi- 
narily much more conservative in their prenuptial routine, since the 
female would be unable to see the details; but occasionally body 
ornaments are present in this group as well. There are numerous 
intergrades between a well-marked courtship, as exemplified in the 
bizarre love dances of the jumping spiders, and almost no courtship 
at all; the fundamental mechanism and the particular path that each 
group has followed to arrive at its present specialization are subjects 
that must be discussed at length. 

The prime descriptive and analytical studies of spider courtship 
and sexual biology, following the classical work of Anton Menge, 
were made in the United States by G. W. and E. G. Peckham in 
1889 and 1890, and by T. H. Montgomery in 1903 and 1910. In 
addition to fascinating descriptions of the sexual processes in many 
species, quite adequate explanations of the significance and evolution 
of various phenomena in terms of selection were presented. The 
Peckhams were strong exponents of sexual selection as outlined by 
Darwin, and concluded that the female jumping spider responded 
to the charm and beauty of the posturing male and made a conscious 


selection of a mate. They believed that the males were more 
numerous and, especially in cases where there was male dimor- 
phism, that the brighter male was preferred by the female. They 
argued that the numerous ornamental features on the bodies of the 
male jumping spiders were developed as a result of sexual selection. 
They rejected A. R. Wallace's views that such epigamic characters 
were a result of a surplus of vital energy that went with maleness: 
because the male was more vigorous, he was more highly colored 
and likely to be more successful in his suit with the female, and 
thus would more surely and more often leave progeny. 

In 1910 Montgomery rose to the defense of ordinary natural 
selection, and in a masterful essay virtually refuted the claims of 
the Peckhams with regard to sexual selection. Montgomery be- 
lieved that the adult male "is excited simultaneously by fear of and 
desire for the female, and his courting motions are for the most 
part exaggerations of ordinary motions of fear and timidity. By 
such motions he advertises himself to the female as a male, but there 
is no proof that he consciously seeks to arouse her eagerness by 
esthetic display . . . there seems to be no good reason to hold that 
the female is actuated in her choice by sensations of beauty." 6 
Montgomery defined courtship in a more limited way than do 
modern arachnologists, and believed that in some vagrants there was 
none at all. However, judging from his descriptions, his interpre- 
tation is in most cases a modern one. Commenting upon spiders 
that have good sight, he said as follows: "What we do know is 
that the male by his courtship, a set of motions resulting from the 
conflicting states of sexual desire and fear, exhibits or advertises 
himself as a male; and that the female on sight of this courtship 
recognizes him as a male and accepts him if she be eager, or else 
becomes gradually stimulated by watching him." 7 Montgomery 
further believed that many secondary sexual characters in the male 
"may be most readily explained as being conserved by simple selec- 
tion. Peculiar male ornamentation would be selected because it 
insured quicker sex-recognition, therefore prompter mating. The 
male is thereby more surely accepted by the female, not selected by 
her in the sense of Darwin. The process is much more an announce- 
ment of sex by the male than a choice by the female, and results in 

S T. H. Montgomery, "The Significance of the Courtship and Secondary 
Sexual Characters of Araneads," The American Naturalist, Vol. XLIV (1910), 
pp. 151-2. 

'Ibid., p. 169. 


the female accepting the sex rather than the individual." 8 Mont- 
gomery did not subscribe to Wallace's belief that the males ex- 
hibited a higher degree of vitality, but argued instead that the need 
of greater protection by the females was the reason for their less 
conspicuous coloration, as in birds. 

It has remained for W. S. Bristowe to take up the problem where 
Montgomery left off, and to extend and elaborate his thesis on the 
basis of a much vaster literature and innumerable observations of 
European spiders. Bristowe's views were presented in convincing 
fashion in 1929, in a long paper entitled "The Mating Habits of 
Spiders, with special reference to the Problems surrounding Sex 
Dimorphism." In this treatise he pointed out that the complicated 
visual displays of the jumping spiders probably arose by ordinary 
natural selection. 

Primitive spiders were short-sighted hunters that groped their 
way as they walked and stretched out their front legs to test the 
substratum. Perception of the environment was accomplished by a 
chemotactic sense largely confined to the extremities of the append- 
ages. Since sight was limited, it was necessary for the male to touch 
the spoor, the threads, or the body of the female to discover her 
presence. Since the males were able to detect the presence of a 
mate often before she was touched, those males that started to ad- 
vertise their identity early by means of their front legs were more 
likely to survive the assault of their larger, predaceous mates. 
Aiovement of the appendages and parts of the body enhanced the 
chances of survival and also increased the possibility of finding a 
mate. All these advances in posturing were accompanied by a 
gradual improvement in the acuity of the eyes, likewise arrived at 
by selection. Males tend to produce more pigment than females, so 
those that were able to develop strikingly colored spots in front, 
visible to the female, were able to survive more often. The various 
antics and decorations worked hand in hand. 

The most generalized types of courtship are exhibited by those 
spiders in which distance perception is feebly developed, the ma- 
jority being short-sighted hunters. More specialized displays have 
arisen in two ways: By improvement in the acuity of the eyes, as 
in the long-sighted hunters; and by development of expansive webs 
that enlarge the limits of perception by touch, as in the web build- 
ers. These divisions approximate in a general way the systematic 
position of the species. 
., p. 173. 



The Short-Sighted Hunters. Most of these spiders are nocturnal 
creatures of the ground that rely almost entirely on touch to inform 
them of the character of their environment. They test the surface 
by means of their legs, which act both as organs of touch and of- 
fensive weapons. Their approach to the female is usually a bold 
one, since most of them approximate her in size, and a mere touch 
is sufficient to inform them of her sex and species. Further, this 
physical contact probably gives the female the same information. 
Recognition is almost instantaneous and largely based on the chem- 
ical sense. There remains only for the male to stimulate the female 
until mating can be accomplished. He does this by stroking and 
tickling her body, while at the same time maintaining a firm grip 
on her with his legs or chelicerae, so that she cannot escape. 

The tarantulas are wonderful subjects for the study of mating 
behavior in the short-sighted spiders. Alexander Petrunkevitch has 
described the courtship of Dugesiella hentzi thus: 

When the restlessly wandering male happens to touch with 
his legs some part of the body or a leg of the female, he at once 
stops short and begins to strike simultaneously and violently 
with his anterior, sometimes with all four front feet. . . . This 
continuous beating with the front legs upon the body or legs 
of the female constitutes the first step in the courtship on the 
part of the male. In case the female does not attempt to run 
away, the male soon shifts his position until he is facing the 
female. The behavior of the female during the first stage of 
the courtship is composed of two elements. At the first touch 
she raises the front legs and assumes the attitude of defense and 
threat. The subsequent touching results in her rising high on her 
hind legs while still holding up the front legs. Finally, she opens 
the fangs and the male catches them with the hooks on his front 
legs. . . . They serve admirably to guard the male against possi- 
ble injury or even death while at the same time aiding him in 
the act of coitus. For he now forcibly pushes back the cephalo- 
thorax of the female with his front legs and drums with the 
patellas of the palpi on her sternum, all the time advancing. 9 
The mating that follows lasts only a minute or two, after which 

A. Petrunkevitch, "Sense of Sight, Courtship and Mating in Dugesiella 
hentzi (Girard), a Theraphosid Spider from Texas," Zool. Jahrbucher Syst., 
Vol 31, p. 373. 


the two sexes part, the female ordinarily making no attempt to 
attack the male. 

Many of the small running spiders spin little silken cells under 
stones or in tiny nooks on trees. Wulfila saltabunda, one of the 
smaller anyphaenids, weaves a little curtain beneath the leaf of an 
herb or bush and stands upright on the silk. The male stands be- 
neath the sheet and drums on it with his long front legs and palpi, 
and at intervals pulsates his abdomen up and down. The female 
often responds by tapping with her front legs and palpi, and vi- 
brates the sheet immediately above the male. The male will court 
the female in this position for hours, but mating ordinarily does 
not occur until evening. He seems able to avoid the female with- 
out great effort, and to be relatively immune to her attacks. How- 
ever, she is much more powerful and can kill him with ease if he 
approaches her too insistently when she is pregnant or otherwise 
not ready for mating. 

Some of the gnaphosids, notably Drassodes and Zelotes, are said 
to take possession of an immature female by enclosing her in a 
silken cell. Just after her final molt and before she has attained 
her full strength, the male mates with her. This is possible since the 
male matures earlier than the female and is able to recognize her 
as a prospective mate even though she is immature. It is the habit 
of many of these spiders to live in adjacent silken sacs under the 
same stone or piece of bark. Not uncommonly, a male in the 
penultimate stage, when he presumably has no instinct for recog- 
nizing or sequestering a mate, will be found in a sac with an im- 
mature female. This suggests that the association in many instances 
may be only a fortuitous one. 

A few of the sedentary spiders with inferior eyesight have given 
up life on webs and have become vagrant secondarily. The most 
interesting example is that of Pachygnatha, one of the big-jawed 
spiders that live in grass and vegetation especially in cattail marshes. 
The male prowls among the grass roots and finds his mate by touch. 
He seizes her and, aided by special spines and long teeth on his 
chelicerae, holds hers firmly until her mating instincts have become 
aroused or her hostility forces a retreat. 

Among the crab spiders we find few of the preliminary activi- 
ties identifiable as true courtship. These spiders live on the ground 
and on plants and are for the most part diurnal in habit. The eyes 
of some are fairly large, but the spiders seem to make little use of 


sight in their hunting or courting, a fact which may be partially 
accounted for by their habits of deception and inactivity. When a 
male discovers the female of his species, he immediately climbs 
upon her back or seizes an appendage with his chelicerae. He is 
much more agile, and can tickle and caress her body until he is able 
to accomplish his purpose. In some of these spiders the males are 
very much smaller, and usually more darkly marked than the 
females. The latter often walk around with a tiny long-legged 
male clinging to their backs, paying little attention to his activities. 
Certain spiders have interpolated in the sequence of their court- 
ship an habitual act that tends to set them apart from all others. 
The male of the stocky little species of Xysticus spins a thin web 
over the female, attaching tiny silken lines from her abdomen and 
legs to the substratum. This web has been called the bridal veil, 
and its spinning is one of the extraordinary prenuptial habits of 
many crab spiders. 

The Long-Sighted Hunters. It is among the spiders of this 
group that we find those notorious for their love dances (Text Fig. 
2). Almost all are day hunters, a habit in keeping with their need 
for light to display themselves properly during courtship. Some of 
them are well-known vagrants, and have received such expressive 
names as "wolf spider," "lynx spider," and "jumping spider" in rec- 
ognition of their life of action. However, even in this group with 
the best eyes, reliance is only partially placed on sight during court- 
ship; and in most instances the event does not occur unless the male 
actually touches the female, even though he may perceive her by 

The whole makeup of the prenuptial display posture, antics, 
and epigamic ornaments is distinct for each species. While de- 
veloping these features nature has had to keep many allied species 
separate, and thus has evolved by selection many different kinds of 
dances. The female has become conditioned to respond only to 
those performed by her species, and rarely makes mistakes. The 
actual mating is usually preceded by a certain amount of stimula- 
tion by the legs of the male, and it is this final action that com- 
pletely precludes the possibility of any related species being ac- 

In most wolf spiders, the palpi and front legs are provided with 
some kind of ornamentation that contrasts sharply with the rest of 
the body. Where such epigamic characters are present, their 


Richard L. Cassell 

Black widow, Latrodectus mactans, with prey 


Lee Passmore 

a. Tarantula, Aphonopelma, and tarantula hawk 

Lee Passmore 

b. Tarantula, Aphonopelma, and tarantula hawk 


movement is usually part of the courtship ritual. Among the small 
Pardosae the palpi, usually bedecked with jet-black hairs or varie- 
gated with black and snow-white ones, receive a large share of the 
ornamentation. The larger lycosids usually have the front legs 
darkened and occasionally provided with brushes of conspicuous 
black hairs. 

The courtship patterns of American wolf spiders were first in- 
vestigated in detail by Montgomery in 1910, and more recently, in 
1936, were made the subject of special analysis by B. J. Kaston. 

A few of our species may be mentioned. Pardosa milvina (Plate 
XXV and Text Fig. 2, A) is a small, long-legged wolf spider with 
black head and palpi. 

The courtship motions are as follows: The male stands with 
his body well elevated above the ground (an attitude that a 
female takes only when she is aggressive) on his three posterior 
pairs of legs, his head higher that his abdomen, so that the long 
axis of his body describes an angle of 3o-40 with the surface 
of the ground. He waves his palpi upward in the air (i.e., 
straightening them out before his head) flexes them outward, 
from one to three times, then draws his body slightly backward 
and downward, rapidly waving in the air the outstretched palpi 
and first pair of legs, and spasmodically shaking the whole body 
with the violence of the movement. The vehemence and to 
some extent the attitudes reminds one forcibly of a small terrier 
barking at a cat. The movement of the palpi exhibits most 
clearly their relatively huge, black terminal joints. When the 
male is timid, or not very eager, he may wave only his palpi, 
and these slowly and alternately instead of together. The male 
repeats these motions several times, usually becoming more ve- 
hement each time, then moves a step nearer the female, repeats 
them again, moves nearer again, so that in a short time his out- 
stretched shaking forelegs come in contact with the female. 10 

A closely related species, Pardosa saxatilis, raises the forelegs 
alternately and at the same time wigwags with his jet-black palpi, 
using them alternately as well. In Pardosa emertoni, the front legs 
are held up in the air and the palpi are flexed and jerked, and fol- 
lowed by movements of the abdomen. Pardosa modica makes little 

10 T. H. Montgomery, "Studies on the Habits of Spiders, Particularly Those 
of the Mating Period," Proc. Acad. Nat. Sci., Philadelphia, 1903, pp. 83-4. 


use of his front legs during the visual courtship but wigwags with 
his palpi, often standing high on the tips of his tarsi. Within the 
same group such striking differences in courtship are often found. 
Lycosa gulosa is a comon grassland spider varying in color from 
gray to nearly black, and exhibiting only slight differences between 
the sexes. From its courtship antics it once was given the common 
name of "purring spider." B. J. Kaston explains: 

Immediately upon coming in contact with the female, or 
within three minutes thereof, the male begins to drum his palps 
rapidly against the floor of the cage. These drumming move- 
ments are made so rapidly that a distinct purring or humming 
sound can be heard. The palps are used alternately and are 
raised only a very short distance during the process. The body 
is held at an angle so that the posteriar end of the abdomen 
almost touches the floor. As a consequence when the male be- 
gins to twitch his abdomen in a vertical plane, the tip strikes the 
floor. However, I could not detect any sounds made by this 
part of the body. It is highly probable that the vibrations set 
up in the substratum by the tapping movements of the palps 
and abdomen are perceived by the female. This may exert an 
exciting influence on her in a manner analogous to that which 
occurs in web-building species, where the male tweaks the 
threads of the female's snare. 11 

The male of Schizocosa crassipes has a thick covering of black 
hairs on the tibiae of the front pair of legs, which are conspicuous 
epigamic brushes. He extends his long first legs out in front and 
taps the floor with both about four or five times, simultaneously 
and in rapid succession. Then the forelegs are raised and the body 
is elevated high upon the posterior legs, while at the same time the 
palpi are extended downword to touch the floor below the face. 
In this position, the brushes on the front tibiae are very conspicu- 
ously displayed. He advances toward the female with a rhythmi- 
cally repeated waving of legs, jerking of body, and posturing. A 
closely allied species, Schizocosa bilineata, bedecked with similar 
ornaments on the front legs, seems on the other hand to make no 

11 B. J. Kaston, "The Senses Involved in the Courtship of Some of the 
Vagabond Spiders," Entomologica Americana, Vol. XVI (1936) (new series), 
p. 114. 



use of them during mating; in fact, seems to have no visual court- 
ship at all. 

The European Pisaura mirabilis is remarkable for its habit of 
presenting the female with a fly as an inducement to mating. Bris- 
towe has described the activity in the following manner: 

A male was given a fly and placed in a box with a female. 
He proceeded to enwrap the fly with silk, and then walked 
about with it in a jerky fashion until presently the attention of 
the female was attracted, and she approached him. He held out 
the fly to her, and after testing it with her falces, she seized hold 
of it. The male then crept to a position almost underneath the 
female, a little to one side, and inserted his right palp. After 
twenty-five minutes he withdrew his palp and joined the female 
at the fly. This is rather a remarkable piece of instinct a car- 
nivorous creature like a spider deliberately giving up his food 
as an offering to the female. 12 

The Peckhams first brought to the attention of naturalists the 
bizarre courtship antics of the American jumping spiders. The 
females of this group are for the most part pleasantly colored in 
grays and browns, while upon the males has been showered an in- 
finite variety of color and ornament. The chelicerae are enlarged, 
molded into odd form, and usually colored in iridescent purple, 
green, or gold. The principal feature of the face is a row of four 
great pearly-white eyes, and it is embellished above with crests or 
plumes and overhung with bright hairy fringes. The first legs are 
wonderfully ornamented with peculiar enlargements of striking 
colors, and are clothed with fringes of long colored hairs, pendant 
scales, and enlarged spines. Although less attention has been given 
to the other legs, they also are sometimes supplied with unusual 

The Peckhams thought that the male jumpers were much more 
numerous and that "it was highly improbable that a female ever 
mates with the first male that comes along. . . . She rejects the ad- 
vances of one after another; she flies and is pursued; she watches, 
with great attention, the display of many males, turning her head 
from side to side as they move back and forth before her; she be- 
comes so charmed as even to respond with motions of her own 
body. If we may judge by her attitude, she is observant of every 

12 W. S. Bristowe, Proc. Zool. Soc. London, Vol. I (1926), p. 330. 


posture that the male takes, and appreciative of his every claim of 
beauty." Whereas we reject the sexual selection of the Peckhams as 
not truly representing the facts, it must be admitted that the final 
results are the same. Through the elimination of certain males 
directly by killing them for food, and indirectly by rejecting them 
as mates, there is an active female selection. 

During their antics, the male jumping spiders make every effort 
to bring into position the striking features of their bodies. Many of 
them stretch out their front legs and wave them rhythmically and 
insistently, or take an imposing attitude with arms outstretched like 
a semaphore. Others lower these legs and keep them motionless so 
that nothing interferes with the view of the bands and marks on 
head and clypeus. Some tilt upward to display an iridescent rose or 
gleaming metallic abdomen. In some the intensity of the dance 
verges on frenzy, whereas others perform their pantomime with 
grace and decorum. Some fascinating descriptions are given by the 

Tutelina elegans is one of the most common eastern American 
jumping spiders. 

Both sexes are beautiful. The male is covered with iridescent 
scales, his general color being green; in the female the coloring 
is dark, but iridescent, and in certain lights has lovely rosy tints. 
In the sunlight both shine with the metallic splendor of hum- 
ming-birds. The male alone has a superciliary fringe of hairs 
on either side of his head, his first legs being also longer and 
more adorned than those of his mate. The female is much 
larger, and her loveliness is accompanied by an extreme irrita- 
bility of temper which the male seems to regard as a constant 
menace to his safety, but his eagerness being great, and his 
manners devoted and tender, he gradually overcomes her opposi- 
tion. Her change of mood is only brought about after much 
patient courting on his part. While from three to five inches 
distant from her, he begins to wave his plumy first legs in a 
way that reminds one of a windmill. She eyes him fiercely and 
he keeps at a proper distance for a long time. If he comes close, 
she dashes at him and he quickly retreats. Sometimes he becomes 
bolder and when within an inch, pauses, with the first legs out- 
stretched before him, not raised as is common in other species; 
the palpi also are held stiffly out in front with the points to- 
gether. Again she drives him off, and so the play continues. 


Edwin Way Teak 

Spider relatives: Harvestmen on aphis-covered rose shoots 


a. Molting. Carapace and chelicerae freed 

George Elwood Jenks 

George Elwood Jenks 

b. Molting. The shed skin 

TRAP-DOOR SPIDER, Bothriocyrtum californicum 

Lee Passmore 

c. Cradle of eggs in burrow 



A. Pardosa milvina Hentz. B. Habronattus viridipes Hentz. C. Peckhamia noxi- 
osa Hentz. D. Hyctia pikei Peckham. E. Peckhamia picata Peckham. F. 

Euophrys monadnock Emerton. 
(Redrawn from Kaston, Emerton and Peckham). 


Now the male grows excited as he approaches her, and while 
still several inches away, whirls completely around and around; 
pausing, he runs closer and begins to make his abdomen quiver 
as he stands on tiptoe in front of her. Prancing from side to 
side, he grows bolder and bolder, while she seems less fierce, 
and yielding to the excitement lifts up her magnificently irides- 
cent abdomen, holding it at one time vertically and at another 
sideways to him. She no longer rushes at him, but retreats a 
little as he approaches. At last he comes close to her, lying flat, 
with his first legs stretched out and quivering. With the tips of 
his front legs he gently pats her; this seems to arouse the old 
demon of resistance, and she drives him back. Again and again 
he pats her with a caressing movement, gradually creeping nearer 
and nearer, which she now permits without resistance until he 
crawls over her head to her abdomen, far enough to reach the 
epigynum with his palpus. 13 

The largest American jumping spiders are the massive, hairy 
species of Phidippus (Plates 30, 31 and 32; Plates XXXI and 
XXXII), which are gaily marked with light spots and often gaudily 
colored in carmine, orange, and yellow. The face is usually distin- 
guished by tufts of curled hairs and bands of colored scales and 
hairs. The elegance of their front legs is especially notable, with 
long flowing fringes of colored hairs. Some species wave these 
handsome legs so vigorously that they cross at the tips, but in most 
instances they are brought to an angle of about forty-five degrees, 
and, as the male sways toward the female, or approaches her in 
zigzag fashion, are moved up and down to bring into view the 
plumes and iridescent plates. 

Representative of another group very numerous in species is 
Metaphidippus capitatus. When courting, this species approaches 
the female rapidly until a couple of inches away, arms extended 
upward, then stops and drops them down close to the surface. In 
this position, the face, variegated with snow-white bands and with 
contrasting gleaming bronze scales, becomes the center of atten- 

Peckhamia picata (Text Fig. 2, E) is one of the antlike spiders. 

13 G. W. and E. G. Peckham, "Observations on Sexual Selection in Spiders 
of the Family Attidae, Occasional Papers Nat. Hist. Soc., Wisconsin, Vol. i 
(i) (1889), p. 46. 


The most important difference in the sexes is the greater 
thickening of the first legs of the male. These are flattened on 
the anterior surface and are of a brightly iridescent steel-blue 
color. Unlike most of the Attid males, this species keeps all his 
feet on the ground during his courtship; raising himself on the 
tips of the posterior six, he slightly inclines his head downward 
by bending his front legs, their convex surface being always 
turned forward. His abdomen is lifted vertically so that it is at 
a right angle to the plane of the cephalothorax. In this position 
he sways from side to side. After a moment, he drops the abdo- 
men, runs a few steps nearer the female, and then tips his body 
and begins to sway again. Now he runs in one direction, now 
in another, pausing every few moments to rock from side to 
side and to bend his brilliant legs so that she may look full at 
them. 14 

The little male of Habrocestum pulex is not so gaily colored as 
some of his relatives, but he makes up in enthusiasm for his lack of 
brilliance. His whirling dance has been excellently described by 
the Peckhams: 

He saw her as she stood perfectly still, twelve inches away; 
the glance seemed to excite him and he at once moved toward 
her; when some four inches from her he stood still and then be- 
gan the most remarkable performances that an amorous male 
could offer to an admiring female. She eyes him eagerly, chang- 
ing her position from time to time so that he might be always in 
view. He, raising his whole body on one side by straightening 
out the legs, and lowering it on the other by folding the first 
two pairs of legs up and under, leaned so far over as to be in 
danger of losing his balance, which he only maintained by sid- 
ling rapidly toward the lowered side. The palpus, too, on this 
side was turned back to correspond to the direction of the legs 
nearest it. He moved in a semicircle for about two inches and 
then instantly reversed the position of the legs and circled in 
the opposite direction, gradually approaching nearer and nearer 
to the female. Now she dashes toward him, while he, raising his 
first pair of legs, extends them upward and forward as if to 
hold her off, but withal slowly retreats. Again and again he 
circles from side to side, she gazing toward him in a softer mood, 
"Ibid., p. 43. 


evidently admiring the grace of his antics. This is repeated 
until we have counted in circles made by the ardent little 
male. Now he approaches nearer and nearer and when almost 
within reach, whirls madly around and around her, she joining 
and whirling with him in a giddy maze. Again he falls back and 
resumes his semicircular motions, with his body tilted over; she, 
all excitement, lowers her head and raises her body so that it 
is almost vertical; both draw nearer; she moves slowly under 
him, he crawling over her head, and the mating is accom- 
plished. 15 

In the many American species of Habronattus, the front legs 
and the face are lavished with decoration. The enlarged tibiae of 
oregonense, the hirsute legs of agilis, the iridescent blue metatarsi 
of hirsutus, the pink palpi, scarlet clypeus, banded face of other 
species, are only a few of the expressions of color and ornament in 
the group. Some of the species have the third legs modified, and 
among them is viridipes with a strangely formed patella armed with 
a pale spine and marked with a black spot. During courtship he 
finds it a difficult task to balance himself while endeavoring to ex- 
hibit two pirs of legs. 

When he gets to within an inch of the female, he lifts the 
first legs nearly at right angles with the body, giving them a 
bowed position, with the tips approaching each other, so that 
each leg describes a semicircle, while the palpi are held firmly 
together in front. Up to this time he has held the body well 
above the ground, but now he lowers it by spreading out the 
second and fourth pairs, at the same time bringing the tips of 
the third pair nearer the body and arching the legs over the 
posterior part of the cephalothorax in such a way that the proxi- 
mal ends of the tibiae nearly meet. As he stands in this position, 
the female, who is watching him eagerly, has the front surface 
of the apophysis plainly in view over the dorsal surface of the 
cephalothorax, and face and clypeus are also well exposed. Now 
he approaches her very slowly, with a sort of creeping move- 
ment. When almost near enough to touch her, he begins a very 
complicated movement with the first pair of legs. Directing 
them obliquely forward, he again and again rotates each leg 
around an imaginary point just beyond the tip; when they are 


at the lowest point of the circle, he suddenly snaps the tarsus 
and metatarsus upward, stiffening and raising the leg and thus 
exposing more completely its under-surface. While this is going 
on with the first pair, he is continually jerking the third pair up 
higher over his back, as though unable to get them into a satis- 
factory position, and the abdomen is kept twitching. 16 

Such a display can be carried even farther to include virtually 
all the legs. Euophrys monadnock is a boreal spider that lives in the 
moss and lichens of open pine forests, frequently being found in 
the western mountains. The handsome little male (Text Fig. 2, F) 
displays the orange femora of his hind legs when he postures before 
the female. 

The palpi, jet-black with yellow ends, hung down in front; the 
first legs, black with pale tips, and fringed with long, thick, pur- 
plish scales, were thrown diagonally upward; the body was 
raised high on the tarsi of the second and third pairs, the third 
being lifted so that the colored femora would be seen over the 
second, while the legs of the fourth pair were dropped and held 
at just the angle that brought the femora into view between 
those of the second and those of the third pair. In this difficult 
attitude, the spider began to move. There was none of the awk- 
wardness shown by Pellenes (Habronattus) in trying to keep the 
third leg in position; indeed, there was no muscular action vis- 
ible as he glided smoothly back and forth, while the female, 
turning from side to side, kept him constantly in sight. 17 

The Web Builders. The spiders in this category are for the most 
part species that have poor eyesight. Many are confirmed sedentary 
types or put a considerable reliance on silk, thus effectively obvi- 
ating a real need for keen vision. In fact, they have extended their 
snares in ways that carry far beyond the limits of ordinary sight. 
Through the medium of her web threads, the male is able to per- 
ceive with reasonable certainty the presence of a female of his spe- 
cies, and to diagnose her attitude. Courtship among the web spin- 
ners usually consists of finding out how the land lies, then tele- 

16 G. W. and E. G. Peckham, "Additional Observations on Sexual Selection 
of the Family Attidae," Occasional Papers Nat. Hist. Soc. } Wisconsin, Vol. i 
(3) (1890), p. 119. 

17 G. W. and E. G. Peckham, "Revision of the Attidae of North America," 
Trans. Wisconsin Acad. Sci., Vol. XVI (1909), p. 360. 


graphing to the occupant of the web the arrival of the male. In 
later stages a tactile stroking of the body precedes the coition. The 
male web spinner has an advantage in that he can approach the 
female at a distance and is not immediately vulnerable to her attack. 
A hasty retreat follows notice from the female that he is unwel- 
come. The whole routine of tweaking the threads, approaching the 
female on the surface of the web, and further stimulating her at 
close quarters, constitutes a tactile display of courtship equal in 
interest to that of the long-sighted spiders. 

Among the web builders we find some females that are very 
tolerant of their males and accept their advances eagerly. Some live 
together quite amicably for weeks, and others are gregarious by 
habit, spinning huge communal webs in which the sexes live in 
seeming equality. Withal, there also exist in this group females 
notorious for their aggressiveness, which are known to destroy their 
males before or after the mating. Specialization in the orb weavers 
has taken them along a path where there is a premium for vigorous 
response to the touching of their snare by any interloper. The 
spider hurls itself over its web and, by a remarkable exhibition of 
trapeze artistry, quickly subdues and enswathes its prey. It is there- 
fore not surprising that so finely trained an aggressor should occa- 
sionally fail to recognize the advances of a male of her species. The 
latter is in especial danger if the female is not fully adult, has already 
mated, or is gravid. After the mating he is in great danger if he 
tarries too long; it is then that he is most often killed. 

Among the web spinners are some that are more closely allied 
to the long-sighted hunters than to their own group, and, except for 
the silken sheet web over which they run in an upright position, 
resemble the former in their courtship and mating attitudes. Males 
of the Agelenidae are in most cases equal to the females in size, and 
superior in agility. Agelena Pennsylvania a, the commonest grass 
spider of the naevia group, moves upon the web of the female and 
signals to her by tapping the silk with his legs and palpi. His ad- 
vance is usually slow and measured until he is able to touch her 
with his legs, whereupon he actively seizes her. In most instances 
resistance is not strong; the male grasps her hind femora in his 
chelicerae and carries her to the entrance of the silken tunnel, where 
mating often occurs. He throws her on her side and, his head point- 
ing in the opposite direction from hers, turns her over and applies 
the palpi from either side. 

The tangled-web spinners (family Theridiidae) include many 


species among which the females show little hostility to the male 
before mating and enter actively into the preliminary maneuvers. 
The description of the courtship of Theridion tepidariorum by 
Montgomery illustrates the general habit of the whole genus. 

The introductory steps of the mating are as often made by the 
female as by the male, and she often shows quite an insatiable 
eagerness, even sometimes leaving food to approach the male. As 
soon as the male commences to move upon her web she recog- 
nizes him as a male of her own species, and, when she is eager, 
commences immediately to signal to him, both spiders being on 
the lower surface of the web and upside down (the usual posi- 
tion). The female hangs to the web with the third and fourth 
pairs of legs, and shakes the longer second and first pairs vigor- 
ously and spasmodically in the air (when those legs are not at- 
tached to web lines), otherwise with them she shakes web lines 
to which they are hooked. This 'signalling' is a sign of eagerness 
on the part of the female, and so far as I have observed she makes 
it at no other time than when she is eager and notices the ap- 
proach of a male of her own species. There are individual dif- 
ferences in the mode of signalling, as well as differences in 
accord with the degree of eagerness of the female; sometimes a 
female signals without moving from her original position, some- 
times with the signalling she moves by short steps towards the 
male. When she is not eager she either remains motionless, or 
else rushes hostilely toward the male as at an object of prey; in 
both cases the male makes no advances, and when she is mark- 
edly aggressive he escapes by dropping from the web. The 
whole attitude of the male is that of combined timidity and 
eagerness; he is much smaller than the female and upon a foreign 
web, and usually acts with great caution. 18 

In this species the female may mate with many males and, except 
when heavy with eggs, rarely rejects the advances of a suitor. 
Whereas the male usually leaves hurriedly after mating, in some 
species of this group he moves to one side of the web, refills his 
palpi with semen, and returns to mate frequently. Among the sheet 
weavers of the family Linyphiidae, the male is also a privileged con- 
sort and is only rarely menaced by an intractable female. 

18 T. H. Montgomery, "Studies on the Habits of Spiders, Particularly 
Those of the Mating Period," Proc. Acad. Nat. Set., Philadelphia, 1903, p. 


A - 

^ * 



Lee Pussmore 

a. Exposed burrow 

4. Male 

'"Ik* TOI^:-- 

Lee Pcasmore 

c. Cork-door nest held open 
CALIFORNIA TRAP-DOOR SPIDER, Bothriocyrtum californicum 


a. Capturing a ground beetle 

Walker Van Riper 

b. Lifting the cork lid 
CALIFORNIA TRAP-DOOR SPIDER, Bothriocyrtum californicurn 


The male spider must often coax the female out from her retreat 
before mating; sometimes he spins a series of lines as a bower in 
which the pairing can take place. The female of Metepeira laby- 
rinthea spins a labyrinth of tangled threads behind her orb web and 
stays in it much of the time. Other orb weavers hide in a leafy 
retreat near their webs and communicate with the orb by means of 
a signal line held in the claws of one of the legs. According to 
G. H. Locket, the English arachnologist to whom we owe much 
for his keen observations of the web-spinning spiders, the male of 
Zilla x-notata "climbs to the center of the female's web and usually 
seizes the line communicating with the female's hiding place with 
his four front legs. With his back legs he seizes one of the adjacent 
radii at the centre and starts a series of jerking and plucking move- 
ments on the communicating line, using himself as a sort of spring 
at the angle of the radii. If the female does not respond he then 
usually climbs to her retreat, but returns again after an interplay 
of legs . . . eventually the female comes out, also making plucking 
motions, and, after a short interplay of legs, the male begins making 
thrusts at her epigynum; the palps are then applied alternately." 

Among the orb weavers we find some species in which the male 
is a mere pygmy hardly worthy of the female's notice. During the 
mating season there are often three or four tiny males, only one- 
fourth the length of the female, hanging in the outskirts of the web 
of the large orange argiope, Argiope aurantia. They make known 
their presence by plucking and vibrating the web lines. 

When advancing toward the female, the male seems to pause 
and pull at the strands of web, as though to notify her of his 
approach. When he comes toward her from in front she im- 
parts a slight motion to the web with her legs, which seems to 
serve as a warning, as he either moves away or drops out of the 
web. When he comes from behind she pays no attention to 
him until he begins to creep on to her body, when she slowly 
raises one of her long legs and unceremoniously brushes him 
off. 19 

No observations have been made of the mating of the bolas 
spiders of the genus Mastophora. This male is such a tiny creature 
that he probably has complete immunity from the attack of the 
female, and clambers over her grotesque body like a tiny parasite. 

19 Peckham, "Observations on Sexual Selection in Spiders of the Family 
Attidae," op. cit., p. 55. 


The need for any courtship in such animated spermatophores should 
not be very great. 


The transfer of sperm is accomplished in a most amazing manner 
by means of the palpus and the epigynum. Whereas in most animals 
the copulatory act contributes little or nothing to knowledge of the 
group, in spiders the details are of great interest and in many cases 
of deep significance. During the mating the female becomes quies- 
cent and remains in a kind of cataleptic state until its termination. 
In many species, the female first contributes to the mating by align- 
ing parts of the epigynum so that the corresponding units of the 
male palpus can be properly oriented. The attitude maintained by 
the sexes is most constant within the species, and the details some- 
times give us data on the general position of the spiders of the series. 

Two principal embraces are found among spiders. In the taran- 
tulas, the six-eyed spiders, and the aerial web spinners, the male 
usually approaches the female from in front, and, moving under- 
neath until his cephalothorax lies beneath her sternum, applies his 
palpi directly. This is frequently referred to as the Dysdera em- 
brace. Among the web spiders it is a quite favorable position, since 
the female hangs inverted below the male and does not greatly 
menace him. On the other hand, the male wandering spiders that 
use this type of embrace are in a dangerous situation beneath the 
jaws of the female. Retreat after the mating, when the female has 
largely lost her sexual ardor, is likely to be hazardous. In many 
instances, the males carefully disengage themselves and then leap 
back and away quickly, showing that they have become conditioned 
to compensate for a changed attitude in their mates. 

The second position, the Lycosa embrace, is the one used by the 
wolf spiders and the running spiders of the higher families. Here 
the male crawls over the body of the female, and, with head pointed 
in the opposite direction from hers, reaches around the side of her 
abdomen to apply a palpus to the epigynum. There is far less danger 
to the male when he assumes this position, and he is more or less in 
command of the female until he disengages the palpus and runs 
away. He serves the right side of her epigynum with his right 
palpus, and swings around to the other side when using the left 
palpus. Some of the vagrants have so modified their bodies that it 
has been necessary to change the type of embrace. Thus, the ab- 


domen of a female of the stocky crab spiders is often so wide that 
the male must crawl to a ventral position in order to apply his 
short palpi. 

The actual copulation, accomplished by means of the secondary 
genital structures, consists in the orientation and pressing of the 
embolus into the atriobursal orifice of the female. Many of the 
primitive spiders that use the Dysdera embrace apply both the palpi 
simultaneously to the orifices just beneath the genital furrow. Since 
both palpi are applied directly from beneath, it follows that the 
right palpus enters the left orifice, and the left palpus the right 
orifice, of the female. Other spiders of that series, for example the 
tarantulas and their allies, apply each palpus alternately, but prob- 
ably use the same side for insertion as indicated above. In all the 
higher spiders this situation is reversed, with corresponding palpi 
serving the corresponding female orifices. This most interesting fact 
indicates that specialization in the epigynum and palpus has been 
accompanied by profound changes in the insertion of the embolus. 

The actual union of the secondary genital structures may be of 
very brief duration, only a few seconds, or it may be prolonged 
for several hours. When the organs are highly complicated, the 
insertion is apparently aided by a preliminary lubrication of the 
palpus accomplished by drawing it through the chelicerae and is 
finally consummated only after the manipulation of several different 
elements. The palpus may be scraped across the epigynum until a 
spur on the tibia, on the tarsus, or on the bulb itself becomes fixed 
in a particular groove. Once firmly anchored in this starting point, 
the palpus swings to assume a position that, with the aid of ridges, 
grooves, and other processes on the epigynum corresponding to its 
own outline, makes it possible to guide the embolus to exactly the 
right point for entering the orifice. At this stage, the bulb of the 
palpus is still largely in its resting position, lying folded in the cup 
of the tarsus, and the preliminary contacts serve to hold it firmly 
in place. Most spiders have at the base of the bulb various thin 
pouches, or hematodochae, that swell up with the influx of blood 
until they attain enormous size. This distention causes the entire 
bulb to turn on its axis, which action forces the embolus into the 
appropriate opening. The whole embolus (usually a thin spine or 
heavy spur but often a coil that may consist of several turns) is 
screwed into the epigynum, following the corresponding tubes in 
this organ until it reaches the receptaculum seminis. Semen is then 
pumped into this receptacle by means of a strong blood pressure in 


the palpus, brought about by contractions of the muscles of the 

The female retains the viable sperms in her receptacles for long 
periods and dispenses them at the time of egg laying. Although the 
epigynum has two separate pouches without communication, it is 
not necessary for the male to supply both of them with sperms to 
accomplish the impregnation. This usually happens, however, in- 
asmuch as the male exhausts one palpus and then applies the other 
one to the other orifice. 

Polygamy is the rule in spiders, though habits vary. The female 
and male, if he escapes safely, may pair again. After an initial copu- 
lation the female may reject forcibly any male that approaches her, 
or may submit many times to various males, even after her eggs 
have been laid. In some spiders it is probable that only a single 
coition occurs, the epigynal openings being blocked with a tough 
plug following mating. This is especially noticeable in the com- 
mensal comb-web spiders, Conopistha and Rhomphaea, in which the 
epigynum is capped with a hard conical cover. In many of the 
small species of Aranea, notably those of the mineata and juniperi 
groups, the separate epigynal openings are plugged with a black 
material so tough that in some instances it has been described as an 
integral part of the epigynum. In the mated Peucetia, the green 
lynx spider, the epigynum is covered with a hard blackish layer, 
probably composed of dried semen and collateral liquid, and there 
is usually present a small process from the male palpus, broken off 
during the mating a fact which aids greatly in associating the 
proper male and female when there are more than one species of 
Peucetia in a particular region. 


The pedipalps are the second pair of appendages of the head and 
lie on each side of the mouth, being inserted behind the chelicerae. 
They are six-segmented organs consisting, from base outward, of 
coxa, trochanter, femur, patella, tibia, and tarsus, and thus lacking 
the additional metatarsal segment present in the legs. The basal 
segment is the coxa, and it usually bears a conspicuous lobe, the 
endite or maxilla, that lies at the side of the labium and serves as a 
cutting and crushing instrument while feeding. The remainder of 
the pedipalp is the leglike palpus, whose tarsus is ordinarily armed 


Walker Van Riper, Colorado Museum of Natural History 

a. Portrait of a tarantula, Aphonopelma 


Walker Van Riper, Colorado Museum of Natural History 

b. Side view of tarantula, Aphonopelma 


J. M. Hollisler 

a. Banded Argiope, Argiope trifasciata, in web 

J. A/. Hollisler 

b. Spiny-bodied spider, Gasteracantha cancriformis, on leaf 


in females with a single terminal claw, while in the males it is en- 
larged and transformed into a copulatory organ. 

The spider's palpus is undoubtedly the most unusual intromittent 
organ that has been developed in any group of animals; its parallel 
is found only in some crustaceans, in dragonflies, and in the rare 
arachnids of the order Ricinulei. The whole process of its employ- 
ment is a complicated one, requiring detailed, elaborate acts and 
routines before it is successful. What do we know about the devel- 
opment of this curious mode of copulation? There is no recapitu- 
lation of its origin and evolution in the lives of spiders themselves. 
Nevertheless, nature usually accomplishes new things by small steps 
and leaves behind traces of the path that has been followed, omitting 
only a few missing links to be filled in by speculation. T. H. Mont- 
gomery and various other araneologists have attempted to outline 
the spider's path, and they have all followed the same line of rea- 

Mating among the earliest spiders or their precursors must have 
been by means of direct contact of the genital openings. In insects 
and in some arachnids as well, the male intromittent organ is directly 
connected with the vas deferens, and through this tube courses the 
products of the testes. The scorpions appress their abdomens close 
together, effecting the transfer by means of an eversible copulatory 
organ. This same habit is found in the harvestmen, but the intro- 
mittent organ is usually a long tube that conveys the semen. The 
prime step toward araneid copulation is that of voiding a sperma- 
tophore and then transferring it by means of an appendage, thus 
doing away completely with direct copulation. The male solpugid,. 
one of the most primitive of all arachnids, seizes the female, and,, 
by pinching her abdomen, causes her to fall into a state of torpor,, 
whereupon he ejaculates and transfers the semen to her receptacle 
with his chelicerae. Among the pseudoscorpions, the male grasps, 
the hands of the female in his and pulls her back and forth in a 
courtship dance, displaying at the same time the ram's horn organs 
at the base of his abdomen. When the female is sufficiently stimu- 
lated and responds with the necessary dancing movements, the 
male lets go her hands and extrudes a globule of semen or sperma- 
tophore that is attached to the floor by a thread and stands free 
on this line. At just the right moment, when the female dances over 
the spermatophore, the male grasps her genital cleft with his stout 
front legs and forces the drop into the aperture. Comparable habits. 


are known among the mites, where the chelicerae or legs are used 
to transfer the semen. 

The final step in araneid copulation is the modification of the 
appendage into an organ where the sperm can be stored some time 
before pairing. Having the semen secure in a reservoir at the end 
of the palpus does away with the need of ejaculating it during or 
immediately preceding the mating, and lessens the risk of losing the 
female during such a preliminary routine. The intermediate stages 
of the araneid mode of copulation have been dropped out com- 
pletely, and do not even persist in some form in the memory of 
the race. What we see is the culmination of the whole process, 
something unbelievably complicated, the proper performance of 
which is part of the instinctive makeup of the male spider. 

The palpus of the male only gradually developed into the com- 
plicated organ we now observe. At first it resembled that of the 
female, and was armed at the end with a single tarsal claw that 
picked up the spermatophore and pressed it into the female vulva. 
Gradually the claw became transformed into a cup-shaped recepta- 
cle, from which the liquid was less easily lost, and finally the cup 
was closed at the end until only a small opening remained through 
which to take in and drain out the semen. This receptacle is the 
all-important element of the palpus, and in its simplest form is made 
of three more or less well-defined parts: a basal expanded portion 
termed the fundus, a coiled intermediate tube called the reservoir, 
and the delicate terminal ejaculatory duct. We see this elementary 
receptable in the palpi of many spiders where it has remained very 
simple, and can still discern it as the prime element of those in which 
the structure has become greatly elaborated. 

At first, the receptaculum seminis was appended to the tarsus as 
a simple extension, but in this position it was quite liable to be 
broken or injured in some way. Specialization has proceeded to 
protect it and its delicate terminal duct, and to make it more effec- 
tive as an intromittent organ. Around it has been developed a pro- 
tective cover called the bulb. The tarsus itself has been excavated 
to form a receptacle in which the whole organ can lie when at rest. 
Muscles and blood pouches have been evolved to make possible the 
ejection of the semen. On the bulb itself have arisen processes that 
are used to orient the parts of the palpus in relation to those of the 
epigynum, and apophyses on the tibial and other palpal segments 
to act in a similar manner. 

As is true for the male, the gonads of the female are hidden deep 


in the abdomen. From the two ovaries come off oviducts that join 
to form a single tube, the uterus, which opens externally through 
a transverse slit at the middle of the epigastric furrow near the base 
of the abdomen. It is probable that in ancient spiders the sperma- 
tophore of the male was pressed into the small opening, or into a 
pouch formed in front where it was to be stored. There are still 
many spiders having only simple paired receptacles just in front of 
the genital furrow, and no external evidence of the organ we know 
as the epigynum. All the tarantulas, and the many true spiders with 
generalized palpi (the Haplogynae), belong in this series, possessing 
relatively simple male and female genitalia. The males introduce 
their palpi, frequently simultaneously, into the transverse genital 
opening and into the receptacles known as spermathecae which 
serve as storage vessels for the sperms. Only the terminal part of 
the organ, the embolus, is pressed into the spermathecae. 

The epigynum of the female is composed of two essentially sym- 
metrical independent units, each of which serves as a sheath for 
the male embolus of its particular side. There is a very close corre- 
spondence between the physical proportions of the duct leading to 
the female spermatheca, and the embolus of the male, a natural 
result of parallel evolution. In all the higher spiders there exists a 
pair of outside openings into which each male embolus can be in- 
serted without gaining entrance through the medial genital pore 
within the body itself. Much of the perfection and elaboration in 
the palpi and epigyna must be attributed to this new position of the 
orifices, which makes possible the adoption of a different mode of 
pairing, in which the male is less vulnerable. 

The external epigynum has become specialized in various ways. 
In many spiders there is an atrium, surrounded by a distinct rim, 
within which lie the orifices. These latter are separated by median 
ridges that guide the embolus into its particular channel. At the 
front or behind may be a hood or tubercle articulating with an 
apophysis of the palpus. A conspicuous finger often overhangs the 
atrium and serves to fix the palpus in just the right position to make 
the pairing possible. It should be noted that not every apophysis of 
the male palpus has been developed to fit a corresponding depression 
in the female epigynum. As in all structures of animals, the ortho- 
genetic tendency to become more elaborate may go far beyond the 
needs of the animal. Many of the spurs and strange projections in 
complicated palpi may prove only useless luxuries that contribute 
nothing to mating. 


The very close correspondence between the male and female 
genitalia of insects ted Leon Dufour to the formulation of the so- 
called "lock and key" principle. It was his belief that the crossing 
of species was impossible for physical reasons, and that the male 
organ could not be introduced into that of a strange female because 
of differences in length, shape, and size. The female organ was re- 
garded as an unyielding lock that could be opened only by a key 
that corresponded exactly with its form. Whereas we must reject 
the theory that these organs are adaptations that exclude the cross- 
ing of species, and instead assign that function to fundamental in- 
stinctive patterns probably based on chemical stimuli, it must be 
admitted that in spiders the differences between the genitalia of 
allied groups are usually sufficiently great to make pairing impos- 
siblein effect a "lock and key" presenting an impassable barrier to 
all but the most closely related species. 

It must be kept in mind that the secondary genitalia of spiders 
are extremely ancient organs probably fully evolved long before 
the late Paleozoic Era, where we find fossil spiders. Both primitive 
true spiders and living tarantulas, discretely separated even at that 
time, have similar palpi, indicating that the general features of their 
organs antedate the separation of the two suborders. It is little 
wonder then that in the palpi and epigyna are clues to the general 
phylogeny of the whole group. These organs have undergone 
changes corresponding closely with the specialization of spiders 
themselves. Indeed, sexuality and the araneid mode of copulation 
are adaptations that have probably contributed more to spider evo- 
lution than have any other features. 


The Evolution of Spiders 


The proud jumping spider of today, attired in flowing robes of 
ermine and crimson and with great smoky eyes intently following 
every moment of a gleaming bluebottle fly, bears little resemblance 
to its reserved, myopic forebears. The sedate orb weaver, hanging 
from a web of wondrous design, has come a long way from the 
clumsy land creature that first attempted to climb into the shrubs. 
So changed are many spiders that we can scarcely discern in their 
bodies any clues pointing to their origin. 

From fossil evidence we know that spiders are ancient creatures, 
and that they were confirmed land animals before the vertebrates 
had got free of the bondage of aquatic life. A large part of their 
evolution must have been undergone during the Devonian Period, 
which has left one record of an enigmatic spider, Paleocteniza, from 
the Rhynie Chert of Scotland, occurring with mites and numerous 
excellently preserved arachnids of the extinct Anthraco?narti. Splen- 
did fossils come from the coal measures of the Carboniferous Era, in 
both Europe and the United States, revealing that at that time highly 
developed, typical spiders were already in existence. Much remains 
to be learned of earlier araneids, and of the arachnid group that gave 
rise to them, since we have no evidence to show that spiders have 
been derived from any other living or extinct group of arachnids. 
Nor do we have any conclusive evidence that the arachnids evolved 
from any particular arthropod group. The classical theory of Ray 
Lancaster, which postulates the trilobites as the ancient group from 
which have been derived scorpions and typical arachnids on one 
hand, and eurypterids and king crabs on the other, has been se- 
verely criticized. More recent evidence, however, strengthens this 
general thesis and points to the derivation of these diverse arachnid 
groups from relatives of the conservative trilobites living in the 



Cambrian seas. An alternate theory would have the arachnids de- 
rived from some land creature, similar perhaps to the sluglike Peri- 
patus, but of which at present there exists no record. 

The phylogeny of spiders has long been the subject of much 
speculation, and there is still no general agreement as to the funda- 
mental paths that were followed. This volume attempts to lay 
down only the broad features of spider evolution, and acknowledges 
the inclusion of much speculative matter. 

The phylogeny of any group of animals can be postulated by 
means of the fossil record, and also by aids from taxonomic classifi- 
cations, which are frequently indicative of the racial history of a 

The ancestral stock from which come all major spider groups 
originated some time before the Carboniferous Era. These creatures 
probably bore a close resemblance to the spiders fossilized in the 
coal measures, with abdomens encased in hardened plates wide ter- 
gites above, sternites below, and hard, narrow pieces (pleurites) on 
the sides. Four pairs of similar fingerlike appendages were present 
beneath the abdomen at about the middle. Just in front of these 
was a pair of spiracular openings leading to book lungs, and a second 
similar pair was present farther forward, at the base of the abdomen. 
Inside the abdomen was an elongate heart into which opened five, 
six, seven, or even more pairs of ostia, each pair representing a seg- 
ment and those at the rear much reduced in size. Thereafter, the 
tendency was to increase the size of the organs in the anterior seg- 
ments and gradually to suppress the posterior ones, resulting in the 
loss of some of the ostia and the supporting muscular systems. The 
gradual reduction and loss of the units of internal segmentation 
were matched in the external plates, which resulted in an actual 
migration forward toward the spinnerets of the anal tubercle. 

The cephalothorax of the ancestral spider was relatively long as 
compared with its width, and was marked by a longitudinal median 
groove. At the front end were eight eyes set close together on a 
low tubercle. The legs were of moderate length, quite stout, and 
each tarsus had at its tip three tarsal claws, the outer paired ones 
relatively long and smooth, the inner unpaired one short and only 
slightly curved. The chelicerae were large, set parallel to the long 
axis of the body, with robust fangs. The gland in the basal segment 
secreted a weak poison, largely unnecessary since to subdue prey 
reliance was placed mainly on the strong legs and sharp fangs. 

The earliest spiders were cautious hunters that groped about on 


the ground and made little effort to establish a permanent station of 
refuge. Food perception was accomplished by sensory leg hairs 
which tested the terrain, for their small eyes were useful only to 
distinguish light from darkness. These sluggish prototypes lived a 
timeless life of leisure on the tangled jungle floor of their humid 
swampland. Only during molting and egg laying was it desirable 
to be concealed from wandering predators, and from less worthy 
adversaries that under those trying circumstances might do injury 
to the eggs or to the spiders themselves. The first step toward a 
life of dependence on silk was the coating of the eggs with excre- 
tory material from the abdomen, voided by coxal glands that opened 
through the abdominal appendages. As the product of the glands 
became more suitable for use as a gluing and covering agent, and 
the spinnerets more adept in their application of the gummy liquid, 
greater possibilities for the use of the crude silk opened on all sides. 

These early spiders were perennials. Each female produced and 
cared for many egg masses during her life with varying degrees of 
efficiency and success. Those survived that were more adequately 
protected by a silken cover, and guarded in long vigils by the 
mothers, whose regard for the safety of the egg mass was being 
tried and modified by an increasingly hostile and enterprising band 
of predators. 

By the late Paleozoic, the two principal groups of spiders known 
today had been developed: the My galomorphae , or tarantulas and 
their allies; and the Araneomorphae, the true spiders. Discretely 
separated even in the coal measures, these two lines have grown up 
side by side. In many respects their accomplishments have paralleled 
each other, a natural development since both were originally en- 
dowed with similar equipment and potentialities. However, for 
various reasons, the true spiders surpassed the tarantulas during the 
Tertiary and became the dominant group. 


Our first sight of the typical mygalomorph spider is in the coal 
measures, where we find it little changed from the ancestral spider 
that preceded it. During the Paleozoic Era, when much of North 
America was a dismal, swampy area covered by great forests of 
strange plants and trees, there lived in the region of modern Illinois 
primitive spiders whose abdomens were armored with hardened 


plates. So familiar is their outline that we immediately associate 
them with spiders visible about us, and discern a close resemblance 
to the liphistiids and the trap-door spiders. During the same era, 
this early mygalomorph was also found in Europe, more numerous 
in species and so much more diversified that the imprints seem to 
belong to several distinct types. All have well-marked tergites. 

The Illinois spiders from the Pennsylvanian shales of Mazon 
Creek are placed in the genus Arthrolycosa, and in the family 
Arthrolycosidae, and they are remarkably like the modern species 
of the family Liphistiidae. However, nothing is known of their 
spinnerets, claws, sternum, or of other features largely used in clas- 
sification. After a brief glimpse of them in the coal measures of the 
northern hemisphere, we lose sight of them completely and can 
only speculate on their subsequent history. 

From creatures like Arthrolycosa and its European cousins has 
been developed all the assemblage of modern spiders known as 
liphistiids, trap-door spiders, funnel-web tarantulas, and typical ta- 
rantulas; in short, all of the My galomorphae in the broad sense. If 
we agree with Eugene Simon, the master arachnologist, that the 
liphistiids are only primitive members of the mygalomorph spiders, 
we have no difficulty in accounting for the restricted, more typical 
recent members. The insistence of many specialists that the myga- 
lomorph spider of the Paleozoic completely lacked dorsal segmen- 
tation of the abdomen is unreasonable. The tarantulas are present 
in the Paleozoic with plates on the back of the abdomen; and many 
of them have retained well-marked evidences of dorsal segmentation 
through three or four hundred million years until the present time. 


Certain shadowy forms from the Carboniferous Era, contempo- 
raries of the oldest tarantulas, have been assigned with some con- 
fidence to the Araneomorphae, or true spiders. They appear to lack 
hard plates on the abdomen, and to assume in a vague way at least 
the form of some of the highest spiders. In what ways do these 
emergent creatures, from which is derived the vast array of mod- 
ern true spiders, differ from the Paleozoic tarantulas? How did the 
branches separate? 

The fundamental change may well have been one of behavior, a 
change in habit or attitude rather than a physical alteration. In some 


way it is related to their greater use of silk, to their more expert 
spinning, and to the retention of the anterior median spinnerets as 
functional organs until the principal lines of true spiders were well 
established. Associated with this divergence from the tarantulas 
was the gradual change in position of the chelicerae. In modern 
representatives these are now twisted at right angles from the long 
axis, with the fangs pointing toward each other. Just what advan- 
tage this development brought is not completely clear, but it may 
be that the improving eyes and the new chelicerae could be used 
together to subdue insects more effectively. Cutting edges were 
being developed on the coxae of the palpi to aid in crushing the 
body of the prey. The venom was becoming more potent and the 
voluminous glands were pressing beyond the limits of the cheliceral 
segments into the head itself. 

Loss of the heavy abdominal plates was another consequence of 
the change in life. This armor disappeared gradually and still is 
vaguely indicated in a very few modern true spiders. P ale o diet yna, 
a spider from Baltic amber, retains conspicuous plates; and this 
slow divestiture suggests the possibility of finding many more fossil 
true spiders retaining dorsal plates. 

The course of true-spider evolution has been charted largely by 
silk spinning. The Araneoworphae began their history with the same 
equipment as the parent tarantula group eight functional spinnerets 
of nearly equal size. But whereas the tarantulas were content to 
spin in a modest way, the true spiders began to use silk more often 
and with greater efficiency. Since the lateral spinnerets undoubt- 
edly were bisegmented at an early date, and had the advantage of 
greater length and strategic position, it was natural that these should 
be developed and improved at the expense of the unisegmented 
median pairs. The great reduction in size and early loss of both 
anterior median and lateral spinnerets in all but a few relict myg- 
alomorph spiders reflect their failure as spinners. The true spiders, 
on the other hand, retained all these spinnerets for a long period, 
and some still keep the anterior median pair. In this connection it 
is worth noting that the metatarsal comb the calamistrum used to 
brush across the spinning field of the median spinnerets, was in all 
likelihood an early invention, and that all true spiders once spun 
cribellate threads. The retention of the anterior lateral spinnerets 
as prime spinning organs, probably made possible by persistent use 
of the incipient cribellum, was the key to true-spider superiority, 


and actually caused the divergence of the true spiders from the 
parent line. 

It was inevitable that, in addition to the formal silken covering 
over the egg mass, many threads would be scattered more or less 
haphazardly from this spinning center. Such wild lines were in- 
strumental in giving to the mother spider another advantage in her 
efforts to guard the eggs, communicating the approach of an inter- 
loper by vibrations on the threads. The range of touch perception 
was thus in one step expanded far beyond mere contact with the 
sensory hairs on legs or body; the deadly predator or the blunder- 
ing insect often became the prey of the vigilant spider. In this two- 
dimensional maze of threads, with the egg sac as central theme, was 
the germ of all the webs that have made the true spider dominant. 

The stringing-out of silken lines continued during the whole life 
of the spider, as well as at the egg laying, and has continued to the 
present time as the dragline habit of modern spiders. With a secure 
line attached to the spinnerets, the spider could now venture upon 
precipitous surfaces with a certainty of quick recovery from falls. 
Since the dragline of true spiders is ordinarily spun through the 
anterior lateral pair, the tarantulas, in suppressing these spinnerets, 
virtually precluded the future possibility of becoming aerial spiders. 

The lifeline of the whole group of true spiders became their 
silken threads, and those that refused to accept subservience to this 
material died out. Every spider became sedentary to a degree, and 
none has been able to divest itself completely from silk since those 
early days. Each major group of spiders diverged from the others 
with essentially the same type of spinning equipment, and with a 
well-founded instinctive knowledge of silk spinning. In each of the 
lines similar types of webs and traps for the capture of insects have 
been evolved separately. 

In one group the anterior median spinnerets have been perpet- 
uated in a modified form as the cribellum. These creatures come 
down to modern times in a more or less homogeneous line as the 
"cribellate" spiders (p. 137). The whole series probably diverged 
quite early from the main stem, and, although their physical fea- 
tures mark them as a more generalized group, they have done re- 
markable things with their heritage. All the remaining true spiders 
lost the anterior median spinnerets, but in most of them vestigial 
evidences can still be observed. 

During the early history of the ecribellate true spiders, a trend- 
already running a similar course among the cribellate types toward 


the simplification of various organs was operative. The mutations 
began at different times and progressed at different rates, so that in 
modern types generalized features sometimes exist side by side with 
profound specializations. The tendency has been to simplify the 
fundamental systems, to make fewer segments and functional units 
(such as book lungs, tracheae, ostia, spinnerets) do the work of the 
greater ancestral number. 

The abdomen was developing into a highly developed center for 
silk spinning, and in most lines tended to become shorter; in some, 
globose. The spinnerets gradually attained a position at the tip of 
the abdomen, near the anal tubercle itself, indicating the virtual re- 
duction of the abdominal segments to four. Some of the spinnerets 
later became elongated and modified to perform special types of 
weaving, and others became so reduced in size that in certain cases 
only the anterior lateral pair remain as functional spinning organs. 
A notable achievement was the transformation of the hind pair of 
book lungs into a pair of tracheal tubes soon after separation from 
the cribellate line; this development was followed in most spiders by 
fusion of the openings into a single tracheal spiracle. In a few lines 
the front pair of book lungs was also converted into tracheae. The 
number of ostia in the heart was reduced from four to three pairs, 
in some species even to two pairs, and the remaining ostia assumed 
the function of the lost members. 

Changes of many kinds were also taking place in the cephalo- 
thorax and its appendages. Especially notable was the migration of 
the eyes from the original local center at the front edge of the 
carapace, to the sides and to other positions of greater advantage. 
The anterior median pair was lost early by a whole group of species 
that persists until the present time as six-eyed spiders, and whose 
other characteristics indicate that they are among the most gen- 
eralized ecribellate true spiders. Other types enlarged their eyes, 
and, with appropriate changes in the legs and body, came to place 
considerable reliance on sight as an aid in gaining a livelihood. 

The early ecribellate spiders were at first terrestrial types that 
stalked over the soil and low vegetation in an upright position, trail- 
ing their dragline threads behind. Some of the lighter ones began 
essaying trips into the herbs and shrubs, and learned to use their 
claws to climb from twig to twig, hanging back-downward from 
their silken lines. The third dimension was becoming a spacious 
reality to these extroverts, and with its spaciousness came complete 
freedom from attack by ground creatures. The egg sac was in- 


stalled in the center of the tangle of threads, completely safe from 
flying predators, which could not reach it without becoming en- 
meshed in the lines. And from entangled insects of many kinds the 
spider was securing its food. The aerial web spinners (p. 157) be- 
came specialists for life on silken lines, modifying the unpaired 
claws of the tarsi into effective hooks. 

Many spiders remained creatures of the soil, and for running or 
climbing made little or no use of the unpaired claw. Some of these 
hunters (p. 193) lost the unpaired claw, developing instead adhesive 
claw tufts that allow great ease of climbing. 


The Tarantulas 



door spider, purse-web spider, and liphistiid bring to mind some of 
the most famous of all spiders spiders that rival in size the largest 
land invertebrates, spiders that have become renowned for their 
wonderful burrows and handiwork. All are four-lunged spiders 
belonging to the suborder Mygalomorphae; they are often referred 
to as mygales but in this book are collectively known as "taran- 
tulas" or mygalomorph spiders in contrast to the "true spiders" of 
the suborder Araneomorphae. 

The mygalomorph spiders are more generalized than the true 
spiders and ancestral to them. As a group they are longevous, all 
living more than a single year and some of them attaining great 
age as age is measured in invertebrates: up to or even exceeding 
twenty-five years. They are large, probably averaging more than 
an inch in length as compared with less than one-fourth that size 
for the true spiders. Some of the typical tarantulas attain a body 
length of three and one-half inches; at the other end of the scale, 
the pygmies, the tunnel and sheet weavers of the genus Micro- 
hexura, are one-eighth inch long. Along with great size the myg- 
alomorphs perhaps retain as a consequence the second pair of book 
lungs and other generalized features correlated with their primitive 
station among spiders as a whole. 

Although it must be conceded that the true spiders have attained 
a higher degree of development as evidenced by their greater 
numbers, variety of structure, and multiplicity of habit the taran- 
tulas should not be thought of as vastly inferior. They have become 
notably specialized in their own way, and in instinctive behavior 
have nearly kept pace with their cousins. 

The most important single character that distinguishes the myg- 
alomorph spiders is the articulation of their chelicerae termed 



paraxial as contrasted with the diaxial position of true spiders and 
other details of the mouth parts. The chelicerae (Plate XV) are 
robust and two-segmented, as usual, but with their long axis par- 
allel to that of the body, and with movement in a vertical plane. 
As befits these powerful spiders, the fang of the chelicera is a stout, 
curved weapon. In order to drive the fang into the victim, the body 
must be elevated. These creatures strike with great speed, but be- 
cause of their poor eyesight and the necessity for waste motions, 
their method is probably inferior to that of the true spiders. When 
confronted by man or any creature outside its normal experience, 
the tarantula throws itself back and maintains its body in a position 
of readiness to strike. This is a defensive attitude, but also one fa- 
vorable for attack. 

The venom glands of the mygalomorph are entirely contained 
within the basal segment of the chelicera. Since its offensive needs 
are met by a powerful body and robust jaws, the necessity for 
great quantities of potent venom is minimized. In most tarantulas 
the coxa of the palpi also lacks the endite or maxilla, an expansive 
lobe used in crushing and cutting the prey. 

All the Mygalomorphae have two pairs of book lungs, clearly 
visible on the ventral surface of the abdomen and notable for their 
large size. Only one family of true spiders, the Hypochilidae, has 
retained this four-lunged condition, and they are the most gen- 
eralized of all true spiders in many other respects as well. 

A moderate number of mygalomorph spiders range up into the 
temperate zones, but the group is essentially tropical and subtropical 
in distribution, about fifteen hundred species being known from 
these zones all around the world. During the Paleozoic Era, their 
ancestors dwelt in the swampy, humid forests that became the coal 
measures of the United States and Europe. No tarantulas are known 
from the Mesozoic, but we can be sure that they were well rep- 
resented, and perhaps at that time equaled the true spiders in num- 
bers and variety. Because of their secretive habits, which have 
resulted in a meager fossil record, few Cenozoic mygalomorphs are 
known; small numbers have been found in the Baltic amber of the 
Oligocene, and in the Oligocene shales of the Florissant formation. 
At some time during the early history of the Mygalomorphae 
the line split into two principal branches, which have descended to us 
side by side as our modern fauna. On the one hand are the typical 
tarantulas and the trap-door spiders; they represent the largest and 
the best-known series. The second group is somewhat inferior in 


physical equipment (if we measure this in terms of the degree of 
change from ancestors), and has come down as a reminder of what 
most of the mygalomorph types were like during the Mesozoic. 
These latter we refer to as the atypical tarantulas. 


In this series, which includes the tarantulas, the sheet-web ta- 
rantulas, and the true trap-door spiders, there is no visual evidence 
of dorsal segmentation of the abdomen. The maxillary lobes are not 
at all developed in the American species, but in some exotic forms 
a small angled spur or a well-developed process may be present. 
Nearly all have but four spinnerets, the hind lateral and median 
pairs; these are located close in front of the anal tubercle. The 
commonly associated characteristics of tarantulas large size and 
hairy covering should not mislead one in identifying members of 
this group. Many are relatively small in stature. Only the wander- 
ing hunters, the true tarantulas, are thickly clothed with velvety 
wool and long silken hairs; others appear quite naked by compar- 

A few of the mygalomorphs have become vagrant, but none 
has attained the degree of freedom enjoyed by certain true spiders. 
Failure to improve vision has resulted in the development of very 
few accomplished runners, jumpers, or climbers, and none of these 
tarantulas has become dependent on silk as have the aerial true 
spiders. Their reliance on touch is perhaps even stronger than in 
the araneomorphs; the hairy covering of the vagrants, for example, 
serves admirably to make them aware of the presence of their prey. 

The typical tarantulas have been most successful in living a 
secretive life hidden in the ground, with the consequence that many 
have become specialists in subterranean existence. Their general 
makeup fits them eminently for a successful life in tropical regions, 
where competition is not so keen. Few Americans realize that in 
the southern portion of the United States exists a rich and varied 
fauna of mygalomorph spiders, eighty or ninety species including 
many with curious habits. 

Trap-Door Spiders. Many spiders tunnel into the soil, but the 
true trap-door spiders of the family Ctenizidae are the most accom- 
plished burrowers and the most gifted artisans. They and their 
relatives can claim to be the inventors of that superb mechanism to 


ensure privacy, the trap door, for they represent a stock that was 
probably capping burrows with doors long before many true-spider 
emulators were evolved. The first description of this interesting 
device was given by Patrick Browne, who in 1756 illustrated the 
nest of a West Indian species in his Civil and Natural History of 
Jamaica. A few years later the nests of Nemesia were described 
from France, being likened to "little rabbit burrows lined with silk 
and closed with a tightly fitting movable door." Although trap- 
door spider nests continued to attract popular attention thereafter, 
it was not until 1873, when J. Traherne Moggridge published his 
careful studies on the habits of these animals, that any comprehen- 
sive treatment was accorded them. 

Moggridge was able to distinguish four distinct types of nests 
among the species he studied. The first was a simple tube, a cylin- 
der closed with a thick, beveled door, which he termed the "cork 
door"; the second was a simple tube closed with a thin or "wafer" 
door; and the third type was a simple tube with a thin outer door 
and a second door part way down. Moggridge's fourth classifica- 
tion was the most complicated: a nest capped on the outside by a 
thin door, and having an oblique side tunnel, connected with the 
main tube, at the entrance of which was a trap door. Several other 
types of nests have since been discovered in various parts of the 
world, some of them much more complicated than those described 
by Moggridge. Furthermore, the distinction between the cork 
door and the wafer door, while valid enough in the extremes of 
each type, gradually disappears as we examine long series of inter- 
graded nests. 

The true trap-door spiders have developed a comblike rake of 
large spines on the margins of their chelicerae, and this they employ 
as a digging instrument. With its aid they are able to cut and scrape 
away small particles of earth, which they mold into balls and carry 
outside the burrow. They waterproof the walls of the tube by 
applying a coating of saliva and earth, so that the surface becomes 
smooth and firm. Then they apply a silken lining of variable thick- 
ness and extent, in some cases not fully coating the burrow, while 
in others covering the whole tunnel with a thick fabric. 

When the maturing spider outgrows its burrow, it enlarges the 
domicile by cutting and scraping off bits of earth with its rake 
and carrying them away from the site. Rocks embedded in the soil 
may oblige the spider to pursue a tortuous course, or to dig a new 
tunnel in a more favorable situation. It rarely deserts its burrow 


Purse web of Aiypus abboti against tree 

J. M. Hollister 


a. Door open 

Robert E. Ball 

Robert E. Ball 

b. Door half open 

Robert E. Ball 

c. Door closed 


voluntarily. When forcibly removed, it will accept the unoccupied 
tunnel of another spider, or a cavity especially made for it, and 
proceeds to remodel this in a characteristic way to suit the pattern 
of previous homes. 

Although spiders of many other families burrow, the trap-door 
mygalmorphs have far outstripped them in the excellence of their 
tunneling. They have become specialists that dig with better in- 
struments, line with greater care, and are the originators of the 
intriguing practice of capping the burrow with a perfect lid. While 
this trap door is not a unique accomplishment of these spiders, 
having been developed independently by several other groups, it 
bespeaks a mastery not closely approached by any emulator. 

The typical burrow is spacious enough in part of its length to 
allow the spider to reverse position at will. Within its confines the 
spider finds a haven until violent or natural death. What are the 
advantages of this abode, which has become such a dominant ele- 
ment in the lives of these spiders? In the first place, it is the 
property of a single, unsocial individual and can become, with the 
passage of time, more and more adequately coated with silk, more 
and more familiar in its every part, and thus increasingly acceptable 
to the spider. It is a retreat from the rays of the sun, the extreme 
heat of which is shunned by nocturnal and diurnal forms alike. 
Its hinged lid, which can be opened or closed at will, prevents rain 
and surface water from entering, thus keeping the nest drier than 
surface situations. Since all the burrowing spiders live more than 
a single year, the tunnel serves to temper the extremes of inclement 
weather over long periods. The tube beneath the surface is cooler 
during the summer heat, and somewhat warmer during the extreme 
winter cold. Relatively inconspicuous because of its location on the 
surface of the ground, the burrow opening may be made even more 
difficult to discern through the efforts of the spider. During the 
hottest part of the summer, when inimical parasitic wasps are pres- 
ent in maximum number, the opening may be closed tightly with 
earth and silk. Mosses, leaves, sticks, and other debris can be placed 
to advantage on the lid and around the entrance, the result to 
human eyes at least hinting of camouflage. When in active use, 
the burrow can serve as an ambush from which the spider rushes 
out to seize its prey; and once an insect is caught, the nest becomes 
in most cases the dining room. At the proper season the burrow 
may also serve as a mating chamber, the eggs being laid and en- 
closed in their sac within its confines. Later it becomes the home 


of the young spiderlings, often for many weeks after their emer- 
gence from the egg sac. 

The opening to the surface is the spider's only contact with the 
outside. It is the vulnerable element in the circumscribed abode, 
but at the same time it allows the creature to be menaced from only 
one direction. On the surface, an inferior sensory equipment places 
the trap-door spider at great disadvantage in combat with its 
specialized enemies. Within the burrow, it faces the enemy pro- 
tected by a silk door, and should that be torn away, it still has a 
favorable situation for the use of its strong jaws. 

While demands for privacy have probably inspired the perfec- 
tion of the underground castle of the trap-door spider, it is more 
intriguing to think of the domicile in terms of response to the rav- 
ages of some arch enemy. By far the most fearsome assailant is the 
spider wasp, a common name for various species of Pompilidae, 
which are exclusively spider predators. Other enemies may wreak 
their toll in an insidious way and possibly destroy more individuals 
than does the wasp, but this gleaming tyrant is a predator of the 
first magnitude whose prey is the large, adult spider and whose 
victory is won in hand-to-hand struggle. 

Actively foraging over the soil, unerringly directed by a sense 
not conditioned by previous experience, the wasp arrives at the 
trap door, beneath which sits the prospective victim possibly 
aware, through its delicate tactile sense, of the presence of an in- 
truder. If unprepared, or if its resistance is finally broken down, 
the spider quickly finds itself confronted by an enemy that has lifted 
the trap door or gnawed through it and entered the spacious bur- 
row. The struggle that ensues is not a battle of giants. It is a very 
unequal one from which the wasp almost always emerges the victor. 
Swift and sure in movement, liberally endowed with fine sensory 
equipment, and armed with a deadly sting, the wasp confidently 
assails a larger creature fighting on a prepared battleground in the 
deep recesses of its burrow. After a brief struggle the wasp para- 
lyzes the spider with venom from its fiery sting, whereupon it 
proceeds to deposit on the spider's abdomen an egg, from which 
will hatch a voracious larva. Doomed to lie helpless while furnishing 
fresh food for the larva, virtually dead if not actually so, the once 
mighty spider finds its castle converted into a crypt. Industrial 
skill has failed to make the burrow impregnable to its most formid- 
able enemy. 

During the growing period, when the spider is remodeling and 


strengthening its closed tube, it is less subject to the attacks of 
marauding wasps that, in order to satisfy the food requirements of 
their offspring, pass up the smaller burrows in favor of mature or 
nearly mature prey. 

We pass now to consideration of the three better-known 
types of trap-door spiders found in the United States. The first of 
these constructs the classical type of nest that Moggridge called the 
"cork nest." The most familiar domicile of this type is made by 
Bothriocyrtum calif ornicum, the common trap-door spider of south- 
ern California. Examples of this nest (Plate XI) are to be found in 
many collections, and may even be purchased from various biologi- 
cal supply houses. It is the typical nest illustrated in many works 
on natural history. Another group of spiders that is widely dis- 
tributed across the southern United States, the genus Pachylomerus, 
also makes this type of nest. These spiders are very handsome 
animals, with a nearly oval, black, shining cephalothorax and legs, 
and a dusky abdomen. 

The cork nest (Text Fig. 3, A) is a simple tube without side 
branches, lined completely with silk. Ordinarily the burrows are 
shallow, from five to eight inches in depth, with a diameter essen- 
tially the same throughout and great enough, especially near the 
entrance, to permit the spider to turn around. The distinctive fea- 
ture of this nest is the door (Plate XI). It is made of layers of earth 
and silk, and is so constructed that it fits perfectly and tightly closes 
the mouth of the tube "much as a cork closes the neck of a bottle" 
so Moggridge described it. The cork door cannot stand open; it 
falls and closes of its own weight, and the tube mouth is beveled to 
receive it. 

In West Florida Pachylomerus audoumi digs its burrows in the 
sides of steep, stream-cut banks in moist and shady ravines. Ari- 
zonan and Mexican Pachylomerus favor open spaces in the sun- 
baked creosote-bush deserts. In southern California Bothriocyrtum 
californicum makes its tunnels on sunny hillsides that in early 
summer bear a thick covering of native grasses. The spiders that 
build the cork nest are plump animals (Plates XII and XIV) with 
rather short legs and a broad carapace. They are the finest bur- 
rowers, and have, in addition to the well-developed cheliceral rake, 
rows of short digging spines on the first legs, which aid in scraping 
and cutting the soil. Their bodies are rounded and fit the burrow 
snugly, with the legs pressing closely against the sides. Their struc- 
ture bespeaks strength and ruggedness. As is true of most spiders, 


they are active during the evening and at night, but they rarely 
leave their burrows. At the exit of its tube, holding the door ajar, 
sits the spider, ever watchful for the approach of food. On occa- 
sion it will rush forth to capture an insect, but most of its prey 
is taken without completely leaving the burrow. Inside the nest it 
is an agile creature; outside, a clumsy one. When disturbed, it 
closes the door firmly and holds the lid with chelicerae and claws, 
bracing its legs against the sides of the silken burrow. In this posi- 
tion, considerable force is necessary to dislodge it. Even with the 
aid of a knife blade one has difficulty in forcing the door. 

Two well-known genera, Actinoxia of the western and Myr- 
mekiaphila of the southeastern United States, make the type of 
nest Moggridge called "the double-door branched nest." The trap 
door of this nest is of the wafer variety. It is a thin, suborbicular 
cover almost wholly made up of silk, without layers of earth, and 
lies on the entrance rather than fitting into the aperture. It is not 
substantial enough to serve as an impregnable barrier to an intruder, 
being soft and pliable, and not heavy enough to fall over the open- 
ing if it is pushed back very far. It is only a superficial, hinged 
cover, which is camouflaged outside with moss, earth, or debris. 
The burrow proper is a cylinder lined with silk; but the particular 
innovation in this nest is the second burrow, a secret side chamber 
cleverly concealed by a trap door so constructed that it can close 
either the main tunnel or the side branch. (See Text Fig. 3, B.) 

The burrows of Alyrmekiaphila torreya are found on the leaf- 
mold-covered slopes of Torreya Ravine in Liberty County, Florida. 
This species digs a burrow that averages about ten inches deep. 
The nests are usually found in sandy soil penetrated by a maze of 
roots, and almost always contain at least one or more abrupt bends. 
Halfway down the tubes are the side chambers, one to a burrow, 
marked by wafer-type doors. The entrances to the outer burrows 
are lined with silk, and provided with a peculiar type of door, 
which, when standing open, is more like a silken collar than a trap 
door, but which takes on the appearance of a well-camouflaged 
trap door of the wafer type when closed by a slight push. This 
door the spiders sometimes leave standing open during both night 
and day. 

Most of the tarantulas that make an inner door are about two 
thirds of an inch in length. Their bodies (Plate XIV, male) are 
slimmer than that of Pachylomerus, ordinarily yellowish brown, and 
sparsely clothed with brown hairs. Their legs are longer and they 


Female purse web spider, Atypus bicoLor 

Martin H. Muma 


Lee Passinore 


'^ - : t :>'>-^<-f''<*- 

George M. Bradt George M. Bradt 

a. Surprised in its burrow b. Exposed burrow 



A. Cork door nest of Pachylomerus. B. Double-door of Myrmekiaphila. C. 

Nest of Cyclocosmict with spider in narrow recess. 


lack the rows of spines that the other group has, possessing instead 
a light-to-heavy scopula of hairs on the distal segments. 

The open door of torreya appeals to us as being virtually an 
invitation to enter. Atkinson, who studied a similar species in North 
Carolina, thought that the principal chamber was intended as a 
prison for ants that wandered in and were captured after closing 
the inner door. He called the genus Myrmekiaphila because these 
spiders build their nests near or even in anthills, and he believed 
that the ants make up a large part of the tarantula's food supply. 
Moggridge interpreted similar nests in terms of a protective device. 
A wasp, intent on paralyzing the spider and placing an egg on its 
body, finds a trap door, which may be open or which she may 
open or force, and enters in search of the spider. The spider mean- 
while rushes to the bottom of the burrow and closes the main tube 
with the inner trap door. Should the wasp persist, the spider crawls 
into the side chamber, moving the dual-purpose door to protect 
that opening. Once the main tube has been fully explored and 
found empty, the wasp may leave without discovering the inner 

Cyclocoswia truncata is a trap-door spider remarkable for the 
peculiar shape of its abdomen, and interesting in that it had been 
considered by many as the rarest spider in North America. It is a 
large, fat creature, rather closely related to Pachylomerus except 
for the abdominal structure. This round, leathery, caudally trun- 
cated organ, in the absence of actual observations, had led to in- 
triguing conjectures as to what use it is put by the spider. 

The initial description of truncata was made by Nicholas Mar- 
cellus Hentz, the father of American araneology, who in 1841 gave 
it the name of My gale truncata. His specimens, all of which were 
females and all since lost, came from Alabama. In his words: 
". . . this spider dwells, like other species of this subgenus, in cylin- 
drical cavities in the earth. Though many specimens were found, 
I never saw the lid described by authors as closing the aperture of 
its dwelling. The very singular formation of its abdomen, which 
is as hard as leather behind, and which forms a perfect circle, in- 
duces me to believe that it closes with that part, its dwelling instead 
of with a lid, when in danger." What Hentz meant by "the lid 
described by authors" is inexplicable, unless he was referring to the 
lids of nests of closely related spiders, since, to our knowledge, he 
was the first man to see and record the species. Along with draw- 
ings of the animal, Hentz included a sketch of "the hole in which 


it resides," a simple, circular aperture in the ground, unadorned by 
semblance of lid, turret, or silken structure of any kind. Did Hentz 
actually see the entrance to a burrow? Did he draw upon nature 
or his imagination as a model for this sketch? We know that he 
never saw a lid, and we can only surmise as to whether or not he 
saw the entrance. 

We next hear of truncata in 1871, when Ausserer created two 
new genera, Chorizops and Cyclocosmia, for spiders distinguished 
from their nearest relatives by possession of a truncated abdomen. 
My gale truncata was made the genotype of Cyclocosima. Later, a 
second species of the genus was discovered near Tonkin, Indo-China. 
Thus, Cyclocosmia truncata enjoys the distinction, along with the 
American alligator and other animals, of having its nearest relative 
in Asia. 

In his monumental work, American Spiders and Their Spinning- 
work, McCook treated the natural history of spiders in great detail. 
His chapter "Enemies and their influence on habit" speculates fur- 
ther on Cyclocosmia. Led on by the singular "adaptation" of the 
abdomen, and encouraged by the work of Hentz and Ausserer, 
McCook sees in this hard disk "one of the most curious examples 
of relation of structure to enemies, or perhaps of the reaction of 
hostile environment and agents upon structure." Relying solely 
upon Hentz for his information, but cautiously warning that 
Hentz's conjectures need confirmation, he agrees that it is not im- 
probable that truncata uses its abdomen as a door. He further 
appends a beautiful sketch of the spider in this imagined position, 
and remarks: ". . . and one may imagine the intellectual confusion 
of a pursuing enemy, which finds its prey suddenly disappearing 
within a hole in the ground, but which, when investigated, presents 
nothing but a level surface where certainly a hole ought to have 

Credit for the rediscovery of Cyclocosmia largely belongs to 
Dr. H. K. Wallace of the University of Florida, who found the 
well-hidden burrows in the bottom of Torreya Ravine. Other colo- 
nies discovered in Alabama and Tennessee have since widened the 
known distribution of these curious spiders. Cyclocosmia seems to 
prefer a rather steep slope in a shady, cool, somewhat damp loca- 
tion. The first burrows found were in a vertical bank protected 
by the overhanging roots of a large tree, a situation characteristic 
of the ravines in Torreya Park, where small streams have been 
actively eroding their courses. These exposed red and yellow, sandy 


clay surfaces are partially covered with mosses and liverworts. The 
burrows are straight, cylindrical, and almost vertical in every in- 
stance. They are enlarged for two-thirds their upper length, then 
narrow abrupty until they are exactly the diameter of the hard 
abdominal disk of the occupant. Specimens are usually found head- 
first in the bottoms of the burrows, presenting their armor plate 
to the intruder. In this position they fit the cylindrical cavity so 
nicely, and they hold on with their claws so tenaciously, that it is 
necessary to dig the earth away in order to extricate them without 
injury. When disturbed, some back up their burrows to where 
there is room for them to turn and present their fangs. 

The burrow of Cyclocosmia is covered by a hinged trap door, 
which is similar in shape to that of Pachylomerus but much thinner 
and quite flexible, thus belonging to the wafer type. Most of the 
doors appear to be located in and under leafmold on the sides of 
the banks, a circumstance that makes them difficult to locate. 

It has now been established that Cyclocosmia is simply another 
trap-door spider, but an extraordinary one; what, therefore, can 
we conclude regarding the previous interpretations by older stu- 
dents of the use of its abdomen, interpretations that have persisted 
even into recent books and papers? Obviously, it is disproved that 
the spider closes the top of the burrow with its abdomen. In addi- 
tion to the fact that there is a wafer trap door covering the en- 
trance, it is impossible for the abdomen to plug the outer opening, 
because of the difference in diameter. Cyclocosmia seemingly has 
two lines of defense against enemies: its well-hidden surface door 
and its ability to run down to the bottom of its burrow and com- 
pletely plug the tube. (See Text Fig. 3, C.) 

The protective devices of the trap-door spiders herein considered 
may be briefly reviewed as follows: Pachylomerus and Bothriocyr- 
tum rely upon a fortress guarded by a heavy cork door, which they 
hold shut with surprising strength. Myrmekiaphila and Actinoxia 
build a weak, flexible cover that serves only to keep out rain, but 
is well camouflaged; they depend upon the deception of the con- 
cealed side chamber deep within their burrow. Cyclocosmia trun- 
cata carefully hides the wafer door to its nest, and to intruders 
presents its tough body armor as a shield. 

Sheet-Web Tarantulas. The spiders of the family Dipluridae 
have followed a course in their development quite different from 
either the trap-door spiders or the tarantulas. They spin a silken 


funnel in a crevice, under rocks, or in thick vegetable growth, and 
then continue the silk out over the ground as an expansive sheet. 
The spider hides in the funnel, and waits for insects to fall upon the 
funnel or become entangled in the sheet webbing, whereupon it 
rushes out and captures its prey. This type of web is called a sheet 
web; it is the same in general plan as those spun by the American 
grass spiders, by some wolf spiders, and by one group of atypical 
tarantulas. The spiders that use this device for capturing insects 
are usually agile creatures, which can rush to the location of their 
prey with great speed. Their movement on the flat sheet has, in a 
nice comparison, been likened to a skier gliding over the top of the 
snow, whereas the bulky insects make headway on the yielding silk 
like a man walking through heavy drifts. 

The sheet-web tarantulas are specialized creatures. They have 
developed the best eyesight of all the mygalomorph spiders. Their 
bodies are quite long and flat, and the tarsi of their long legs are 
provided with an unpaired claw, as in the trap-door spiders. Since 
much of their prey drops on the webs during the day, they hunt 
equally well then as at night. Their spinnerets are frequently 
greatly elongated and widely separated. The terminal segments of 
their long lateral spinnerets are provided with many small spools, 
from which can be spun a wide sheet of silk when the organs are 
moved from side to side. Except for two genera (Hexathele of 
New Zealand and Scotinoecus of Chile, which have six) only four 
spinnerets are present. 

Most of the diplurids live in the tropics, where large species and 
great sheet webs are conspicuous objects. In the United States 
occur only two genera, and they are not notable for size or for 
their web building. Microhexura is of particular interest because 
it is one of the smallest of all tarantulas, averaging about one-eighth 
inch in length. These tiny creatures carry their egg sacs around 
with them in their jaws, held beneath the body between the front 
legs much as in the fisher spiders. Three different species are now 
known, one from the high mountains of North Carolina and Ten- 
nessee and the other two recently discovered in the mountains of 
Washington and Idaho. Although we can probably assume that 
these tiny diplurids spin a sheet web, its exact character has not 
been observed. They live under pieces of bark, decaying wood, 
logs, and deep debris, in moist deciduous woods or fairly dense 
coniferous forests. 

The species of Evagrus are considerably larger than Microhex- 


ura, running half an inch, and even longer in the tropics. All the 
North American species build thin webs on the ground, especially 
in rocky situations, with the funnels hidden away in crevices. They 
are all pale yellow or light brown, excepting those from Mexico, 
which are mostly black. The male is remarkable in having the 
tibia of its second legs much swollen and armed near the middle 
with a heavy spur, which aids in holding the female during pairing. 

Tarantulas. Largest of all spiders are the immense hairy creatures 
of the family Theraphosidae, which Americans call "tarantulas." 
Although these mygalomorphs have nothing in common with the 
wolf spider of southern Europe, which truly deserves the name 
"tarantula," they have so completely usurped this appellation that 
an attempt to change it would be futile. In most of Spanish Amer- 
ica, the covering of hairs on the legs and bodies of these creatures 
has earned them the name of aranas peludas "hairy spiders." Not 
inappropriately, they are dubbed by the Brazilians carangueigeiras, 
because of the long bony legs especially of the males (Plate XV) 
and their stance and gait give them a superficial resemblance to 
crabs. In Mexico, native Indian names have largely been displaced 
by "tarantula," which is applied to almost any large spider. But in 
Central America, where these creatures are reputed to be danger- 
ous to horses, they are still called aranas de caballo, or matacab olios. 
Outside the Americas, the tarantulas are widely referred to as 
"mygales," or "bird spiders." This latter name is inappropriate and 
largely inaccurate, because most of the species are ground loving 
and have little opportunity to attack birds in trees. 

No matter by what name the tarantulas are known, they excite 
the imagination because of their great size and notoriety. In the 
steaming jungles of northern South America live the largest and 
bulkiest representatives of the whole tribe, enormous creatures that 
have no peers for size anywhere else in the world. A male Thera- 
phosa from Montagne la Gabrielle, French Guiana, measured three 
inches from the front edge of the chelicerae to the end of the abdo- 
men, and had a leg span when fully extended of ten inches. This 
specimen, which was black all over and only moderately hairy, 
weighed nearly two ounces. An enormous female Lasiodora, from 
Manaos, Brazil, the bulkiest tarantula I have ever seen, had a body 
three and one-half inches long, and measured nine and one-half 
inches with the legs extended. Quite handsome in her clothing of 
fine brown hairs, she weighed almost three ounces. 


Our United States species are pygmies by comparison. A full- 
grown male of Aphonopelma from Arkansas was found by W. J. 
Baerg to weigh a little less than one-half ounce. The greatest total 
length of the carapace and abdomen of this specimen was about two 
inches. A representative female of the same species closely approxi- 
mated the male in weight and body length. Large females often 
weigh as much as two-thirds of an ounce after they have been well 
fed. The long legs of our southwestern males span six or even 
seven inches. 

Owing to their formidable appearance, the tarantulas have ac- 
quired the reputation of being dangerous. This reputation they do 
not live up to either in belligerence or in the virulence of their 
bite. For the most part, they are sluggish creatures, which attack 
only when goaded to an extreme. Although our species are credited 
in many accounts with being great jumpers, leaping is not their 
specialty, and they ordinarily strike over a distance of only a few 
inches. In point of fact, they make fine pets, and some quickly 
become so tame that they can be picked up and handled with ease. 
The venom of most seems to have little harmful effect on man, but 
the powerful chelicerae of large species are capable of producing 
painful wounds. 

About thirty species of tarantulas live within the limits of the 
United States, for the most part in the arid Southwest. Their ab- 
sence from Florida and the southeastern states is rather surprising, 
since that area is seemingly ideal for these hairy spiders. Their 
eastern limit is the Mississippi River, and they occur north to a line 
starting between Missouri and Arkansas and ending on the Pacific 
Coast in the San Francisco region. 

Tarantulas abound in the tropics and there have developed many 
interesting types. A few of them have become arboreal and move 
over the surface of trees with great facility, frequently nesting in 
bromeliads and other stations far above the ground. Even the 
ground-loving species are good climbers, since their tarsi are pro- 
vided with thick brushes of hairs, which enable them to climb a 
vertical pane of glass with ease. The tarantulas of our American 
Southwest (Plates 12 and 13; Plates XV, XVI and XVII) on the 
other hand, are more restricted in habit. They are all ground loving, 
and dig their own burrows or live in those abandoned by rodents. 
Once they have become attached to a burrow and its particular 
surroundings, they stay there during their whole life. The area in 
which they hunt is small, usually only a few feet on each side, and 



V .** 

a. Clambering over stone 

b. Portrait 
MALE TARANTULA, Aphonopelma 

Richard L. Cassell 

George M. Bradt Lee Passmore 

a. Female on desert soil b. Web-covered entrance to burrow 

. Female and egg sac in exposed burrow 
TARANTULA, Aphonopelma 



they rush back into the safety of their tunnel at the slightest dis- 
turbance. Rarely do they live in regions of dense forest or heavy 
undergrowth, preferring open areas on hillsides, mixed desert 
growth, or the fringe of cultivated lands. The burrow usually has 
a loose webbing at the entrance (Plate XVI), spun there after the 
night's hunt and indicating that the spider is at home. During the 
winter months the opening may be plugged with silk, leaves, and 
soil, and, in some instances, a little mound of earth surmounts it. 

All spiders need water, and tarantulas are no exception. Indeed, 
Baerg attributes the complete disapperance of a large colony of 
Mexican tarantulas near Tlahualilo, Durango, to a drop in the normal 
rainfall from nine to three inches. On the other hand, small quan- 
tities of water poured into the burrow will often bring the spider 
rushing out into the open a procedure that affords an easy means 
of collecting them. The tarantulas in the damp rain forests of the 
American tropics frequently live above the ground, and after heavy 
rains may be seen wandering around in the open. Aversion for 
water may well have inspired some of these creatures to become 
arboreal, and thus escape regular deluges that they might have ex- 
perienced on the ground or below the surface. 

Tarantula burrows (Plate XVI) are often tunnels under large 
stones. Within spacious confines the mother spider spins a tremen- 
dous sheet, upon which she deposits her large eggs. She then covers 
them over with a second silken sheet and binds the edges together 
to form a flabby bag. For six or seven weeks she watches over this 
sac, occasionally bringing it to the entrance of the burrow to warm 
it in the direct sunlight, until finally the babies emerge. The spider- 
lings are gregarious, and they often remain in the burrow for some 
time after emergence; eventually they disperse by walking out of 
the hole and moving in all directions. Since they are much too large 
to balloon away on silken lines, they settle down in the general 
neighborhood of the burrow, hiding under chips and stones for a 
time and then occupying tiny burrows in the ground. As with all 
spiders, there is a tremendous mortality in the young stages: from 
each sac perhaps only a pair of tarantulas reach maturity. 

Adulthood for the spiderlings is very far in the future, since ten 
years are usually required for either sex to become sexually mature. 
The females and the immature males live in similar burrows in the 
ground, remaining virtually indistinguishable until the last molt, at 
which time some are surprisingly revealed as males. Many a large 
spider of this group has been kept in a cage for years, known by 


some common feminine name, when suddenly its true sex becomes 
manifest. The males are much darker than the brownish females, 
often nearly black, and have an abdomen set with rusty red hairs. 

Their final transformation gives the males an entirely different 
outlook on life. Whereas they have been content for years to live 
in a dark burrow, they now desert it and wander over the country- 
side in search of mates. This activity occurs late in the year, from 
July into November, and during this period they may be seen cross- 
ing the highways of the Southwest, frequently in considerable 

Most of the tarantulas observed wandering in the open are males, 
and these are seen only during mating season. Few survive the year 
in which they become mature; many die a natural death, others are 
killed by the female during courtship or after mating. It is quite 
different with the females, whose unusual longevity has been pre- 
viously noted. 

Living to a ripe old age is quite an accomplishment, for taran- 
tulas are plagued by many enemies. Various rodents dig into their 
burrows, and, unmindful of the poisonous hairs, use the spiders for 
food. The young are preyed upon by many birds, and lizards, frogs, 
and toads, and some snakes find them quite suitable dietetically. 
Insidious enemies are the small-headed flies of the family Acroceri- 
dae known to confine their attentions exclusively to spiders, in the 
bodies of which they develop as voracious maggots. The species 
of Pepsis, giant metallic blue or greenish digger wasps with rusty 
wings, specialize in tarantulas, in fact occur only where these large 
spiders are found. Preferred prey because of their greater bulk, the 
females offer a far more generous supply of nutritional food to this 
predator than do the males. The long legs of the male seem to give 
him some degree of safety, and when he elevates his body high on 
his legs, the "tarantula hawk" has such difficulty in stinging him 
that she may abandon her efforts. 

On those occasions when the female tarantula ventures forth 
during the day, she is fair game for the great tarantula hawks 
(Plate 12 and Plate XVII). The details of the ensuing struggle, 
quite as unequal as in the case of the trap-door spiders, are given 
by Petrunkevitch: 

The Pepsis comes deliberately to the tarantula on the side 
of the cage and drives her down to the ground. The next mo- 
ment she closes in on her victim in the manner already de- 


scribed, and bending her abdomen under the venter of the 
tarantula, introduces the sting between the third and fourth 
right coxae, close to the sternum. The tarantula struggles vio- 
lently and rolls with the Pepsis over and over on the ground. 
After a few struggles, the Pepsis lets go her hold on the taran- 
tula, walks off a couple of paces, turns and comes directly 
toward the jaws of the tarantula. Without the slightest hesi- 
tation, she slips under the tarantula, which raises as high as she 
can on all her legs. The Pepsis grabs the fourth left leg with her 
mandibles. The tarantula tries to bite here enemy, but the Pepsis 
holds her off by pressing her feet against the feet of the spider, 
while at the same time continuing her hold on the fourth leg 
with her mandibles. Meanwhile, she bends her abdomen and 
searches for the place to pierce with her sting. Now she finds it. 
It is the same place as in the first specimen, that is, the articula- 
tion membrane between maxilla, first leg, sternum and lip. In 
a few seconds the tarantula is paralyzed. The position of the 
two is very remarkable. The tarantula sits in her normal way, 
but the Pepsis lies on her right side, head toward the posterior 
end of the tarantula, sting in the place mentioned. After at least 
half a minute, the Pepsis withdraws her sting and walks off. 
The tarantula remains motionless. Presently one leg of the 
tarantula moves. The Pepsis returns, climbs on the tarantula, in- 
serts her sting between the sternum and the third coxa and holds 
it there for about a minute. 20 

All that remains is the transport of the heavy spider, often 
weighing eight or ten times as much as the wasp, to its grave, which 
may have already been dug. Once the victim is within the pre- 
pared cavity, an egg is deposited on its abdomen and the burrow 
sealed up. The paralyzed spider provides a fresh food supply for 
the larva of the wasp, and, though remaining alive for months, 
will almost never recover from the effects of the venom. 

The tarantula reacts to its enemies in various ways. By throw- 
ing itself back on its haunches and elevating its head to expose for- 
midable fangs, it assumes a defensive attitude that may frighten 
away timid adversaries. If a tormenter persists in goading the 
spider, it often elevates its abdomen, and, working its hind legs 
rapidly, scrapes loose a small cloud of extremely fine abdominal 

20 A. Petrunkevitch, "Tarantula versus Tarantula-Hawk: A Study in In- 
stinct," Journ. Exper. Zoo/., Vol. 45 (1926), p. 381. 


hairs. When these come in contact with mucous membranes of 
the eyes or nose of mammals or man, a very disagreeable urtica- 
tion results, which persists for some time. In discouraging some 
types of enemies, such as small mammals, this may be effective, al- 
lowing the spider to escape while the aggressor is recovering from 
the effects of the poison and is still partially blinded. (The bald 
spot on the abdomen of tarantulas is often a result of a full use of 
this covering of poisonous hairs; after each molt the spider is 
provided with another even covering of hairs and setae.) Unfor- 
tunately, this protective device can have no effect on those insect 
enemies, the solitary wasps, which are most important as predators. 

The body hairs of tarantulas have long been known to have 
in urticating effect on the skin of man; in allergic individuals they 
often produce distressing symptoms. It is quite probable that a 
toxic substance is present on the hairs, and the effect is not en- 
tirely mechanical. Support for this view is seen in the fact that 
alcohol in which these spiders have been preserved is capable of 
producing the characteristic itching and stinging. 

Because all United States species are ground forms, their food 
consists largely of the animals available in their restricted hunting 
areas. Beetles and grasshoppers are most frequently captured, but 
many other kinds of insects, and such crawling creatures as sow 
bugs, some millipedes, and other spiders, fall to their lot. It is well 
known that our species will kill and eat frogs, toads, mice, and liz- 
ards in captivity, and it is reported that occasionally these small 
creatures are captured in natural surroundings. During the summer 
months the tarantula catches and eats insects almost every night, 
frequently gorging itself. On the other hand, long periods of fast- 
ing seem to have little effect on the spiders. In order to ascertain 
just how long they could go without food, Baerg kept several of 
them supplied only with water. One of the females lived two years 
and four months without food, and other females almost matched 
this record. 

Though the belief is more widely held than is justified, tarantulas 
have long been known to capture and feed on small birds. The first 
record of this behavior was published in 1705 by the Swiss natu- 
ralist Maria Sibylla Merian in her Metamorphosis Insectorian Suri- 
namensiitm. A fine color plate shows one of the South American 
my gales in the act of feeding on a hummingbird. The spider, a 
great brown creature said to belong to the genus Avicularia, has its 
fangs imbedded in the breast of the gaily colored bird, which has 

Walker Van Riper, Colorado Museum of Natural History 

Black widow, Latrodeclus mactans, with egg sac 


Shamrock orb weaver, Aranea trifolium, on flower 

Joseph R. Swain 


been struck from its nest. Mme. Merian's report (which was re- 
ceived with considerable skepticism, since it was not believed at the 
time that any vertebrates could be consumed by spiders) was later 
followed by many claims that birds, lizards, and other animals were 
habitual prey of the great tarantulas and even of other smaller spi- 
ders. Corroboration of the early stories came in 1863 from H. W. 
Bates, in his book The Naturalist on the River Amazon. This tal- 
ented observer actually saw the capture and killing of one of two 
birds that were attacked, and very accurately depicted the spider in 
the act of feeding on it. Since that time, the debate has been con- 
cerned with the question of the capability of the spider actually to 
make use of the body of the vertebrate as food, not with its ability 
to capture it. 

That a powerful, predaceous creature, armed with strong fangs 
and potent venom, can kill a bird, a mammal, a snake, or a lizard is 
not an astonishing thing. The arboreal tarantula cannot differenti- 
ate between a bird or -a large insect, and makes its capture in exactly 
the same manner by springing upon it and striking it with its fangs. 
Spiders predigest their food by flooding the wound with secretions 
from the maxillary and other glands, softening the tissue so it can be 
sucked into the body. The powerful buccal secretions are known 
to have a digestive effect on meat, so it is not strange that even the 
bodies of vertebrates can be taken through the small mouth open- 
ing. A tarantula can reduce the fat body and wings of a large satur- 
niid moth to an insignificant vestige, and do so thorough a job of 
it that one wonders if chitinous outer parts were not absorbed 
along with the softer portions. It can reduce the bulk of a fat mouse 
or the body of a small rattlesnake in the same way, feeding on the 
gruesome corpse for many hours. 

In the United States the lessened opportunity to capture small 
vertebrates has kept our tarantulas largely insect eaters a quite 
different situation from that in Brazil, where the ground-loving 
species of Granrmostola and Lasiodora are believed to kill and feed 
on frogs, lizards, and small snakes in their natural surroundings. 
In captivity, these large spiders definitely preferred such small cold- 
blooded animals, and would generally pay no attention to various 
insects offered as food. While experimenting on spider venoms, 
Drs. Brazil and Vellard of Sao Paulo kept fifty of the tarantulas in 
good health for eighteen months on a diet of frogs, lizards, and 
snakes. Small rattlesnakes and the venomous Eothrops were killed 
and eaten as readily as any other kind of snake. 


When a Grammostola and a young snake are put in a cage 
together, the spider tries to catch the snake by the head, and 
will hold on in spite of all efforts of the snake to shake it off. 
After a minute or two, the spider's poison begins to take effect 
and the snake becomes quiet. Beginning at the head, the spider 
crushes the snake with its mandibles and feeds upon the soft 
parts, sometimes taking twenty-four hours or more to suck the 
whole animal, leaving the remains in a shapeless mass. 21 

One of the interesting bits of folklore prevalent in Mexico and 
Central America is the legend of the matacaballo. For many years 
it has been a general belief that tarantulas bite the fetlocks of mules 
and horses and cause the loss of the hoof. According to the story, 
the spider hunts out the sleeping animal at night and takes a narrow 
strip of hair from above the hoof for its nest building, using an acid- 
like secretion to make the hair slough off more easily. The site of 
the injury then becomes inflamed, infection occurs, and the hoof is 
lost. In another version, all goes well unless the spider is disturbed 
and bites the hoof. In order to prevent hair clipping by the mata- 
caballo y the natives run their animals through a footbath of water 
covered with about an inch of crude oil. The tarantulas do not like 
oil-covered hair, so the animals gain temporary immunity from the 
presumed scourge. 

It is now known that this often fatal disease is actually caused by 
a bacillus that is very prevalent in the soils of Central America. 
During the rainy season, the skin of the hoof becomes chapped and 
the bacillus is able to enter through small abrasions. Needless to 
say, tarantulas use only their own white silk for their nests. 


One of the two principal branches of the My galomorphae has 
culminated in the Atypidae, the purse- web spiders; they are the 
namesakes of the series known as "the atypical tarantulas." This 
series includes the most generalized of all living spiders, the liphi- 
stiids (family Liphistiidae) , which have changed little since the 
late Paleozoic and are the last remnant of an ancient group that 

21 J. H. Emerton, Psyche, 1925, Vol. 39, p. 60. (Part of English abstract of 
part of article by Vital Brazil and J. Vellard, Memorias do Institute do 
Butantan, 1925, Vol. II, and 1926, Vol. III.) 


failed to alter its form to cope with altered environment. More 
advanced offshoots from this same primitive stock are the sheet- 
web atypical tarantulas (family Mecicobothrndae), the folding- 
door tarantulas and relatives (family Accatymidae), and the 
above-mentioned purse-web spiders. The atypical tarantulas have 
paralleled in their development the other principal branch of the 
suborder, the tarantulas and trap-door spiders, and have matched 
rather closely their handiwork in silk. 

The outstanding characteristic of this whole series is the clear- 
cut visual evidence of segmentation on the dorsum of the abdomen. 
In the past, the abdominal tergites of the Liphistiidae have been 
hailed as evidence, along with the spinnerets and some other fea- 
tures, to set the family apart by a very wide margin from all other 
spiders, and place it in a separate suborder. This early evaluation 
of the liphistiids has become so fixed in the minds of most spider 
students that they have denied that any other living spiders are 
segmented in the adult stages. One has only to look at the abdomens 
of Antrodiaetus, Hexura, or At y pus to see tergites that differ little 
or not at all from those of Liphistius. And a study of the other 
features of these genera demonstrates with little question that the 
relationship between the more generalized Liphistius and its modern 
cousins is a real one. 

The atypical tarantulas are of moderate size, few of them ex- 
ceeding an inch in length, and in general form and appearance they 
resemble the typical trap-door spiders. Most of them are accom- 
plished burrowers, but only the folding-door tarantulas and close 
relatives have the chelicerae fitted with a rake of coarse teeth for 
digging. The unpaired claw is present on the tarsi, but no claw 
tufts or tarsal brushes have been developed. The full complement of 
eight spinnerets is present in the liphistiids, and the pudgy lateral 
pairs bear some resemblance to those of ancient spiders. The other 
atypical tarantulas long ago lost the anterior median pair. The per- 
sistence of the anterior lateral pair is noteworthy, since it is present 
elsewhere among the mygalomorph spiders only in one or two 
primitive members of the family Dipluridae. The anterior lateral 
spinnerets are two-segmented and functional in Aliatypus, uniseg- 
mented and small in Atypoides and most other genera, and com- 
pletely missing in Antrodiaetus. 

In some respects the atypical tarantulas have outdistanced the 
typical tarantulas, even though the physical heritage of the former 
includes more generalized features. The male palpus is provided 


with a conductor of the embolus a shield for the protection of the 
delicate tube found in none of the typical tarantulas and apparently 
similar to that found in the true spiders. The epigyna of the females 
all agree in having four primary seminal pouches, whereas in almost 
all higher My galomorphae and true spiders there are only two. 

The atypical tarantulas are hardy creatures that live much far- 
ther north in the United States than any of the typical tarantulas. 
Some of the folding-door tarantulas are common in our Pacific 
Northwest, and extend even into British Columbia and Alberta. 
In Europe At y pus is found in England, and the same species occurs 
in Denmark, a location that would place it above the 50th parallel 
north. In the United States Atypus is uncommon in the north but 
has been taken in Massachusetts and Wisconsin, well above the 4oth 

Liphistiids. The liphistiids are the most primitive of all living 
spiders, still maintainng the appearance and probably the funda- 
mental structure of their ancient Paleozoic forebears. They occur 
only in the Orient, but are reviewed here for comparison with the 
other atypical tarantulas, which are predominantly American. Li- 
phistius lives in hilly districts in the Malay States and adjacent 
Sumatra, where five species occur, and in similar situations in Burma 
and northern Indo-China, each of which has a single species. The 
genus Heptathela comprises a single species from the southernmost 
Japanese island of Kyushu and the Luchu Islands, and one from 
Shantung, China. 

A series of tergites, all of which are conspicuous, hardened 
plates set with rows of erect setae, is a striking feature of the 
liphistiids. All twelve primary abdominal segments can be recog- 
nized by external tergites in Heptathela, whereas at least nine are 
distinct in Liphistius. The generalized condition of the abdomen 
is further seen in the median position of the spinnerets. The great 
space between them and the anal tubercle represents those reduced 
segments behind the sixth that in higher spiders are completely 
incorporated into the tubercle. Four pairs of spinnerets are pres- 
ent, but the median pairs are greatly reduced in size. The lateral 
spinnerets of Liphistius are short, thick, fingers, with a large basal 
segment and an apical portion that is divided transversely into many 
small rings, thus said to be multisegmented. In the other atypical 
tarantulas, the spinnerets have shifted much farther back, but in 


no case do they reach the anal tubercle. In the typical tarantulas 
and in all true spiders, the posterior segments are so much telescoped 
or obliterated that the spinnerets and anal tubercle lie close to- 
gether. In Heptathela the posterior median spinnerets are reduced 
in size and fused into a single tiny colulus; so these spiders are usu- 
ally said to have seven spinnerets. 

The internal features of the abdomen are also of particular in- 
terest in this family. Five pairs of ostia are found in the heart of 
Liphistius, the fifth pair belonging to the sixth somite, and this 
number has not as yet been found in any other spiders. Although 
Heptathela appears to have a more primitive external segmentation, 
its ostia are reduced to four pairs, showing that the external fea- 
tures have not kept pace with internal changes. 

The liphistiids differ from the atypical tarantulas in several 
other respects than those enumerated above. The sternum is very 
narrow and unmarked by sigilla. The eyes are well developed and 
seem to be specialized rather than primitive, since the lateral ones 
are enlarged and the anterior median very much reduced in size. 
The coxa of the pedipalp does not have a maxillary lobe even 
slightly developed; in this respect the liphistiids agree with the 
majority of the typical tarantulas. 

The liphistiids live in burrows lined with silk, the entrance to 
which is closed by a simple trap door of the wafer type sometimes 
fastened down by the spider with threads from the inside. A num- 
ber of lines of heavy twisted silk radiate from the lower lip of the 
opening, serving as signal lines to warn the waiting spider of the 
approach of insects. Sometimes the whole tube is set in the open 
against the side of a wall, instead of being at least partially embedded 
in the soil. The trap door and any exposed part of the tube is 
covered with sand, thus to some extent camouflaged against the 
natural background. Some of the liphistiids live in caves. The food 
of these spiders usually consists of ground insects of various kinds, 
but the cave-dwelling variety often subsist on a single species of 
grasshopper or cricket. 

These primitive spiders are clumsy animals, which do not put 
down dragline threads as do all other spiders. Ordinarily they as- 
sume a stance with the front three pairs of legs directed forward, 
an attitude suited to life in a narrow silken tube. They are said to 
be awkward movers, and when "placed on their backs on a flat 
surface cannot right themselves." 


Sheet-Web Atypical Tarantulas. It is of particular interest that 
among the atypical tarantulas we should find a group that parallels 
very closely the sheet-web tarantulas of the family Dipluridae. 
The hind spinnerets of these spiders are greatly elongated (par- 
ticularly the terminal segment, which is flexible) and rather widely 
spaced; this is probably an adaptation for spinning the sheet web, 
and it illustrates how in widely unrelated creatures similar activities 
often lead to the production of similar morphological features. The 
resemblance between Hexura and the diplurids is an amazing one. 
We find it running over a silken sheet web as do its distant relatives. 
Were we not deterred by what appear to be more fundamental 
features, we would ordinarily place them close together, perhaps 
deriving one directly from the other. 

As in most atypical tarantulas, six spinnerets are present, and the 
one-jointed anterior lateral pair is much reduced in size. The 
distance between the spinnerets and the anal tubercle is not so great 
in Hexura as in Antrodiaetus, but this can be attributed to the mi- 
gration of the spinneretts back and to the side a frequent occur- 
rence in the Dipluridae. The abdomen is provided at the base with a 
large brown tergite. The chelicerae entirely lack a rake or digging 
instrument such as is developed in the folding-door tarantulas. The 
palpus of the male has a well-developed conductor of the embolus, 
and the whole organ closely resembles that of the other atypical 

First found in the state of Washington, the typical species is 
Hexura picea, a dusky-brown spider about one-fourth inch long. 
It lives under leaves, trash, and pieces of wood or back on the 
ground in pine woods, there building a loose sheet web in which 
it stays and over which it runs. The male has long projecting 
chelicerae armed with prominent spines. A second species of Hex- 
ura, which differs chiefly in its paler coloration, has been reported 
from northern California. 

The genus Mecicobothrium, on which the family name Meci- 
cobothriidae is based, is represented by a single known species in 

Folding-Door Tarantulas and Their Kin. Except for Ac cat y ma 
of Japan, a little-known genus that may be the same as our better- 
known Antrodiaetus, the members of the family Accatymidae are 
exclusively American. Two species are known to come only from 
California: the turret spider Atypoides, and Aliatypus, which covers 


its burrow with a trap door. The remaining genus, Antrodiaetus, 
has numerous species; they are widely distributed in the southern 
states right across the country, and in the mountain states and the 
Pacific Northwest are the commonest mygalomorph spiders. 

An important feature of this group is the possession of a distinct 
rake on the chelicerae. For this reason they have long been placed 
among the true trap-door spiders of the family Ctenizidae, a group 
they resemble closely, but one that has taken an entirely different 
route in its development. In Antrodiaetus the anterior lateral spin- 
nerets have been lost, but in the other two genera the six spinnerets 
are all present, with the same arrangement as in At y pus. The pres- 
ence of two, three, or four well-marked tergites at the base of the 
abdomen in both sexes is invariable; these are strikingly large and 
distinct, set with rows of transverse setae as in the liphistiids. 

The turret spider, Atypoides riversi, lives in the foothills of the 
Coast Ranges of California, and is found in abundance along shaded 
streams and in thickets in the San Francisco Bay region. Its turrets 
are well-known objects. They are ordinarily open at the top, lack- 
ing completely a closing flap or trap door, but on occasion will be 
completely spun over and closed with silk and debris. The burrow 
is very long, usually inclined, and is lined completely and rather 
heavily with white silk. The aerial portion may be only a short 
chimney, but quite often there is a long tube, which, penetrating 
thick grass, moss, or debris, finally terminates in the expanded white 
lip of the turret. The spider takes whatever building materials are 
handy leaves, small twigs, moss, bits of lichen, pine needles and 
fastens them on the outside of the silken collar. Often most in- 
geniously constructed, the turret provides an excellent lookout for 
the spider, which sits in the entrance at dusk and catches the insects 
that come within its reach. 

The turret spiders are about half an inch long, with yellowish 
brown carapaces and darker brown or purplish abdomens. A re- 
markable feature of the male is the presence of a long, projecting 
process on each chelicera, which probably is concerned with mating 
since no similar spur exists in the female. The tiny anterior lateral 
spinnerets are composed of a single joint, and, judging from their 
reduced size and lack of spinning equipment, are rapidly being 
aborted. The median groove of the carapace is a linear impression. 
The dorsal tergites on the abdomen are well marked, three being 
represented clearly in each sex. 

The second exclusively Calif ornian genus is Aliatypus, which 


comprises a single known species having about the same range as its 
congener, the turret spider, and sometimes found in the same col- 
onies. The burrow of Aliatypus calif ornicus is comparatively long, 
and either goes straight down into the compact soil or is provided 
with pronounced bends. The silken lining is quite thin, but thickens 
around the opening, which is covered with a trap door of the 
wafer type. The burrows are usually found along roadside banks 
and streams, where the spider seems to prefer exposed soil only 
thinly covered with vegetation. 

The female Aliatypus resembles the turret spider, but has a some- 
what broader carapace marked by a round median groove. The 
male resembles the female quite closely, and completely lacks a 
distinctive spur on the chelicerae such as is present in Atypoides. 
The male palpi are thin appendages fully as long as the first pair of 
legs. In this genus the most interesting characteristic is that the 
anterior lateral spinnerets are nearly equal in size to the posterior 
median, and are also two-jointed. Well-developed spigots show 
that they are still functional appendages a fact that marks them as 
the most generalized of all mygalomorph spinnerets, except those 
of the Liphistiidae. Since they are bisegmented, we can state with 
confidence that they are definitely the anterior lateral pair, and 
thus corroborate on direct evidence what has been the presumption 
of the majority of araneologists. 

The type genus of the family Antrodiaetus is in many respects 
the most highly developed. The short anterior lateral spinnerets, 
greatly reduced in size in Atypoides, have here been completely 
lost. The carapace has the median groove present as a longitudinal 
impression. In the males the abdominal dorsum has three distinct 
tergites above the base, and in the females one or more is present. 
The chelicerae of the males are armed with a prominent tubercle 
set with black setae. 

These spiders live in burrows, which may descend a foot or 
more in the soil, and which often have prominent bends. The upper 
part of the burrow is usually well lined with silk; in western species 
the opening is often concealed under stones or hidden in debris. 
As a result of their secretive habits and their well-hidden burrows, 
relatively few females are known in collections, whereas the males, 
which rove around in the late summer, are quite common. An ex- 
ception may be made for some .eastern species that dig their nests 
right in the open, and are easy to find. 

About a dozen species of Antrodiaetus have been described from 


various parts of the United States. Several are known from the 
Southeast, and one of these occurs rather commonly near Washing- 
ton, D. C In 1886 George F. Atkinson studied a species in North 
Carolina and, because of the singular means by which it closed its 
burrow, called it a "folding-door tarantula." There are two equal 
doors, each forming a half circle, which hang on semicircular 
hinges; when closed, they meet in a straight line over the middle 
of the hole. Each night the spider throws open its burrow, and each 
morning closes the doors, as shown in Plate 16. On the method of 
capturing its prey, Atkinson had the following to say: 

One evening I placed several ants in the jar containing the 
nest. When an ant approached, so near the door as to send a 
communication to the spider of its presence, the spider sprang 
to the entrance, caught a door with the anterior legs on either 
side, and pulled them nearly together, so that there was just 
space enough left for it to see the ant when it crossed the open- 
ing. When this happened, the spider threw the doors wide open, 
caught the ant, and in the twinkling of an eye had dropped back 
to the bottom of the tube with its game. This I saw repeated 
several times during the months of January and February. 22 

Purse-Web Spiders. In the low hammocks of Georgia and 
Florida lives one of the most remarkable members of the tarantula 
fauna. It has received the common name of "purse-web" spider 
from the resemblance its web bears to the silken purses so much 
favored by ladies over a century ago. In 1792 John Abbot, eminent 
entomologist and artist of Savannah, Georgia, first described the 
tubes of the species that bears his name: "This singular species 
makes a web like a money purse to the roots of large trees in the 
hammocks or swamps, five or six inches out of the ground, fastened 
to the tree, the other end in the ground about the same depth or 
deeper. To the bottom of that part in the ground the spider retreats. 
I imagine they come out and seek their food by night as I never 
observed one out of its web. In November their young ones in vast 
numbers cover the abdomen of the female and the abdomen then 
appears very shrunk. The male is the smallest, but has the longest 
nippers. Taken in March and is not common." 

Atypus abboti digs a deep burrow in the soil at the foot of a 

22 G. F. Atkinson, "Descriptions of Some New Trap-Door Spiders, Their 
Notes and Food Habits," Entomologica Americana, Vol. 2 (1886), p. 116. 


tree. This it lines with silk, then prolongs the silken lining up the 
side of the tree. The aerial tube (Plate 15) is securely fastened to 
the bark by threads, and in full-grown females is about ten inches 
long and three fourths of an inch wide. Smaller specimens spin cor- 
respondingly smaller tubes, which are almost invariably placed up- 
right against a tree. The top of the tube is open, but the silk is so 
flattened and pressed together that the natural opening seems to be 
closed. An even covering of sand and other fine material serves to 
color and darken the white silk and make it less conspicuous. In 
Florida the tubes are most often found attached to sweet gums, 
oaks, and magnolias in deep forest where the soil is damp and rich 
in organic material although they have also been observed in dry 
woods where the sandy soil has little or no covering of humus. 

In Atypus bicolor, a large spider shown in Plate XIII, the tubes 
of old females are often eighteen inches long. This species occurs 
from Maryland south into western Florida, and westward into Mis- 
sissippi. They live for the most part in mesophytic woods. Near 
Quincy, Florida, I found them abundant in deep woods near a small 

The tube of Atypus takes form in a characteristic manner. The 
female spins a small, horizontal funnel or cell on the surface of the 
soil, and from this base works both upward to lay out the aerial 
tube, and downward into the soil. The funnel is pierced above, 
and a two-inch section of vertical tube is set up against a tree. This 
design is accomplished by laying down many single lines and spin- 
ning the whole together into a strong fabric. The spider then 
begins excavating and spinning the subterranean part of her habita- 
tion. She molds the soil into small pellets, which she disposes of 
through the opening at the top of the aerial web. The covering 
of debris over the surface of the tube comes, surprisingly, from 
within the burrow instead of being laid on from the outside: the 
sand and small particles are pressed outward through the web until 
the whole surface is evenly covered. After the first section of aerial 
tube is completed, another length is spun and coated with sand. 
Thus by sections the web moves up the side of the tree, until it 
attains the full length for the species. Like an iceberg, the finished 
tube penetrates the ground much farther than the length of its 
visible, aerial portion. It is heavily lined with silk, which becomes 
stronger day by day as the spinnerets constantly lay down their 
dense bands. 

The European species of Atypus have habits similar to our 


American forms, with this exception: they only rarely extend their 
nest up the side of a tree. Instead, they spin a very short aerial tube, 
about two inches long, which rests on the ground, is suspended 
in the grasses, or is attached to stones. The end of this tube is closed 
and, as in our species, the spider never leaves the web. The leath- 
ery tube, rendered less conspicuous by its covering of sand and 
debris, would seem to afford considerable protection to the spider; 
this seems to be borne out by the fact that the atypids are largely 
immune to the attacks of pompilid spider wasps. Because the areial 
purse web is completely enclosed, and continuous with its subter- 
ranean portion, predators must cut through the web to locate the 

The purse- web spider remains just inside the subterranean por- 
tion of her nest while waiting for prey, but at the slightest notice 
of a passing insect she moves into the aerial web. Her course is 
charted by the movement of the tube, and when the insect crawls 
over the surface, she rushes to the proper point and strikes her long 
fangs through the web, around or into the body of her prey. Hold- 
ing it until completely subdued, she at the same time cuts the tube 
and pulls it inside. A slight rent is left in the silk, which will later 
be sewed together, and in due time covered over with sand so 
evenly that no sign of the break is evident. A tidy housekeeper, 
Atypus when through feeding brings the shrunken remnant of her 
prey to the opening at the top of her web and casts it out. In the 
same way, she voids her milky white, liquid fecal material through 
the opening with such force that it is shot several inches away. 

In June the males become adult and leave their webs to wander 
in search of a mate. Until the time they become fully adult they 
live in nests that are to all appearances identical with those of the 
females, and occasionally in season they can still be found in their 
tubes. The mating behavior of our American species has not been 
described, but it is probably similar to that of the better-known 
European types. When the male finds the tube of a female, he 
drums upon it with his palpi, and presumably is able to ascertain 
by the reactions of the female to this drumming, whether he is go- 
ing to be welcome. After a short period, he cuts open the tube and 
enters, and the break is repaired by the female. Mating occurs deep 
in the tube. It is believed that the male lives in the burrow for 
many months before he dies. The eggs are deposited within the 
burrow, and hatch during the summer months. The young may 
stay with the female for long periods, but in most instances they 


leave the nest in the late summer and disperse by ballooning. Their 
threads are usually a heavy band of parallel strands less fine than 
those of true spiders. Some of the young, it is thought, do not take 
to the air but merely walk a short distance from the maternal nest 
and begin work on tiny tubes of their own. 

The purse-web spiders are the most extraordinary of all the 
atypical tarantulas, as regards both their physical features and their 
singular habits. The marks of their primitive origin are clearly 
shown in the presence, above the base of the abdomen in each sex, 
of a single well-marked tergite, and the considerable separation of 
the anal tubercle from the posterior spinnerets. In the reduction of 
their cardiac ostia to three pairs is clear evidence that their heart 
has become specialized, or simplified, at a much faster rate than 
have other features of the abdomen. The chelicerae, though not 
provided with a rake for digging, are modified into effective shov- 
els for carrying loads of sand or pellets of soil. The fang is a long, 
thin spine well designed to pierce the silk and hold the prey. 

The species of Atypus are found in the north temperate zones of 
Europe, Japan, and the eastern United States. Species are also known 
from Java and Burma in the eastern tropics. Another genus of the 
same family is Calommata, which is largely restricted to tropical 
areas in Africa and the Orient. The four American species of 
Atypus are all confined to the eastern portion of the United States, 
and are most abundant in the extreme southeastern part of their 
range. Only three of our species are well known, and only two of 
these moderately common. 

The females of all the American species are predominantly brown 
in color, shining, and only very sparsely set with covering hairs. 
The robust body is provided with quite short legs and long chelic- 
erae, and runs about half an inch in length although bicolor, the 
largest known species is often an inch in length. The males are 
similar to the females in most respects, but have longer legs. In 
niger, a shining black spider most closely related to the European 
species, the disparity in size of the sexes is not particularly marked; 
but in the other species the males are somewhat smaller than their 
females, and very brightly colored. The abdomen of Atypus abboti 
is a beautiful iridescent blue or purple, set against black legs and 
carapace. Atypus bicolor has carmine legs, which, contrasting with 
its deep-black carapace and abdomen, make it the most striking of 
all our species. 


The Cribellate Spiders 



a flat spinning organ close in front of the anterior spinnerets are 
called "cribellate spiders." This organ, which exists in addition to 
the usual six spinnerets, is known as the "cribellum." It is the 
homologue of the anterior median spinnerets, and has been retained 
as a functional spinning organ, whereas in other true spiders it is 
represented by an inconspicuous vestige. 

The cribellum (Text Fig. 4, C) may be likened to the fused spin- 
ning fields of two spinnerets lying nearly flat against the surface of 
the abdomen, all but the tips of the originally paired fingers having 
disappeared. The dual character of the organ usually is evident on 
close examination, which shows an actual division of the field by a 
longitudinal line or ridge, or a pinching at the point of division. The 
spinning field itself is covered by thousands of tiny spinning open- 
ings, which give it a sievelike appearance under magnification, and 
from which come exceedingly fine threads of viscid silk. The ordi- 
nary silken threads of cribellate spiders are derived from glands 
opening on spinnerets, as in other spiders. Whenever cribellar silk 
is combined with the regular threads, the line becomes so character- 
istic in color and physical appearance that it is called a "hackled 

Invariably accompanying the cribellum is an accessory comb of 
hairs called the "calamistrum." This is a line of curved setae, dif- 
fering somewhat in appearance in the various families, and always 
found upon the metatarsis of the hind legs (Text Fig. 4, E). The 
use of the cribellum and calamistrum together as a spinning and 
carding apparatus to produce the cribellate thread is essentially the 
same among all the spiders of the group. Let us consider the method 
of a typical hackled band weaver of the genus Amaurobius. 

The cribellum of Amaurobius is divided longitudinally by a 


distinct septum, on each side of which lies a spinning field. Because 
of this division, the hackled band spun by Amaurobius consists of 
two ribbons instead of the one band usually found in the cribellates 
that have obliterated the limits between the two spinnerets. The 
two ribbons are borne by two strands of dry silk presumed to come 
from the ampullate glands. To spin its composite hackled band, 
Amaurobius holds the hind leg of one side at right angles to the long 
axis of its body, with the tarsus resting against the metatarsus of the 
leg of the other side. The metatarsal comb is then rubbed back and 
forth over the cribellum, drawing out two ribbons that are attached 
to two lines of dry silk coming at the same time from the spin- 
nerets. After a period of incessant spinning, the spider shifts to the 
other leg, supporting it as before by resting the tip across the oppos- 
ing metatarsus. The result is a fairly regular, ribboned band of silk 
that seems to the naked eye a single thread, and has a characteristic 
bluish color. 

The cribellate spiders have retained more units of spinning 
equipment than have any other true spiders, and have maintained 
all of them as functional organs. It is thus not surprising that none 
have become truly vagrant, and that all rely to a very large extent 
on their viscid threads to capture insects. The very fact that they 
have retained the cribellum, with its glands of sticky silk, indicates 
their reliance on it in some measure to entangle their prey. 

In the cribellates, the unpaired claw on the tarsus is usually pres- 
ent, but it is lacking or reduced in size in a few members that may 
be taking their first steps toward becoming vagrant types, or have 
learned to do without these tarsal hooks in their webs. Some cribel- 
lates are confirmed aerial spiders and spin tangled webs, sheet webs, 
and orb webs, from which they hang downward. Others run over 
an irregular blanket of webbing in an upright position. The cribel- 
late spiders have produced web structures closely paralleling those 
of the ecribellate spiders, the only difference being the use of the 
hackled band by the former. 

The cribellates are quite sociable creatures. During the mating 
season the males enter the webs of the females and live there as 
partners until presumably they die a natural death. This tolerance 
carries even beyond the mating season, for among the cribellate 
spiders we find nearly all our social spiders. Some members of al- 
most every family are known to live together, in colonies similar to 
those of certain gregarious caterpillars. 

One of the controversial and perplexing problems in spider 


A. Line trap of Miagrammopes. B. Triangle web of Hyptiotes. C. Cribel- 

lum and spinnerets of Amaurobius. D. Tarsal claws of Amaurobius. E. 

Metatarsus and tarsus of Hyptiotes, showing calamistrum. F. Retiarius snare 

of M enneus (after Ackerman). 


Richard L. Cassell 

Banded Argiope, Argiope trifasciata, with swathed prey, dorsal view 


Richard L, Cassell 

Banded Argiope, Argiope trifasciata, ventral view 


phylogeny has to do with the origin of the cribellate spiders and 
their relationship to the ecribellate families. By some they are held 
to be a homogeneous group derived from a single line of ancestral 
spiders that put their fading anterior median spinnerets to a new 
and original use by inventing the calamistrum. On the other hand, 
the cribellate spiders can be regarded as a remnant held over from 
a time when all spiders were cribellate, and the modern forms can 
then conceivably originate from one or several distinct lines. The 
presence among these spiders of some in which the second pair of 
book lungs is still persistent suggests a very early origin for the 
group, and also strongly indicates that all ancestral spiders were 
provided with cribellum and calamistrum. If we subscribe to this 
belief, then it can be put that the ecribellate spiders have lost the 
spinning organs, rather than that the cribellates have gained them. 
In this book we consider the cribellate spiders in a single chapter, 
even though among them are certain discordant elements that sug- 
gest a multiple origin. 


One of the oldest American spiders is Hypochilus thorelli, a 
strange relic of the past, whose forebears were probably aerial con- 
temporaries of the Paleozoic ground tarantulas. The only known 
living relatives of Hypochilus are two species of a related genus, 
Ectatosticta, found in China and Tasmania. Although we regard 
spiders of the family Hypochilidae as being true spiders, they share 
many of the features of the tarantulas, the most notable being pos- 
session of the posterior pair of book lungs, which in all other true 
spiders have been transformed into tracheae. These lungs are situated 
beneath and about at the middle of the abdomen, and their spiracles 
open at the sides of a prominent furrow. The chelicerae are pro- 
vided with venom glands entirely contained within the basal seg- 
ment, and the heart has four pairs of ostia as in the tarantulas. 
Perhaps the most distinctive badge of the true spider is the articula- 
tion of the chelicerae. In Hypochilus we find the chelicerae largely 
intermediate in type between those of the true spiders and those of 
the tarantulas; since the claws do not point toward each other, they 
are in many respects nearer those of the latter. The cribellum of 
this spider is a rounded plate lacking the median dividing ridge but 
pinched before and behind to indicate its original dual character. 


It sits on a low elevation that strongly suggests the segment of an 
ordinary spinneret. 

Hypochilus shows a greater difference from the tarantulas in its 
habits of life than in its physical features. Whereas no tarantula 
has become a confirmed aerial cobweb spider, the hypochilids and 
a great many other true spiders have. It is quite possible that spiders 
resembling the hypochilids were the first to break away from the 
conservative tarantulas, and that Hypochilus thorelli is a modern 
representative of an ancient group that gave rise to all true spiders. 

Hypochilus has a very restricted range. It is found in the can- 
yons of the mountains of the southeastern United States, where it is 
quite abundant at elevations from one to about five thousand feet, 
and especially so in the Great Smoky, the Nantahala, and the south- 
ern half of the Blue Ridge Mountains. It prefers dark situations 
under overhanging rocks, and natural arches in forested areas near 
streams. Its webs conspicuous objects even from a distance are 
often found close together under the rock ledges. They are shaped 
like lampshades with the top pressed against the overhanging sur- 
face, and consist of a very heavy mesh of cribellate threads over a 
basis of dry silken lines. 

The spider hangs underneath this net with its long legs touching 
the sides of the aerial portion. It resembles most closely the true 
spiders of the family Pholcidae, and is remarkable for the great 
length of its banded legs. Hypochilus does not seem to have the 
power of autotomy, and its legs do not break off at a point weak- 
ened and predetermined for this purpose, as in other spiders. The 
males, which mature in the fall, differ little from their dull, yellowish 
mates. The male palpus is of very generalized design, and is pro- 
vided with a conductor of the embolus as in the atypical tarantulas 
and most true spiders. The epigynum of the female is quite simple 
and presents no external openings. In the internal epigynum are 
four receptacles a feature shared by the atypical tarantulas and 
some of the most primitive true spiders. 


One of the very common house spiders of the southern Ameri- 
can states is Filistata hibernalis, a large animal whose webs are often 
prominently outlined on the outside walls of buildings. This spider 
hides in a crevice during the day, and at night comes out to spin 


on its web, placed over the retreat as a rounded net, which soon 
gathers to its sticky lines an unkempt covering of dust and debris. 
The web, often more than a foot in diameter, is composed of a 
series of regular, radiating lines of dry silk over which has been 
spun many lines of cribellate bands. The touch of an insect vibrates 
the web, and the disturbance is communicated to the hiding spider. 

The hackled band of Fihstata is composed of four different 
kinds of silk. The cribellum is combed with a very short calamis- 
trum, and many tiny loops are produced, which, bundled together, 
give a most irregular shape to the characteristic threads. The spider 
is said to lay down a dry line of two threads, to retrace its steps 
upon this, and then to put down the irregular hackled lines, thus 
accomplishing its purpose in three operations rather than in a single 
one as does Amaurobius. 

The female of the common house Filistata is about half an inch 
long, and is quite variable in color, being light brown, dark brown, 
or often velvety black. Older specimens are usually much darker 
than the young ones. The male is pale yellow, smaller, and his 
slender body is fitted with much longer legs, which, during court- 
ship, he uses to hold the front legs of the female as the couple 
parades back and forth in a prenuptial dance. 

The members of this family are considered quite generalized 
spiders because of the simplicity of their palpi. Nearly a dozen 
species, some very much smaller than hibernalis, occur in the ex- 
treme southern parts of the United States. 


In this group are included the great majority of cribellate spiders 
and almost all of those that occur in the temperate regions. About 
two hundred species are known from North America, but for the 
most part these represent only a few different types. The preva- 
lence of their meshed webs on the ground and on vegetation every- 
where is an index of their abundance and comparative success. 
With few exceptions, they are confirmed web spiders and stay in 
their snares most of the time, walking upright over the bluish sheet. 
Their sedentary bent has not molded them into such aerial types as 
in the Uloboridae, but some do climb vertical meshes and are at 
home in aerial tangles. Three claws are almost invariably present 
on the tarsi, but they are never aided in their climbing by accessory 


claws. Many are swift runners that can be seen dashing across paths 
with the celerity of vagrants. Their habits are thoroughly interest- 
ing, although they are not known to do things quite as amazing as 
do some of the aerial web spinners. 

Three different families occur in American fauna, the Dictyni- 
dae, Zoropsidae, and Oecobiidae; two other families of somewhat 
greater interest are not found within our territory. One of these 
latter, the Eresidae, is made up of robust, moderate to large crea- 
tures, similar to jumping spiders, and often quite brightly colored, 
especially the males. Some of them are fine tunnelers and are even 
known to use a trap door to close their tubes. Many spin sheet 
webs connected with tubular retreats. Some species of Stegodyphus 
join together and spin an immense communal web over bushes, 
forming an irregular saccular retreat partitioned in various ways, in 
which many individuals live amicably together. 

The second exotic family is the Psechridae, whose only repre- 
sentation in the New World is one small group from Mexico, 
whereas several large conspicuous types are common in the Pacific 
regions. These spiders will often spin a huge web, at the center of 
which is a flat sheet similar to those made by the sheet-weaving 
Linyphiidae. The spiders creep over the ventral surface of the sheet, 
hanging back-downward, as do the aerial ecribellate spiders, on 
greatly elongated legs of which the terminal segments are flexible. 
One of the strange features of the psechrids is the presence of well- 
developed claw tufts on the tarsi. These are probably used for a 
very different purpose than are the claw tufts of the wandering 
spiders. Perhaps they aid in unfastening the median claw, and serve 
in the same way as the accessory claws of the orb weavers. 

Among the largest typical cribellate weavers of the American 
Dictynidae are the ground spiders of the genus Amaurobius. Many 
of the females are robust creatures attaining a length of three-fourths 
of an inch. Their colors are usually brown or black, but the dorsum 
of the abdomen is variegated, with a series of yellowish chevrons 
forming a pale band. The males, not far inferior in size, are usually 
in evidence only during the fall and very early spring, and are 
rarely seen during the rest of the year. A single native species 
Amaurobius bennettiis common in the eastern part of the United 
States, but many others abound in the mountains of the western 
states and in the northern woods. 

Amaurobius spins a large irregular web in dark, moist situations. 
Whereas much of the silk may be hidden from sight, not infre- 


. The tarantula assumes a defensive attitude . 


&>' W^i 

. Passmore Lee Pass more 

b. The wasp inserts its sting c. Pulling the bulky prey to 

prepared burrow 



Lee Passmore 

a. Female and pygmy male b. Egg sac 

SILVER ARGIOPE, Argiope argentata 

Lee Passmore 

Lee Passmore 

Lee Passmore 

a. Banded Argiope, b. Humped orb weaver, 

Argiope trifasciata Aranea gemmoides 



quently the web is placed in plain view against a vertical surface. 
The dry framework of the snare is commonly put down as a series 
of lines from the central retreat, in which the spider stays most of 
the time. Over the dry lines the cribellate silk is spun loosely, mak- 
ing a thick mat upon which the spider runs. The spinning activities 
are best observed at night; then the carding can easily be seen in 
the rays of a flashlight. At this same time males may be found near 
the female web. 

Amaurobius' egg sac is a flattened bag, attached to a stone and 
usually covered over with a mesh of threads. The females stay with 
the eggs for long periods, often being found with the sac some time 
after the young have hatched. 

One of the commonest members of the genus in the eastern 
United States is the domestic Amaurobius ferox, an immigrant from 
Europe. This spider, which is much darker and somewhat larger 
than the common bennetti, lives in cellars, under floors of houses, 
and under wood and debris near human habitations. It is rarely 
found far from man. 

Australia is particularly well supplied with spiders related to 
Amaurobius; the habits of certain varieties are of special interest. 
In the Jenolan Caves of New South Wales lives a gregarious species, 
Amaurobius socialis, which spins great webs on the roof. These 
giant reticles, one of which measured twenty feet in length and 
more than four feet at its greatest width, hang from the roof and 
are draped over the stalactites. They are closely and densely woven 
to the consistency of a heavy fabric, such as a shawl, and are filled 
with openings through which the spiders retreat to the interior. 
Mating, egg-laying, and emergence of the young all occur within 
the limits of the web, as among many truly gregarious spiders. 

Also in New South Wales may be found certain gregarious 
spiders, perhaps relatives of Amaurobius^ which infest orange 
groves. They mat the limbs with a thick covering of web so densely 
woven that it affects the normal respiration and development of 
the tree. The leaves wither and fall, the dead branches are left, 
covered with unsightly webbing. Such spiders can become a pest 
of nearly equal malevolence to tent-building insects. 

In the genus Dictyna are small spiders, averaging one eighth of 
an inch in length, which are known by the unwieldly name of 
"lesser mesh web spinners." Some few of these are brightly colored 
in reds, browns, and tans, with here and there a brilliant yellow 
spot, but for the most part their bodies are dull, clad plainly in gray 


hairs. Though several different groups of these small spinners are 
known, they are all similar in appearance and in habits. Some of the 
smallest live under debris on the ground, where they spin tiny webs 
and are rarely noticed; others of larger size spin on the walls of 
buildings, and on plants. Their lacy meshes are conspicuous ob- 
jects, but, aging, become obscured with dust and lint. Since ap- 
proximately one hundred different species of Dictyna are known 
from North America, mention can be made here only of a few 
species whose habits are illustrative of the whole group. 

Dictyna annulipes (formerly muraria), a small species with a 
large oval abdomen, has its dull body quite completely masked by 
a covering of light gray hairs, which on the carapace form three 
distinct stripes, and on the abdomen outline a pattern of darker 
chevrons. Favorite sites for its web are board fences and the walls 
of buildings. A tiny crevice between boards will provide this spider 
with an adequate retreat from which it can lay out the dry founda- 
tion lines of its snare. These lines frequently radiate with the most 
precise regularity, and, when crossed evenly with the thick hackled 
bands, reveal a web as delicately spun as a lace doily. One observes 
that annulipes often chooses the outside of a window sash as a 
location for its snare, and lashes it to the smooth glass as well as to 
the adjacent wood. 

Early summer is usually the pairing season for these friendly 
little spiders, and at this season the male may been seen in the web 
of the female. He resembles her closely in general appearance, but 
is somewhat more slender and has longer legs. His head is aften 
quite elevated, arching over the long, curved chelicerae. These 
latter are provided with a stout spur near the base; they turn up- 
ward at the tip, and curve strongly outward at the middle, leaving 
a conspicuous opening between. In some species of this particular 
group, the conspicuous chelicerae are known to be used to hold the 
jaws of the female during the mating, and it may be presumed that 
they render the same service for our own species. 

A close relative of annulipes is Dictyna valuer ipes, a slightly 
larger spider, similarly clothed in pleasing gray raiment, which pre- 
fers open sunny fields for its home. The usual sites are the ends of 
weeds and grasses (Plate III), and especially the dried stems and 
stalks left over from the previous growing season. Upon this har- 
vest skeleton volucripes spins its characteristic mesh; the foundation 
lines bridge from stem to stem, and over them is woven a criss-cross 
of viscid bands, to form perfect little lattices and other pleasing 


symmetries. During the summer white, lens-shaped egg sacs are 
hung in the deeper parts of the tangle, and after the young hatch 
they spend some time in the web with the mother. 

Much more brightly colored than either of the above-mentioned 
species is Dictyna sublata, often light brown in color with its oval 
abdomen marked in yellow above, and its legs almost white. Sub- 
lata hides its web in the leaves of bushes instead of placing it in 
the sun. It will find a leaf with slightly rolled edges, then spin a 
thin, sheetlike web across the opening to form a shallow bowl; in 
this it remains and here its egg sacs are placed. 

The villagers of certain mountainous portions of Michoacan, 
Mexico, are plagued during the rainy season by immense swarms 
of flies that invade their homes. Their defense against these pests 
is unique. They rely upon the mosquero (Coenothele gregalis), a 
tiny cribellate spider one sixth of an inch long, which lives in vast 
colonies on the twisted oaks and scrub trees at altitudes of about 
eight thousand feet. The nest of a mosquero community is often 
more than six feet square, and thickly invests each branch of an 
entire tree with a spongy inner layer of dry silken lines and an 
outer envelope of sticky hackled-band threads. The villagers cut 
a branch from the tree, and suspend the animated fly trap from the 
ceilings of their homes. The accommodating houseflies alight on the 
sticky threads, whereupon they are enveloped and dragged into the 
inner galleries to become the prey of the colony. After the fly 
season is over and the spiders have become mature, the adults desert 
the colonial web, perhaps to start new colonies elsewhere. Their 
eggs and young remain, develop in the inherited nest, and are on 
hand during the next fly season. In the field the webs of the mos- 
quero resemble those of processionary caterpillars. 

In the inner recesses of the communal web live many small 
beetles of the genus Melanopthalma said to attend to the cleanliness 
of the nest by keeping it free of debris. These commensals live on 
the small bits of food discarded by the mosquero. Also living in 
complete harmony with the colony is one of the running spiders, 
Poecilochroa convictrix, which is also supposed to be a commensal 
though its exact status is less certain. 

The presence of thick brushes of scopular hairs beneath the 
metatarsi and tarsi of the cribellates of the family Zoropsidae, and 
the absence or great reduction in size of the median claw, would 
seem to indicate that these spiders are hunters. Indeed, they are 
often compared to the hunting clubionids, which they resemble in 


general appearance and in superficial features. However, Zoro- 
crates y the only American representative, still relies on an expan- 
sive web to snare its prey. The net, resembling to some extent that 
of Amaurobius y is usually placed beneath stones, and made into an 
effective trap by spinning many viscid hackled bands over its dry 
framework. It may be that Zorocrates' scopular brushes contribute 
to better movement over the surface of its web, or perhaps that this 
spider is on its way to becoming a vagrant form and therefore 
spends part of its time outside the limits of its snare. Several species 
of Zorocrates live in our southwestern states, but they are still little- 
known creatures. 

In the related group of cribellate spiders, Acanthoctenus, known 
only from tropical America, true tarsal claw tufts are present in 
addition to the thick scopular brushes beneath the metatarsi and 
tibiae. These flattened creatures often sit under bark, closely ap- 
pressed to the surface, and move with great speed when they are 
touched, their claw tufts aiding them in holding on to surfaces, as 
with the ecribellate vagrants. Acanthoctenus combines a sedentary 
aptitude with running ability. It spins a loose web, embellished 
with sticky bands to entangle its prey. 

One of the few cribellates that has attained a nearly cosmopoli- 
tan distribution is Oecobius annulipes, a tiny spider less than one 
eighth of an inch in length, which is one of the few American repre- 
sentatives of the curious family Oecobiidae. The generic name of 
this spider signifies "living at home," and well characterizes these 
dwarfs found in and on the walls of dwelling places. The micro- 
scopic webs of Oecobius are frequently spun over cracks in the 
sides of buildings; they are only about the size of a postage stamp, 
but seem quite adequate to entangle the tiny insects used for food. 
The spider, which is pale white or pale brown and marked with 
distinct black points, is common in the southern part of the United 
States and has long gone under the name parietalis, but it is now 
known to be identical with the universally distributed annulipes. 
Several related species of Oecobius ocur in the southern part of this 
country, living under stones, on trees, or on buildings. 


The most pronouncedly aerial of all the cribellate spiders are 
those of the families Deinopidae and Uloboridae, groups largely 


tropical in distribution that press northward in small numbers into 
the temperate zone. Within the limits of the United States are 
found representative species, many of which are remarkable for 
their physical appearance and strikingly resemble bits of dried leaves, 
twigs, thorns, buds, scales, and similar natural objects. The common 
name of "stick spider" has been applied to some of them; the name 
characterizes the whole group rather well, even though not all are 
elongate. All do hang downward from a more or less intricate web, 
and in their movement on silken lines parallel closely such aerial 
ecribellates as the orb weavers and tangled web weavers. By some 
students these spiders are regarded as closely allied to their ecribel- 
late cousins, but the extensive use of the hackled band sets them 
apart and indicates only a distant relationship. The third tarsal claw 
is present, modified to suit the needs of confirmed sedentary types. 
In this series of species have been developed some most ingenious 
devices for capturing prey. The ogre-faced spiders have perfected 
a method of expanding and hurling a sticky net over flying insects. 
Not to be outdone by their cousins, the uloborids construct a splen- 
did orb web rivaling in excellence that of the orb weavers of the 
family Argiopidae. The triangle spider, Hyptiotes, has abandoned 
all the orb save a single sector of four rays. Even more niggardly 
is the tropical stick spider, Miagrammopes, which employs but a 
single line on which it spins a band of sticky silk. 

Ogre-Faced Stick Spiders. The name "ogre-faced spider" is 
applied appropriately to species of Deinopis (from the Greek, mean- 
ing "terrible appearance") because of their weird aspect and the 
enormous size of their posterior median eyes, which, projecting 
forward like great headlights, render inconspicuous the remaining 
six. The habits of these spiders, particularly their nocturnal net 
casting, would seem to demand good night vision, and this doubt- 
less accounts for the development of such large eyes. The American 
species of Deinopis is quite rare, uncommon even in the extreme 
southeastern portion of the country and is apparently the only mem- 
ber of the family reported from the United States. Quite a number 
of species, many with grotesquely formed heads and humped and 
lobed abdomens, are known from the tropical region all around the 
world. Nothing has been published on the habits of our ogre-faced 
spider, but it seems certain that it will be found to perform in the 
same way as the species of Menneus and Deinopis in Africa and 


This American ogre-faced spider, Deinopis spinosus, is a slender 
creature, which hangs from a small web of dry silk on very long, 
stiltlike legs during its casting operations. When mature, the female 
is about two thirds of an inch long, and frequently has as .a notable 
feature an abdomen armed above and near the middle with short 
projections. The male is smaller and more slender than his mate, 
and his thin legs are at least three times as long as his whole body. 
A dark band running the length of the abdomen below, and a few 
lines and spots above, are the only distinctive pattern on the other- 
wise drably marked bodies of these spiders. 

During daylight hours the ogre-faced spiders are usually to be 
found pressed flat against the bark of a branch near their snares. 
They assume a characteristic position: the forelegs are stretched out 
in front along a twig, while the hind legs grasp the twig and hold 
the body firmly. The resemblance of this spider to a bud, spine, or 
some other natural irregularity in the bark is a most striking one, 
and must certainly pay dividends by giving the creature some im- 
munity from predators. Completely quiescent during the day, 
Deinopis rouses to action at sundown, moves into the small tangle 
of dry silken lines, and prepares its capturing web. 

Conrad Ackerman has described in fine detail how Menneus, an 
African ogre-faced spider, spins her web and captures her prey. 
The animal lays down a horizontal foundation line, and from this 
stretches parallel vertical lines down and across to outline a rec- 
tangular base, all of dry silk. Across this base she spins a series of 
transverse bands of sticky silk, which she cards from her cribellum 
in the normal manner. The result of this latter operation is a small 
reticle of sticky lines about the dimensions of a postage stamp, 
which Mennens grasps in her four long front legs while with her 
hind legs she holds herself securely to the dry lines of the web. In 
this position, hanging back-downward, the spider waits for a night- 
flying insect usually a moth to arrive within the limits of her 
casting area. (See Text Fig. 4, F.) 

When her prey comes within reach, Menneus suddenly 

stretches the elastic snare to its full expansion, which appears 
to be five or six times its size when closed, and hurls herself for- 
ward, throwing the net over the moth and closing it down upon 
it with her four front legs. The moth is helpless and the spider 
at once bites it. After waiting a few moments, she carefully 
extracts it from the web and the insect does not move, probably 


because of the paralyzing effect of the poison injected at the 
bite; but to make certain that it cannot escape, the moth is en- 
shrouded in silk spun across it, the hind legs drawing out the silk 
from the spinners and applying it to the insect. 

This method of snaring a victim was compared by Ackerman to 

enveloping it as the Retiarius with his net enveloped his oppo- 
nent before piercing with his trident in the Roman gladiatorial 
combats, or better, like the old-fashioned butterfly net on two 
sticks, held by the two hands, which was thrown over an insect 
to catch it. 23 

A single web suffices Menneus for a whole night of casting. 
After removing a victim from the sticky lines, she pulls and read- 
justs until the web again takes its essential rectangular shape. Then 
she resumes her vigil, feeding on the unlucky insect while she holds 
what may be only a tattered remnant of her snare. When the spider 
has satisfied her appetite, and usually with the approach of morn- 
ing, she rolls up the web and some of the adjacent foundation lines, 
drops the ball to the ground, and moves to her normal daytime 
resting place against a twig. 

This intriguing method of capturing prey has no exact counter- 
part among spiders of any other family, but the device parallels in 
a general way that of the bolas spider (vide infra). 

Hackled-Eand Orb Weavers. An outstanding achievement of 
the Uloboridae has been the invention of an aerial orb web equal 
in symmetrical beauty and similar in fabrication to that of the 
ecribellate orb weavers. It is believed by many that this creation is 
a novelty separately arrived at, not one result of an ancient habit 
common to allied spiders that later diverged. The germ of an orb 
web is observable in the great regularity of the webs of hackled- 
band spinners less versatile than the Uloboridae. Even the irregular 
mats of Amaurobius and Filistata are based on a framework of dry 
rays arising from a central retreat. Many species of Dictyna spin 
aerial sheets of such regularity that in form they approach sectors 
from the webs of the uloborids. 

Once a symmetrical design had been realized, lifting the orb 

23 C. Ackerman, "On the Spider, Menneus camelus Pocock, Which Con- 
structs a Moth-catching, Expanding Snare," Annals of the Natal Museum, 
1926, p. 418. 


web from a surface to an aerial station was a relatively simple step. 
The orb web of Uloborus lies most often horizontal, or slightly 
inclined, and is only rarely the vertical structure of the typical orb 
weavers. The horizontal position is a less favorable one, dependent 
for success on insects that fly upward against it or drop down upon 
it; whereas the vertical web can intercept much larger flying fauna. 

Featherfoot Spiders. As has been noted, the curious spiders of 
the genus Uloborus are most numerous in the tropics of the world, 
relatively few varieties occurring in the north. Several distinct 
species are found in the southern United States, but only one, 
Uloborus americamis, appropriately named the "featherfoot spider" 
(see Plate XXIV), is common all over the United States and in south- 
ern Canada. This uloborid has a carapace longer than broad, which 
is provided in front with eight eyes, in two rows, whose small size 
confirms the slight reliance this aerial creature places on eyesight. 
Its chelicerae are moderately robust, but no venom glands are asso- 
ciated with them a condition almost unknown in other spiders, 
and suggesting that the sicky spiral of the orb web and the jaws 
of the spider are adequate to quiet its prey. The long front legs are 
often curved, in many species being provided with the tufts of 
feathery hairs that are the source of their common name. The abdo- 
men is often surmounted with humps and bedecked with pencils 
of hairs. A pronounced variation in coloration is characteristic, and 
pale white, speckled, lined, or all black specimens are often found 
in the same species. 

The relatively small orb webs of the featherfoot spider, four or 
five inches in diameter, are usually placed close to the ground in 
moist, shaded situations on low bushes and underbrush, on dead 
sticks, in hollow stumps, or among rocks. The invariably horizontal 
web is composed of the same elements as that of the typical orb 
weavers: foundation lines, radii, dry spiral scaffolding, and a con- 
centric series of sticky spirals. Before laying down these latter, 
Uloborus spins a typical preliminary spiral scaffold of dry silk that 
is used as a bridge to the next radius. The spirals are a composite oi 
viscid and dry threads, as in the Argiopidae, but here the sticky 
material is carded from the cribellum with the aid of the very regu- 
lar row of calamistral hairs on the fourth metatarsus. The spider 
has never depended on artistic perfection for its capturing snare, 
but rather on the sticky lines, and close examination shows that the 
web is imperfect in many respects. Quite often it is most unsym- 


a. Male and female, with eggs, in tangled web 

George Elwood Jenks 

b. Female holding mass of recently hatched young 
LONG-LEGGED CELLAR SPIDERS, Pholcus phalangioides 

George Elwood Jenks 


Richard L. Cassell 

a. The spider approaches as the cricket touches the capture threads 

Richard L. Casstll 

b. Nooses of swathing film are combed over the leg 



metrical especially during the cocooning season, when the feeding 
instinct is replaced by a maternal one and irregular in its details, 
but it remains quite as pleasing to the eye as the snares of the typical 
orb weavers. 

Special features of the web are the hub, which is closely and 
beautifully meshed, and the ribboned decorations or stabilmenta 
that ornament the orb and possibly add to its strength. The most 
frequent form of the stabilmentum is a scalloped band that crosses 
the central portion of the orb; it is scarcely visible at the delicate 
hub. Other variations are numerous, a common one being a ribbon 
coming from a nearby sector to form a V-shaped figure; or four 
ribbons forming a cross; or broken or completed circles around 
the hub. 

In position, the featherfoot spider lies stretched out beneath 
the hub of her web, her legs directed forward and backward to 
form a bridge between the stabilmenta and make a complete band 
across the snare. As she hangs there, swaying with the breeze, she 
often resembles a bit of leaf or stick. When her eggs are laid, she 
places the several elongate sacs in a row across the web, and then 
aligns her long body so that she becomes almost indistinguishable 
from them one in a line of bits of debris. 

Among the tropical uloborids, it is interesting to note, are many 
social spiders that spin immense webs, where large numbers of males 
and females live amicably together. These colonial webs are fea- 
tured by a large central retreat suspended from many long silk lines 
running in all directions and forming a loose maze. Most of the 
males, as well as many females and spiderlings, live in the inner part 
of the web; but from time to time and this is a particularly fas- 
cinating part of their activity individuals detach themselves and 
move to open spaces on the periphery, there to spin their own 
characteristic round webs. The outer part of the communal web 
provides snare-space for all the spiders, and part of the time they 
live singly in their tiny orbs. Mating takes place in the central re- 
treat, and the egg laying occurs there as well. 

Several social species are found in the United States, but their 
communal webs are rarely notable for size. Uloborus arizonicus, 
occurring in the Santa Rita and other mountain ranges of south- 
ern Arizona, will completely invest a low shrub with its web, and 
several dozen individuals will live there together. Except for size, 
the colonies of this species closely resemble those of the tropical 


Triangle Spiders. Almost anywhere in the United States may be 
found the peculiar triangular snare of the spider Hyptiotes, which, 
because of its small size and retiring habits, is far less familiar than 
the web it spins. A small creature, rarely more than one sixth of 
an inch in length, the triangle spider hangs back-downward from a 
dried twig in its favorite trapping site, and is no more noticeable 
than a bit of dead wood, a bud, or a piece of bark. The carapace is 
broad and low; it supports a thick, oval abdomen on which are 
usually visible slight humps set with a few stiff hairs. Drably 
clothed in grays and brown, Hyptiotes harmonizes rather well with 
the dry branches of its home, and affords a striking illustration of 
close resemblance to environment. All eight eyes are present in this 
species, but one minute pair is so well hidden in the hair covering 
that the spider was once thought to have only six eyes. The male 
ordinarily becomes adult in the early fall, and at that season may 
sometimes be found near the web of the female, which sex he re- 
sembles closely except for smaller size. 

Two well-marked species of Hyptiotes occur in the United 
States and Canada. The common species in our eastern states is 
Hyptiotes cavatus, Hentz's triangle spider; while the boreal tri- 
angle spider, H. gertschi, is abundant in the western part of the 
country, and largely replaces the other species in eastern Canada, 
where it occurs as far south as Maine and New York. 

The web of the triangle spider (Text Fig. 4, B) is best under- 
stood by comparing it, as did Professor Bert G. Wilder in his early 
studies of cavatus, to an ordinary pie. The orb of Uloborus is an 
entire pie; that of Zilla, one of our typical orb weavers, is a pie with 
a piece cut out of it; and that of Hyptiotes is the missing piece. This 
triangular web consists of a fifty-to-sixty-degree sector with radii 
twelve to twenty inches long. It invariably consists of four rays of 
dry silk, across which are laid down ten or more viscid lines of 
hackled band that correspond to sections from the spiral line of an 
orb web. The four rays are attached to an arc line tied to twigs, and 
converge near a point on a single bridge line fastened to some nearby 

The spinning of the web, often accomplished during the early 
hours of the evening, is a most interesting process; and the details 
corroborate the belief that its structure is derived from the uloborid 
orb web. The first line is a bridge from the resting site of the spider 
to an adjacent dried twig. It is customary for Hyptiotes to place 
the bridge line by hand, moving around the periphery of her hunt- 


ing grounds to the point of attachment and then pulling the line 
tight; but in many instances air currents are called upon to balloon 
the line to a mooring point, as is the practice of the typical orb 
weavers. A vertical thread from one end of the bridge line is tied 
to a twig, and forms the arc of the sector. The third principal line 
returns to near the other end of the bridge line and completes the 
triangle. Then, between the radial lines, Hyptiotes places two more 

At this stage the spider has constructed a sector of four rays 
attached at one end to a single line and at the other to an arc thread. 
Upon this must now be placed the viscid threads that will make the 
web a trap. But before the sticky lines are added, Hyptiotes spins 
a row of three or four dry scaffolding threads, extending from the 
apex toward the middle of the triangle, that serve to steady the 
web by holding the radii in place, and that will simplify the laying 
down of the cribellar silk by providing a bridge from ray to ray. 
These scaffolding threads are analogous to the dry spirals or spiral 
bridge of the ecribellate orb weavers, are put down in the same 
sequence from the apex of the triangle (or hub) outward, and are 
eliminated in much the same way bitten out when the web is fin- 

To lay down the viscid sections, Hyptiotes crawls along the up- 
permost ray nearly to the point at which it joins the arc line, spins 
and attaches a band of sticky silk, then crawls back toward the 
middle of the triangle, spinning as she goes and holding the thread 
free of the ray. When she reaches the outermost scaffolding thread, 
she descends upon it to the ray immediately below, and upon this 
returns, reeling the sticky line back in, until she is immediately be- 
low the first point of attachment. Here she fixes her line. In 
order to put down this first vertical cribellar thread, which extends 
only three inches or so between the two upper rays, Hyptiotes must 
often crawl forward and backward a dozen inches. One might ask 
at this point why Hyptiotes does not drop down directly to the 
ray below? The triangle spider knows her web only by the touch 
of the silk, cannot see or know the position of the other rays, and 
is dominated by instinctive actions that keep her pursuing a pre- 
scribed course. 

The spider continues this roundabout process until the four rays 
are bound together by a slightly zigzag vertical line of three sec- 
tions. She then crawls around the triangle to the top ray once 
more, and starts on a second line, using her legs to measure its dis- 


tance from the first. The final number of these partial spirals varies 
from ten to more than twenty. As the series meets the scaffolding, 
these latter threads are cut out of the web. 

The finished web is an extraordinary structure, and is employed 
in an extraordinary way to provide the spider's food. Hyptiotes 
takes up a position at the end of the bridge line, near the apex of the 
triangle, her hind legs touching the silken anchor almost in contact 
with the twig. With her front legs she pulls the line until the whole 
web becomes taut; then, holding the slack thus gained over her 
body, she settles down to wait for her prey. A small moth or other 
flying insect strikes the web and adheres, struggling violently in the 
viscid coils. Immediately Hyptiotes lets go of the slack. The web 
snaps forward, carrying the spider out a short distance with it, and 
the resultant vibration of the swaying, sticky line causes the victim 
to become more firmly enmeshed. Hyptiotes seems able to estimate 
the character of the insect from the nature of its frantic struggles 
and acts accordingly. The snare may be drawn tight once more 
and snapped, and this action will be repeated again and again until 
the spider is ready to crawl over her lines to the victim. 

Hyptiotes never bites her prey as do many other web spiders, a 
fact undoubtedly related to the absence of poison glands in this 
family. Instead, she comes up to the insect, turns her back to it, 
and, rolling it over and over with her legs, covers it with a thick 
bluish web. Completely helpless, the victim is carried back to the 
resting site and sucked dry in the leisurely manner characteristic 
of the triangle spider. This method of overpowering prey by means 
of thick bands of silk is analogous to the habits of the comb-footed 
spiders and the typical orb weavers. 

Not infrequently, when the trap has been sprung for the first 
time, Hyptiotes will move forward and, grasping the radii in her 
front legs and cutting some of the lines, will gradually bundle up 
the web and hurl sections of it over the victim. By so doing, she 
destroys the web almost completely, and must spin a new one for 
her next period of trapping. But inasmuch as one victim provides 
this small spider with sufficient supply of food for a day or more, 
the loss of the snare does not materially handicap her. 

One wonders whether Hyptiotes has not gone to more trouble 
than the web is worth in producing her triangle trap. Although it 
will probably catch more insects because of its vertical position 
and greater size, almost as much spinning and silk goes into its fabri- 
cation as is expended in the horizontal web of Uloborus. Further- 


W. A. Pluemer 

Orange Argiope, Argiope aurantia, in web, side view 


Edward A. Hill 

Spiny-bodied spider, Micrathena gracilis, spinning 


more, the trick of snapping the trap in order to further enmesh 
the prey may well be an unnecessary precaution; and the careful 
enshrouding of the bound victim is likewise an act of doubtful 
necessity. It is true, however, that the same kind of objection to 
needless efficiency can be leveled against the snare of the typical 
orb weavers. 

The Single-Line Snare. The stick spiders of the genus Miagram- 
mopes are creatures of the tropics, and although they occur in the 
West Indies and in Mexico, do not quite reach the subtropical 
zones in the United States. They must be mentioned here because 
of the marvelous trapping device they have developed a device that 
represents an even greater simplification of the orb web than does 
the snare of Hyptiotes. The four-rayed triangle is reduced to a 
single line. 

The stick spiders resemble Hyptiotes in general structure, but 
they are more elongate, and are thinly covered with dull grayish 
hairs over a dusky brown body, so that they almost perfectly re- 
semble small, thin sticks. On the carapace are four pairs of eyes, 
the two front pairs being so small and so well hidden that only the 
hind ones are easy to discern. The front legs are long and thick, 
stretched forward in close contact with each other; against them 
presses the short second pair; while the hind legs extend backward 
along the sides of the abdomen, and fit closely against the body to 
enhance the remarkable sticklike appearance. 

The snare of Miagrammopes (Text Fig. 4, A) is a single horizon- 
tal line, attached at both ends to branches, that stretches about four 
feet across open spaces in the forest. Conrad Ackerman has de- 
scribed the activity of spiders on the Natal coast, which, after laying 
this basic line, then card out a heavy band of viscid silk across its 
center for a distance of approximately eighteen inches. The next 
step resembles the triangle spider's method. Miagrammopes moves 
to the end of her foundation line, and, assuming a position in which 
she almost touches the mooring twig with her hind legs, appears to 
be a continuation of it. She draws the line very taut, until she has a 
loop of slack to hold over her body. The thick center of the snare 
offers an attractive and familiar-looking resting place for gnats, 
flies, and a whole host of flying insects. Whenever one alights, the 
stick spider lets go the loose thread and shoots forward with the 
elastic line for about half an inch. The release of tension jerks and 
sways the thread, causing the victim to become more completely 


entangled. Miagrammopes then rushes to the site of the capture and, 
again like Hyptiotes, further enswathes the unlucky insect in bluish 
silk, which she reels and combs from her spinning organs. When her 
victim is completely helpless, she cuts it loose and holds it in her 
jaws and palpi. She then closes the rent in the trap, and crawls back 
to her retreat, where she adjusts the line for the next capture. 


The Aerial Web Spinners 



treated in this chapter are those that spin silk from their bodies 
and produce many types of aerial webs. Whereas their relatives 
developed alertness, speed, brute strength, and a minimum use of 
silk, to become hunters, the sedentary types on their gossamer lines 
swung far aside from that line of ecribellate spider evolution. Theirs 
is a story of silk; on tiny claws that have become increasingly effec- 
tive as hooks, they hang upside down from the threads of a circum- 
scribed web, rarely leaving its confines voluntarily. Their sense of 
sight is rather poor; for this deficiency they have compensated by 
spinning expansive tangles, sheets, and formal web designs to enlarge 
their area of action, the struggles of an insect in the farthest recesses 
of the snare are communicated to them. Within the confines of 
the web the sedentary spiders have become supreme autocrats. 

They are a motley crew running to all sizes and shapes. Many 
are shy, lie immobile in the web, and when disturbed drop on drag- 
line threads to the security of deep underbrush. Others stay hidden 
away in retreats or under objects until their traps are touched by 
small animals. Some are quite agile and run nearly as well as hunt- 
ing spiders; others, in appearance well proportioned for running, 
have legs too long and thin. A few specialize in inaction; they hang 
like inanimate slivers or clods in their webs, to all intents part of 
the debris that adheres to the lines. Others, possessing greatly 
elongated abdomens that they wave gently back and forth, resemble 
in form and action common caterpillars. Most are fat creatures 
with short legs that seem molded for an acrobatic life. The great 
majority are tiny and inoffensive; therefore they rarely come to our 
notice; but some of the orb weavers are giants, in bulk exceeding 
some large hunters. 

The webs of the sedentary spiders, displayed on every side in a 
myriad of sizes and designs, vary from crude artistry to extraordi- 



nary workmanship. Such diverse structures did not come into being 
at a single stroke; they are the results of long, random experimenta- 
tion, during which only those suited to the minimum needs of the 
moment had survival value. From the first wild dragline threads laid 
down in haphazard fashion on and around the egg sac have evolved 
by progressive steps the many remarkable snares that today meet 
the eye. At first there were mere tangles of lines stretched without 
particular design, roughly filling an allotment of space between 
suitable supports. Probably altogether composed of dry silk, these 
mazes were suitable for stopping jumping or flying insects, and 
retarding their movements through the entangling toils. The addi- 
tion of viscous drops to the lines was a later development, which 
transformed the stopping web into an adhesive trap. Among the 
lines was stationed the egg sac the central theme, and the theoreti- 
cal point from which all space webs take their origin. 

The first spiders that climbed into shrubs were daring adven- 
turers leaving behind the soil domain so long cherished by their 
forebears. They could become full-fledged aerial types only after 
the web novelty had proved its worth as a means of providing food. 
But once the space web was in reality successful, the incessantly 
spinning spiders began to explore its possibilities in all directions. 
Some suspended a horizontal platform of rather loosely woven silk 
through the middle of the maze and maintained the egg sac at its 
core. Clinging to the underside of this, they learned to seize insects 
that, arrested in flight by the maze of threads, would drop to the 
upper surface of the sheet. 

The orb web would seem to stand alone as a glorious creation, 
an incredible novelty designed by superior artisans. That it is only 
an advanced stage arrived at by the same slow steps that realized 
the dragline, the stopping maze, and the horizontal platforms is 
shown in the numerous intermediate examples. The orb web is 
merely a formal expression of the horizontal platform. Probably 
at first composed wholly of dry silk, it is now provided with a large 
area of sticky spirals, and has been swung to a near-vertical position 
to make it a more effective snare. Almost invariably associated with 
it are some of the lines that were once the stopping maze. 

The space webs exhibit a most interesting evolutionary series. 
Each major web type has been sponsored by different groups of 
aerial spiders. The primitive line weavers still rely largely on the 
tangle of threads for protection and as a means of stopping their 
prey. The comb-footed spiders spin a maze, sometimes a sheet, and 


almost invariably fix guy lines with sticky globules to hold their vic- 
tims. The sheet web weavers use both maze and sheets of various 
forms. The sticky spirals of the orb weavers hold fast an array of 
jumping and flying insects. Along with the webs, there have de- 
veloped most interesting techniques for overpowering and enmesh- 
ing the victims; and the basic factor upon which these techniques 
depend is the spider's ability to move upon the web. 

The successful venture in silken lines is made possible by the 
unpaired median claws, which lie between the much longer outer 
pair and near their base. The median claw in aerial spiders is 
shaped like a hook, and is provided with a few small teeth. Associ- 
ated with it are various modified hairs, which, often curved and 
toothed, are called "spurious" or "accessory" claws. The median 
claws are used almost exclusively for clinging to the lines of dry 
silk. They are displaced slightly to the sides, those of the first and 
second tarsi toward the anterior and those of the third and fourth 
tarsi toward the posterior outer claw. This facilitates grasping of 
the threads, which fit into the hook of the claw without requiring 
a turning of the tarsus. When walking in the web, the spider draws 
the tarsi across the threads to catch the median claw, which grasps 
the line at an acute angle and twists it to make the grip firmer. 
The spurious claws orient the threads so that they can be hooked 
by the median claw, then act to clear the thread from the notch 
by uncoupling and hurling it out. With this effective device, the 
aerial spider moves through deep mazes or across vertical meshes 
with ease and precision. 

Before passing on to brief sketches of the major groups of aerial 
spiders, some generalizations can be made that indicate the pro- 
found differences between them and the hunting spiders (discussed 
in the following chapter). Both are derived from the same prim- 
itive stocks, and on their separate roads both have become amaz- 
ingly specialized. The success of each line is attested by the vast 
number of species found living side by side, and by the develop- 
ment in each series of a wide and amazing variety of types. In 
terms of degree of change from prototypes, the sedentary spiders 
have outdistanced the hunters. The spinners live in holes under 
the ground, they live near or on the surface, they live in surface 
vegetation, shrubs, and high up in trees. They have invaded aerial 
space with their threads, and claim it as their own by mere place- 
ment of their three-dimensional webs. As for the vagrants, they 
are dominant on the soil and in the various strata of plants. They 


often claim space beneath the soil by digging a tunnel; and the 
water spider has invaded the fresh water with great success. Above 
the ground, the vagrants move on all types of surfaces and climb 
into shrubbery with great agility. It may be seen, therefore, that 
they live side by side with the aerial spiders, but both are neverthe- 
less to a large extent insulated from each other, almost as if they 
were in two worlds. King in its own domain, the hunter is usually 
a weakling in the clutching web of the sedentary spider. Outside 
its web, the sedentary spider is no fair match for the average hun- 
ter. The superiority of either line can never be tested except in 
terms of which one shall give rise to the dominant spider of the 
future. Both have accomplished great things, and stand as equals 
that have reached their goals by different roads. 


The members of this group can be regarded as a major segment 
of that series that took to an aerial life. They resemble in general 
features and equal in developmental rank the primitive hunters and 
weavers. For the most part, they are pale spiders that live in dark 
places, there laying down a relatively simple web of dry lines or 
sheets and relying on this to secure their livelihood. Most are little 
changed from the presumed ancestral types. The palpi and epigyna 
are quite simple, though in one family, the Pholcidae, they appear 
to be specialized by numerous processes that largely mask the other- 
wise generalized nature of the organs. The posterior respiratory 
organs are tracheae. In the Telemidae are two openings to the 
tracheal tubes, but in the other families only a single one is present, 
the usual position being well in front of the spinnerets. The chelic- 
erae of the Pholcidae are soldered together along the midline as in 
the Scytodidae and related families, but in the other members of 
the series they are free. Males and females are quite similar in size 
and appearance; often they are found living amicably together in 
the webs. During the mating, the pholcids insert both of the palpi 
simultaneously, as do most of the primitive hunters, and the stance 
is the generalized type of that group. Little is known about the 
mating habits of other members of the series. 

The line weavers of the family Pholcidae (Plates VII and XIX) 
have small globose or elongate bodies suported on exceedingly long 
and thin legs, a physical feature that causes them to be mistaken for 


the daddy longlegs. The leg tarsi are often made flexible by the 
presence of numerous transverse creases or sutures in the integu- 
ment. Eight eyes, set close together on an elevated tubercle, are 
usually present, but the anterior median pair may be lost, and in 
some cave species all eyes may be reduced in size or completely 
missing. The long-legged pholcids occupy a position between the 
higher sedentary types and the spiders of very primitive level. 
Their derivation from prototypes similar to the present cribellate 
Filistatidae through loss of the cribellum and modification of a few 
other features is quite plausible. Although commonest in warmer 
regions, they are quite numerous in temperate areas, as is well 
shown by the presence of eight genera and about forty species in 
the North American fauna. 

The pholcids spin, in dark places, loose, irregular webs, some- 
times with a distinct closely woven sheet. Males live in the same 
webs as the females and resemble them closely, but may be recog- 
nized by the great size of the palpi, which are enlarged to form 
thickened appendages. The females carry the eggs in their chelic- 
erae, glued together into a spherical ball and tied lightly with a few 
silken lines; later they may be found holding the mass of recently 
hatched young. Most pholcids are pale white or yellow, but some 
are more gaily colored in pastel greens and blues. Many become 
domestic, especially in our southwestern states, where species of 
several genera find conditions in houses and buildings quite as suit- 
able as in the open. 

These long-legged line weavers are like some of the orb weavers 
in having a most interesting habit that becomes operative when 
prospective insect prey is caught in the net. They shake the web 
violently to hasten thorough entanglement, then, when the capture 
is being made, twist the victim around and swathe it with silk. This 
aggressive action turns into a defensive gesture when the spider is 
disturbed, and it pumps up and down on its long legs so violently 
that it becomes a mere blur. This whirling or shuttling, which be- 
comes increasingly violent when the stimulus is repeated three or 
four times, usually takes place when the web or the body of the 
spider is touched, but on occasion other stimuli provoke the re- 
sponse. When thoroughly aroused, the spider retreats to dark re- 
cesses within the web, or drops down from it to run rapidly and 
hide away in some dark corner. 

The best-known member of the family is the long-legged cellar 
spider, Pholcus phalangioides (Plate XIX), which occurs in houses 


almost everywhere in the world. A relatively large creature with a 
pale white, elongate body a quarter of an inch long and legs two 
inches long, it covers the ceilings and walls of our cellars and 
neglected rooms with its maze of cobweb. 

In this section mention may be made of three families of prim- 
itive line weavers that differ from the pholcids in having six as the 
normal number of eyes. All are tiny creatures, rarely more than 
an eighth of an inch in length, which live retiring lives in dark 
places under stones and debris on the ground or in caves. The 
relatively small number of species known from North America 
reflects a failure to explore our caves adequately, rather than any 
true sparsity of these minute animals. The sheet weavers of the 
family Leptonetidae have relatively slender bodies and fine, long 
legs. The eyes form a V-shaped figure, four close together in front, 
the posterior median pair set quite far back. The web is an extensive 
sheet of finely spun tissue placed in fissures on cave walls, and has 
no definite maze of lines associated with it. Tiny white egg sacs 
containing few eggs are placed on the walls near the web or hung 
from the web itself by a thread. Several species are known from 
the southern portions of the United States. Closely allied to the 
leptonetids are some tiny cave spiders of Europe and Africa, the 
Telemidae, which lack book lungs and have four orifices leading to 
tracheal spiracles. Telema tenella of the eastern Pyrenees is eyeless. 
In the western United States occur representatives of another fam- 
ily of these primitive spiders, the Ochyroceratidae, which have 
tiny globose abdomens much like those of the pholcids. The six 
eyes are placed in a transverse row across the front of the head. 
A typical species is Usofila gracilis, which, only one twenty-fifth 
of an inch in length, occurs in Alabaster Cave, California; other 
species live under debris on the soil outside caves. 


The comb-footed spiders of the family Theridiidae are for the 
most part thickset sedentary types that hang upside down from 
the dry threads of irregular maze webs. Most are small spiders, 
suspending their snares on plants with lines so fine that they are 
often unnoticed, or hiding them in burrows or fissures in the soil 
and under debris. Less well hidden are the webs of drab, house- 
loving Theridion tepidariorum, which, soon covered with dust and 


debris, form the cobweb anathema of the neat housewife. One of 
the most handsome and colorful members of the family is the black 
widow, whose beauty, however, is marred by its unsavory reputa- 
tion. A few theridiids have hard bodies ornamented with curious 
spines; in others the abdomen is drawn out to amazing lengths. 
Most are inveterate spinners, but a few curious types (Conopistha) 
live in the webs of other spiders as commensals, and another group 
(notably Euryopis) has forsaken a formal web for an errant life. 

Most of the theridiids have rather soft, light-colored abdomens, 
oval or globose in form, and long, slender legs that lack spines. One 
of their special features is the presence, on the tarsi of the fourth 
pair of legs, of a line of enlarged, curved, and toothed setae that 
form a distinct comb used to fling silk over the prey. In most of the 
comb-footed spiders, the comb is strong and distinct, but in the 
smallest ones it may be difficult to see, and in some others it has 
become reduced to a few modified setae. Their relatively small 
eyes are set close together in a group near the front of the head. 
Sight enters their lives only to a limited degree, since they live in 
dark places and become active chiefly at night. Some males are 
mere pygmies beside their bulky mates, and there is often a marked 
sexual dimorphism. The theridiids occur in great numbers in the 
temperate and tropical zones; within the United States and Canada 
several hundred different species representing about twenty-five 
genera are found. Thus mention can be made of only a few that 
typify the group, or are outstanding for peculiarities of habit. 

The snare of the comb-footed spiders (Text Fig. 5, B) is not the 
simple mass of irregular lines that casual study would seem to indi- 
cate. It has incorporated into its limits some interesting innovations. 
A densely woven sheet of silk is often a feature, serving as a shelter 
under which the spider retreats. Leaves and debris, or grains of 
sand, may be used as building materials. One of the most interesting 
homes is the bowl of the boreal Theridion zelotypum. Composed of 
dried spruce needles or other plant parts sewed together with silk, it 
provides a strong, waterproof tent beneath which the spider can 
hide with its eggs and young. In some instances the theridiids 
leave their spherical egg sacs suspended in the scaffolding of lines 
in plain sight. 

On the outskirts of the web at the proper season may be seen 
the mature males, which are received for the most part with kind- 
ness during courtship and following mating. Males are killed oc- 
casionally, but not with the regularity ascribed by popular belief. 


The recently hatched young remain with the mother for some time, 
and receive consideration far beyond what one might expect from 
simply organized creatures. The common Theridion notatum of 
Europe and no doubt similar spiders from many other parts of the 
world feed their young for several days by regurgitating fluid upon 
which the babies make their first meals. Thereafter for several 
weeks, the mother and babies feed together upon insects caught 
and dragged to the retreat. 

A typical theridiid web has, in addititon to a central maze with 
or without the retreat, a series of longer guy lines that anchor the 
whole against supporting surfaces. These guy lines are held taut 
near their base by inconspicuous studs of viscous silk. Small insects 
walking against the lines are held by the glue; when their struggling 
breaks a line, they are lifted bodily by its contraction. The dis- 
turbance quickly brings the spider to the spot, and the size of the 
intruder determines to some extent the reaction. 

A pictorial story of the technique used by a black widow spider 
to subdue a large wingless Jerusalem cricket (Stenopelmatus) is 
shown in Plates XX and XXI and Plate 6. The spider approaches 
cautiously, no doubt forewarned of the size of the prey by the 
strength of the pulls on the lines, then turns completely around to 
present its long hind legs to the victim. With the aid of the comb 
on its flailing hind legs, it draws out heavy lines of sticky silk and 
ties them to the leg of the insect, until a strong band is formed. 
The spider next turns and injects its venom by piercing the leg 
with its tiny, sharp chelicerae. (Ordinarily the victim is not closely 
approached until completely fettered.) Then begins the task of 
lifting the still struggling insect off the snare floor and moving it to 
a suitable point in the maze. By numerous small steps, during which 
various threads are tightened and others put down, the bulky vic- 
tim is hoisted gradually into the air until it is about three inches 
from the floor. Now follows the banquet. The spider feasts lei- 
surely for three or four days upon the body of the tightly bound 
prey; then the much shrunken remains, sucked dry, are gradually 
lowered beyond the inner maze and dropped to the ground. 

The theridiids have long been noted for their engineering skill 
in lifting objects of great size. Common domestic Theridion tepi- 
dariorum is credited with having overcome and lifted small snakes, 
mice, and other animals. After presenting the details of captures of 
various small snakes by this spider, McCook has the following to 


It is worthy of mention, in connection with these incidents, 
that the belief that a special enmity exists between spiders and 
serpents is very ancient. Pliny says that the spider, poised in its 
web, will throw itself upon the head of a serpent as it is stretched 
beneath the shade of a tree, and with its bite will pierce its brain. 
Such is the shock that the creature will hiss from time to time 
and then, seized with vertigo, will coil round and round, but 
finds itself unable to take flight or even to break the web in 
which it is entangled. This scene, concludes the author, only 
ends with the serpent's death. 24 

One of the more spectacular feats of Theridion reported by 
McCook was the subduing of a small mouse: 

A very curious and interesting spectacle was to be seen Mon- 
day afternoon in the office of Mr. P. C. Cleaver's livery stable 
in this city. Against the wall of the room stands a tolerably tall 
desk, and under this was a small spider, not larger than a com- 
mon pea, who had constructed an extensive web reaching to the 
floor. About half-past eleven o'clock, Monday forenoon, it was 
observed that the spider had ensnared a young mouse by passing 
filaments of her web around its tail. When first seen the mouse 
had its fore feet on the floor and could barely touch the floor 
with its hind feet. The spider was full of business, running up 
and down the line and occasionally biting the mouse's tail, mak- 
ing it struggle desperately. 

Its efforts to escape were all unavailing, as the slender fila- 
ments about its tail were too strong for it to break. In a short 
time it was seen that the spider was slowly hoisting its victim 
into the air. By two o'clock in the afternoon the mouse could 
barely touch the floor with its fore feet; by dark the point of 
its nose was an inch above the floor. At nine o'clock at night 
the mouse was still alive, but made no 'sign except when the 
spider descended and bit its tail. At this time it was an inch and 
a half from the floor. 

Yesterday morning the mouse was dead, and hung three 
inches from the floor. The news of the novel sight soon became 
circulated, and hundreds of people visited the stable to witness 

34 Pliny, Natural History, Chap. X, p. 95, quoted in H. C. McCook, Ameri- 
can Spiders and Their Spinningivork, Vol. I (1889), pp. 241-2. 


it. The mouse was a small one, measuring about one and a half 
inches from the point of its nose to the root of the tail. 25 

This spectacle, watched with amazement by many people and 
interrupted by the clumsiness of a "meddlesome boy" who acci- 
dently broke the web (instead of by the intervention of the 
S.P.C.A., as, is usually the case), is a compliment to the strength and 
elasticity of the multiple threads of the line weavers, and to their 
engineering prowess in elevating tremendous loads by block-and- 
tackle methods. 

A high percentage of our comb-footed spiders belongs in the 
genus Theridion, perhaps the largest of all spider genera and typ- 
ified by Theridion tepidariorum. Most other species are smaller 
and more brightly colored. The globose female of Theridion differ- 
ens, one-eighth inch long with a reddish brown abdomen marked 
above by a red, yellow-edged stripe, places her large white egg sac 
in the nest. Her web is found on low plants of all kinds, and con- 
sists of a small tent, barely covering the spider, from which an ir- 
regular network of lines spreads out across the limits of the plant. 
Representative of another species group is Theridion frondeum. 
This spider has a pale white or yellow body boldly marked with 
black, but extremely variable in color and pattern. Some examples 
are almost entirely white, unmarked, whereas others have narrow 
dark lines or bands on the cephalothorax, and small black spots, 
dusky bands, or dark stripes and patches on the abdomen. These 
handsome theridiids, represented by one or more species almost 
everywhere in the United States, live on low plants and prefer 
moist, lightly shaded areas in woods or along streams. 

Closely allied to the theridiids are the species of Tidarren, the 
best known of which, fordum, resembles tepidariorum in size and 
coloration and lives in similar situations. Whereas the males of 
Theridion are inferior to the females in size a disparity reflected 
chiefly in the lesser bulk of the abdomen, the males of Tidarren are 
babies by comparison. The female Tidarren fordum is often nearly 
one third of an inch in body length, whereas the males are rarely 
larger than one eighteenth of an inch. At the proper season these 
pygmies often cluster in the webs of the females, usually a dozen 
or more to a web and rarely fewer than two or three, and seem to 
be tolerated. The males of the known species of this genus carry 

^McCook, ibid. 


only a single palpus, a large bulbous affair, the mate of which is 
extirpated just before full maturity. 

Remarkable for their social habits are the species of Anelosimus, 
close relatives of the theridions but having more elongate bodies. 
Our single well known species, studiosus, is a light brown spider 
one sixth of an inch long with dark upper and lower stripes on the 
abdomen. It is abundant in the South, and occurs as far north as 
New Jersey. Its communal web is placed on shrugs and trees, and 
ordinarily comprises an unsightly mass of dead leaves tied together 
with silk and serving as a retreat, around which extends a sheet of 
silk attached to twigs. Several individuals live together in the nests, 
which, except for size, are like those of other gregarious species. A 
very similar species abundant in Brazil, Venezuela, and Panama is 
Anelosimus eximius, once dubbed socialis and well known for its 
social habits. Colonies of hundreds or thousands of individuals, 
males and females and immature stages, spin a light, transparent 
web, similar in texture to the sheets of the grass spiders, which has 
little definite form and may completely invest sizable shrubs and 
even trees. Some are a yard across, and are spun fourteen or fifteen 
feet up into the foliage of trees. The spiders wander about freely 
within these confines, and feed communally on insects that are 
captured at the periphery of the web and carried into the interior. 
Sometimes found in the webs are such vagrant spiders as Sergiolus 
and the two-eyed Nops; they may be predators or perhaps sym- 
bionts, but their exact relationship to the aggregation is not known. 

One group of theridiids deserves mention both for curious body 
forms and for commensal habits. These spiders are mostly small, 
and, except for the vermiform types, rarely exceed a third of an 
inch in length. Their legs are long and very unequal, and the tarsal 
claws are remarkable in that the unpaired one is long, only slightly 
curved, and may actually exceed the paired claws in length. The 
tarsal comb is reduced to three or four modified setae. Both the 
cephalothorax and abdomen are subject to curious variations within 
the three known genera. In Ariamnes, the abdomen is drawn out 
into a long and slender cylinder that ends in a point; in Rhomphaea, 
it is usually triangular in shape, sometimes extremely high, and oc- 
casionally vermiform as in the preceding genus; in Conopistha, the 
abdomen takes many forms, being spherical, triangular, or cylin- 
drical, and embellished with lumpy or pointed projections. In both 
Rhomphaea and Conopistha the heads of the males are ornamented 


with rounded lobes, protruding trunks, elevated spines, or other 
curious processes, some of which may bear the eyes. 

Our single species of Rhomphaea is fictilia, a silvery spider with 
darker bands on the cephalothorax and a single band down the 
middle of the abdomen. It occurs all over the United States. The 
body, variable in length and about a quarter-inch long, is somewhat 
triangular, but in some examples may be drawn out into a vermi- 
form appendage half an inch long. This long-legged spider spins 
a tiny web between leaves or blades of grass, where it hangs like a 
straw. Its egg sac is a yellowish object shaped like a slender vase 
and about the same size as the spider. Fictilia closely resembles 
some of the more typical wormlike spiders of the tropical genus 
Ariamnes, and like them is able to bend its elongated abdomen back 
and forth. Regarding this appendage, F. O. P. Cambridge has the 
following to say: 

This, as I have myself observed in Brazil, is wriggled to and 
fro, looking like a small caterpillar. But of what service to the 
spider this accomplishment may be is not easy to guess; for on 
the one hand it seems likely to attract the attention of grub- 
eating wasps and ants, though on the other it may attract, within 
striking distance, gnats and small flies who become curious to 
ascertain what the wriggling phenomenon may portend. 26 

The best-known genus is Conopistha, which comprises the multi- 
tude of commensal types heretofore known by the generic name 
Argyrodes, of which quite a number of species occur in the United 
States. All are known to spin tiny webs of their own, but they are 
more frequently found hanging in the webs of orb weavers, line 
weavers, sheet weavers, and not uncommonly in the snares of grass 
spiders. While hanging in these webs, legs closely drawn together 
against their bodies, they present an amazing resemblance to straws, 
twigs, scales, bits of leaves, and debris, so camouflaged that they 
are completely lost except to the most practiced observer. Largely 
immune to attack from their hosts because of small size, and per- 
haps also because of their cautious movement within the lines (in 
limited sectors of which they lay down threads of their own), they 
feed upon the tiny insects disregarded by the host. 

One of our commonest species is Conopistha trigona, a yellow- 
ish, triangular spider scarcely an eighth of an inch long. The ab- 

88 Quoted by J. H. Comstock, in The Spider Book (1940 ed.), p. 352. 


domen is high and pointed. The head of the male is ornamented 
with a rounded horn between the eyes and another, more slender, 
just in front, but that of the female remains normal. A related 
species is Conopistha nephilae, a pretty black and silver spider 
abundant in the South that favors the webs of the larger orb weav- 
ers, notably those of the silk spider Nephila. The head of the male 
is produced in two long lobes, of which the upper one bears the 
four median eyes. A close relative called pluto lives in the webs of 
the black widow spider in northwestern Mexico. Another common 
species, Conopistha cancellata, has an elongate, triangular, gray or 
brownish body marked with a few silver spots and set with paired 
lobes on the side and at the end of the abdomen. The head of the 
male is produced in a rounded lobe on the clypeus, above which 
are two pits. This spider resembles a piece of bark or a dead leaf 
when lying in the web of an orb weaver or of a grass spider. 

Typical comb-footed weavers place complete reliance on a maze 
of dry lines, sticky droplets, and films from the lobed glands to 
ensnare insects. A few theridiids, on the other hand, have been 
able to divorce themselves from silk as the only means to capture 
prey. These spiders are small, comparatively flattened types, with 
legs of moderate length. They live under stones, in moss and leaf- 
mold, and move over the soil and vegetation with great speed. 
Little is known about them, but they seemingly hunt their prey as 
do the hunting spiders, and spin no formal webs. At least two 
genera from North American fauna, Stemmops and Euryopis, be- 
long to this series, but mention will be made only of the latter 
group, which is widely distributed and represented by numerous 

The species of Euryopis, which resemble in a superficial way 
some of the crab spiders, have heart-shaped abdomens pointed be- 
hind and covered with a dorsal shield set with long setae. Our 
commonest eastern species is Euryopis funebris, a handsome black- 
ish spider one-eighth inch long, whose abdomen is bordered with a 
silvery white stripe. Several species of similar pattern occur in the 
South, and prominently in the western part of our country. An- 
other series of species, which includes Euryopis argentea, is nearly 
black and has the abdomen pointed with four to six pairs of small 
silvery white spots. A very similar species is Euryopis spinigerus, 
orange or brown with a more distinct dorsal shield and more con- 
spicuous curved bristles. 

The spiders of the genus Hadrotarsus, known from the Aus- 


tralian region and ordinarily placed near the Oonopidae, are sed- 
entary types similar to Enryopis that have become vagrant 
secondarily. Although they have lost their unpaired claws, they 
still retain spurious claws and numerous other features that point 
to an origin from the comb-footed spiders. 


The addition of a formal horizontal platform marked a signif- 
icant departure from the irregularity of the tangled space web. 
This strengthened zone of thin and loose webbing, with the egg sac 
at its hub, quickly became the theme of a new type of snare in 
which the upper and lower mazes and the guy lines now played a 
subsidiary role. The germ of the platform was present in the webs 
of some of the comb-footed spiders, but developed no further 
there; the closely woven sheet of the sheet web weavers and the 
geometric snare of the orb weavers, however, are its direct results. 
These latter spiders represent a common stock that, though early 
branching onto separate roads, has come down to modern times as 
two closely allied lines. So much in common have these dominant 
aerial spinners that they were for a long time classified within the 
limits of a single large family. The comb-footed spiders diverged 
from the line at nearly the same time, perhaps because of failure to 
introduce regularity into their web by exploiting the platform, and 
took a path toward perfection of lobed glands and tarsal combs. 

The sheet is a yielding table upon which drop flying and jump- 
ing insects, usually after being halted in midair by a superstructure 
of crisscrossed lines guyed to adjacent vegetation. The sheet web 
weaver clings upside down beneath the blanket, runs over the sur- 
face with rapidity, and pulls its prey through the webbing. The 
principal sheet acts as an effective screen against enemies from 
above, as well as a relatively efficient snare. A second sheet is often 
present beneath the hanging spider, apparently serving as a barrier 
to attack from below. The sheet webs (Text Fig. 5, A) are used for 
a long time; when partially destroyed by winds or falling debris, 
they are replaced after a few hours of spinning. In some instances, 
the stopping maze above the trap is missing, or is represented only 
by a few guy lines. Snares placed near the ground are effective in 
stopping and holding collembolans and small insects of many types. 

The sheet web weavers of the family Linyphiidae far exceed in 


J. M. Hollisler 

a. Shamrock orb weaver, 
Aranea trifolium 

J. M. HaMstcr 

b. The garden spider, 
Aranea diadema 

J. M. Hollisttr 

c. Orb weaver, Neoscona 

}. M. Hollister 

d. Orb weaver, Neoscona, on leaf 



Walker Van Riper, Colorado Museum of Natural History 

Wolf spider, Geolycosa missouriensis, at mouth of burrow 


A. Maze and sheet web of Linyphia. B. Maze and capturing lines of Therid- 

ion. C. Casting line and globule of Mastophoi a. D. Maze and domed orb 

web of Allepeira. E. Maze and orb web of Metepeira. 


numbers of genera and species the total for any comparable group 
in the temperate zones; they are the dominant aerial types. Most 
of the species are small, even minute, and they occur in vast, little- 
noticed numbers under soil debris. As a group they have more 
elongated bodies than the comb-footed spiders, and their legs are 
set with long spines. Few of them become the obese lumps so fre- 
quently found among the orb weavers; many run over the soil with 
a speed that belies their dependence on a fixed space web. Their 
chelicerae are large, strong, and well-toothed, the straight maxillae 
little if at all inclined over the labium. The presence of stridulating 
organs, most frequently a file on the side of the chelicerae and a 
scraping spine on the femur of the palpus, further differentiate them 
from the orb weavers. 

Sexual dimorphism is not pronounced, except in the species 
with modified heads, and there is often considerable similarity in 
size and coloration of the sexes. Male and female live peaceably 
together in the webs during the summer months. 

Most linyphiids are rather plainly colored, but there are no- 
table exceptions; some are carmine red (Ceratinopsis), and many 
have distinctive dark patterns on light bodies. As is true of most 
sedentary spiders, especially of those that live in dark situations, the 
eyes are small, and little used, if at all, for the location and capture 
of prey. Linyphiids for the most part prefer the shade, conse- 
quently they live hidden away in dark places under natural debris 
on the ground, or beneath the leaves of living trees. Many species 
dwell in caves or animal burrows, and have in certain instances 
partially or completely lost the eyes. 

The linyphiids are divided into two principal groups, which, 
quite distinct in their extremes but completely bridged by inter- 
mediate forms, are placed by many araneologists in separate fam- 
ilies. The first of these, the Linyphiinae, includes the largest species, 
as well as numerous spinners of extraordinarily beautiful webs. As 
regards physical characteristics, the pedipalp of the female usually 
retains the tarsal claw, and the palpus of the male lacks tibial apoph- 
yses. In general the legs are longer and thinner, and are set with 
more numerous spines than those of the Erigoninae (the other 
principal group); and the tibiae are almost always furnished with 
dorsal and lateral spines. Many small species belong in this group, 
but space allows mention of only a few of the larger representatives. 

One of our largest and best-known linyphiids is the filmy dome 
spider, Linyphia marginata, which abounds in temperate North 


America, and is also common in Europe. An elongate spider meas- 
uring one sixth of an inch, the adult female has a dusky cephalo- 
thorax with a paler marginal stripe, and a whitish abdomen heavily 
marked with dark bands and stripes. Marginata's conspicuous webs 
are often placed along paths or streams in shady, moist woods. The 
outstanding delicacy and beauty of the snare are fully revealed 
when the rays of the sun strike it. There is a maze of threads, ex- 
tending in all directions and tied to adjacent vegetation, at the 
center of which is a domelike sheet three to five inches in diameter. 
The spider hangs below the apex of this dome. Flying insects strike 
the highest lines of the superstructure, drop among the closer 
threads, then upon the dome itself. There they are greeted by the 
spider, which pulls them through the webbing, trussing them up 
with additional silk lines while making the capture and afterward 
repairing the rent in the sheet. Sometimes the web is shaken to 
hasten the dropping of the prey. The lines of the maze and the 
sheet are slightly viscous, but the drops do not gather into the 
sticky globules used by the orb weavers and comb-footed spiders. 

The common bowl and doily spider, Frontinella communis, 
found almost everywhere in temperate and tropical North Amer- 
ica, is quite similar in appearance to the filmy dome spider. It spins 
two separate sheets in its snare, the principal one shaped like a shal- 
low bowl, under which the spider hangs, and the second one a 
horizontal sheet placed below the spider. A stopping web, largely 
filling the bowl and extending above it, is tied to twigs of low 
bushes. Snares characterized by a secondary sheet are spun by 
various other members of the group. Many smaller linyphiids tie a 
flat platform web among low plants and move about over the lower 
surface, but they drop to the ground and run away when disturbed. 

A few of the linyphiids spin no web and have become errant 
types. Drapetisca alteranda is the best-known American type. This 
spider is commonly observed sitting flat against tree trunks, where 
it pursues its prey and around which it scurries when menaced. Its 
mottled gray and white body closely resembles the bark of aspens, 
birches, and beeches, on all of which the spider may be found; 
against such a background it is difficult to distinguish. 

The second principal group of linyphiid spiders, the Erigonmae, 
or dwarf spiders, consists of small spinners that live obscure lives 
under debris. The pedipalps of the females usually lack tarsal claws, 
while those of the males are armed with tibial apophyses. Most are 
shorter-legged than their relatives, and live closer to the soil, run- 


Richard L. Cassell 

c. Tiny fangs inject the venom 

d. The bulky insect is lifted above the floor 

Richard L. Cassell 



Lee Passmore 

A female humped orb weaver, Aranea gemmoides, clinging to a plant 

Walker Van Riper 

A female humped orb weaver, Aranea 

gemmoides, hanging in the hub of her 

orb web 


Edwin Way Teale 

A fisher spider, Pisaurina mira, 
with egg sac 


ning over it quite actively when shaken from their tiny webs. They 
come to light chiefly when leaves, moss and organic debris are 
sifted over a sheet by the careful collector. The erigonids are well 
known for their aeronautic habits; in autumn they constitute a 
large part of the total group of fliers. Since most of them are less 
than one tenth of an inch long, they can fly in adulthood as well 
as in the younger stages. 

The small descriptive information given these spiders reflects an 
incomplete knowledge of their habits rather than their importance, 
since they are represented by a large number of genera and species. 
A high percentage of the spiders of the northern hemisphere, as 
well as most of the hardy boreal types that penetrate far into the 
cold north and frequent the tops of our highest mountains, belongs 
to this group. Their tiny flat webs, fortified with a dense covering 
of viscid droplets, must reap a tremendous harvest of tiny insects 
to maintain such a population. 

Some of the best-known members of this series belong in the 
genus Erigone, which includes numerous dark brown or black spi- 
ders with smooth and shining carapaces armed on the sides with 
heavy teeth. The chelicerae and the pedipalpi are likewise often 
studded with sharp spines. These erigonids are frequently found 
along the edges of streams or lakes, where they place two-inch- 
square webs among the grass roots or suspend them across stems 
over the water. 

Many male erigonids have heads pitted and modified into gro- 
tesque shapes. A slender horn, somewhat thickened at the end and 
set with rows of stiff hairs, extends forward between the eyes of 
Cornicularia. In Gnathonargus unicorn a single, long, slender horn 
projects from the middle of the clypeus. A rounded lobe carries the 
posterior median eyes of Hypselistes florens, and of many similar 
species, high above the remaining pairs. One of the most amazing 
of all erigonids is the European Walckenaera acuminata, whose eyes 
sit in two groups at the top and middle of a slender tower more 
than twice the height of the head itself. Often associated with these 
bizarre modifications are deep, conical pits usually placed just back 
of the posterior lateral eyes. The use to which such pits are put ap- 
pears to be known only for the European Hypomma bituberculata. 
W. S. Bristowe noted that during mating the female seized the male 
by the head and inserted the claws of her chelicerae into the 
rounded pits. This observation suggests that many other species 
with pitted heads may perform in a similar manner, and further, 


that the head modifications, even though pits are absent, may be 
associated with interesting copulatory routines. The conclusion 
that modified heads and pits have arisen quite recently and inde- 
pendently in various groups of erigonids is supported by the close 
relationship with species that do not exhibit these secondary sexual 

Among the most interesting spiders of this subfamily are some 
that have become typical cave forms. Anthrobia mawmouthia, 
found in the Mammoth and other caves in Kentucky, has lost all 
traces of eyes. It lives under stones in the cave, there spinning small, 
flattened egg sacs that contain a few unusually large eggs. Another 
tiny species, Phanetta subterranea, is a characteristic feature of cave 
systems from Indiana and Kentucky to Virginia. All its eyes are 
usually present, but frequently they are much reduced in size, and 
occasionally the anterior median pair is missing. 

The cave spiders of the subfamily Nesticinae resemble the 
theridiids in appearance, and have a somewhat similar comb of 
toothed bristles on the hind tarsi, but their mouth parts and genital 
organs ally them with the series of sheet web spinners. Their webs 
are loosely meshed sheets and tangles hung on the walls of caves or 
hidden under stones. The females drag globose egg sacs around 
with them, attached to the spinnerets in wolf-spider fashion. The 
nesticids always live in dark situations, evidencing a decided predi- 
lection for caves, mines, and tunnels. They are pale spiders; their 
eyes are reduced in size or missing; and their allegiance to cave life 
is reflected in their loss of pigment. 

Several different nesticid types occur in the United States. A 
darkly marked species, Nesticus cellulanus (introduced from Eu- 
rope), lives in cellars and in dark corners in houses and barns. Our 
common Nesticus pallidus, a pale yellow spider, one seventh of an 
inch long, found all over North America, lives under stones or 
boards on the ground, in burrows and cave entrances, and deep in 
totally dark caverns. Outdoors specimens all have normal, well- 
pigmented eyes, whereas some cave dwellers have lost the anterior 
median pair. 

The pirate spiders (family Mimetidae) are curious aerial types 
that creep into the webs of other spiders and kill them. These hand- 
some cannibals, so far as is known, feed exclusively upon other 
spiders and never use silk for a snare. Their bodies are delicately 
marked with dark lines and spots. A principal feature is the pres- 
ence of a series of very long, regularly spaced spines, with smaller 


spines between, forming a rake on the metatarsi and tarsi of the 
front pairs of legs. Other structural details would seem to ally the 
pirates either with the sheet-weaving linyphiids or the orb weavers, 
but their virtual failure to use silk in any way keeps their position 
obscure. In many respects they resemble the enigmatic Archaeidae 
from Baltic amber deposits, modern species of which have been dis- 
covered in South Africa, Australia, New Zealand, and southern 
South America. 

About a dozen mimetids occur in the United States. Typical 
situations are ground debris, vegetation, and, of course, the webs of 
other spiders. The species of Mimetus are about one fourth of an 
inch long, and have rounded abdomens with two angled humps 
above the base. The species of Ero are about half as large, shaped 
much like Mimetus, and have small humps on the top of the ab- 
domen, with a covering of stiff brown hairs. The egg sacs of Ero 
are spherical bags covered with a loose network of brownish silk; 
this is twisted to form a thread by which the bag is suspended above 
the ground. 

All the mimetids are slow-moving, stealthy cannibals that have 
become experts in their nefarious trade. Mimetus preys on the orb 
weavers and the comb-footed spiders, and in the South is frequently 
found in the webs of Tidarren fordum. Ero attacks and subdues its 
prey with an expertness that belies the animal's seeming innocence. 
This small pirate will craftily enter the tangled lines of TheruKotfs 
web, and clear a space of threads without making its presence 
known to the occupant. When all is prepared, Ero pulls at the 
lines, then awaits the approach of the aroused spinner, which hur- 
ries to the spot with customary confidence. At just the right mo- 
ment, Ero grasps the legs and body of Theridion with its long front 
legs, and, holding on firmly with the coarse rake of spines, quickly 
bites the femur of the victim's front leg. A complete collapse of 
Theridion, the consequence of a remarkably virulent venom, is al- 
most instantaneous, and the victor immediately begins sucking the 
body juices from the bulky prey. Only on rare occasions are the 
tables turned, and the pirate made a victim of its own seduction. 


The two-dimensional snare known as the orb web is a crowning 
achievement of the aerial spiders. To the layman the web is an 


engineering triumph, a fixed geometrical object that symbolizes 
spider and partially allays unreasoning distrust of the creature. To 
poets of all times, the orb, divorced from the spinner itself, is a 
celestial creation founded on beauty, its graceful spirals symbolic 
of the heavens and its mystery, its fragile lines a measure of the 
evanescence of life. To the evolutionist, it is only the last step of 
a series that has resulted in a circular design an inevitable shape; 
and the spider has no more to do with spinning such a symmetrical 
web than "a crystal has with being regular." The orb web, among 
all objects produced by lesser creatures an unrivaled masterpiece, 
is above everything a superb snare. Contemplating it, one echoes 
the words of the meditative Fabre: "What refinement of art for a 
mess of Flies!" 

The orb web, quickly strung up and as quickly replaced when 
defective, brings to the trapper an abundance of the choicest flying 
insects. It exploits a food supply that is active both by day and 
night, and, in the adult winged state, available only by chance to 
other aerial spinners. Almost invisible in ordinary light, the lines 
stretch across space as a tough but yielding net, into which fliers 
blunder, to be held by sticky, elastic threads that make the most 
powerful wings ineffective. (That a similar trap, produced by a 
like series of instinctive actions, should have evolved among a sep- 
arate line of spiders might well seem an impossibility. Nevertheless, 
the cribellate uloborids have fashioned a web that, except for sub- 
stitution of the hackled band for the beaded spiral lines, is a faithful 
reproduction of the snare of the orb weavers.) 

This most highly evolved of all aerial webs is the result of the 
random activities of aerial prototypes, which finally established 
order among the irregular lines in the horizontal platform. During 
most of its history, the flat snare was enclosed in the original maze 
of crossed threads. At first the lines of the platform intersected 
haphazardly to form an irregular framework made of dry dragline 
silk spun from the same glands as in modern forms. Over this skel- 
eton was laid a covering silk produced by different glands and 
dispensed through the posterior spinnerets, with which were mixed 
draglines from the ever active front spinnerets. These two elements, 
the framework and the covering, remain discrete throughout the 
evolution of the aerial flat snares. 

This definite pattern underlies the sheet web of the linyphiids, 
even though the finished sheet may not appear to be based on a 
definite plan. These weavers begin at the center of the dome, put 


down straight lines an inch or two long, then cross them by over- 
spinning shorter lines. These principal framework lines need only 
to be lengthened, and they become the radii of the orb weaver, 
which likewise puts down its rays from the hub outward. The 
primitive radii were numerous, closely spaced, and probably fre- 
quently branched so that the interval between adjacent radii at the 
edge of the web was little greater than that near the center. (The 
silk spiders still use this device to produce their strong net webs.) 
All these framework lines were originally dry draglines, and remain 
dry in all spiders. The webbing that crossed the radii was at first 
dry or very slightly viscous, a condition reflecting both the pres- 
ence of only small amounts of sticky silk and the failure to concen- 
trate it in heavier drops. 

In the early orb weavers, the webbing over the dry framework 
corresponded to the viscid spiral of the higher orb weavers. The 
tremendous accomplishment that it represented was the formalizing 
of an irregular maze into a series of regular lines crossing the radii 
at nearly right angles. The first regular lines were probably series 
of curves that covered a sector of the whole, then larger loops oc- 
cupying half the circle, and finally complete spirals that produced 
the relatively symmetrical orb web. These lines may well have been 
long dry rods covered with a viscous coating. At this time the 
formal round platform, entirely enclosed within the maze of criss- 
crossed threads, was still only a platform on which insects dropped. 
By slow stages the accompanying mazes, especially the one above 
the platform, were lost, but only in the highest orb weavers are 
they gone completely and even here their vestiges may still be 
seen in the tangle that leads to the retreat and the hidden egg sac. 
The gradual inclination of the orb, and the final near vertical posi- 
tion, were inevitable refinements. 

The evolution of the orb web progressed hand in hand with 
changes in the silk and in the spiders themselves. The silk glands 
gradually became a voluminous part of the abdominal contents, and 
were able to produce silks of differing properties. (In some modern 
forms there are more than six hundred separate glands producing 
five different kinds of silk.) Viscid silk was manufactured in larger 
quantities, and, when concentrated on the spiral lines, changed the 
round platform from a stopping net to an adhesive snare. As these 
early spinners developed, various groups branched off the main line 
to become sidetracked at different development levels. Some come 
down as probable replicas of early spiders, and their webs are sig- 


nificant as indicating intermediate stages. The basilica spider, Al- 
lepeira, still entirely encloses its web within a maze of threads. The 
labyrinth spiders, Metepeira, largely preserve the lower maze as a 
tangle placed behind the orb, in which the spider rests. 

The spiders that inherited the tradition of the formal orb trap 
comprise a multitudinous group, of which many are familiar because 
of large size, bizarre form, and bright coloration. They are specially 
noticeable during the fall months, when their orbs, and the spiders 
themselves, attain maximum size and cover the vegetation in great 
profusion. Many of the spinners are fat little creatures that hang 
serenely in the hubs of their webs, head-downward, claws pulling 
the rays taut, poised to move in the direction of any disturbance. 
Others are less bold; they sit in the comparative security of a leafy 
nest, but they are attentive to the thread that communicates with 
the center of their snare. All are accomplished trapeze artists, and 
swing across the lines with grace and precision. They have pro- 
duced many different types of orb webs; but while their success 
must be largely attributed to the perfection of this trap, they have 
also sacrificed much to gain their pre-eminence among the space 
web spinners. 

They resemble the linyphiids rather completely in fundamental 
features. The cephalothorax is lower and wider in front; the eyes, 
invariably small and little used, lie near the front edge. The cheli- 
cerae are large and strong, and the maxillae are short and parallel, 
never pointed inward. The legs may be long and well spined, but 
they are frequently quite short and stout. They lack the stridulat- 
ing organs present on the chelicerae of the linyphiids. Sexual di- 
morphism is often very pronounced. In many instances, the males 
are quite safe within the bounds of the female's web, but not infre- 
quently she is an ogress. 

The developmental history of the orb web is only vaguely indi- 
cated in the spinning of modern orb weavers, which retain the 
essential details as an instinctive racial memory. The baby spider 
weaves its remarkably symmetrical web soon after leaving the egg 
sac, and thereafter, throughout its lifetime, modifies the plan only 
in minor ways. The spinning of an orb web is an involved process 
consisting of a series of separate steps. The spider must first delimit 
the area of operations by framing it with silken lines. The first and 
most important line is a more or less horizontal bridge on which the 
whole web is hung. There are two way of establishing this bridge 
line. A thread may be emitted from the spinnerets and floated in the 


air until it catches on some object; whereupon it is pulled taut. Al- 
ternatively, the spider may fix a line, carry it, by dropping or walk- 
ing, down one side of the area to be covered, across and up the 
other side to the point of attachment, holding the line free of en- 
tanglement all the time. Once the bridge line is fixed, it is strength- 
ened by additional threads as the spider moves back and forth across 
it. (See Text Fig. 6.) 

From some point on the bridge line the spider now drops down 
to a lower point and fixes a plumb line to grasses, twigs, or any 
substratum. To this plumb line the spider next attaches a third line, 
and, holding it free, climbs back up to the bridge, along it for a 
distance, then attaches and tightens the third thread. There is now 
formed a triangle, its dimensions dependent upon the distance trav- 
eled on the bridge line, whose apex points down and in which the 
round snare can be placed. 

These foundation lines may be roughly rectangular, trapezoidal, 
or otherwise configured, and are dependent upon the local condi- 
tions and the habits of the species. 

Within the framework the spider now lays down the radii. 
First it must put down a diameter line to pass through the point 
that is to be the center of the orb. This may be accomplished by 
dropping down from the bridge line, or by walking the diameter 
line, held free, around the framework to the opposite point, where 
it tightens and fixes the line. From some point on this initial diame- 
ter line originate all the other radii of the web, each put down by 
carrying it around to the desired attachment point over the already 
fixed lines. According to McCook, the radii are as a rule laid alter- 
nately on the opposite sides of the enclosed space, but there may be 
less regularity that he supposed. The tension on the lines, no doubt 
susceptible to testing by the spider, may well influence it in setting 
down the radii, which are often placed with quite remarkable ac- 
curacy to form nearly equal angles at the center, but in other cases 
are grossly asymmetrical. 

After fixing the last radius, the spider usually goes to the point 
where the radii converge and strengthens it by spinning a mesh of 
lines termed the hub. A part of the hub is made while the radii are 
being placed and stretched, and it is completed after the last one is 
fixed. Around the hub are then spun several spiral turns, which, 
because they are laid down and pulled to form irregular notches, 
are termed the "notched zone"; they serve to strengthen the central 
area and tighten the radii. The next step is to put down across the 


whole series of radii a spiral thread that holds them in place during 
the subsequent spinning. The turns of this "scaffolding spiral" are 
wide apart. 

Up to this point all the lines (the foundation, radii, hub, and 
scaffolding spiral) are of dry silk. They are the framework of the 
primitive platform. 

Beginning at the outer margin beyond the scaffolding spiral, the 
spider now puts down viscid spirals upon the dry web skeleton. It 
is guided, to some extent at least, by the scaffold, by tensions in the 
lines, by the nearness of outside lines, and by various other factors. 
Before the full circular turns begin, the spinning may be directed to 
filling in corners with short curves connecting few radii, or with 
longer loops that sometimes swing halfway around. As the spider 
gradually approaches the center, the dry lines of the scaffolding 
spiral are bitten out, wound up, and discarded, or sometimes eaten. 
The viscid spirals and loops, ordinarily composed of a single coiled 
thread from the beginning point to the end near the center of the 
orb, are placed down with a slow and deliberate motion in a very 
special manner. The spirals may be spun clockwise or counter- 

These sticky lines are composite; they consist of a dry core of 
two closely joined threads covered evenly on the outside with a 
viscous film derived from different glands. Following attachment 
of the compound line to a radius, it is grasped by the claws of one 
hind leg; these, as the spider's body swings across the space, pre- 
pare to fix the thread on the next radius. At the same time, the line 
is grasped near the middle by the claw of the other hind leg, 
stretched rapidly to half again its length, then let go with a snap. 
The result is an elastic line that contracts to the width of the space 
between the radii; upon magnification, it is shown to be beaded 
with a series of small round drops of sticky silk. The stretching of 
the silk line breaks up the viscid film and distributes it along the line 
like beads on a necklace. 

The web is now essentially finished, and the spider returns to 
the hub, often to alter it in the way characteristic of its group, which 
consists of biting out the center or ornamenting it in various ways 
by adding distinctive bands of silk. These bands, decorative loops, 
or zigzags of thick, white, flossy texture, presumably strengthen 
the center of the orb; from this attribute they have received the 
name "stabilmenta." They seem to be vestiges of the early custom 
of overspinning the central portion to provide a resting space in 


*"'' "" ' f *' ';""' * " ' 


Lynwood Chace 

Lee Passmore Gtorge Elwood Jenks 

a. Portrait b. The pendent egg sac, opened to 

show young 

THE BOLAS SPIDER, Mastophora cornigera 


George Elwood Jenks Walker Van Riper 

Feather-foot spider, Asymmetrical orb web of banded 

Uloborus americanus, with egg sac Argiope, Argiope trifasciata 

JRS George Elwood Jenks 

Female of tuberculate Cyclosa, Cyclosa turbinata, on egg string 


A. The foundation lines delimit the snare. B. Radii are laid down in 

the frame. C. A dry scaffolding thread spirals out from the hub. D. The 

viscid spiral coils are laid down from the outside and the scaffolding 

thread removed. 


which may have been slung the egg sac. The habit is largely lost 
by modern types, but some of the weavers have revived and ex- 
tended it to produce striking patterns over considerable areas of 
the web surface. It may be added that these bands, along which the 
spider sometimes aligns its legs, doubtless give protection from 
certain enemies. 

Recapitulating, the finished orb web consists of various distinc- 
tive parts. A strong, moderately elastic framework, strengthened 
by overspinning each line one or more times, holds in proper tension 
a series of radial lines of dry silk. At the center is a thickened or 
meshed hub, with or without extensive bands of silk, being the 
strategic center of the web, the place where the spider hangs with 
its claws touching the radii. Beyond the hub is usually a free zone 
devoid of spiral lines; then comes the series of sticky spiral coils 
that act to snare prey. The spider hangs downward or away from 
the web, even when it is nearly vertical, and moves by grasping the 
dry lines with tiny claws. The spider is anointed with an oil that to 
some degree prevents the sticky lines from adhering to it. 

When an insect becomes entangled in the lines, the whole web 
is agitated by the struggles, and the vibrations are communicated to 
the spider. Quickly it swings across the web to the site of the dis- 
turbance, directed by the pulls on the lines, all the while trailing 
behind it a dragline thread, on which it can drop to the ground or 
save a fall if brushed from the snare. Its long legs tap the prey, 
further informing the spider of the nature of the victim, and bring- 
ing on a response commensurate with the problem of subduing it. 
Small, weak insects are seized and quickly enwrapped, but larger 
and more active ones are treated with greater caution. The prey 
is seized, held by some of the legs and turned round and round, 
while it is trussed up with silk. Jets of fine filaments, thrown out al- 
ternately by the spider's hind legs, are combed over the insect and 
envelop it like a mummy. The bite may be administered either 
during the capture or later, when the prey is caried back to the hub 
and feeding begins. 

The struggling victim often cuts and entangles many spiral seg- 
ments and radii, and may cause whole sectors to sag. During the 
capture, broken lines are tied together with threads by the spider, 
which deftly grasps the lines with its claws and pulls them together 
around the rent. This effective repair of the web is carried out at 
other times as well, by some species; still others allow the snare to 
become a shambles. 


Mention of web repair always brings to mind the views of Fabre 
and others who regard spiders as creatures that, while spinning 
their webs, must run through the same series of inflexible and in- 
stinctive actions from start to finish. The spider can build another 
orb with the pattern and peculiarities of its clan, but cannot repeat 
an earlier step out of its turn, cannot repair a rent in the lines. By 
cutting some of the lines it can be shown that the mechanical spider 
often spins blindly to produce an imperfect caricature of a snare. 
However, spiders seem not to be quite the automatons that this 
view demands. 

Many higher orb weavers spin a new web almost every night. 
Retaining the foundation lines intact, they remove the ragged 
threads and law down fresh radii and capturing spirals. (It is at 
this time that they frequently eat the rolled up balls of silk.) Their 
webs are prepared for a single or for only a few captures; conse- 
quently there is little incentive to repair a web that will not be 
used again. Even so, much informal repair, by overspinning broken 
areas, does go on. 

Some of the orb weavers use the snare for a longer period, and 
probably do far more informal repair of the rents. It is well known 
that the silk spiders replace only a part, usually one half, of their 
large web at one time. In other instances, there may be quite formal 
repair by replacement of a series of loops, or by keeping intact areas 
of loops and adding only the spiral or complete turns. The seem- 
ingly tremendous task of completely replacing an orb web ordi- 
narily requires less than an hour. The spinning is often done during 
twilight, when it is easy for an observer to watch the whole process, 
but others spin during the early morning. 

The principal groups of orb weavers are well represented in the 
temperate region of North America. Much of what we know about 
their natural history must be credited to the energy of the Reverend 
Henry C. McCook, whose fascinating and comprehensive three- 
volume work, American Spiders and Their Spinnings or k, is one of 
the classics in arachnology. Superbly illustrated and still authori- 
tative, this is a primer to which layman and spider specialist alike 
can refer for dramatic essays on our orb-weaving spiders. 

That all orb weavers represent a single series is undoubted, but 
that they should all be placed within the single family Argiopidae, 
the most common practice, is debatable. Some modern types repre- 
sent lines early detached from the main stream, and now forming 


a. Wolf spider, Geolycosa turricola, side view 

J. M. Hotlister 



>. Burrow of wolf spider, Geolycosa, in grass 

J. M. Hollister 


Walker Van Riper, Colorado Museum of Natural History 

Grass spider, Agelenopsis, on egg sac 


isolated groups only imperfectly bridged by intermediate forms, if 
at all. 

The big- jawed spiders of the subfamily Tetragnathinae are in 
certain respects among the most generalized of all orb weavers. 
Most are greatly elongated spiders with very long, thin legs; the 
chelicerae are of great size, especially those of the males, which 
often project forward in a horizontal position. During mating, the 
chelicerae of the female are gripped in those of the male by means 
of long spurs that clamp the fangs, and, thus firmly hooked, are 
rendered impotent. Most tetragnathids live in grassy areas, and are 
especially common on the border of swamps and along streams. 
Some place their snares horizontally over and close to the water, but 
more frequently they are inclined or vertical, and framed in grass 
or shrubs. The snare, which has an open hub, is quite delicate, and 
is best suited to the capture of midges, mosquitoes, crane flies, and 
other small insects with weak flight. 

The stilt spiders of the genus Tetragnatha, which appress their 
slender bodies and legs closely against stems or hang as inanimate 
straws in the center of their webs, are the best-known members of 
this series. When disturbed, they drop on their draglines, often to 
the surface of the water, over which they stride like aquatic bugs. 
A dozen or more species occur in our fauna, most of them widely 
distributed and abundant. One of the largest is the half-inch-long 
Tetragnatba elongata, a grayish stick spider with great jaws longer 
than its carapace. Even commoner is Tetragnatha laboriosa, a 
smaller, yellowish species with a silvery abdomen, which lives in 
grass, often in dry areas. 

The thick-jawed spiders of the genus Pachygnatha resemble the 
stilt spiders, but their chelicerae are shorter and heavier, inclined 
downward, and their legs are shorter. They live near the soil in 
deep grass or under debris in damp places, cattail swamps being 
especially favored. They do not spin a usable web, but wander in 
search of small insect prey, as do the short-sighted vagrant spiders. 
They are limited quite largely to the north temperate zone, and are 
replaced southward by smaller, globose species that still use an orb 
web as a means of capturing insects. These latter belong in the 
genus Glenognatha, and differ in having the single tracheal spiracle 
advanced far in front of the spinnerets. Our best-known species is 
Glenognatha foxi, an eighth-inch-long, pink and silver spider of 
quite globose shape, which lives in meadows and grassy situations 
all over the South. Its delicate orb web, three or four inches across, 


is usually found anchored in a horizontal position about two inches 
above the ground, tied to grasses and weeds. A much larger species, 
Glenognatha emertoni, one fourth of an inch long, lives in the 
Santa Rita Mountains and other high ranges in southern Arizona. 

The members of the subfamily Metinae are closely related to the 
tetragnathids, but are more advanced in their structural features 
and far more diversified in their general appearance. All of them 
spin the orb snare, leaving the hub open; some of their webs are 
remarkable atypical creations. The species of Leucauge are bril- 
liantly colored spiders, green and silvery white, often spotted with 
gold, orange, or copper; and our commonest species, venusta, well 
merits its name. The species of Meta, whose best-known member 
is the half-inch-long, brown and yellow Meta menardi (common 
in Europe and possibly introduced from there into this country), 
approach the typical orb weavers in form. Their inclined webs are 
placed in dark places, often in shallow caves, and the large, snow- 
white egg sacs are suspended by a short thread from near-by walls. 

The most interesting member of the Metinae is the basilica 
spider, Allepeira conferta, a moderately elongate creature one third 
of an inch long, whose cylindrical abdomen is furnished with a 
hump on each side near the base. It much resembles Leucauge. Its 
web is of especial interest, since it is to a large extent intermediate 
between the sheet web of the linyphiids and the typical orb web. 
Often placed deep in well-shaded spaces in bushes, this snare con- 
sists of a large maze of intersecting lines that include a light sheet 
web and additional irregular lines. The dome is an orb web, con- 
structed of a large number of closely spaced radii and crossed by a 
spiral line of presumably viscid silk, that has been pulled and guyed 
into dome shape. (See Text Fig. 5, D.) 

Largest of all orb weavers are the silk spiders of the subfamily 
Nephilinae, exotic dwellers of the tropics, whose bodies are often 
more than two inches long and whose thin legs sometimes span 
eight inches. Their great round webs of golden silk, which will 
run over three feet in diameter and are supported by lines of great 
length, are found spanning forest paths or hanging high in trees. 
The giant female is attended by pygmy males scarcely longer than 
her cephalothorax, which, although almost too small to be accept- 
able as food, must still cautiously approach her only after prelimi- 
nary tweaking of the web threads. People who walk along paths in 
deeply forested areas frequently stride into the tough lines before 
they see them. Small birds are easily ensnared, and quickly make 


their plight hopeless by their struggles, which bind the many lines 
together into strong bands. The use to which the silk of this spider 
has been put by primitive peoples and its failure as commercial 
silk have been noted. 

Our only silk spider is Nephila clavipes (Plate 10), a long- 
bodied, olive-brown species with lighter spots on the abdomen and 
long legs provided with thick brushes of conspicuous black hairs. 
Now largely confined to the extreme southern states, this Nephila 
was probably the same one that lived much farther north at Floris- 
sant, Colorado, during Oligocene times. The bodies of the older 
females are fully an inch long, specimens from the tropics often far 
larger. The quarter-inch-long male is less than one percent of the 
female's bulk. 

The orb webs of Nephila are not replaced as frequently as those 
of other orb weavers, since they have features that make them far 
more permanent. The dry spiral scaffolding line is looped back 
and forth, and is a permanent part of the web. The radii are numer- 
ous; they are branched so that the interval at the outside of the web 
is little more than near the center. The viscid spirals are loops for 
the most part, only rarely complete circles. The hub is eccentric, 
and is located high up near the side of the web. 

The ray spiders of the family Theridiosomatinae are small, 
globose orb weavers, which have diverged rather sharply from the 
more typical members of the group, and seem to lie in the vague 
intermediate zone between the three principal families of aerial 
spiders. Our best-known species is the widely distributed Theridio- 
soma radiosa, once believed to be the same as a species found in 
Europe. Females run about one tenth of an inch long, and have 
rounded, oval, highly arched abdomens marked with many small 
silvery spots. The remarkable egg sac, a brownish, pear-shaped 
bag, is suspended by a long, often forked thread from the branches 
of trees or the sides of stones. The aerial station makes it immune 
to depredation by crawling insects. 

The ray spider is commonest in dark, damp situations, and 
favors shaded woods, the underbrush along streams, and nooks at 
the base of cliffs. The web, usually vertical in position and three to 
five inches in diameter, is a most remarkable structure. It is first 
spun as a reasonably typical orb snare with a meshed hub and sev- 
eral spiral turns in the notched zone, then the hub and these threads 
are bitten out. The radii, a dozen or so in number, are next rear- 
ranged so that they converge upon a small number of lines that 


radiate from a point at or near the center. These rays, in turn, con- 
verge upon a short trap line that is attached to a convenient twig 
or surface. The spider rests its body on the rays or the orb, and, 
sitting upright and facing away from the snare while holding the 
slack line loosely between its front legs, pulls the web into the 
shape of a cone or funnel or an umbrella turned inside out, as 
McCook described it. When an insect strikes the web, the spider 
lets go the line; and both snare and spider spring back to aid in 
the further entanglement of the victim. Only one of the rays, com- 
prising three or four radii, is badly damaged with each capture; so 
the spider uses the trap several times. 

The upright position is most unusual for an aerial spider. It is 
made possible by the spider sitting upon a foot basket of taut lines 
and clinging with its hind legs. The resemblance of this device to 
that of the triangle spider is most striking. Hyptiotes uses a single 
sector, hangs back-downward from the ray threads, and springs 
forward on the line when the trap is released. A single capture 
destroys the triangular snare, but Theridiosoma has several sectors 
in reserve. 

In the subfamily Argiopinae are handsome orb weavers second 
only to the silk spiders in size, and far better known, especially in 
the North, where their bright colors and large webs make them 
conspicuous creatures. More closely allied to the typical orb 
weavers than to the groups already mentioned, the Argiopinae differ 
from these former in having the posterior eye row strongly curved 
backward. The typical web of Argiope, the principal genus and 
the only one that will be discussed here, is ordinarily somewhat in- 
clined, but may be nearly vertical. It is provided with a sheeted 
hub. Frequently the web is accompanied by a tangle of lines be- 
hind the orb, the so-called "barrier web," and less occasionally by a 
thinner tangle in front. These are probably vestiges of the stopping 
mazes of the primitive orb weavers; as was the case with these pro- 
totypes, they provide a protective screen against some enemies. At 
the center of the web is a stabilmentum consisting of a zigzag band 
of white silk in nearly vertical position, usually occupying a third 
of the diameter of the orb. In some instances it is vaguely indi- 
cated, but ordinarily it is a conspicuous mark, a signature of this 
group of spinners. The spider hangs at the hub, head-downward as 
usual, with the legs at each side of the stabilmentum; by appropriate 
stimulation it can be induced to shake the web vigorously (as do 
the long-legged cellar spiders and many orb weavers) until it be- 
comes an indistinct blur. The males are very much smaller, about 


one fourth as long, and mature much earlier than do their mates. 
In midsummer they are often found in tiny, imperfect webs near 
the snares of immature females; later they lurk in the threads of the 
barrier webs of mature, greatly enlarged females. 

Three well-marked species, widely distributed in both North 
and South America, are almost the only members of this striking 
group that have penetrated into the New World from their head- 
quarters in the Oriental and Australian regions. The silver argiope, 
Argiope argent at a (Plate XVIII), is a comon and characteristic 
spider of the American tropics, and reaches to our southern states, 
where it is locally abundant from Florida to California. The center 
of its web is provided with a two-banded stabilmentum forming a 
cross of white silk; the spider, mostly metallic silver and yellow, 
with the abdomen divided behind into rounded lobes, lies with legs 
stretched out in pairs to cover this zigzag cross. 

Orange Argiope aurantia (Plates 2 and 21; Plate II), the females 
of which have bodies running to more than an inch in length, is 
mostly black; the abdomen, with a pair of low humps at the base, is 
marked above with bright yellow or orange spots. The legs of 
young females are conspicuously ringed in black and white, but in 
adults they are usually all black. The large webs, often two feet 
in diameter, are placed upon shrubs or herbaceous plants along 
roadsides, in gardens, and around houses, also in meadows and 
marshes. The spiders usually remain in the center of their webs 
even during the hottest and sunniest days. Many flying insects are 
captured in the snare, but a favorite food is grasshoppers, which 
abound on the web sites. The large, pear-shaped egg sacs (whose 
spinning has been described) can be seen tied to shrubs in the fall 
or early spring. 

The banded argiope, Argiope trifasciata (Plates 14, 19, and 20; 
Plates I and XXIV), rivals the previous species in abundance, espe- 
cially in the West, but not in size. The abdomen is evenly rounded, 
oval in shape, without humps, and usually silvery white or yellowish 
and crossed by narrow, darker lines. A very beautiful spider, 
trifasciata, lives in essentially the same locations as Argiope aurantia, 
but may often be found in drier situations. The snares are very 
similar, and placed to entrap the same kinds of insects. The egg sac 
is cup-shaped, with a flattened top. 

The spiny-bodied spiders of the subfamily Gasteracanthinae are 
brightly colored creatures whose hard, leathery abdomens are orna- 
mented with prominent spines. The spinnerets are located at the 
tip of a conspicuous elevation. Several of these spiders occur in the 


United States, but most live in the tropics, where an amazing array 
of bizarre types has developed. The genus Gasteracantha is poorly 
represented in the Americas; only three or four extremely variable 
species are found. The genus Micrathena, comprising more than a 
hundred long-bodied species, with flat or elevated abdomens bor- 
dered by long spines or thick spurs, is exclusively American. 

The spiny-bodied spiders hang on short legs in the centers of 
their webs, looking rather like chips of wood, bits of leaf, or plant 
fruits. The sharp spines make them unpleasant morsels for birds, 
lizards, and vertebrate animals, but their worst enemies, the solitary 
wasps, fill mud cells with them, not at all deterred by the armor. 
G aster acanthus webs are inclined or vertical, and have open hubs. 
The radii or foundation lines are ornamented with a series of floc- 
culent tufts of whitish silk. It has been suggested that these may 
serve as lures for midge-eating insects, which, deceived by the white 
flecks, might fly into the orb and be caught. 

Two species of Gasteracantha are found in the United States, 
but one, tetracantha, is very rare. The other, Gasteracantha cancri- 
formis (Plate 14), is common in the southern states. It is subject to 
considerable variation. It has a yellowish or orange abdomen 
spotted with black and fringed by six spines. 

Our species of Micrathena are equally spectacular in their bright 
coloration and curious shapes. Micrathena saghtata (Plate 22), an 
arrowshaped species having a white or yellow abdomen armed with 
a tiny basal and median pairs, at the apex a greatly enlarged pair, 
of divergent redtipped spines, is common even in the Northeast. 
Lumpy Micrathena gracilis, a light brown species, whose elevated 
abdomen is set with five pairs of short spines, is representative of 
a quite different series. These, and others not mentioned here, have 
small males that in shape do not closely resemble the females. 

The typical orb weavers of the subfamily Araneinae so far out- 
number those of other subfamilies that in the temperate regions 
they are the dominant group. Their physical characteristics are a 
generally thick-set appearance, bulky abdomens and relatively short 
legs, but some have become elongate types that can run quite 
rapidly. The abdomens of the typical orb weavers are subject to a 
very considerable variation in shape. Some are leathery, and sur- 
mounted by humps or spines that make them resemble those of the 
spiny-bodied spiders, from which they differ in not having the spin- 
nerets on the end of a tubular eminence. Sexual dimorphism is 
pronounced in many genera, especially in the bolas spiders; in cer- 
tain cases the males may be essentially equal in size to the females, 


except for the bulk of the abdomen. It is among these orb weavers 
that the male seems to run the greatest risk while courting, but he 
has learned to reduce the danger by dropping on his dragline when 
his attentions are evidently unwelcome. His long front legs are 
usually armed with rows of spines that aid in holding the female, 
and in keeping her at arm's length when she pursues him. With the 
exception of the few species that have modified their ensnaring 
habits, the typical orb weavers spin a circular web, but considerable 
differences are found in the details of the orb and accompanying 

The small, elongated species of Cyclosa (Plate XXIV), usually 
about one fourth of an inch long, have conical humps at the end 
of the abdomen. Through the center of their beautiful snares, fur- 
nished with many radii and closely set spirals, often lies a stabilmen- 
tum consisting largely of the remains of insects and debris tied 
together with silk. The eggs are later added to the string. The 
spider sits at the hub, bridging the space between the segments of 
the string and blending so completely with it as to be practically 

The webs of most orb weavers still maintain, at least in vestigial 
form, the ancient mazes of their prototypes. In the labyrinth spider, 
Metepeira (Plate 23 and Text Fig. 5, E), the maze has been retained 
as a prominent, irregular net, which the spider uses as a base and in 
which it hangs its leaf retreat and string of eggs. Many species occur 
in the United States; they vary in size from one-fifth to one-half 
inch in length. The orb web is usually complete, with several trap 
lines leading from the hub to the retreat of the spider in the tangle. 
The spiderlings use the labyrinth as a nursery web after they break 
out of the egg sacs, and it is reported that they sometimes feed upon 
small insects caught in the tangle. 

Several of these typical argiopids habitually spin incomplete orb 
webs, entirely omitting the spiral lines and radii from a segment 
equal to the space between two or three radii. This they accomplish 
by spinning rounded loops, and swinging back and forth many times 
instead of making complete circles. Associated with such snares is 
a trap line, sometimes virtually bisecting the open sector but usually 
in a different plane, that leads to a nearby retreat. The species of 
Zygiella spin incomplete orbs of this type, but better known to 
Americans are those of Aranea pegnia and A. thaddeus, which have 
far wider distribution. The lattice spider, Aranea thaddeus, is about 
one-fourth inch long and has a rounded abdomen of a pale, yellow- 
ish color with darker sides. Its beautiful silken retreat is usually 


attached to a near-by leaf; inside the retreat lies the spider, hold- 
ing the trap line stretched to the center of the orb. Spiders that use 
these trap lines first swing to the center of the web, then directly 
toward the point where the prey is entangled. 

A great many of our largest orb web weavers spin a complete 
orb and communicate with it by means of a trap line stretched 
from a retreat of folded leaves. Typical is the common shamrock 
spider, Aranea trifolium (Plates 7 and 18). This animal, often more 
than a half inch long, has an evenly rounded, white to pink abdomen, 
usually marked above with a three-lobed spot resembling a sham- 
rock. Its carapace is banded with brown, and its legs are conspicu- 
ously ringed with white and brown. The male is only about one 
fifth of an inch long. Even more stikingly colored is the related 
round-shouldered weaver, Aranea raji, which, common over most 
of the United States and well known in Europe, has a bright orange 
body and an abdomen marked by contrasting darker lines of an 
indistinct folium. 

Larger even than the round-shouldered orb weavers are some 
that have a bulky abdomen produced into prominent basal humps. 
These gray or brown spiders sit at the side of their complete orb 
webs in a crevice, under chips of wood, under bark, or in a more 
formal leafy retreat. One of the most familiar is Aranea gemmoides 
(Plate XXII), which is widely distributed from Nebraska westward. 
It varies from pale yellow to near black. The commonest eastern 
representative is Aranea nordmanni, a somewhat smaller and darker 
spider, with folium on the abdomen, which is thought to be similar 
to a European species. 

Included among the typical orb weavers is one small group that 
has repudiated the orb web in favor of a distinctive and extraordi- 
nary method of capturing insects. These are the bolas spiders of 
the genus Mastophora (Plates III and XXIII), fat creatures of above- 
average size, whose bodies are ornamented in a most grotesque 
manner. The carapace is bedecked with sharp, branched crests or 
horns, and set with many small, rounded projections; the volumi- 
nous abdomen is lined and wrinkled and surmounted with rounded 
humps. These bizarre specializations, reminiscent of similar orna- 
mentation in the dinosaurs and other groups of animals, are not 
known to play an important part in the life of the spiders. 

The hunting site of female Mastophora is usually the outer 
branch of a shrub or tree, most often high off the ground. On this 
the spider hangs in plain sight. Mementoes of her previous activities 
are numerous silken lines that soon form a thin coating over the 


twigs and the leaves. Hanging to the lines, or hidden among the 
near-by leaves, may be one or more egg sacs, beautifully and dur- 
ably made and featuring a long, coarse stem drawn of! from the 
globular base. During the daylight hours Mastophora clings to a 
twig or leaf, completely immobile, perhaps deriving some protec- 
tion from her resemblance to various inanimate objects. Even 
when handled, she shows only a momentary evidence of life, and 
may be rolled around in cupped hands like a marble. Few spiders 
are so completely inscrutable. 

But Mastophora is a creature of the evening and night, and as 
one watches her then in the performance of her marvelous routine, 
one forgives the earlier listlessness. The disappearance of the last 
rays of twilight is the signal for action; she takes up her position 
for the evening's sport. 

With plump body swinging from the ends of her legs, she moves 
to one end of a branch and affixes her thread to the lower side by 
pressing her spinnerets against the bark. Grasping this thread with 
one of her hind legs and holding it away from the branch, she 
crawls several inches farther along and pastes the other end firmly 
in place. The result is a loosely hung line, which she often strength- 
ens with an additional dragline thread. This strong trapeze is hung 
far enough below the branch to allow a clear space for casting. 

Moving to the center of the line, Mastophora now touches her 
spinnerets and pulls out, to a length of about two inches, a new 
thread that lies clear of the other. Keeping it attached to her spin- 
nerets and held taut, she combs out upon it quantities of viscid 
silk. Each hind leg alternates in producing the liquid, until a shin- 
ing globule as large as a small bead is formed. 

The spider now pulls this line out still farther, allowing the 
weighted portion to drop part of the distance to its natural point of 
equilibrium, then she turns and severs it just below the globule with 
the claws of one of her hind legs. The freed line swings back and 
forth like a pendulum, but the spider turns quickly and approaches 
it, searching and groping with her front legs until she is able to 
grasp it. Quickly she swings her massive body and seizes the trapeze 
line by the hind legs of one side, adjusting the casting line between 
her palpi and one of her long front legs. Poised and ready now is 
the boleadora, waiting with the patience that characterizes her 
for the approach of a suitable victim. (See Text Fig. 5, C.) 

Also aroused to activity at this time are many nocturnal insects, 
which soon fly along accustomed lanes, dipping down close to the 
foliage and fluttering in and out among the branches. A large- 


bodied moth, its wings spreading nearly two inches, it great eyes 
shining red in the last rays of reflected light, dips down toward the 
hunting grounds of the spider. As the insect approaches, Masto- 
phora gives every evidence of knowing that a prospective victim 
is near. She moves her body and adjusts her line, as if in tense ex- 
pectancy. At just the right moment, when the moth comes within 
the reach of the line, the spider swings it rapidly forward in the 
direction of the flier. The viscid ball strikes on the underside of a 
fore wing, and brings the moth to an abrupt stop, tethered by an 
unyielding line, which will stretch a fifth its length before breaking. 

Fluttering furiously at the sticky end of the lasso, the moth 
makes every effort to free itself, but the spider is quickly on hand 
to give the final coup. She bites her victim on some part of its 
body. With the venomous bite resistance ends quickly; and the 
paralyzed moth can be rotated and trussed up like a mummy in 
sheets of silk. Mastophora then sets to work feeding on the body 
juices of her catch. This bountiful food supply will keep the spider 
busy for some time. After having satisfied her appetite, she cuts the 
shrunken remnant loose from the trapeze line and drops it to the 
ground below. Later in the night a second capture may be made, 
but Mastophortfs needs for food are usually well met by a single 
sizable victim. 

It must not be concluded that the life of this spider is quite 
as simple as the incident portrayed might indicate. Mastophora 
may wait in vain for a flying creature to come near enough for 
capture. In many instances, her aim may not be as accurate as pic- 
tured, or the prospective victim may be too large to be held even 
by the strong band of silk. But patience is one thing at which 
spiders excel, and Mastophora is no exception. Should no victim 
reward her after half an hour of waiting, she winds the globule and 
line into a ball and eats it. Quickly she spins another line, prepares 
another sticky bead, and resumes her vigil. 

How wonderfully complex is the pattern of instinctive activities 
that make up the casting habit of Mastophora! Although endowed 
with glands that produce silk in copious quantities, the spider bases 
her whole economy on a blob of sticky silk dangling at the end of 
a short line. And still not content with a niggardly use of this vital 
material, she eats the viscid globule if it is not put to use. The 
trapeze line, the pendulum thread, the viscid globule, and the in- 
stincts of a hungry spider, have in her combined to produce one of 
the most sensational of all devices for the capture of prey. 


The Hunting Spiders 



the most part bold creatures that put only moderate reliance on 
silk to gain a livelihood and spend much of their life in the field. 
They run upright on the soil and on vegetation, and maintain this 
upright attitude even when on webs. Among them are conspicuous 
extroverts, whose open ways have earned them such names as "wolf" 
and "fisher" spiders, "running" and "jumping" spiders, and other 
names that describe quite suitably the characteristics of animals 
that pursue and overpower their prey by strength, speed, and alert- 
ness. Their strong, usually elongate and cylindrical bodies are pro- 
pelled by stout legs of moderate length, as befits runnmg creatures. 
Many are big-eyed hunters with keen sight that stalk their prey 
during the daytime. But at the same time we also find numerous 
allies of retiring, even secretive habits short-sighted vagabonds that 
skulk under the dark security of debris, that come out only at night 
to grapple fiercely with small creatures touched by their groping 

The line of the vagrants starts with the same shy, short-sighted 
ancestral spider that gave rise to the aerial sedentary types. Origi- 
nally far less venturesome than its cousins, this prototype retired to 
the cover of a stone or a crevice, where it deposited its eggs and 
enclosed them in silken sheets. Then around itself and the precious 
bag it spun a silken tube or cell, at first left open at both ends, later 
closed behind, or in front as well. In this compartive security it 
spent most of its time, departing only for short hunting forays, 
after which it dragged the prey back to be devoured at leisure. 
Allegiance to silk was a moderate one. Dragline threads were put 
down during the foraging; and the elementary subservience to these 
lines still remains firmly fixed in the habits of the boldest and swift- 
est of the vagabonds. Silk was used by the males for sperm webs, 
and invariably by the females to make the flattened egg sacs, which 
were composed of lower and upper sheets joined at the margins. 


Few of the hunters have completely given up the silken cell as 
a base. Some found such comfort there that they have remained in 
it throughout their history, and have modified it only by embellish- 
ing the entrance with various types of webs. Ariadna lies in the 
tube and waits for insects to trip on the signal lines that radiate 
from the mouth. Many funnel-web spiders spin a little silken collar 
around the opening and await callers with like patience. The well- 
hidden funnel of the grass spiders provides a sanctuary from the 
gate of which the spider may survey its vast sheet web where drop 
leaping or flying insects. All these spiders are fundamentally hunt- 
ing types; they represent a very distinct line from those creatures 
that use the third claw as a hook to swing through space. The 
sedentary vagrants rarely produce aerial webs of consequence, and 
they emulate only poorly the superb devices of the aerial snarers. 

Most of the early hunting spiders found it advantageous to move 
away from the bonds of silk. Improvement in vision made possible 
a life of action far from the retreat even during the daytime, and 
some were quickly molded into swift vagrants, with little need for 
a fixed station. Two distinct lines have been followed by the 
higher hunting spiders: one culminates in the wolf and lynx spiders, 
and the other in the jumping spiders. 

Whereas the curved, unpaired claws were the prime determi- 
nants of the departure of the aerial spiders from the main line of 
spider evolution, these had little to do in laying down the path of the 
vagrants. The wolf spiders and their kin retain the median claw, 
but it is small in size and not used as a hook. No claw tufts or 
accessory claws are ever present, but in some of the heavy ground 
forms the lower surface and sides of the distal leg segments are 
covered with thick pads of hairs. The gradual development of 
better eyesight in their prototypes made possible longer and longer 
forays away from the cell, thus leaving the egg sac vulnerable to the 
attacks of predators. During the egg-laying season the females 
remained near their sacs to guard them from depredation, and fre- 
quently were on hand until the progeny had emerged and dispersed. 
The lynx spiders and funnel-web spiders still guard their eggs in 
this fashion. Other early spiders learned to mold the flattened egg 
sac into a round ball and carry it around with them by the mouth 
parts beneath the body. The fisher spiders still use this cumber- 
some method. Both the stationary vigil and the unwieldy ball put 
strong restraint on the normally active lives of these spiders. To 
ease the curb, some transferred the round sac to their spinnerets so 


that it could be dragged, a position that permitted normal hunting. 
This habit is the badge of the wolf spiders. 

In the remaining vagrant line, the unpaired claw has been lost 
and the tarsi are supplied with adhesive claw tufts that allow the 
spiders to climb with great ease. In some of the wandering ctenids 
Cupiennius and its relatives the fading median claw may still be 
seen beneath the claw tufts; it serves to bridge the gap between the 
three-clawed and two-clawed vagrants. The type reaches its acme 
in the big-eyed jumping spiders, which are the most alert and in 
many ways the most highly developed of all spiders. Another prin- 
cipal branch has been the series of laterigrade families culminating 
in the typical crab spiders. Finally, at the very base of the series 
are the six-eyed hunting spiders, the remnant of an ancient group 
that has retained many primitive features. 


The handsome wolf spiders of the family Lycosidae are expert 
hunters that have few peers among their kin, and among all araneids 
are excelled only by the jumping spiders. They occupy almost 
every variety of terrestrial habitat, and seem to be at home in all 
as dominant predators. Some are amphibious types that rarely stray 
far from water, skating over or diving under the surface when they 
are menaced. Others have become adapted for a secretive life in 
areas of shifting, open sands, into which they dig tunnels and on 
the surface of which they hunt during the night hours. Most nu- 
merous in prairie regions, the wolf spiders abound wherever a 
plentiful insect food supply is available among the grass roots, and 
where the sunshine penetrates all but the densest clumps. 

Many wolf spiders have deserted their hereditary silk-lined cell 
for a life in the sun. Others, more conservative, return periodically 
to the retreat; some pass much of their life there, leaving it only to 
hunt. Quite a few have improved the retreat by changing it into a 
deep tunnel in the soil, in certain instances closed by a movable 
trap door. Only one group of wolf spiders, Sosippus, has moved in 
the other direction that is to say, toward a greater dependency on 
silk; it spins a sheet web similar to that of the grass spider. 

Except for mere size, which varies widely between tiny quarter- 
inch Piratas and giant Lycosas, an inch and a half or more long, 
there is a surprising similarity in appearance among the wolf spiders. 


The elongate cephalothorax is usually high and narrowed in front, 
and bears eight eyes whose size and position immediately distinguish 
the lycosids from almost all other spiders. Set close together on the 
lower part of the face is a row of four small eyes that point for- 
ward and slightly to each side. Immediately above these are two 
very large eyes that point forward, and farther back on the dorsal 
part of the head are two large eyes that look upward. The spider 
is thus able to see in four directions, and, because of the size and 
acute vision of some of these batteries, can perceive moving animals 
at a distance of several inches. The legs and chelicerae are robust, 
as befits such powerful hunting creatures; the oval abdomen is of 
moderate size. 

The capture of prey by the wolf spider is marked by vigor and 
power. The spider pounces upon its victim and, holding the body 
in its strong front legs, bites and crushes with its stout chelicerae. 
The capabilities of this rapacious hunter are not without limitation, 
however, when contrasted with those of higher animals. Although 
keen and long-sighted among spiders, its vision hardly merits com- 
parison with that of many insects. Its prey is perceived by sight, 
but the character of the moving object is probably not at all evident 
until the spider touches it. The diurnal lycosids are undoubtedly 
able to make greater use of their eyes than the nocturnal types; 
but these latter are conditioned to respond to the slightest disturb- 
ance of the soil of their hunting ground. Furthermore, the wolf 
spiders have a tapetum that reflects light rays back through the eye 
retina, and presumably improves their night vision. 

The female wolf spider is, in the fashion of her sex, a creature 
of variable temper. Notorious for her rapacious activities, she 
nevertheless displays a solicitude for her eggs and young that can 
scarcely be matched by any other spider. The mother Pardosa, 
which it will be recalled encloses her eggs in a carefully molded 
spherical bag, attaches the sac to her spinnerets and drags it around 
with her (Plate XXVI) wherever she goes. It make no difference 
that it is often as large as she is; this egg bag is a precious thing to 
her; she will defend it with her very life, and will fight viciously 
to retain it. Her instincts are most powerful ones, but ironically 
she is easily fooled and will accept for a time, and almost without 
question, a substitute sac from which the eggs have ben pilfered, a 
piece of cork, or a wad of paper or cotton of the proper size and 

After two or three weeks, her young develop to a point where 


they can leave their crowded quarters. The mother then bites open 
the sac at the seam, and within a few hours a whole brood of tiny 
spiderlings has climbed upon her back and huddled there in a mass 
(Plate XXV) . The cluster will completely cover her abdomen and 
much of her carapace, and very often is composed of more than 
one layer of spiderlings. It seems to be true that the mother must 
open the egg bag, and that without her assistance the babies will 
often perish. 

During the time of carrying the young, the mother engages in 
normal hunting activities, and her children must accommodate 
themselves to a strenuous life. She will run with great speed when 
pursuing or being pursued, turn to defend herself when cornered, 
and during all these wild gyrations the spiderlings cling to her back. 
When brushed off, they quickly crawl back upon their perch if 
they have the opportunity. During this period they do not take 
food, a fact that has led to considerable speculation as to how they 
are able to survive. By some they were thought to derive energy 
from the sun and air. However, adult spiders are notorious for 
their ability to go without nourishment, and the spiderlings are 
equally tolerant. Their bodies are provided with a food supply, 
and this is adequate to maintain them until they start feeding. While 
they are riding on their mother's back, which may be for a full 
week, they are merely biding their time until the next molt, after 
which they will leave to take up separate lives in the grass, and will 
begin their own hunting activities. The spiderlings do drink water 
during their stay, and probably find a sufficient supply in the dewy 
film that often covers them fct night. They have been observed to 
move to water and take their fill when the mother stops to drink, 
then clamber back on her abdomen. 

The success of the wolf spiders in surviving is unquestionably 
due in part to the initial protection given the eggs and young by 
the mother; that is to say, by maintaining a vigil over the sac, by 
carrying it always with her, by seeing that it is broken open and 
that the young are permitted to emerge. Thereafter, however, the 
clustered spiderlings seem to remain with her through their in- 
clination rather than hers. She pays little attention to them, and 
abandons them if they fall off and cannot reach her of their own 

It is possible to give in this brief section only a glimpse into the 
lives of a few American wolf spiders. A wealthy fauna made up 


of many distinct groups with fascinating activities awaits the en- 
thusiast who cares to investigate further. 

The wolf spiders of the genus Pardosa (Plate XXV) are small, 
but they make up in abundance what they lack in size. In physical 
appearance they feature large eyes occupying nearly the entire 
width of the head, which is quite precipitous on the side. More 
gracefully built than the typical lycosid, they have a slender body 
supported by long, thin legs set with long, black spines. Their 
slender tarsi lack for the most part the conspicuous brushes of the 
larger lycosids. Their colors tend to be dark, frequently black, but 
the cephalothorax is usually marked by a pale longitudinal stripe 
continuous with a light band on the abdomen. The heads and fore- 
legs of the somewhat smaller males are often brightly variegated 
with white and black patches of hairs, features believed to be dis- 
played during courtship activities. 

The Pardosae are true vagrants and do not use any retreat for 
long, wandering instead over the soil and low vegetation in moist 
areas. All are sun-loving creatures and abound in the spring, at 
which time the males become mature and cavort in front of the 
more plainly colored females. Except in the far north, where more 
time may be necessary for complete development, they live only 
one year; in the case of the males, months less. Noted for their ex- 
cessive agility, they climb into flowers and over plants, and the 
spiderlings are often seen ballooning in the fall. 

Dozens of species of Pardosa live in temperate North America 
and occupy many different habitats. The moss- and lichen-covered 
slopes of the Far North and the highest mountains support distinc- 
tive dark species. In the dried grasses of meadows and along road- 
sides live small species striped in black and gray. In the Southwest, 
rocks and bare sands along creeks serve as the homes for speckled 
species that are hardly visible when not in motion. Most Pardosae 
abound in damp, grassy situations near bodies of water. Many are 
amphibious, being able to run over the water freely and to crawl 
under the surface by holding on to plant stems. One of the British 
species, Pardosa purbeckensis, lives in the intertidal zone and takes 
to the water during high tides, in the manner described below by 
W. S. Bristowe: 

The following day was sunny and a lot of the spiders were 
actively running about, but as the tide rose, they retreated to 
the higher portions of the plants. Presently I saw one which I 


Walker Van Riper, Colorado Museum of Natural History 

Crab spider, Misumena calycina, on flower 

Walker Van Riper, Colorado Museum of Natural History 

Crab spider, Xysticus gulosus, with prey 


had been watching touch the water several times, like a bather 
feeling the temperature with his toe before taking the plunge, 
and then it deliberately walked down the stem of the plant be- 
neath the surface, taking with it a bubble of air, caught by means 
of its hairy body. 1 watched several others, and the same thing 
occurred, and this is therefore, how they survive the high tide. 
I was puzzled at first by seeing that they dived long before they 
were forced to by the submergence of their plant, but this was 
explained by an individual that got dislodged, for it could not 
dive without the help of something firm to hold on to, and even 
the tip of a leaf swaying in the current was not sufficient aid. 
Although they can run over the surface, they are far more com- 
fortable beneath it, especially in the rough weather, so the wis- 
dom of their submerging whilst something firm remains to cling 
to becomes clear. 27 

Pardosa is a small lycosid. There are some smaller the "pirates" 
of the swamp-loving genus Pirata, and the shy Trabea of shaded 
woods but in the main the typical wolf spider is larger and more 
stoutly built, and will often attain notable dimensions. Most of the 
typical wolves belong to the genus Lycosa (from the Greek mean- 
ing "wolf," or "to tear like a wolf"; it is also the common name for 
the whole group), and strength is the keynote of their makeup. The 
carapace is low and the sides of the head broadly rounded, so that 
the eyes ordinarily do not occupy the whole top of the head, but sit 
in a group at the center of a dome. The rather short, heavy legs are 
often supplied with dense brushes of hairs beneath the tarsi and 

These typical wolf spiders (Plate XXVI) are very handsome 
creatures. Their bodies are evenly covered with a dense coat of 
black, brown, or gray hair, which gives them a velvety appearance. 
Paler markings of various kinds, arranged in spots, patches, and 
stripes, add variety to the rich coloration of the hairs. Whereas the 
upper part of the body tends to harmonize with the terrain, the 
underside of both body and legs is often boldly marked with black 
patches and stripes. 

Lycostfs egg sac is almost always white in color. The female 
molds it into a nearly spherical object, and, turning and spinning 
over the edges, leaves scarcely any evidence of the seam where the 

27 W. S. Bristowe, "A British Semi-Marine Spider," Ann. & Mag. Nat.. 
History, (9), XII, pp. 154-5. 


two sheets have been joined. It is in many ways a much more fin- 
ished piece of work than the flattened bag of Pardosa, and would 
appear to be better adapted for dragging. 

Many of these lycosids are very active day hunters. Various 
handsome and distinctively striped varieties abound in grassland and 
in grassy areas along roadsides over most of the United States. One 
of the best known is long-legged Lycosa rabida, whose gray cephalo- 
thorax is marked by two chocolate-brown stripes and whose ab- 
domen displays a median brown stripe margined in yellow. A close 
congener is punctulata, in which the dark dorsal stripes are conspic- 
uous, and the venter of the abdomen varied with a series of small 
black points and markings. The body of Lycosa hentzi, a Florida 
species, is yellowish, and resembles dried grass. All these striped 
wolves are good climbers and often ascend high into grass bunches 
and low shrubs. 

One of the most interesting habits of the Lycosidae is the ex- 
tended and highly developed tunneling practiced by certain species. 
The splendid burrows made by them were not, of course, perfected 
in a single step. We can trace their gradual evolution in the habits 
of their creators. At the outset the wolf spider took temporary 
refuge beneath a stone, and lined the area with its characteristic 
silken cell. But space requirements for the growing spider often 
made it necessary either to enlarge the cell or to abandon it. There- 
fore, in order to employ the first of these alternatives, the spider had 
to develop the use of its chelicerae as digging instruments, and of its 
silk to bind the soil so it could be removed from the premises. The 
primitive burrows that resulted from attempts to enlarge the living 
quarters were only shallow depressions in the earth immediately 
below the cell retreat and many contemporary wolf spiders still 
dig this type of pit. But other species increased their proficiency, 
moved their burrows to favorable sites in the open, and dug tunnels. 
Some made a further improvement by erecting at the burrow's 
mouth an elevated turret to serve as a lookout. Developing along 
another line, a few lycosids have learned to cover the entrance with 
a movable lid similar to those of the trap-door spiders. 

All the burrowing wolf spiders of the United States are large 
spiders that live more than one year, and in some instances do not 
attain full maturity until the second year. The spiderlings establish 
their burrows soon after they leave the mother, and gradually en- 
large them as they grow. They dig with their chelicerae, which are 
not, however, provided with a rake as are those of the trap-door 


spiders. They tie the soil together with silk into little pellets, which 
they carry in their chelicerae and drop a short distance from the bur- 
row entrance. The walls of the vertical tunnel are lined with silk, a 
very important material in the construction of the domicile; and the 
spider's movements are facilitated by a ladder of webbing that allows 
it to climb quickly and surely to the surface. The considerable 
reliance of these wolf spiders on silk is further noted in the various 
refinements associated with the burrow opening; the turret, the win- 
ter and aestivating closures, and the trap door all are dependent 
on it. 

The typical burrow (Plates 25 and 26; Plate XXV) conforms 
throughout most of its length to the size of its occupant, but an en- 
largement, usually in the middle portion, allows the spider to turn 
around and serves in the exact sense of the word as a living room. 
Because of cramped quarters, mating ordinarily takes place on the 
surface, after the males have enticed the females to come outside. 
As for their maternal habits, the burrowing wolves transport their 
egg sacs and young around with them, even while moving in and 
out of the narrow tunnel. They have learned to carry the sacs to 
the entrance, where they can be exposed to the rays of the sun; a 
mother will sit just inside the opening, and turn the bag over and 
over with her legs and palpi to warm all its surfaces. (This habit 
appears to be a necessity for nocturnal species, and for those that 
scarcely move outside the tunnel entrance during their day hunting.) 
Whereas the vagrant wolves are usually rid of their young a week 
or so after they have clustered on the mother's back, the spiderlings 
of the burrowers may remain with their parent for long periods, 
sometimes over winter in the tunnels. 

Collectors seeking specimens will find that the burrowing lyco- 
sids may occasionally be duped by using a decoy an insect tied to 
a string, a wad of beeswax, or a stem to which the enraged spider 
will cling long enough to be pulled out of its burrow. When the 
spider sits near or has been coaxed to the entrance by some meth- 
od, a quick jab with a knife blade or heavy forceps will close the 
lower part of the tube and make capture easy. Digging the bur- 
rower out may prove a laborious undertaking if the tunnel is tor- 
tuous or established in rocky soil. Those that live in sand are easily 
taken with shovel or trowel, but it is a wise precaution to put a 
stem into the burrow, or fill it with dry sand, and then follow its 
course down. The spider will usually retreat to the narrow bottom 


and lie there quietly, well hidden with soil and not easily discov- 
ered until completely unearthed. 

Along the margins of North American streams and in sandy 
fields live a number of pale species that may here be termed "bank 
wolves." The best known of these is Arctosa littoralis, a whitish 
spider one-half inch in length that is flecked with many dusky 
markings, and often blends remarkably with the sand or gravel on 
which it sits. It is quite at home in loose sand, and frequently digs 
a burrow in this material, binding the grains together with silk and 
encircling the entrance with a collar of small stones. Littoralis is 
widely distributed from Canada to southern Mexico. Most of the 
individuals seem not to dig any sort of burrow, and instead will be 
found hiding under stones along lake shores and water courses. 

The largest of our wolf spiders is Lycosa carolinensis, a mouse- 
gray spider that combines a vagrant life in the open with the more 
prosaic one of the burrow. Females of all ages can be found wan- 
dering about or hiding under debris, the adults often dragging 
their huge egg sacs or carrying their numerous young. In the 
north these inch-long creatures assume a uniform dark grayish- 
brown, and the whole venter of the body is jet black. Examples 
from Texas and northern Mexico are far larger in size, lighter in 
color, and have the venter speckled or banded with black. 

The burrows of carolinensis are most commonly encountered in 
open country on relatively dry hillsides and in prairies covered with 
a sparse growth of low plants. The upper part of the tunnel is 
always inclined, and the deeper part is often quite tortuous, lying 
among roots and stones. The entrance is large and may lack any 
external modification, though on occasion this great spider builds a 
high turret of grasses, sticks, or stones around the hole. 

A particularly interesting variant on the turret theme is that 
of Lycosa aspersa, the "tiger wolf." This handsome spider, dark 
brown in color and possessing stout legs marked by many pale yel- 
lowish stripes, lives in open woodland in our eastern states and digs 
its tunnel straight down six or seven inches into the rich humus. 
Around the mouth it erects a high parapet of moss and debris, and 
over the top of this spins a canopy, leaving an opening on one side 
only. On top of the canopy are placed bits of soil, moss, and leaves, 
so that the whole nest is well hidden and blends with its site. In 
many instances the canopy is more than just a rigid covering; it 
becomes a hinged lid that may be lifted and dropped to close the 


a. A female Lycosa covered with young 

Walker Van Riper 

Edwin Way Teale 

b. Portrait of male 
Pardosa milvina 

L. W. Brownell 

c. Turret of burrow 
of Lycosa carolinensis 



a. With captured fly 

Lee Passmore 

Lee Passmort 

b. With attached egg sac 


opening, and in this form is comparable to the wafer doors of the 
true trap-door spiders. 

Mary Treat was the first to describe the burrow of the tiger 
wolf; she observed over an extended period the life and general 
activities of a colony of twenty-eight of these spiders. In spite of 
their well-camouflaged nests, half of which were sealed during 
most of August, all but five tiger wolves fell victims to the digger 
wasps during that month. Those that escaped had completely ce- 
mented down the lids of their nests until the wasp season was over. 
Such a tremendous toll seems to suggest that aspersa is no safer 
living underground than her several close relatives, which rarely 
dig into the soil, and then make only a shallow cavity. 

In the southeastern part of the United States live many large 
Lycosae to which the common name "sand wolves" may be applied 
with considerable accuracy. A representative species, the most 
widely distributed of the whole series, is Lycosa lenta, a pale wolf 
covered evenly with grayish hairs and only lightly marked above 
by a dusky pattern. Intensive daytime collecting in Florida, where 
these sand wolves are most numerous, rarely produces examples of 
the several different varieties; at night, however, under the rays of 
the headlamp barren areas and seemingly unproductive habitats be- 
come bejeweled with their eyes, and it is possible to capture quarts 
of specimens within a short time. 

These wolves are extremely abundant on white sands, where 
they lie quietly with their legs outspread. They have fine eyesight, 
but rely almost entirely on touch to capture insects. When the sand 
is tapped with a pair of forceps, the spider rushes over to grasp 
and w T restle with the instrument almost as it would with normal 
prey. Most intriguing of all the sand wolf's reactions occurs when 
it is disturbed: It turns a somersault, dives into the sand, and disap- 
pears, leaving on the smooth surface no sign of where it has gone. 
Careful investigation shows that there is a well-hidden burrow 
closed by a perfectly concealed trap door. This door is coated 
above by a fine layer of sand; it is very thin, even thinner than the 
most tenuous wafer door of the trap-door spiders but essentially 
similar to it. The sand wolf opens the lid quicky and crawls head- 
first into the cavity, closing the door after her with her legs. 

The burrowing life has left such small imprint on the bodies of 
its practitioners that they appear to differ in no important respects 
from the vagrant wolf spiders. They produce subterraRean dwel- 
lings comparable in excellence to those of many trap-door spiders, 


but without benefit of the specific modifications that the latter 
enjoy. Only in the "earth wolves" of the genus Geolycosa do we 
find features that suggest a first step toward true adaptation to a 
subterranean life. Many wolf burrowers have thick, round bodies 
and modified appendages, but in Geolycosa the cephalothorax is 
higher and more strongly arched than usual, and the chelicerae are 
unusually robust. The front legs are very stout and proportionately 
thicker in both sexes, and all the legs lack prominent dorsal spines. 
The earth wolves are confirmed exponents of a subsurface existence, 
and spend almost all their lives within the burrow. Extremely shy, 
they are reluctant to move very far from the opening even when 
capturing insects, and usually sit partially inside, ready to retreat 
at the slightest disturbance. Most other wolf spiders will wander a 
few feet from the opening to wait for prey, or even forage long 
and far from their tunnel retreat. These may be approached at 
night with a lamp and easily captured, but the nervous earth wolves 
must be dug out of the soil. 

The species of Geolycosa (Plates 25 and 26) are to be found 
over most of the United States and temperate Mexico. Some are 
yellow-brown spiders clothed with whitish hairs, but most have 
dark red and brown bodies, masked by a covering of slate-gray or 
brown hairs. The undersides of body and legs are usually marked 
with jet-black bands and spots. They dig their burrows from six 
to twelve inches into the ground the depth being somewhat de- 
pendent on the character of the soil and line the whole with silk. 
Ordinarily the tunnel goes almost straight down, and is enlarged 
in the middle portion or at the bottom. 

Some of the palest American earth wolves (such as <wrighti 
and pikei) live in the open sand of beaches and inland dunes, while 
the darkest species, rafaelana, digs in the red, sandy soil of our 
southwestern deserts. Those that live on bare surfaces ring their 
burrow openings with an inconspicuous collar of coarse sand grains 
glued together with silk. Still other earth wolves (miss our iensis and 
turricola) are found in the plains or on hillsides where there are 
numerous small objects suitable for use in turret-building. These 
spiders almost invariably erect a prominent lookout from whatever 
materials are close at hand, fitting the pieces together with metic- 
ulous care by bending pliable straws and pine needles to the shape 
required. The turret, which has been likened to an old-fashioned 
log cabin chimney, is bound together with silk and has a smooth 
inner lining continuous with the silk of the burrow. Some are 


similar to the nests of birds and exhibit workmanship requiring 
quite as much skill. 

One small group of wolf spiders has given up vagrancy in favor 
of a sedentary existence on the top of a sheet like that spun by the 
grass spiders. It is generally believed that these sedentary wolves 
once placed only moderate reliance on silk, and that snare-spinning 
habits were acquired later in their history. The typical lycosids 
were probably running spiders at the time they learned to haul their 
egg sacs about, and the fact that the sedentary wolves still use this 
practice in their webs suggests that the sheet is a secondary devel- 

The sedentary variety differ only slightly from the typical wolf 
spiders. The cephalothorax is flatter; the eyes are somewhat more 
widely separated; the lower margin of the chelicera is usually 
armed with four stout teeth, in comparison with the three or two 
of most other lycosids. The legs are rather long, and the tarsi and 
metatarsi are so thickly covered with hairs as to form quite wide 
brushes, particularly on the front pairs. The posterior spinnerets 
are considerably longer than the anterior ones; their apical segment 
is prominent, and they are probably used to a considerable extent in 
putting down the fine and closely spun webbing of the snare. 

The sedentary wolves appear to be most abundant in tropical re- 
gions but some species extend into the southern portions of the tem- 
perate zoneSosippus floridanus, for example, which spins its funnel 
retreat under beach debris and lays its sheet over dry sand. This 
spider is quite dark in coloration, the deep red to brown carapace 
being marked with a median pale line and broader marginal stripes 
of white or yellowish hairs. The abdomen is dark gray above, with 
darker flecks on the sides, and with a broad median stripe, also low 
in tone, running its full length. The females average about two 
thirds of an inch. Common Sosippus calif ornicus of Arizona, south- 
ern California, and adjacent Mexico is quite similar to the Florida 
species, but much paler, being light brown or even yellow. It bears 
a close resemblance to some of the large grass spiders, and when 
moving over the sheet may easily be mistaken for those swift 


There is one group of spiders that is rarely observed far from 
the moist edges of streams and lakes, and that includes some mem- 


bers wonderfully adapted for life near or on the water surface. 
These amphibians are the handsome vagabonds of the family Pisau- 
ridae, animals of large or even giant size that resemble the wolf 
spiders closely in appearance but differ from them quite distinctly 
in certain habits. The pisaurids broke away from the true wolves 
early in their history, became committed to existence in moist areas, 
and now seem largely limited in their distribution by the presence 
of permanent streams or ponds. Often referred to as "water spi- 
ders," they are however no more than cousins of the European 
Argyroneta, a spider that has conquered the aquatic medium to 
such an extent that it lays exclusive claim to that title. They are 
also called "nursery web weavers" because of the spinning industry 
of the females, but the most accurate appellation is that of "fisher 
spider" a name that properly conveys their predaceous bent and 
amphibious aptitude, as well as their occasional fondness for little 

The typical fisher spider of the genus Dolomedes (Plate XXVI) 
is a huge gray or brown spider with an oval abdomen and a longitu- 
dinal cephalothorax more flattened than in the majority of the ly- 
cosids. The integument exhibits many appressed plumose hairs, in 
addition to various simple hairs and spines. The eyes have much 
the same arrangement as in the Lycosidae, but the dorsal row of 
four is not so strongly curved, and rarely is markedly larger than 
the front row. This would seem to indicate that the range and 
acuity of the fishers' eyes are less than those of the typical wolves. 
They are big-eyed hunters, nevertheless, and seem to have excellent 
day vision. 

No obvious physical features in the bodies of the Pisauridae 
identify them as spiders of the water, but they walk over the sur- 
face with a grace nearly equal to that of the water-striding insects. 
The tarsal hairs are probably arranged to give buoyancy and to 
push them when skating, but no conspicuous brushes or appendages 
adorn their legs. Much of their success as pond skaters must be at- 
tributed to their extreme lightness, which, repudiating their physical 
bulk, keeps them from breaking through the surface film. Their 
slight weight, however, while of great advantage on the surface, 
becomes a liability when the situation calls for submarine action. 
The aquatic pisaurids cannot swim as does Argyroneta, and seem 
able to break the water surface only with great effort. Diving is 
impossible unless they are able to exert considerable force with their 
legs on some convenient support, and they remain submerged only 


by clinging to underwater leaves and stems bobbing up to the 
surface like corks when they release their hold. 

The aquatic pisaurids are able to remain beneath the water for 
long periods. One instance of forty-five minutes has been noted, 
and the limit is probably much longer. The body hairs capture 
bubbles of air, thus making the spiders even lighter; and although 
this further impairs their swimming abilities, some of the bubbles 
come in contact with the respiratory orifices and furnish the needed 
oxygen for their underwater sallies. 

About a dozen species of Dolomedes are known from the United 
States, and some of them vie with the giant wolf spiders for the 
honor of being our biggest true spiders. Perhaps the largest is a 
robust fisher spider covered with dark brown hairs mottled by lines 
and spots of grayish and yellowish hairs, Dolomedes okefenokensis, 
first discovered in the Okefenokee Swamp in Georgia. The females 
often attain a body length of more than an inch and a half, and 
their lightly ringed legs span four or five inches. The male is 
considerably smaller than his mate and somewhat more brightly 
colored, the pattern of dark spots and pale lines usually being quite 
distinct. Similar species occur commonly in the northern states, 
and, even though of smaller size, seem formidable enough when 
happened upon along beaches or in boathouses. The sluggish 
streams and marshes of the United States, particularly those of our 
southeastern states, harbor many species of these vigorous creatures. 
Dolomedes albineus, an ash-gray spider of average size, is a con- 
firmed aquatic type and deserves special mention. It rests with legs 
outspread and head downward on the trunks of cypress and tupelo 
trees in the southern swamplands, completely motionless until dis- 
turbed, when it whisks out of sight around the tree trunk like a 
squirrel, or dashes into the water to skate away or hide under the 

Brief mention should be made at this point of the species of 
Trechalea, a group of large American fishers similar to Dolomedes, 
of which a single representative extends its northern range into the 
high mountains of Arizona. Trechalea flattens its grayish, black- 
flecked body against a stone at the edge or in the water of streams, 
poised to skate out at the first sign of a struggling insect. The 
activities of this creature mark it as one of our finest fishers, an 
expert with unusually good eyesight, and tarsi that are very long 
and flexible to aid in water walking. 

Most handsome of all American fisher spiders is Dolomedes 


triton, a green-gray animal of moderate size. The upper part of the 
cephalothorax is marked by two silvery white lines passing down 
each side and continuing the whole length of the abdomen. A nar- 
row white band runs from between the eyes to far back on the 
cephalothorax, and the abdomen is further marked with four or 
five pairs of small white spots. On the sternum are six dark spots, a 
distinctive badge of triton which has given the name sexpunctatus 
to a common form of the species. This spider is the most truly 
aquatic of all our Dolomedes and haunts the wettest portions of 
swamps and streams throughout the United States. It is often seen 
on the water surface, its hind legs moored to the edge of a water 
plant and its other legs far outstretched and lightly pressed into the 
water film. When disturbed, it will run over the water and hide 
in the aquatic vegetation, and when closely pursued it clambers into 
the water and hides underneath leaves or debris. 

Dolomedes triton is a close relative of the English Dolomedes 
fimbriatus, the "raft spider" of the Cambridgeshire fens. This 
handsome fisher "has earned its name from its habit of constructing, 
out of a few dead leaves and some threads of silk, a small raft on 
which it sets sail on the face of the waters. From this raft it sallies 
forth over the water in pursuit of its prey, for it can run easily on 
the liquid surface." Although raft making has not been credited 
to triton, very likely it occasionally utilizes similar small floating 
islands when it hunts. 

The food of the amphibious fishers consists mainly of the larger 
terrestrial insects from bank vegetation, and of aquatic insects in 
various stages that are found crawling in the shallow water or living 
on the muddy edges. On occasion, however, these predators have 
been seen capturing small fishes and tadpoles and feeding upon their 
bodies. This activity can be considered peculiar and surprising only 
if the preconceived notion exists that spiders must feed solely on 
insects and are unable to assimilate the bodies of vertebrates. The 
truth of the matter is that spiders rarely hesitate to attack any 
creature that comes within certain size limits. A tiny, squirming 
fish, twice the size of the spider itself, is no more formidable an 
opponent than a robust grasshopper, and is as easily dispatched. 
The spider bites with its strong mouth parts, and its venom proves 
very active on cold-blooded animals. Furthermore, its powerful 
digestive juices appear fully as effective on the bodies of fishes as on 
those of the invertebrates that are its habitual food. 

There are a number of well-authenticated instances of the ang- 


ling prowess of our North American Dolomedes, enough to suggest 
that the capture of tiny fishes is not a rare occurrence. While fishing 
in a swampy region of the upper St. Johns river in Florida, Dr. 
Thomas Barbour watched the capture of small cyprinodont fishes 
by spiders that swarmed on the floating lettuce and other vegeta- 
tion. "A tiny flash of silver caught my eye, and I looked again, to see 
a spider carrying a small dead fish, perhaps an inch long, across a 
wide leaf to the dark interior of a large lettuce cluster. I thought 
that probably the spider had found a dead fish by chance and I relit 
my pipe, when about six feet away in another direction the episode 
was repeated. This time the little fish was still struggling feebly in 
the spider's chelicerae. Later, I saw a third fish being carried off 
which was dead and quite dry." 28 Some Dolomedes have been seen 
to capture trout fry in hatcheries, and are considered capable of ac- 
counting for a good number of such tiny fish. The owners of bal- 
anced aquaria have sometimes been puzzled by the disappearance of 
prize fish, subsequently to discover a spider robber with part of its 

It is improbable that vertebrate prey forms more than a small 
portion of the total food of the aquatic fisher spiders. One wonders 
whether the toll even closely approaches the great number of 
spiders of all sizes that are eaten by trout and other surface-foraging 
fish. A far more frequent user of this food source than our native 
species is such an exotic fisher as the African Thalassius. The skill 
shown by this predaceous creature in capturing tiny fish, as reported 
by the Reverend Nendick Abraham of Natal, is well worth men- 

That night about 1 1 o'clock, when I had finished my day's 
work, I sat down by the aquarium to watch the spider, with the 
hope that I might see how the fisherman caught his fish. The 
spider had taken up a position on a piece of stone, where the 
water was not deep, and had thrown out its long legs over the 
water, upon which their extremities rested, making little de- 
pressions on the surface, but not breaking the "water skin." The 
tarsi of the two posterior legs firmly held on to a piece of rock 
just above the water level, the whole of the body was well over 
the water, the head being in about the centre of the cordon of 
legs, and very near the surface of the water. 

28 T. Barbour, "Spiders Feeding on Small Cyprinodonts," Psyche, Vol. 
XXVIII (1921), pp. 131-2. 


After watching for some little time, I saw a small fish swim 
towards the stone and pass under the outstretched legs of the 
spider. The spider made a swift and sudden plunge. Its long legs, 
head, and body went entirely under water, the legs were thrown 
around the fish with wonderful rapidity, and in a moment the 
powerful fangs were piercing the body of the fish. The spider 
at once brought its catch to the rocks, and began without delay 
to eat it. Slowly, but surely, the fish began to disappear, and 
after the lapse of some time the repast was over. 29 

Frequently the fisher spider is able to land its prize only after 
a prolonged struggle, during much of which it may be completely 
submerged and hanging on grimly to the struggling fish. The pre- 
digestion and eating of the prey must be accomplished on land, since 
the digestive juices of the spider would be diluted and lost in water. 

The pisaurids are not all noted for their amphibious activities; 
many, while abundant in moist areas, do not enter the water itself. 
The best-known American example is Pisaurina mira, a fisher spider 
of open woodland that often wanders far from water. About half 
an inch long when full-grown, Pisaurina is a very pretty spider 
extremely variable in its color and pattern. Its most common shade 
is a light yellow-brown, marked the whole length of cephalo- 
thorax and abdomen by a wide darker band bordered by white. 
Pisaurina is frequently found on bushes and low vegetation. 

Other species of this series have become elongate spiders mark- 
edly resembling the slender crab spiders of the genus Tibellus. 
Several kinds are found living on vegetation in the extreme southern 
portions of the United States. Their bodies are a very pale yellow, 
and are in some instances marked with narrow longitudinal lines 
of darker color. When at rest they lie with their long legs closely 
appressed to the surface of stems. At least one exotic group of 
these spiders, the genus Euprosthenops of Africa, builds a funnel 
and sheet web similar to those of the grass spiders. This snare is 
often more than a square yard in extent, spreading over the 
branches of shrubby acacias with the funnel near the ground; and 
Euprosthenops is reputed to hunt on the underside of the sheet as 
do the true sheet-spinning sedentary types such as Linyphia. By this 
use of silk far exceeding that of the true wolf spiders, the pisaurids 

29 Newspaper article by Nendick Abraham quoted by E. C. Chubb, "Fish- 
eating Habits of a Spider," Nature, Vol. 91 (1913), p. 136. 


Lee Passmore 

a. Female and egg sac 

Lee Passmore 

b. Male 
THE GREEN LYNX SPIDER, Peucetia viridans 


Martin H. Muma Lee Passmore 

A fisher spider, Dolomcdes scriptus Grass spider, Agelenopsis 

An immature male sits in its tunnel 

'' ' 

A/or/tn //. A/wwa 

Web of a grass spider, Agelenopsis, blankets the soil 


are seen to intergrade with the Agelenidae in their habits as well as 
in structure. 

The pisaurids are often cited, and with considerable justification, 
as providing the outstanding example of maternal devotion among 
all spiders. Many spiders guard their eggs for varying lengths of 
time, but few have made of it a complicated ritual that gives pro- 
tection to the young until they are ready to scatter. Only the wolf 
spiders exercise equal care, and they are close allies of the pisaurids. 

The first act of the pisaurid mother in behalf of the coming 
generation is the spinning of a silken cover around her eggs. The 
sac is a great ball, usually housing several hundred eggs, which is 
at first white but usually becomes gray or even brownish. From 
the time it is made until the spiderlings are ready to emerge, the 
mother carries this treasure around with her wherever she may go, 
holding it between her long legs and underneath her body (Plate 
XXII). The claw tips of her chelicerae are inserted in the ball, her 
pedipalps press around the sides in front, and silken lines from her 
spinnerets moor it securely from behind. It is often so large that 
the mother is forced to run on the tips of her tarsi in order to hold 
it clear of the ground. The difficulty of transporting such a tre- 
mendous object seems to be very great, and it is fortunate that this 
habit is operative at a time when the normal desire for food is con- 
siderably inhibited. A few of the fisher spiders transfer the egg 
sac to their spinnerets and drag it about as do the wolf spiders, but 
most of them have retained the ancient and awkward method. 

Dolomedes carries the ball until just before the young are ready 
to emerge, or until a short time after emergence, then fastens it to 
a suitable spot at the end of a branch of some herbaceous shrub. A 
three-lobed leaf is often chosen as the site, and the leaflets are pulled 
down and tied with silk to form a cosy retreat, the nursery web. 
It may be supposed that the female aids the young to escape by 
opening the egg sac; thereafter the babies quickly spin their tiny 
lines and scatter within the confines of the nursery. The mother 
remains outside the retreat guarding the spiderlings until they have 
molted and moved away, a period often of more than a week. 

Pisaurina mira usually prepares her nursery well in advance even 
of the egg laying. She displays a decided preference for the poison 
ivy, using its leaflets for the top and sides of her retreat and spinning 
up the opening below with a platform of silk. After the eggs are 
laid and enclosed in a sac, Pisaurina hangs on the outside of the 


nursery until just before they hatch, at which time she suspends 
the bag in the nursery. 


The lynx spiders of the family Oxyopidae are handsome hunters 
that have become specialized for a life on plants. They run over 
vegetation with great agility, leaping from stem to stem with a 
precision excelled only by the true jumping spiders. A few are 
more indolent, and sit in flowers or press their bodies close against 
dried stems while they await the appearance of suitable prey. The 
lynxes hunt mostly during the daytime, aided by a relatively keen 
eyesight comparable to that of the wolf and fishing spiders. Al- 
though they trail a dragline even when jumping, silk does not enter 
much into their lives, and they never make use of webs to capture 
their prey. 

The typical lynx is a strongly built creature with a high, oval 
cephalothorax and a rounded abdomen tapering to a point be- 
hind. Its thin legs are all about the same length, quite long, and 
armed with long black spines. The tarsi always lack brushes of 
hairs, but the absence of such pads does not seem to detract from 
its climbing ability. It has dark eyes placed either in two rows so 
strongly curved that they seem to form a circle, or in four rows 
of two each. They are unequal in size, the anterior median pair 
being very small and some of the others quite large, as befits the 
spider's active, diurnal life. 

The lynx spiders are best represented in warmer regions; but 
more than a dozen species occur within the limits of the United 
States, and a few are common far into the north. One of the con- 
spicuous varieties is the green lynx, Peucetia viridans (Plate 29 and 
Plate XXVII), which is abundant in the southern states from coast 
to coast, and also occurs in Mexico and Central America, where it 
is the commonest and most widely distributed member of its group. 
The female is a large spider often three fourths of an inch in length, 
and her slender mate is not far inferior in size. Peucetia is usually 
colored a bright transparent green variegated with rows of small 
red spots. A red patch usually adorns the face between the eyes. 
Rows of long, black spines are a conspicuous feature of the thin 
legs, which are ringed with red at the joints. 

Most of the examples from the eastern states are tinted the same 


bright green, and there may be a relationship between color and 
habitat, but so far lynx has not been identified as a confirmed resi- 
dent of any particular species of plant. However, in California, a 
favorite site for the spiders is the dull green foliage of the wild 
buckwheat (Eriogonum fasciculatum), and the egg sacs are fre- 
quently found tied to the yellowish flowers of this woody shrub. 
Many of these western lynxes are yellow or even brown in color, 
and have the whole dorsum blotched with large red markings that 
often form a complete band. Some of the Old World Peucetiae 
are reported to live almost exclusively on a single plant. One 
variety is said to frequent the fresh green tufts and to be bright 
green in color; whereas others that habitually seek the dried areas 
of the plants are yellow and strongly marked with a pattern of 
pinkish spots. 

The straw-colored egg sac of the green lynx (Plate XXVII) 
will be found securely lashed to the outer twigs of her plant home, 
and over it the patient mother hangs, head-downward, hugging the 
bag with her long legs. The sac is nearly as large as the spider her- 
self, and far more bulky a rounded object whose thick outer cover- 
ing is embellished by many small, pointed projections. From the egg 
sac extends a maze of lines to near-by leaves, investing the whole 
branch in a silken web, where the young can remain until they are 
ready to fend for themselves. The nest of the green lynx is often 
similar to that of the fisher spiders, and her maternal solicitude for 
the tufted purse and the young that break out of it is not less strong 
than in the makers of the nursery web. 

The remaining lynx spiders of America are far inferior in size 
to the green Peucetiae, but they are more numerous in species and 
more diversified in color and pattern. Common and representative 
is the striped lynx, Oxyopes salticus, which is at home in both the 
temperate and tropical zones of North and South America, and is 
well known in many of our northern states. This pretty little spider 
is about one third of an inch long. The female has a pale yellow 
cephalothorax clothed with white scales and varied by four longi- 
tudinal bands of dark scales. Her abdomen is mostly white, and is 
marked above by a dark basal dash and below by a dark median 
band. Her pale legs have a narrow black line beneath the femora. 
The male is slightly smaller, has balck palpi, and a black abdomen, 
which often possesses an iridescent sheen. 

Another species from this group is the gray lynx, Oxyopes 
scalaris, a brownish spider clothed uniformly with gray hairs. This 


common lynx has penetrated farther north than our other species 
and is found all over the United States, being especially abundant 
in the West, where it lives on sagebrush and similar plants. 

The habits of these lesser lynxes are quite similar. All are plant 
spiders, run on low bushes and herbs, and there place their discoidal 
egg sacs suspended in a little web. 


It has been pointed out that the name "water spider" is reserved 
for Argyroneta, one of the most amazing of all animals, a land crea- 
ture that has taken to life in an alien medium. Argyroneta is not 
truly aquatic, since she must still have air to sustain life, but she has 
transferred her aerial environment to a situation beneath the surface 
of the water, and there remains for prolonged periods. Although 
found only in Europe and temperate Asia, Argyroneta is included 
here because no general book on spiders would be complete with- 
out some mention of her extraordinary behavior. 

In appearance Argyroneta is a very ordinary spider about half 
an inch long, plainly clothed in dark brown raiment and unmarked 
by a contrasting color pattern. Nothing in her physical aspect indi- 
cates proficiency in swimming or diving; no appendages are present 
that might serve as effective instruments to propel her or to main- 
tain her beneath the surface. Severely plain when outside the water, 
once Argyroneta dives she becomes a shiny, silvery bubble, trans- 
formed from a drab gnome into "an elfin fresh from fairyland." 

Many spiders shun the water. Others, it has been seen, live near 
it all their lives, and often move over the surface or crawl beneath 
it to stay for short periods. Argyroneta is the only spider that can 
live entirely in the water and that is able to swim and move about 
without having contact with submerged objects. Most spiders are 
able to survive immersion for limited periods because they take a 
bubble of air with them, held closely to their bodies over the air 
spiracles. Argyroneta supplies her primary need for oxygen by 
mounting to the surface and raising her abdomen to capture an air 
bubble. Just how long can she stay under without renewing this 
supply? It has been calculated that if it were possible for her to 
lie motionless in the water, theoretically the armor of air would last 
about sixteen hours. However, Argyroneta is an active swimmer and 
expends her oxygen supply more quickly, making it necessary to 
come to the surface at frequent intervals. 



Walker Van Riper, Colorado Museum of Natural History 

Jumping spider, Phidippus cardinalis, on flower 


The favorite haunts of the water spider are ponds and sluggish 
streams, in which aquatic plants are plentiful and in whose quiet 
waters Argyroneta can best display her swimming talents. The 
first of her underwater domiciles is built in the spring and serves 
her well during the warmer portion of the year. In a suitable bower 
of vegetation not far below the surface Argyroneta lays down a 
platform of silk, suspending it by numerous attachments to ad- 
jacent plants. The closely woven sheet and staying lines are so like 
the water in color that they are quite invisible at first. This frame- 
work finished, Argyroneta swims to the surface for air to provision 
her unique home. She raises her abdomen and hind legs well above 
the water, securing a large supply, then submerges, while the 
brushes of long, curved hairs on her rigidly extended hind legs form 
a screen to aid in keeping the air bubble fast beneath her body. She 
paddles underneath the sheet and releases the air, which pushes up- 
ward and billows the silk into a small air sac. After many trips to 
the surface, the silk has been blown into a miniature diving bell, 
open below, which from the outside appears as a silvery drop in 
the water. There follows additional spinning on the bell and further 
tieing with supporting stays to make the finished retreat a durable 
structure. To it the spider brings fresh air as the need arises. On 
occasion, the bell will be cut open at the top to allow air to escape, 
after which the rent is repaired and the air renewed. 

Much of the life of the water spider is spent within the confines 
of this underwater chamber, where feeding, molting, mating, and 
rearing of the family all take place. Hunting goes on for the most 
part at night, and the prey, consisting chiefly of small aquatic ani- 
mals, is dragged into the bubble to be digested. At the time of pair- 
ing, the male spins his smaller diving bell close to that of his mate, 
then joins the two with a silken tunnel. At other times he will omit 
this preliminary and swim directly to share the bell of the female. 
Considering the cramped quarters, it is probably just as well for the 
satisfactory conclusion of his suit that the male Argyroneta is usu- 
ally larger than the object of his vigorous affections. 

After the mating, the eggs are laid and cradled in a tough sac 
hung in the upper part of the bell, where they hatch after about 
three weeks. The spiderlings move into the spacious lower portion 
and remain there until they depart the nest. Expert swimmers from 
the beginning and equally skilled in underwater architecture, they 
soon fill the waters with their own tiny bubbles of quicksilver. 

In the fall Argyroneta moves into the deeper reaches of her 
water environment and spins another domicile which will serve her 


as winter quarters. Much more durably constructed than the diving 
bell, this home is usually a closed sac spun in the cavity of an empty 
snail shell or a similar shelter. During the cold months the spider 
lies dormant, its life processes at such low ebb that the small cham- 
ber of air proves adequate to its oxygen needs until the advent of 
warmer weather. 


The most generalized members of the whole series of three- 
clawed hunting spiders are the numerous diverse representatives of 
the family Agelenidae: the funnel- web spiders. In physical appear- 
ance they are far less changed from the hypothetical prototype of 
the group than are the wolves and fishers and lynxes. Unlike these 
latter, which are extroverts and big-eyed hunters, most of the agele- 
nids are quite shy and hide under debris or in vegetation in their 
funnel webs. While they are still good hunters for the most part, 
with strong bodies and powerful chelicerae, this activity has become 
contained within the limits of the silken field that they lay out over 
the terrain. Since they spin a web and do use it to trap insects, they 
are called sedentary spiders, but they represent a quite separate 
line from the aerial sedentary spiders. 

The cephalothorax of the agelenids is nearly always oval and 
convex, and the eyes typically lie in two rows near the front edge 
of the carapace. The eyes are not notable for size in any of the 
groups; they are far inferior to those of relatives that have to place 
considerable reliance on sight when hunting. The oval abdomen 
exhibits as a prominent feature spinnerets that, except in less typical 
members, are quite long, and often have the terminal segment of 
the hind pair conspicuously lengthened. The whole body is covered 
evenly with plumose hairs. The legs are long and thin, particularly 
in the most active forms, and are never supplied with brushes of 
hairs beneath the apical segments. In commenting upon the physical 
characteristics of the agelenids, it can be said that evolution has 
caused them to modify their bodies, especially their eyes and legs, 
far less than their vagrant cousins have done. Thus they are called 
generalized; but at the same time, in regard to their way of life, 
they have become highly specialized. 

The funnel web of the agelenids is little changed from the silken 
cell of their forebears, and they still hide it under stones or logs, in 


crevices, and in deep vegetation. The funnel is open both in front 
and behind, thus providing the spider with a rear exit if it is men- 
aced. From the outer opening of the retreat is spread an expansive 
field of white webbing the sheet web which may be placed on 
or just above the soil, or suspended high in vegetation like a ham- 
mock. It forms a smooth runway on which flying insects can alight, 
under the mistaken impression that it is a suitable landing field. 
Once down, they find it a spongy, yielding trap into which they 
sink and over which they drag their bodies with difficulty. For 
the spider, the sheet is a racing course; it is able to run over the 
surface with great speed in an upright position, and catch its prey 
before the insect can reach the edge of the snare. 

The typical agelenid sheet web, composed entirely of dry silk, 
grows up with the spider to adulthood, changing from a small, thin 
mesh into a thick blanket of considerable expanse. It grows by ac- 
cretion, the result of incessant spinning by the active spider during 
most it its life. Upon a framework of long dragline threads, coming 
from the front spinnerets, and outlining the sheet, are put down 
many finer lines drawn from the hind spinnerets, which move from 
side to side like brushes and lay multiple filaments. The sheet web 
is rarely a simple, two-dimensional structure; suspended above it 
will be a network of lines, placed in irregular fashion and attached 
to adjacent grass or twigs, which serves as a barrier to jumping and 
flying insects and causes them to drop upon the sheet. 

Our best-known agelenids, the grass spiders of the genus Agelena 
and related genera, scatter their sheets in immense profusion over 
grass and shrubs, often high above the ground, and frequently on 
or inside houses. In the autumn these webs reach their greatest 
size, and, seen in early morning when they are covered with dew, 
seem to carpet acres of grassland. The spiders themselves are of 
moderate size, with bodies ranging from one half to more than an 
inch long, and are colored variously from pale yellow to dark 
brown. The cephalothorax has light median and lateral stripes, 
while a broader, speckled band runs the length of the abdomen. 
Three or four well-marked species, differing in size, color pattern, 
and habits, will be found in almost any single locality in the United 

Agelena sits in the mouth of her funnel retreat, facing the sheet 
and poised for a swift foray over its surface. A June beetle drones 
through the air and strikes the aerial network; its flight is abruptly 
arrested, its heavy body plummets to the surface of the sheet; the 


lurking spider races swiftly and surely to the site of the disturbance. 
Agelena wastes little time on small insects, seizing them quickly, 
but bulkier prey is approached with more caution. She rushes in to 
deliver quick bites, then retreats until the weakened insect can be 
approached and dragged into the funnel retreat for feeding. Many 
kinds of insects come her way, but the abundant grasshopper popu- 
lation of the grassland probably provides her with the highest per- 
centage of her food. 

The female grass spider lays her eggs in the fall and dies some 
time thereafter, her whole life spanning only a single year. The sac 
is a lens-shaped packet composed of two circular valves sewed to- 
gether around the edges, and is similar in form to those of the crab 
spiders and many others. Several sacs may be made. All are hidden 
in secluded places, frequently under the loose bark of trees. They 
are fastened closely to the substratum, and covered with silk in 
which bits of bark and debris are distributed, but this stratagem 
does not deter parasitic insects from laying their eggs in the masses. 
Investigation of the sacs, even in the late autumn when the female 
is still very much alive and should be able to protect her young, 
will often disclose that the contents have already provided food for 
parasites that now occupy the cradle. 

The nets of the cellar spiders and other agelenids are the same 
cobwebs used so extensively many years ago by European peasants 
to staunch the flow of blood. When several of these clean sheets are 
superimposed, they form a fine transparent fabric, which has some- 
times been used as a canvas by artists. Most of the paintings on 
spider silk were done by an Innsbruck family named Burgman early 
in the nineteenth century, and some may be found in American 
collections. Delicately done, remarkably durable in spite of the 
nebulous canvas, they are exquisite examples of an art that now 
ranks as scarcely more than a curiosity. 


The line of two-clawed vagrants culminates in the jumping 
spiders of the family Salticidae (see Plates 30, 31, and 32; Plates 
XXXI and XXXII). These are specialists. They stalk and attack 
insects with a precision and alertness not possible for myopic types. 
They are big-eyed experts that hunt during the daytime, and far 
outshine the wolf spiders and their kin. Their life in the sun seems 
to have produced a variety and brilliance of coloration not matched 


bv any other spiders; a display of this ornamentation is part of 
their courtship ritual (see Chapter V). Quite friendly little crea- 
tures, they sometimes sit upon a finger and follow one's every move 
with an attention not ordinarily manifest in arthropods bound by 
complex instinctive patterns. Fine eyesight has made them the out- 
standing spider extroverts. The largest eyes of our spotted Phidip- 
pus audax are capable of receiving a sharp image (perhaps ensuring 
recognition of another's species and sex) at a distance of ten or 
twelve inches. Awareness of moving objects by the four pairs of 
eyes, each of wriich receives different-sized images, is possible at a 
much greater distance. The jumping spider spies its prey in the 
distance, creeps slowly forward until very near, then leaps sud- 
denly upon it. 

Almost all the jumping spiders are small; few much exceed half 
an inch, and most fall far short of that length. The short, stout 
body, the rather short legs, and the distinctive eye arrangement 
make them one of the most easily recognizable of all groups. The 
rectangular cephalothorax is large and wide, squared-off in front, 
and often quite high. As in the *wolf spiders, the eyes are set in 
three distinct rows: four, two, and two. Those of the front row 
(small in wolf spiders) are greatly enlarged the middle pair espe- 
cially, which resembles large, smoky pools, and, well supplied with 
rods, give the most perfect image. Above the front row is a second 
row of two tiny eyes, and behind these a third row of two larger 
ones. The abdomen is often oval, but may be thick and wide, or 
greatly elongated, to conform with the cephalothorax. Over the 
whole body is usually present a thick covering of colored hairs 
forming an even blanket, as well as longer hairs and spines that add 
special adornment according to the species. 

These hunters run, leap, and dance gracefully on legs of moder- 
ate length. The first pairs are usually longer and thicker than the 
hind ones, especially in the males, whose front legs are in addition 
bedecked with conspicuous plumes and ornaments prominently 
displayed during courtship. It is a surprise to find the hind legs, 
which are most used in jumping, neither modified nor strengthened 
as they are in such animals as kangaroos and frogs. Apparently the 
small size and slight weight of the spiders make possible those tre- 
mendous leaps up to forty or more times the body length. The leg 
tarsi are provided with brushes of hairs, and their tips have well- 
developed adhesive claw tufts. They leap from stem to stem with 
ease and seeming abandon, and are saved from falls by dragline 
threads laid down wherever they go. They have been observed to 


leap away from a building and catch insects in flight, a feat that 
demonstrates the remarkable co-ordination of their senses and their 
superiority among spiders as hunters. 

The jumping spiders spin retreats of thick, white, slightly viscid 
silk in crevices, under stones on the ground, under bark, or on foli- 
age and plants. Many retire to these little white bags at night and 
during cold days, and also use them as headquarters for molting and 
passing the winter as juvenile or hibernating adults. The females 
lay their eggs in the retreats, usually in spring or summer, and may 
be found guarding their young after the hatching. Often many re- 
treats are found grouped close together under a single stone. 

The salticids abound mainly in tropical regions. There live a 
bewildering number of different types, many of them glittering like 
gems in an infinite variety of patterns. Although less abundant in 
the United States, about three hundred different species occur, and 
many types penetrate far into the north. The jumping spiders live 
for the most part on vegetation. A characteristic element of the 
leaf mold of the whole temperate zone is the tiny, smoky-gray 
species of Neon, whose greatly enlarged dorsal eyes shine out of a 
body only one tenth of an inch long. R. W. G. Kingston, the 
British naturalist, found a plainly marked jumping spider 22,000 
feet up on Mt. Everest, a height at which few animals of any kind 
can live. Tolerant in another way are the few species that have be- 
come domesticated. The graceful zebra spider, Salticus scenicus, 
hunts on fences and the walls of buildings, and is as common in 
America as in Europe. 

A number of jumping spiders exhibit such an amazing resem- 
blance to ants that they are called "ant-like" spiders. In the begin- 
ning these spiders, probably through mere chance, gained a super- 
ficial resemblance to ants by developing slender, cylindrical bodies 
and quite long legs. (In the same way, other salticids became 
plump, and came to resemble certain flea-beetles through the short- 
ening of the body into a globular form.) It is only natural that 
these spiders should run over the soil or vegetation much as the 
ants do sometimes even in association with the latter. Within the 
United States are found various distinct types that show different 
degrees of physical resemblance to ants. There are profound dif- 
ferences in structure between the two, and even the most antlike 
of spiders does not bear too favorable a comparison with an ant 
when parts of the body are closely studied. However, it is an en- 
tirely different matter when the spiders are alive and moving. Then 
they exhibit such an exacting simulation of ants that they are able 


to deceive even trained naturalists and to some of them the word 
"mimic" is with good reason applied. All the antlike spiders have 
quite slender bodies and relatively long and thin legs. In certain 
cases there are deep constrictions in the cephalothorax and abdo- 
men, with these parts narrowed to expose the pedicel. In other 
varieties only the abdomen is constricted, or a seeming division of 
the body into several segments is accomplished by white bands 
across the abdomen and cephalothorax without actual physical con- 
striction. The spiders are small, and approximate in size and color 
the ants they reputedly mimic. 

Whereas the physical resemblance to ants may be a natural con- 
sequence of exploratory body growth within normal range of the 
family, thus mere parallelism, there is reason to believe that some 
degree of physical immunity, perhaps only slight at first, was the 
result of the antlike form. To the best mimics would accrue the 
greatest immunity from those normal enemies of spiders that hesi- 
tate to attack ants. The imitation of ant movement has been instru- 
mental in bringing even greater advantages to the spiders, and 
probably has made unnecessary more profound changes in the body 
itself. The mimics assume the particular stance, walk with the 
same gait, elevate the abdomen, and move their legs in the manner 
characteristic of the models. However, when they are disturbed, 
the assumed posturing and gait are usually dropped, and the spider 
departs the scene in spiderlike fashion. Whether the mimicry is 
a real thing or just the figment of the observer's imagination re- 
mains a moot point, but the advantages to the spider are unques- 
tionable. Our best physical mimics belong to the genus Synemo- 
syna. The commonest species is Synemosyna formica, a slender 
black or brownish spider, about a quarter of an inch long, with deep 
constrictions in the cephalothorax and abdomen. Amazingly antlike 
in form, it walks and runs much as do ants, and uses its front legs as 
ants use their antennae. Formica does not run in ant columns or live 
in nests; it derives advantage only from its form. A Florida relative 
is golden brown in color, and is often found running on folige with 
ants of the genus Pseudomyrma; if this is its habitual environment, 
presumably it would have even greater immunity than its darker 

Although we have several other genera and species of antlike 
jumping spiders, mention will be made only of one more. Peck- 
hamia picata is a small black spider with lightly constricted abdo- 
men and quite thick front legs, which is undeniably antlike in form 
and actions, but is not identified as the mimic of any particular 


species. This spider does not walk in a straight line, but, with abdo- 
men twitching at intervals, "zigzags continually from side to side, 
exactly like an ant which is out in search of booty." The thicker 
front legs are used for walking and support of the forward part of 
the body, but the second pair is raised above the others and made 
to resemble the antennae of ants. The substitution of the second 
legs for the role played normally by the first pair suggests that the 
antlike gait and stance may have been acquired after the front legs 
had already been committed beyond redemption to another use. 
Even while feeding, Peckhamia picata "acts like an ant which is 
engaged in pulling some treasure-trove into pieces convenient for 
carrying," and keeps beating the prey "with her front legs, pulling 
it about in different directions, and all the time twitching her ant- 
like abdomen." The related species, Peckhamia americana, was ob- 
served by Prof. W. M. Wheeler running up and down the trees 
in Florida in files with the ant Camponotus planatus. 

The Peckhams attributed the low fecundity of Peckhamia picata 
(said to produce only three eggs) to its resemblance to ants. As 
have most exponents of ant mimicry, they assumed that ants have 
few enemies and reasoned that protected mimics would not have to 
produce so many offspring to maintain their normal population. It 
seems to be true that many predators shun ants or find them dis- 
tasteful, and that antlike spiders profit from this aversion. How- 
ever, insufficient data on ant mimic fecundity are available to war- 
rant the conclusion that the real protection mimics enjoy results in 
lowered egg production. Instead, low production seems to be re- 
lated to body size and minimum egg size, which limit the number of 
eggs that can be matured for a single laying. Likewise, immunity 
to the attack of the Pompilid wasps often cited as evidence for ant 
mimicry is largely a consequence of size inasmuch as most antlike 
spiders are too small to serve as larval food for the wasps. 

The ant mimicry of the jumping spiders is distinct from that of 
other spiders in that they never enter and live in the nests of ants. 
The dark of ants' nests would take from them full use of the sense 
that has brought them greatest success among the vagrants. 


The superficial resemblance of some two-clawed vagrants to 
crabs has given them the name of "crab spiders," and their ability 
to move sidewise or backward with great facility enhances the per- 


tinency of the appellation. For the most part, they have short, wide, 
considerably flattened bodies, and some of the legs are extended 
laterally at nearly right angles to the body. Those that most nearly 
resemble true crabs are various ambushing species with short, thick 
legs, the first two pairs of which are held sidewise and twisted 
somewhat off the normal axis so that the lateral surfaces become 
nearly dorsal in position. The laterigrade spiders were derived 
from typical hunters with normal prograde locomotion, and they 
exhibit various degrees of development between extreme variation 
and near normality. The laterigrade form and attitude appear 
sporadically among other families of spiders, but those discussed in 
this section form a single line. 

The crab spiders wander about freely on the ground and on 
plants, and have come to rely almost entirely on strategy and the 
chase to capture insects. They spin no capturing webs; they ordi- 
narily settle down in one place only at the egg-laying period, when 
they produce large, lenticular egg bags hidden and guarded for long 
periods by the mother. Their flattened bodies fit them eminently 
for life in narrow crevices, under bark, or in debris, but many of 
them lie appressed to the surface of plants or on rocks or soil in the 
open. Some come out from their hiding places only at night, but 
others seem to be committed largely to the capture of day-flying 
insects. Their reliance on touch rather than sight would appear to 
make them equally expert hunters by night or by day, and many 
hunt at either time. 

The great size of the laterigrade spiders of the families Hetero- 
podidae and Selenopidae (as compared with the relatively small 
typical crab spiders) has occasioned their title of "giant crab 
spiders." Only a dozen species of this tropical group are found 
within the borders of the United States, these limited largely to our 
southwestern states and to Florida. All are half an inch or more in 
body size and have long legs of nearly equal length. 

Amazing for their celerity are the extremely flat species of 
SelenopSy which, closely pressed against rock surfaces in their south- 
ern Arizona canyon habitats, easily elude capture by whisking like 
a squirrel into narrow crevices. Somewhat less speedy are the 
plumper species of Olios, usually tawny or brownish in color, often 
discovered with their bulky egg sac. They retreat into the spiny 
security of prickly pear or cholla cacti. One of the largest, Olios 
fasciculatus (Plate XXIX), achieved a sudden newspaper fame as 
the "barking spider," and this despite the fact that it is mute and 
not provided with sound-making organs of any kind. 


The best-known giant crab spider is Heteropoda venatoria 
(Plate 10), the huntsman spider, a species that occurs around the 
world in the tropical zones, and penetrates northward into Florida, 
where it is quite common, and into the subtropical regions of Texas 
and California. This spider probably came originally from the 
Asiatic mainland, where many close relatives live and from which 
locality we have acquired many of our commonest domestic in- 
sects. It was the belief of Henry McCook that the huntsman was 
distributed by means of ballooning threads, and that its tropico- 
politan distribution was determined by the prevailing trade winds. 
This may be partially true, since it is known that flyng spiders 
cover tremendous distances, but its prevalence can be attributed 
also to a great climatic tolerance, and to domestic habits that made 
it an ideal emigrant in goods carried by boat. None of the close 
relatives of the huntsman spider has been disseminated in a like 
manner, even though the habits of the species are similar and the 
opportunity for transfer was present almost equally to all of them. 

Often having tawny bodies over an inch long and outspread legs 
spanning three or more inches, the huntsmen are the commonest 
and best known of tropical house spiders. They are generally wel- 
come because of their depredations on roaches and other disagree- 
able insects that abound in the poorly constructed homes of the 
tropics. Although they also live under bark and in similar situations 
in the open, they show a marked preference for houses, barns, 
docks, sheds, and other buildings of man. Hidden away in crevices 
by day, they come out at night and hunt or sit on the walls. Be- 
cause they frequently are carried into northern regions in banana 
bunches, Heteropoda venatoria is often called the "banana spider." 
Some of the species of Selenops are also domestic and equally wel- 
come in houses. In Panama one kind lady showed the author sev- 
eral of these flat creatures sitting on the walls of her kitchen, knew 
the location of everyone in her establishment, and praised them as 
being very beneficial. 

The typical crab spiders of the family Thomisidae rarely exceed 
one-third inch in body length. Frequently occurring in abundance, 
conspicuous because of their bright coloration, the approximately 
two hundred species found within the limits of the United States 
are encountered as commonly in the north as in the south. These 
most highly developed of all laterigrade spiders have become spe- 
cialists in ambush; they accomplish by surprise what the jumping 
spider is able to achieve through superlative eyesight and stealthy 
approach. Fortified with extremely potent venom, presumably in 


compensation for weak chelicerae, the small crab spiders are for- 
midable creatures that will attack insects and spiders much larger 
than themselves. 

In one line of typical crab spiders, we find these characteristics: 
elongate body, legs quite long and all about the same length, brushes 
of hairs on the legs, and a pair of adhesive claw tufts on the tip of 
each tarsus. The philodromids are swift runners, and move easily 
on precipitous surfaces. For the most part they live on vegetation, 
and they are colored to conform rather closely with the particular 
surface on which they sit. Especially well camouflaged are the 
running crab spiders of the genus Philodromus, which, with long 
legs spreading far sidewise, press flat against the surface of a tree 
or stem. The common Philodromus pernix of the northeastern 
states, and its many close relatives, have mottled bodies that closely 
resemble the bark of trees; and those of domestic inclination are not 
easily discerned against the weathered boards of fences and build- 
ings. Other species are more brightly colored, and, as in the case 
of the widespread Philodromus rufus, prefer the colored leaves of 
various bushes and trees, under which they attach their tiny egg 
sacs. One of the commonest western representatives of this group, 
Philodromus virescens, has the same bluish gray color as the sage- 
brush on which it is most often encountered. Other philodromids 
run on the ground, where they hide in grass or plants. Thanatus 
climbs well, but other species hide under stones and behave like 
running ground spiders. A tiny species of Ebo, common on the open 
sand along the edges of streams and lakes in the Middle West, 
matches the sand almost exactly in color; it remains unnoticed until 
accidentally disturbed, whereupon it runs a few inches and again 
lies perfectly still. The greatly elongated species of Tibellus, straw- 
colored and lightly marked with dark, narrow lines, frequent the 
grasses in meadows, lying parallel to and close against the stem. 
Easily visible when moving, these spiders will stop suddenly and 
appear to vanish from sight in their natural environment charac- 
teristics that they have in common with the majority of philodro- 

The typical crab spiders, which most nearly resemble their 
namesakes, are the ambushers of the subfamily Misumeninae (Plates 
3, 9 and 27; Plate XXIX). Their short, wide bodies are supported 
by legs of very unequal size, the first two pairs being quite long 
and robust and the hind pairs considerably shorter and weaker. 
The misumenids were probably derived from types similar to the 
philodromids, but their specialization has markedly changed them, 


and they have become rather sluggish creatures that excel as am- 
bushers. They have sacrificed ease of movement for a leisurely life 
in flower heads or on the ground, and have lost the brushes of hairs 
beneath their legs and the tarsal claw tufts present in their forebears. 

The species of Oxyptila and Xysticus (Plate 28) are pre-emi- 
nently spiders of the ground; their colors, dull grays, brown, and 
blacks, mingle with the leaves and organic debris of the soil. They 
squeeze their flat bodies under bark and into cracks. The mottled, 
greatly flattened species of Coriarachne simulate to a remarkable 
degree the bark of trees or old wood of fences and houses on which 
they hide. 

The ambushing crab spiders that live on vegetation and in 
flowers are much more brightly colored than the ground forms, 
but tend equally to cryptic coloration. The delicate green Synema 
viridans, for example, lives on foliage, while some of the whitish 
or colored species of Xysticus are distinctly flower forms. The 
best-known flower spiders of the north temperate zone are the 
numerous species assigned to three closely allied, often confused 
genera, Misumena, Misumenops, and Misumenoides: handsome 
white, yellow, or saffron-yellow creatures often marked with black 
or red bands and spots. All are ambushers, obtaining their liveli- 
hool by strategy. They are usually found in the heads of flowers; 
there, simulating the phlegmatic assassin bugs, they lie immobile in 
wait for insects seeking pollen or honey. Large and seemingly dan- 
gerous bees and wasps, large-winged butterflies, and a host of 
winged insects are seized and quickly dispatched by the pygmy 

In keeping with their habit of deception, these ambushers are 
known to change color from white to yellow, to conform with the 
substratum of their hunting ground. In this connection it should 
be noted that while they may be found on a variety of colored 
flowers, a very high percentage occur on white or yellow ones. In 
the fall A. S. Pearse, the American ecologist, found that 84 per cent 
of all the white spiders (perhaps of two or three species) were on 
white flowers, and 85 per cent of the yellow spiders were on yellow 
flowers. Only 6 to 10 per cent of the spiders were found on flowers 
other than white or yellow. Being homochromous with their flower 
station seems to bring them some advantage in their hunting, as 
well as a measure of immunity from their enemies. It is well known 
that flying insects avoid light-colored flowers in which sit dark 
spiders or insects, or small dark objects placed there by investi- 


The ability of Misumena calycina (or vatia) (Plates 3 and 27) 
to change its color from white to yellow and vice versa was first 
noted about seventy years ago. This fact engaged the attention of 
many naturalists, and led, in some instances, to erroneous applica- 
tion of the same principle to other spiders on little evidence, to 
fantastic claims of change through many hues that have no basis 
in fact. It can easily be demonstrated, however, that Misumena 
calycina and many of her cousins can change, in the course of a 
week or more, from white to yellow on a yellow flower or an arti- 
ficial yellow substratum. The action is reversible, usually requiring 
only five or six days. There is considerable reason to believe that 
the immature stages of this spider are always white, and that the 
changes in color are possible only for mature females, as was 
claimed by Eugen Gabritschevshy, the French biologist. However, 
both juvenile and adult examples of the closely allied Misumenoides 
aleatorius (Plate 9 and Plate XXIX) of the United States may be 
shining yellow, and are reputedly capable of changing back to 

Because of peculiar body form, certain crab spiders have been 
singled out as receiving some sort of protection from their natural 
enemies through resemblance to inanimate objects. Phrynarachne 
rugosa is said to resemble in form and color the fruit of a common 
tree in its forest home. Another spider of the same genus, Phryn- 
arachne decipiens (described under the appropriate name of Orni- 
thoscatoides), is reputed to resemble the excreta of a bird, and the 
illusion is complete when the spider has fashioned its characteristic 
web. Other thomisids have been compared to dried seeds, leaf 
buds, and various flower parts. 


The running spiders are two-clawed vagrants that wander about 
over the soil and on vegetation, aided in their movements by ad- 
hesive tarsal claw tufts. In almost all instances the front legs are 
directed forward and locomotion is normal or prograde, as con- 
trasted with the laterigrade maneuvering of the crab spiders. Their 
bodies, usually elongated and often cylindrical, are furnished with 
quite stout legs, which propel them at great speed. Some rarely 
leave ground hiding places under stones and debris, while others 
climb actively over vegetation arid make their retreats in plants. 
These running hunters, probably typical of the prototypes from 


which have separately arisen the crab and jumping spiders, have 
become specialists in their own way. Whereas they must concede 
superiority in daylight hunting to the jumping spiders and wolf 
spiders, and to a few of the ambushing crab spiders, they have less 
competition at night. Their distrust of sunlight has kept them essen- 
tially night hunters or shy shade hunters under debris by day 
and they have as chief competitors the phlegmatic crab spiders and 
nocturnal wolf spiders. 

The eyes of the running spiders are for the most part set close 
together in a small group near the front of the head, are of small 
and essentially equal size, and are not placed strategically for sight- 
hunting. They probably see moving objects, and may have fair 
close-range vision, but sight does not appear to play much of a part 
in their nocturnal foraging. By day they remain as far as possible 
in the shade of litter; they run rapidly across sunny open spaces 
until able to hide themselves, when they again resume a more de- 
liberate pace. Their front legs searchingly test the terrain, and they 
are uncertain of the character of objects even of the near presence 
of a prospective mate until they actually touch them. However, 
they move about with a seeming boldness that belies this, and they 
can hold their own with long-sighted spiders when they come to 

Many running spiders make flattened, tubelike retreats (Plate 
XXX) of white silk, in which they remain by day, and in which 
they molt, mate, and deposit their eggs. The ground-loving types 
place the eggs under stones or in dark recesses under debris. The 
plant spiders bend leaves or fold blades of grass, then bind them 
down with silk to provide cosy domiciles. The eggs, held in the 
usual two sheets forming a lenticular sac, are guarded by the 
mother; she often remains until the young are hatched and dis- 
persed. Some ground forms cover the sacs with debris, or camou- 
flage them in other ways, before leaving them to their fate. 

The vagrants described in this section constitute a closely 
grouped assemblage of ten families, many of them far more closely 
related than are families in other spider series. Several hundred 
species occur within our borders, but passing mention can be made 
of only a few. 

The vagabonds of the family Gnaphosidae are mostly ground 
spiders of somber coloration with few contrasting markings; the 
dull grays, browns, and blacks deriving from a covering of short 
hairs that gives them a velvety appearance. More flattened than 
their near relatives, the clubionids, they differ from the latter also 


in having the anterior lateral spinnerets widely separated. Typical 
of the group is Herpyllus vasifer, a blackish species one-third inch 
long with bright white markings on the abdomen, which lives out- 
doors under stones, but is even more common on the walls and 
ceilings of houses. It is a close relative of Scotophaeus blackivalli 
of Europe, a mouse-colored species with similar domestic habits. 
Some of the gnaphosids, notably bold, powerful Drassodes, com- 
monest in the north and often an inch long trail a band of silk that 
serves to entangle the legs of opponents while they spar and grap- 
ple at close range. 

A few of our gnaphosids are brightly colored. Outstanding are 
the species of Poecilochroa (Sergiolus), some of which have a 
bright orange cephalothorax and a black abdomen pleasingly vari- 
egated with white or colored stripes and spots. The shining, coal- 
black species of Zelotes runs over the soil in company with their 
close relatives, the small brownish, tawny, or gray Drassyllus. They 
hide under stones or leaves, and often attach beneath stones their 
tough pinkish or brown egg sacs, variously covered with debris or 
lacquered with saliva and excrement to form a horny covering as 
a deterrent to penetration by predators. 

An extremely rare relative of these ground spiders is Prodidomus 
rufus (family Prodidomidae), a pink-bodied creature occasionally 
found in houses. It has been taken on Long Island, as well as in a 
few places in the South. 

The vagrants of the family Clubionidae are less flattened than 
the gnaphosids, often have longer legs, and have the fore spinnerets 
set close together. Those that live on plants have well-developed 
claw tufts and are good climbers. Mostly whitish or brownish, 
one-fourth inch long or smaller, and represented by numerous 
species in the genera Clubiona, Chirac anthium (Plate XXV), Any- 
phaena, and Aysha, the plant hunters live in flat tubular nests, open 
at both ends, in rolled leaves or under bark. Some of these also run 
over plant debris and nest under stones. 

The clubionids that habitually run on the soil exhibit far more 
diversity in size, appearance, and coloration than do the conserva- 
tive plant forms. Among the largest are the inch-long, speckled, 
grayish tramps (Syspira) that wander over the soil of our south- 
western deserts and resemble the wolf spiders. Reddish Liocra- 
noides, of nearly equal size, favors the detritus-covered canyons of 
the Tennessee mountains and California. Intermediate in size are 
many gaudily colored Castianeirae golden, bright red, or black 
with stripes and spots of red, yellow, or white which resemble 


some of the wingless mutillid wasps. And smallest of all are the 
exceedingly active species of Micaria, clothed with brilliant scales, 
and the gray, red, and black species of Scotinella that run with great 

In this series of ground hunters are some that compare with the 
best of the ant mimics, and still others that have become intimately 
associated with ants and live in their nests. Whereas the jumping 
spiders are keen-sighted, diurnal types whose mimicry is influenced 
by reliance on sight, the short-sighted, chiefly nocturnal clubionids 
have developed in a different pattern. Some emulate the jumping 
spiders by running about during the day even in the hottest sun- 
in open places, frequently in company with ants whom they re- 
semble in size and color. Many exotic types are almost exact phys- 
ical mimics. Our numerous species of Micaria, as well as the smaller 
forms of Castianeira, are sun spiders. Their slender golden or black 
bodies, constricted or crossed with white bars, are covered with 
flattened and iridescent or brightly colored scales. Moving actively 
about with quivering front legs, these beautiful vagrants are less 
susceptible to attack than are other species, and are actually shunned 
by certain insect and spider predators in the same way as are true 

A similar immunity is probably enjoyed by the many antlike 
species of Scotinella (or Phrurolithus). Although not diurnal, they 
are often found associated with ants in the soil debris, and occa- 
sionally are seen running with them during the day. A few live as 
myrmecophiles in close association with or even in the interior of 
the ant nest itself. While little can be said of their life underground, 
they seem to be tolerated by the ants, and it is known that they feed 
upon ant pupae and small insects living in the nest. Doubtless they 
live in comparative safety in their little silken cells, in this way 
isolated from the ant colony even when in its midst. These myrme- 
cophiles agree in appearance and color with the particular ant in 
whose nest they live. Scotinella formica, a black spider with a 
shining sclerotized plate on the abdomen, frequently is found in the 
nests of the black ant, Cremastogaster lineolata. The rare Scotinella. 
britcheri, a yellowish spider, lives with yellow ants, and shows the 
effects of its cave existence by lacking much of the normal pig- 
mentation around the eyes. 

Before leaving this series of tramps and vagrants, mention should 
be made of some close relatives of the Clubionidae. The wanderers 
of the family Ctenidae (Plate XXXI) are giants that climb over 
foliage at night or run over the detritus on the soil. Some resemble 


Green lynx spider, Peucetia viridans, and nest 

Lee Passmore 


Richard L. Cassell 

Jumping spider, Phidippus, dorsal view 


the wolf spiders in form, being covered with dense coats of tawny 
or brownish hair. Several species occur in our southern states. 
Lutica is the only genus of the family Zodariidae found within the 
United States. Relic of a group now largely limited to the tropics, 
it occurs only on the Channel Islands off the coast of southern 
California, and on the adjacent mainland. It is noted for the length 
of the front spinnerets, and for the great reduction in size of the 
posterior pairs, which are small, but not lost as has been reported. 
In spite of its name, Storena americana, erroneously attributed to 
Georgia, is a foreigner and belongs to a group with headquarters in 
the Australian region. Near relatives are the spiders of the genus 
Homalonychus, sluggish, enigmatic vagrants with smooth claws 
that sit under stones in the Southwest and in adjacent Mexico; they 
are the only members of the family Homalonychidae. 


There are various spiders whose features mark them as represen- 
tative of the ancestral stocks from which the higher hunting types on 
the one hand, and the aerial web spinners on the other, are thought 
to have sprung. Some of these primitives are active vagrants that 
compete with the running ground spiders whom they resemble in 
general appearance and action. Others are wanderers that stalk over 
the terrain in deliberate fashion, groping with their front legs as 
they hunt. Most of them retire to some sort of base during the day, 
a silken tube or a padded corner, but few use silk with proficiency 
or place much reliance on it as a means of capturing prey (the 
curious warning threads of Ariadna and Segestria, and the tangled 
maze of Diguetia, are extraordinary web types). All of them are 
short-sighted, and because they are active mostly at night, sight 
plays a small role in their hunting. Almost without exception they 
are six-eyed the anterior median pair having been lost very early 
in their history and the eyes, usually placed far forward, are not 
notable for size. In two families, the Plectreuridae and Caponiidae, 
all eight eyes may be present; at the other end of the scale, most 
caponiids have lost all but the anterior median pair. 

The most obvious generalized feature of this whole group is the 
retention of reproductive organs that are but little advanced beyond 
those of the mygalomorph spiders. The genital bulb of the male 
palpus is usually a simple vessel drawn out to a point, much like a 
syringe, and there is 'scarcely any development of the accessory 


processes so characteristic of higher spiders. The epigynum of the 
female is likewise unspecialized, and the orifices that receive the 
emboli are still hidden beneath the integument. As far as is known, 
these spiders still use the primitive embrace of the tarantulas during 
the pairing, and both palpi are inserted simultaneously into the 

One group of these primitive hunters includes the familiar 
Ariadna and Dysdera, and is made up almost entirely of active 
runners whose chelicerae are capable of separate movement. Pres- 
ent near the base of the abdomen are four usually distinct spiracles, 
the posterior pair opening into tracheal tubes. The unpaired claws 
may or may not be present on the tarsi. Most of these spiders have 
elongated bodies, with legs of moderate length. All four of the 
commonly recognized families have representatives within the 
United States, but few species can be mentioned. 

The only member of the family Dysderidae found within our 
borders is the cosmopolitan Dysdera crocata, a half-inch long, 
orange-brown species with a pale abdomen, probably introduced 
into this country from the Mediterranean region, where many 
genera and species occur. The American Dysdera is rarely found 
in natural areas, preferring situations near buildings, where it hides 
under stones, boards, and other litter. An oval cell of closely woven 
silk serves as a retreat; within it are placed the eggs, minus a special 
covering or egg sac. 

Quite similar in appearance to the dysderids are the Caponiidae. 
This group is best represented in the Americas, particularly in the 
Sonoran subregion of North America. All the respiratory spiracles 
open into tracheal tubes, a condition paralleled only in some of the 
aerial spiders. An interesting feature, previously noted, is the pos- 
session in many species of only the anterior median pair of eyes. 
These are quite large, and dark in color. (Transitional conditions 
are found in a genus Nopsides, with four eyes, and in the African 
Caponina, which has all eight eyes still present.) Several species of 
these interesting two-eyed spiders occur in the United States, but 
they are relatively rare and have been little studied. The genera in 
our fauna (Qrthonops and Tarsonops) have translucent keels along 
the ventral line of the metatarsi and rounded apophyses at the base, 
but the use to which they put these curious features has not been 

The six-eyed vagrants of the family Oonopidae y most of them 
less than one sixth of an inch long, live in leafmold or under stones, 


where they feed upon tiny animals ignored by larger spiders. Many 
are colored bright orange and have hard plates on the abdomen; 
others are white or pale-yellow, with soft abdomens. These pretty 
spiders, of which fewer than twenty species are known to occur in 
our southern states, run rapidly; some are fine jumpers when dis- 
turbed. One of the smallest is Orchestina saltitans, a midget about 
one twentieth of an inch long with a soft abdomen. It penetrates 
quite far into the Northeast, where it lives for the most part indoors 
as a domestic spider. It may occasionally be seen hanging by its 
threads from a lampshade, foraging in the medicine closet, or run- 
ning among books on desks. 

The most interesting members of this whole series are the six- 
eyed tube weavers of the family Segestriidae. These cylindrical 
spiders, which retain the unpaired claws on all the tarsi, have the 
first three pairs of legs directed forward, and the front pairs, with 
which they hold victims, armed below with numerous stout spines. 
A typical member is Ariadna bicolor, half an inch long, which is 
found almost everywhere in the United States; it has a purplish 
brown abdomen, and light brown cephalothorax and legs. Two 
related genera, Citharoceps and Segestria (the latter having several 
well-known species in Europe), occur only in California. 

The retreat of Ariadna is a long, slender tube placed in a suit- 
able crevice, with the silk continued outside and around the mouth 
opening as a silken collar. From the inner edge of the mouth orig- 
inates a series of heavy lines that radiate outward like the spokes of 
a wheel, and that are attached at their ends a short distance beyond 
the collar. These radii, often two dozen or more, do not lie flat 
against the substratum, but are supported above the surface by little 
silken piers, one near the opening at the edge of the collar and the 
other out beyond the collar. The spider sits just within the tube, 
its six legs directed forward, in position to leap. The touching of 
one of the trap lines brings it out with surprising swiftness, like a 
jack-in-the-box, to the spot where the unlucky insect has tripped. 
It seizes the victim, then, carrying it, instantly backs into the tube 
again. Even such formidable prey as a wasp is held almost helpless 
within the narrow tube so narrow that the spider itself is unable 
to turn. 

The remaining group of primitive hunters includes Scytodes, as 
well as the quite diverse types conventionally placed in the family 
Scytodidae but representing several distinct lines of family rank. 
In all these spiders the chelicerae are soldered together at the base 


and along the inner edge, and cannot be moved separately. A single 
spiracle opening into the tracheal tube is placed far back toward 
the spinnerets, replacing the forward pair of openings of the pre- 
vious series. The unpaired claw on the tarsi may or may not be 
present. Several different body forms and quite different habits are 
exhibited by the members of the five families, of which all but one 
are known from within American borders. 

All eight eyes are retained by the members of the family Plec- 
treuridae, which are among the most generalized of all ecribellate 
spiders. Plectreurys closely resembles Ariadna in shape, but has 
stouter legs. In the males, the first pair of legs is armed with a stout 
spur at the end of the tibiae. This is similar to what is found in the 
tarantulas, and undoubtedly serves to hold the legs or fangs of the 
female during the pairing. These three-clawed spiders live under- 
neath stones in our southwestern deserts. They have been little 

The tube and net weavers of the family Diguetidae differ from 
their nearest relatives, the plectreurids, in having six eyes in a nearly 
straight row, and in possessing in the male palpus a conductor of 
the embolus. The single known genus, Diguetia, includes a number 
of elongate spiders having bodies thickly covered with white hairs 
to form distinctive bands, and quite long legs ringed in black. Sev- 
eral species occur in the southwestern United States and in adjacent 
Mexico. These spiders suspend a long, vertical, tubular retreat, 
closed at the top and often three or more inches long, at the center 
of a maze of threads. Favorite sites in the desert are the wide spaces 
between the joints of prickly pears and small bush cacti. The fe- 
males incorporate their egg sacs in the tube, laying one upon the 
other like the tiles of a roof. Over the long, silken horn, which is 
widest and flared at the mouth opening, are placed small leaves of 
plants found nearby. Cocoon retreats from different areas differ 
markedly in color, texture, and general composition. 

The false hackled band spinners of the family Loxoscelidae are 
most closely related to the Scytodidae. Loxosceles weaves a large, 
irregular web, the threads of which are similar to those of the 
hackled band weavers. This spider lives under stones and bark, 
and in caves. It is of medium size, yellow or brown, and the 
flattened carapace has six eyes placed in a strongly curved row. 
The legs are long, and lack the unpaired claws on all the tarsi. An 
extraordinary feature is a very long process, the colulus, which is 


a vestige of the anterior median spinnerets, and which is put to use 
while spinning to produce distinctive threads. 

One family of this series, the Thomisoididae, consists of quite 
large spiders that lie flat against large stones and hold their legs in 
the laterigrade fashion of the crab spiders. Instead of running away 
when disturbed, they rub the femora of their palpi against files on 
the chelicerae to produce a sound much like the buzzing of a bee. 
These curious spiders occur chiefly in Chile and adjacent regions, 
and in South Africa. 

The species of Scytodes, sole representatives of the Scytodidae 
in the restricted sense, are mostly very pretty creatures, with bodies 
less than half an inch long tinted in clear white or yellow, and 
delicately spotted and lined in black, or more boldly marked with 
heavy dark spots or bands. The cephalothorax is oval and quite 
elevated, sometimes nearly globose; the abdomen is oval; the legs 
are very long and thin. The unpaired claw of the tarsi is usually 
present and of small size, but it may be completely absent. These 
nocturnal spiders live under stones, in rock fissures, in buildings, 
and even on the leaves of plants, where they put down a thin, flat 
web. The females carry the globular egg mass beneath the ster- 
num, held in the chelicerae. A number of species occur in our 
southern states, but they are well distributed. They have developed 
one of the most interesting devices for capturing prey known 
among spiders, which the following example will serve to illustrate. 

The spitting spider, Scytodes thoracica, handsome in a yellow- 
ish coat marked with small black spots, is a cosmopolitan species 
that occurs far north in the United States. In habit it is domestic, 
and parades leisurely over the walls and ceilings of houses at night 
in search of small food animals. When one is discovered, Scytodes 
gives a convulsive jerk of its body and squirts a viscous gum from 
its chelicerae, usually at a distance of a quarter to half an inch. The 
victim is securely entangled and stuck to the surface by the gum, 
which is laid down by the rapidly oscillating chelicerae in ten, 
twenty, or more closely spaced, paraller bars. The spitting and 
entangling is almost instantaneous; thereafter the spider moves lei- 
surely forward to claim its prey. The viscous liquid is produced 
in tremendously enlarged venom glands, which, although given 
over largely to the production of viscous liquid, still produce a 
quantity of venom. 


Economic and Medical Importance 




inant predators of any terrestrial community. When the fauna of 
the soil and its plant cover is analyzed, they come to light in vast 
numbers, in such convincing abundance that it is evident they play 
a significant part in the life of every habitat. Working in the ex- 
ceptionally rich forest of Barro Colorado Island, Canal Zone, Eliot 
C. Williams estimated about 264,000 spiders per acre of the forest 
floor in a total fauna of 40,000,000 animals (nearly half of which 
consisted of ants and mites). While the fauna of the temperate zone 
has fewer species than the tropics, comparable habitats probably 
support a nearly equal numerical population. In 1907, W. L. 
McAtee found approximately 1 1 ,000 spiders per acre in woodland 
and 64,000 per acre in a meadow near Washington, D. C. From 
data given by Lucile Rice on animal fauna on the herbs and shrubs 
of woodland in Illinois in May, 1934, I have estimated 14,000 spi- 
ders per acre, a number which would be considerably swelled by 
addition of the floor fauna. Yet substantial as these figures are, 
they are completely outdistanced by the total found in England 
by Bristowe in August, 1938; he calculated that 2,265,000 were then 
present on a single acre in an undisturbed grassy area. Further- 
more, Bristowe believes the average number of spiders per acre in 
all England and Wales is no less, and probably much more, than 
50,000, and that the total spider fauna is not less than 2,200,000,- 
000,000. Even when based on these conservative figures, the spider 
population of the United States would amount to an astronomical 

The over-all effect of such a large fauna of predators must be 
a very significant one. Unfortunately, it is not possible to gauge 
accurately the importance of spiders in their environment, because 



of the nearly total lack of pertinent data on their feeding habits. 
By comparison with ants, certainly in the tropics, spiders are less 
important predators; but they are far more important than the 
highly considered birds in the number of invertebrates that they 
destroy annually. Spiders are ordinarily credited with catholic 
tastes and charged with attacking and eating all kinds of insects 
indiscriminately. This is a generalization that is subject to many 
exceptions. Because such space web spinners as the orb weavers 
and various sheet web weavers concentrate on flying insects, it is 
probable that a higher percentage of their catch is made up of 
beneficial insects. On the other hand, some of the hunting spiders 
have been known to concentrate on obnoxious varieties. Much de- 
pends on the location of the webs and the presence of wandering 
vagrants at a site where flights or emergences occur. Webs heavy 
with biting flies or annoying midges bear witness to the efficiency 
of spiders in helping to control economically destructive insects. 
One female black widow is reported to have destroyed 250 house- 
flies, 33 fruit flies, 2 crickets, and one spider during its lifetime. 
But in other locations similar webs may be filled with parasitic flies 
and other types that are considered beneficial. 

Although spiders are not usually thought of as being efficient 
agents of biological control, they have acted that role in a few in- 
stances. During 1923 and 1924 there was a tremendous increase in 
the numbers of bedbugs in Athens, particularly in the Greek ref- 
ugee camps. Even when the inmates of the wooden barracks moved 
out into the roads they could not get rid of the insects, which fol- 
lowed their hosts with their usual persistence. Suddenly there came 
a rapid decrease and by 1925 the bedbugs had been eradicated. 
N. T. Lorando credited this phenomenon largely to the presence of 
the predaceous crab spider, Thanatus flavidus. He was much im- 
pressed by the efficiency with which it dispatched the bugs, de- 
stroying thirty or forty a day, and with its possible exploitation for 
systematic biological control. Later this spider was introduced 
into animal laboratory rooms in Germany by A. Hase, and again 
achieved great success in controlling bedbugs. Another member 
of the same genus, Thanatus peninsulanus, is often found in great 
numbers in warehouses in New York City, where it preys upon 
the many pests of stored cereals and other products. This spider, 
whose natural habitat is the Southwest, has probably been intro- 
duced into several localities on the East Coast along with produce 
from the holds of ships. In the main, however, too few experiments 


in the use of spiders for biological control have been made to in- 
dicate their possibilities in this field. 

Economic entomologists have acknowledged the importance of 
specific spiders as control agents in certain cases. For example, in 
the Fiji Islands the cocoanut palm is ravaged by a moth that fre- 
quently occurs in tremendous numbers. During each outbreak, one 
of the large, strikingly ornamented jumping spiders, Ascyltus ptery- 
godes, increases rapidly in numbers and attacks the caterpillars and 
pupae that survive the efforts of other controls. Again, various 
workers in America have identified spiders as important factors in 
checking cotton worms, gipsy moths, pea aphids, and many other 
destructive insects. They are especially effective in a prepared 
environment such as a cotton or corn field. In any cultivated locale 
many kinds of insects will take up their abode, but the varieties that 
are detrimental to the plant crop are present in concentrated num- 
bers. Spiders quickly overrun such areas and account for a con- 
siderable percentage of the larvae and adults of the pest. Both the 
vagrant species and the web spinners are important here. Their 
catch, when examined, is found to consist largely of the noxious 

If spiders are evaluated on the basis of their direct effect upon 
man in terms of nuisance, disservice, and usefulness, the conclusion 
is that they are essentially neutral. They litter our houses, but their 
unsightly, dust-catching cobwebs render us a distinct service in 
disposing of mosquitoes and flies that have got through our window 
screens. We find a use for their threads in certain types of optical 
instruments; the Papuan natives use their matted webs for silken 
lures and fishnets. Although attempts have been made to rear spi- 
ders and take their silk for fabrics, the results have been unsuccess- 
ful. To the diet of the Laos of northern Siam their bodies add 
much needed fats and proteins, otherwise not obtainable. Spiders 
feed on a great many beneficial insects as well as on undesirable 
ones. On the other hand, their bodies provide food for game fish 
and for birds. And finally, the bites of a few spiders are poisonous 
to warm-blooded animals. Thus one effect cancels out another. 


Inasmuch as spiders are predators that normally specialize on 
insects and only rarely come in contact with human beings, their 


medical significance is not very great. Unlike their ubiquitous 
relatives, the mites, none of the spiders is parasitic on the bodies of 
man and his domestic animals. Furthermore, there is no evidence 
that spiders are the vectors of any of man's disease. From time im- 
memorial spiders have been used as charms to ward off disease, and 
they have contributed their bodies and silk for concoctions deemed 
of medicinal value. At the present time such primitive remedies 
are scorned, and we substitute instead, with like faithfulness, var- 
ious patent medicines and an alphabet of vitamins. 

Spiders once held an honored position among household rem- 
edies. The wearing of a spider in a nutshell hung around the neck 
was current in Longfellow's time, and brings to mind the more 
recent practice of using asafoetida or some other foul-smelling sub- 
stance in the same way to ward off disease. One hundred years 
earlier, the belief was general that spiders, and their products, could 
alleviate many ailments. Indeed, this medical reputation produced 
a reasonable tolerance of house spiders. In rural communities it was 
believed that wherever they were abundant the human occupants 
enjoyed a relative immunity from certain diseases. The Italian 
peasants still hold that cobwebs in stables are directly concerned 
with the healthiness of the cattle. Perhaps, since spiders carry on 
such efficient warfare against stable flies, houseflies, mosquitoes, and 
other disease carriers, these old beliefs have some basis in fact. 

Spider concoctions were administered by mouth or applied ex- 
ternally. Warts and gout, constipation and jaundice, leprosy and 
all the communicable diseases, were treated in varying ways. Spi- 
ders were eaten alive or dead, were rolled up in pills of various 
kinds, were made into ointments to be rubbed on the body, were 
brewed into liquors to be drunk. Less than a hundred years ago 
one Mexican doctor prescribed as a specific a brew of alcohol and 

The use of the silk of certain spiders to stop the flow of blood 
still persists in rural areas of Europe and the Americas. References 
to the cobweb in this connection are frequent in literature, and in- 
dicate a wide application. The clean web of our domestic funnel- 
web spiders was placed over the wound much as sterile pacfs are 
applied, and the numerous fine threads acted (largely in a mechan- 
ical way) to halt the flow. Unfortunately, ordinary cobweb is not 
sterile and its use often resulted in infection. 

Spider silk was also supposed to be of great benefit in the treat- 
ment of fevers. In 1821, N. M. Hentz commented as follows: "It 


has been found lately, that the web of a species of spider, common 
in the cellars of this country, possesses very narcotic powers, and 
it has been administered apparently with success in some cases of 
fever." Hentz named this spider Tegenaria medicinalis in recog- 
nition of the purported efficacy of its web. It is an abundant house 
spider of the eastern United States. In close proximity to it lives 
the cosmopolitan Tegenaria derhami, which is found in cellars all 
over the world and was once an important source of cobweb for 

Deeply impressed in the minds of most people is the conviction 
that spiders of any kind are poisonous, and that many are deadly. 
It is this belief that keeps alive the popular distrust of these com- 
paratively useful animals, a dread which in some cases produces 
hysteria at the mere sight of them. Many regard spiders on a par 
with poisonous reptiles and are always well supplied with tales of 
their virulence. Perhaps not so curiously, these same individuals 
will handle with small concern insects and animals far better 
equipped to do them injury. No spider is too small to be con- 
demmed as poisonous, and great size magnifies the reputation. 

People imagine that they have been bitten by spiders when the 
actual culprits (Honi soit qui mal y pense) are fleas or bedbugs or 
biting flies. The responsibility for mysterious skin eruptions acquired 
during the night is often laid to a spider seen scurrying over the 
rug at the bedside, or serenely spinning its web in the corner of a 
window. It is not uncommon to attribute many types of dermatitis 
to spider bite. All mistakenly. What are the facts? 

Spiders are shy animals that run away from pursuers whenever 
they can. Almost without exception they will walk over the skin 
of man and make no effort to bite, regarding his body merely as a 
substratum. On the other hand, there are occasions when circum- 
stances force them to attack. When they are squeezed or held they 
usually respond by attempting to bite. This is about all that can be 
expected of animals so poorly supplied with the higher sense organs 
that they cannot adequately see or comprehend just what man is. 
The most universally notorious spiders, the black widows, can be 
taken from the familiar security of their tangled webs and allowed 
to crawl over the hand, docilely unaware of the golden opportunity 
to use their venom. 

Some few spiders have been charged with being vicious and 
even with attacking man or animals without provocation. The 
Australian Atrax has such a reputation and is said to be quite bel- 


ligerent. However, one wonders whether these spiders are equipped 
with eyesight sufficiently keen even to see man at a distance of 
several feet. All spiders react to the presence of prey in an ex- 
tremely swift and efficient manner, and in running through the 
stereotyped actions of capturing and killing, they will give the im- 
pression of viciousness. Even their defensive attitudes can be in- 
terpreted as indicative of belligerence. 

By far the majority of spiders are relatively helpless creatures, 
always willing to scurry out of the way, never attempting to bite 
without the greatest provocation. Indeed, many of them must be 
forced by extreme means to bite when their venom is requried for 
experiment. The large spiders alone are capable of breaking the 
tough skin of a human being; the smaller ones can inflict mere 
superficial scratches, which, in some cases, reach the small capil- 
laries and draw a touch of blood. Ordinarily, there is no reaction 
beyond the slight mechanical laceration of the skin, and the sensa- 
tion of pain is comparable to the jab of a pin. Only when the bite 
is inflicted by a large spider armed with very strong weapons will 
there be any considerable injury to the skin. 

The biting apparatus of the spider consists of the two chelicerae, 
and the venom sacs in which the poison is produced. Each chelicera 
has a stout basal segment, broadly articulated to the head, and a 
movable fang. When the spider bites, it presses the sharp, spinelike 
fangs into its victim's body and makes two separate punctures; at 
the same time, muscles squeeze the glands, forcing their poison into 
these wounds. The venom is usually a colorless liquid having the 
consistency of a light oil; it is said to have a bitter taste. The 
amount injected into the prey appears to be extremely variable- 
dependent on the available supply at the moment, the age and con- 
dition of the spider, and the degree of excitation produced by the 
prey. There is reason to believe that its release is to a large extent 
controlled by the spider, and that in many instances the spider re- 
frains from using poison on prey easily held in its grasp and not 
capable of strong resistance. Repeated biting exhausts the venom 
supply; the bites become progressively less poisonous. 

The size of the spider does not give a clear index to the size of 
the chelicerae, the volume of the venom glands, or the character of 
the venom. In two families of distantly related spiders (Uloboridae 
and Heptathelidae) the glands have been nearly or completely lost; 
in some others of closer kinship (Scytodidae and Filistatidae) they 
are partially modified for other purposes and have become tremen- 


dously enlarged. One of the largest American wolf spiders has 
glands proportionately much smaller than those in the black widow 
and in many lesser spiders. The strongly built vagrants have a supe- 
rior physical equipment, with more powerful chelicerae and stouter 
legs to control their prey, and may get along very well with a 
lesser amount of venom. On the other hand, more delicate spiders 
have the problem of subduing large, often dangerous insects, and 
in some cases may compensate for their deficiencies by producing 
a greater or more potent amount of venom. While there is no 
evidence to show that the quantity and virulence of the poison are 
correlated with physique or other factors, it is clear that spider 
venoms vary markedly, and produce different effects. 

Spider poisons are classified on the basis of their action on man 
and other warm-blooded animals. Unfortunately, the various chemi- 
cal compositions are largely unknown and the various toxins still 
unidentified. They seem to be much more complex than those of 
other arachnids, and produce symptoms showing the presence of 
neurotoxins and hematoxins, both of which are sometimes present 
in the same venom. 

The great majority of spiders, and almost all those from the 
United States and other temperate areas, have a venom so feeble 
that its transitory effects are insignificant. In most instances, the 
bite is followed by local symptoms at the site of the punctures- 
burning, throbbing, and similar painful sensations, numbness, stiff- 
ness, and sometimes a very slight swelling. These symptoms usually 
persist for only a matter of minutes, or a few hours at most, then 
disappear entirely which indicates that the action is largely a local, 
mechanical one, and that the venom itself lacks harmful toxins. The 
severity of this type of injury usually does not exceed the sting of 
a wasp; only those individuals inordinately susceptible to the ven- 
oms of arthropods are affected in any important way. 

The poisons of a few spiders, however, are fortified with toxins 
that cause severe local or general reactions. Some contain hema- 
toxins that destroy the cells in the vicinty of the wound until large 
areas of cutaneous tissue are sloughed off, exposing underlying 
muscles and organs. Such a progressive necrosis, often resulting in 
gangrene, is caused by several South American species, notably the 
wolf spider, Lycosa raptoria, of Brazil. Similar grave symptoms are 
attributed to a mysterious and still unknown Argentine spider of 
small size, dubbed "arana homicida" which is charged with most 
of the deaths from spider bite in that country. It has been thought 


to be one of the jumping spiders that bites actively and then escapes 
before it can be apprehended. None of the spiders from the United 
States is known to have a similar hematoxin venom. 

The venom of other spiders contains substances that have a 
special affinity for nervous tissue, and inhibit the normal activities 
of important nerve centers by causing degeneration in the cells. 
These neurotoxins often strike quickly at the respiratory centers, 
causing severe systemic distress at points in the body remote from 
the site of the bite. The best-known spiders with this type of venom 
are the black widows, but various others from tropical regions are 
now credited with possessing similar poisons. It is of very great 
interest that the truly venomous spiders do not represent a single 
group, but include a few representatives from several distantly 
related lines. 

Few people have not heard of that large wolf spider of Europe 
that takes its name from the city of Taranto in southern Italy. The 
reputation of the "tarantula" has persisted through hundreds of 
years, and around its venomous character and the peculiar methods 
identified with the cure of its bite has been built a vast literature 
of superstition and fiction. McCook has written: 

When one is bitten by this spider, so the story goes, at first 
the pain is scarcely felt; but in a few hours after come on a 
violent sickness, difficulty of breathing, fainting, and sometimes 
trembling. Then he is seized with a sort of insanity. He weeps, 
he dances, he trembles, cries, skips about, breaks forth into gro- 
tesque and unnatural gestures, assumes the most extravagant 
postures, and if he be not duly assisted and relieved after a few 
days of torment, will sometimes expire. If he survives, at the 
return of the season in which he was bitten, his madness returns. 

Some relief is found by divers antidotes, but the great specific 
is music. At the sound of music the. victim begins the peculiar 
movements which are known as the "tarantula dance," and con- 
tinues them while the music continues, or until he breaks into 
a profuse perspiration which forces out the venom. Thereupon 
he sinks into a natural sleep from which he awakes weakened, 
but recovered. 30 

And then, quoting an older writer, McCook continues: 
"Alexander Alexandrinus proceedeth farther, affirming that he 
30 H. C. McCook, op. cit., p. 262. 


beheld one wounded by this Spider, to dance and leape about in- 
cessantly, and the Musitians (finding themselves wearied) gave over 
playing: whereupon, the poore offended dancer, having utterly 
lost all his forces, fell downe on the ground, as if he had bene dead. 
The Musitians no sooner began to playe againe, but hee returned to 
himselfe, and mounting vp vpon his feet, danced againe as lustily as 
formerly hee had done, and so continued dancing still, til hee found 
the harme asswaged, and himselfe entirely recovered." 30 

The spider credited with being the cause of tarantism is one of 
the large wolf spiders, Lycosa tarentula, which has been demon- 
strated by modern students to be no more virulent than other 
comparable species of the genus. Various people have tested the 
notorious creature and reported that no ill effects result from its 
bite. The mechanical injury is similar to being jabbed with two 
needles. The pain is very sharp at first, but soon disappears, and 
the tiny wound heals quickly without other symptoms. The reports 
of various Italian doctors have been very contradictory, which is 
understandable when we realize that the real bites were caused by 
different spiders and that many purported ones were probably fic- 

There is no doubt at all that epidemics of tarantism swept south- 
ern Europe; they are matters of recorded history. However, the 
question as to what actually caused these demonstrations has not 
been fully answered, although there are several clues to their origin. 
As time went on, many doubters rose up to declare that the whole 
matter of the tarantula and tarantism was a fraud perpetrated upon 
gullible travelers who paid liberally to see the actions of supposed 
victims. Oliver Goldsmith declared that the peasants very willingly 
offered to let themselves be bitten for the benefit of any tourist, 
and that the whole train of symptoms, and the style attending the 
tarantula dance were more or less in accord with the size of the fee 
paid by the onlookers. 

It is quite probable that several things contributed to the out- 
breaks of tarantism. Some authors have suggested that it was a 
nervous disease, which attained epidemic proportions, then disap- 
peared. An accidental and much less frequent variation could easily 
have been caused by the bite of the "malmignatte" a spider com- 
mon in southern portions of Europe, which has a neurotoxic venom 
capable of initiating serious symptoms. Indeed, this spider has been 
claimed by some workers to be the "tarantula." However, "la 
malmignatte" could not have been responsible for the great out- 


breaks of tarantism, which quickly spread over wide areas and 
claimed more and more victims through mass hysteria. 

A most interesting and convincing theory suggests that the 
dancing mania associated with the cure of tarantism is of religious 

Wherever the tarantati are to dance, a place is prepared for 
them, hung about with ribbons and bunches of grapes. "The 
patients are dressed in white, with red green or yellow ribbons, 
those being their favourite colours. On their shoulders they cast 
a white scarf, let their hair fall loose about their ears, and throw 
their heads as far back as possible. They are exact copies of the 
ancient priestesses of Bacchus." When the introduction of 
Christianity put a stop to the public exhibition of heathen rites, 
the Bacchantes continued their profitable profession but were 
obliged to offer some irrelevant explanation. The local spider 
best supplied their need. 31 

Many large species of Lycosa occur in the United States, but 
not one has been singled out as being particularly venomous. They 
bite readily when handled carelessly, and in some instances the 
result is a wound as painful as a bee sting; but the effects disappear 
much more quickly. As noted, some individuals are abnormally 
susceptible to arthropod venom; upon them the wolf spider may be 
able to inflict a wound of greater consequence. 

Most of the spider bites in the warm lowland region around 
Sao Paulo in southern Brazil are ascribed to Lycosa raptoria and 
other large and abundant wolf spiders. At night these active 
vagrants frequently wander into houses and hide in clothing. While 
dressing in the morning, a person may be bitten on the hands or 
feet by the trapped spider, occasionally on the chest, abdomen, or 
other parts of the trunk. The hematoxic venom produces an ex- 
tremely painful local lesion that sometimes spreads over large areas 
of the skin, reaching maximum severity where the skin is thick and 
the blood circulation relatively poor. (Bites on spots well supplied 
with blood vessels the blood seems to dissipate the effects of the 
venom quickly rarely cause more than a passing injury.) When 
allowed to run its course, the typical wound is difficult to cure, and 
will sometimes become gangrenous. However, a serum has been 
produced that alleviates the condition and brings on quick healing. 

81 T. H. Savory, Biology of Spiders, London, 1928, p. 127. 


In Peru, a similar type of local necrosis is popularly supposed to 
be caused by the "pododora" (Mastophora gasteracanthoides), a 
fat, phlegmatic spider with two conical humps on its abdomen. The 
pododora lives in the vines of grape vineyards and is said to bite 
the workers when they gather the fruit. Evidence that the pododora 
is a villain is somewhat circumstantial, and recent opinion inclines 
to the belief that the real culprit is some other spider, perhaps iden- 
tical to the arana homicida of Argentina. The symptoms of bites 
attributed to the pododora are quite similar to those of Lycosa rap- 
toria, and indicate that the venom largely contains hematoxic ele- 
ments that destroy cutaneous cells. It is possible that some of the 
responsibility for the necrosis, which occasionally results in the 
death of the victim, should be placed on bacterial agents that invade 
the wound. In any event, the evidence against the pododora is 
largely discredited by the fact that the venom sacs in the group are 
tiny, and that the poison itself is known to be impotent in other 
species. Four species of Mastophora are known from the United 
States, but there have been no reports of their biting propensities. 
Indeed, our species are such inscrutable introverts that they exhibit 
little sign of life even when handled to excess. 

Figuring prominently with the wolf spiders as the cause of spider 
bites in southern Brazil are various vagrants of the genera Phoneu- 
tria and Ctenus. Their venom is very active, is exclusively neuro- 
toxic (as in the black widow), and in experimental animals has been 
found to cause tetany, convulsions, progressive paralysis, and finally 
death by suspension of respiration. Its effect on man is far more 
serious than that of Lycosa or the arana homicida. Satisfactory 
serums to counteract the venoms of these species are available. 

From such evidence as noted above, it appears that in tropical 
regions of South America certain lycosids and ctenids are to be 
regarded as dangerous. In the United States and the temperate 
regions in general, wolf spiders and their many relatives, despite 
large size and ferocious appearance, seem to be comparatively 

The great spiders that Americans know collectively as taran- 
tulas are capable of inflicting a deep, painful wound with their for- 
midable chelicerae. Because of their size and hairiness, they are 
feared, and the usual reports credit them with being extremely 
dangerous. Dr. William J. Baerg of the University of Arkansas has 
studied this group of spiders for many years. He has concluded 
that no species from the United States is able to produce anything 


a. A giant crab spider, Olios fasciculatus 

Lee Passmore 

Lee Passmore 

b. A crab spider, Misumenoides aleatorius, on its egg sac 


George Elwood Jenks 

a. Male and female running spiders, Trachelas, in silken cell 

George Elwood Jenks 

b. Running spider, Chiracanthium inclusum, with egg sac 


more than trivial symptoms in man, indeed little more than the 
mechanical injury of breaking the skin. Considerable pain often 
accompanies the bite, it is true, but this ordinarily lasts less than an 
hour. Our tarantulas live such secretive lives that opportunity to 
bite man does not often present itself. Only in the fall of the year 
are they to be seen in numbers, and those seen are males wandering 
about in search of the females. The males are not very belligerent 
and are rather easy to tame. 

The effects of the bites of common North American tarantulas 
on laboratory animals vary considerably. In some instances the bites 
seem to have no noticeable effect on white rats and guinea pigs. 
In other cases these small mammals die quickly. The common taran- 
tula of the Canal Zone and the lowlands of Central America, Sen- 
copelma rubronitens, kills guinea pigs in half an hour, and causes 
painful symptoms in man that persist for several hours. Species of 
Dugesiella and Eurypelma of similar or even larger size produce no 
symptoms of importance on experimental animals or on man. 
Pachylomerus audouini, our largest eastern trap-door spider, was 
allowed to bite man experimentally. Although this spider is as 
large as many of the tarantulas, its venom was seen to be of less 
potency than that of many of the common true spiders. Indeed, 
there is little reason to believe that any of the mygalomorph spiders 
from the United States are dangerous to man. 

However, since the large tarantula group is composed of quite 
diverse elements, we cannot label them all harmless without much 
more data on their venoms. The poison of the largest spiders in 
the world, immense creatures of the genera Lasiodora and Gram- 
mostola from Brazil, is highly toxic to cold-blooded animals, but is 
very nearly ineffective on warm-blooded animals and man. The 
mere mechanical hurt from the fangs of such large spiders is, of 
course, considerable; and this, along with local complications not 
definitely due to the venom, has given them a reputation that they 
do not entirely merit. On the other hand, the venom of Trechona 
venosa, a large funnel-web tarantula but vastly inferior in size to 
many true tarantulas, belongs to the neurotoxic type and was found 
to be dangerous when injected into human beings. 

In the United States the only spiders known to have a venom 
producing neurotoxic symptoms are those belonging to the genus 
Latrodectus, a name derived from the Greek and meaning a "robber- 
biter." They occur around the world in the tropics, and extend 
far into the northern and southern temperate zones. The genus 


comprises a small number of jet-black spiders remarkable for their 
beautiful red markings and notorious for their venomous properties. 
Because of their great variability in color pattern, they have re- 
ceived numerous scientific names; and they have been singled out, 
given appropriate common names, and indicted by peoples from 
widely separated regions of the world. 

In southern Europe and Africa bordering the Mediterranean 
lives Latrodectus tredecim-guttatus, the malmignatte of Corsica and 
Italy, gaily splashed with red and generally feared by the peasants. 
Farther to the east, this same species is mostly black; it becomes the 
"karakurt" or "black wolf" of Russia, and is known by various 
other names in Arabia, the Gulf of Persia, and in northern Africa. 
Much farther to the east, in India and Malaya, is found Latrodectus 
hasselti, whose dorsum is marked by a broad crimson stripe running 
down to the tip of the abdomen, but which otherwise is very simi- 
lar to the malmignatte. Under various names, hasselti is found 
throughout the major islands of the East Indies, and extends down 
into New Guinea and Australia, even eastward into New Zealand. 
In Australia, hasselti is known as the "red-back spider"; in New 
Zealand, as katipo, the night-stinger of the Maoris. 

In southern Africa is found another species of the genus Latro- 
dectus indistinctus, which has the jet-black abdomen marked above 
with small white spots, and which is known as the knoppiespin- 
nekop or "shoe-button spider." Another black species of the Old 
World is the vancoho or menovadi of Madagascar, Latrodectus 

In the Americas, the principal species is Latrodectus mactans, 
the most dangerous member of the genus and the most feared and 
notorious of all. Extremely variable in coloration and almost equally 
abundant in tropical and temperate climates, this species is known 
by many expressive common names. In the United States it is 
called the "black widow" (in reference to the popular erroneous 
belief that the female invariably kills the male following the mat- 
ing), and also the "hour glass" or "shoe-button spider" common 
names describing the shape of the red ventral marking and the form 
of the jet-black abdomen. In the West Indies, it is the cul rouge, 
or veinte cuatro boras. In Peru, it is lucacha; in Chile, guina or 
pallu; in Bolivia, mico; and in Argentina, arana del lino. In A4exico, 
viuda negra is largely replacing the more interesting arana capulina 
("cherry spider") of the Mexicans and the chintatlahua of the 


These species are all jet-black and more-or-less well-marked 
with crimson spots. In all of them, the immature specimens are 
more gaily colored spotted and banded with red or yellow or 
white. In adult females, the dorsal markings on the abdomen are 
frequently lost, leaving the whole spider jet-black, though usually 
it still retains the paler hour-glass marking on the underside of the 
abdomen. The adult male retains much of the bright color pattern 
of the immature stages, and never attains the size of the females. 

At this point it is pertinent to note that there is in the United 
States a second black species, which has been considered only a 
variety of our common black widow. It is brilliantly spotted with 
red or yellow marks on the dorsum of the abdomen, and these are 
retained in the adult female. The pale ventral marking is a trans- 
verse band or triangular spot, representing at most half of the nor- 
mal hour-glass markings of many other species. An outstanding 
characteristic is the fact that the carapace and legs are bright- 
orange or reddish, whereas in all other known species the former is 
black, and the legs are black or banded with black and yellow. This 
"red-legged widow," some years ago named Latrodectus bishopi, 
occurs in southern Florida in company with true black widows. 
Its webs are commonly built three or four feet above the ground; 
they stretch from palmetto to palmetto, resembling some made by 
the sheet web spinners rather than the more irregular snare of the 
black widow. Up to the present time there have been no published 
reports on the poisonous nature of this spider, but there is little 
reason to doubt that its venom will be found different from that of 
its close relative. 

A third species of the genus occurs in the United States, but it 
is less gaudily marked, being ordinarily grayish or light brown. On 
rare occasions it becomes jet-black, thus assuming the typical color- 
ation of the group. In some respects this "gray widow," Latrodec- 
tus geometricus, resembles the common cosmopolitan house spider; 
it lives in similar situations indoors or outside of buildings. It is dis- 
tributed around the world in the tropical zone, and is the dominant 
species over most of Brazil and in the eastern coastal portions of 
South America. Although it is venomous, its reputation is far in- 
ferior to that of the black widow. In the United States it is found 
in southern Florida, especially in the Miami region but also along 
the west coast, and it has been reported from several points on the 
coast of southern California and Mexico. 

The black widows themselves are tangled web weavers that spin 


a rather small snare of coarse silk in dark locations. The core of the 
web is a silken tunnel, in which the spider often spends the daylight 
hours, and into which it retreats when disturbed. Radiating from 
this tube are numerous strands forming an irregular mesh. The 
whole web may be limited to the space in a small burrow, but an 
aerial snare usually projects in all directions for a few inches to a 
few feet. The silk is heavy and strong, and can entangle the largest 
of terrestrial insects that blunder into it. In most instances, the 
webs are placed in or close to the ground. The abandoned burrow 
of a rodent may be appropriated and fitted to the needs of the 
spider. A recess under a stone, a crevice in a dirt bank, the space 
under chips of wood, log piles, stone heaps, or stacked materials of 
any kind, afford excellent sites for the webs of Latrodectus. In- 
deed, man provides so many excellent stations for webs that these 
spiders abound near his habitations. In the northeastern United 
States these spiders are almost invariably associated with littered 
areas, with the dumps of large cities, and with such outbuildings as 
garages, barns, storage sheds, and privies. Indoors, in addition to 
occupying dark crevices, black-widow webs are placed in the 
angles of doors and windows, and behind shutters. Although these 
spiders are reputed to live inside houses, and often do, they are not 
found there as frequently as is generally believed. 

In nature, the black widow spins its web in many situations, 
some of them well above the ground level. The tall cholla cacti of 
Arizona may harbor their nests. They have been reported to live 
in birds' nests in pine trees, and to infest grape arbors in Colorado. 
Almost any situation that provides enough space for a more-or-less 
expansive web, and which is reasonably well protected from intense 
light and inclement weather, may house the black widow. 

Within the United States, the black widow is widespread, oc- 
curring in every state, and in several of the Canadian provinces. 
The species is less common in the North, but even there is locally 
abundant in many places. In the West it attains quite high altitudes; 
it is known to live at or above 8000 feet in the San Francisco Moun- 
tains of Arizona, and in Estes Park, Colorado. In general, however, 
the spider is more abundant at lower altitudes. 

The black widow is a shy, sedentary creature largely nocturnal 
in habit, which lives a retiring life in the small world of its coarse 
web. The females rarely leave their silken mesh voluntarily, and 
are completely out of their element when not in intimate touch with 
the threads. Much more venturesome are the males, which, only 


about a third as large as their mates, must search for the females 
during the brief mating season. In this weaker sex the chelicerae 
are very small, and the creatures are reported never to bite. To the 
females must be given credit for all poisonous injury to animals and 

In spite of their great reputation, the females are timid. They 
ordinarily make no effort to bite, even when subjected to all kinds 
of provocation. Although charged with viciousness, they are never 
aggressive and make no effort to attack, preferring instead to retreat 
and lie perfectly still. The danger lies in the fact that, because they 
live in abundance near man, they may be accidentally squeezed 
against the body in some way. They lie hidden in the folds of cloth- 
ing, or in shoes. When a body contact is established under these 
exceptional conditions, the black widow bites in self-defense. 

It is in the old-fashioned outdoor privies that the black widow 
is particularly dangerous. Ideal sites for nests and webs are found 
under the seats, and a large fly population provides plenty of food. 
The threads of the web often fill large areas beneath the seats, and 
are sometimes touched by parts of the body when the houses are 
in use. A gentle brushing of the web initiates the normal response 
of the spider to the presence of insect prey; it rushes to the site 
and bites the object vigorously, treating it in exactly the same way 
as it would a large insect. Most victims of this type of black widow 
are males, and the injury is centered on the external genitalia. 

The symptoms in man following the injection of the venom are 
now very well known, chiefly through the splendid work of Dr. 
Emil Bogen of California, in a state where a high percentage of 
bites have occurred. The wound causes a trivial initial pain com- 
parable to the prick of a needle, and leaves two tiny red marks at 
the site of entrance of the two chelicerae. Almost immediately there 
develop acute local pains, which reach their maximum intensity 
within half an hour in most instances, and persist for a number of 
hours. Indeed, sharp pain is a prime symptom of the bite; it has 
been described as "intense, violent, agonizing, exquisite, excruciat- 
ing, griping, cramping, shooting, lancinating, aching and numbing, 
and was either continuous and incessant, or paroxysmal and inter- 
mittent." The pain moves gradually from the wound to other parts 
of the body, and finally concentrates in the abdomen and the legs. 

In addition to the intense pain, many other symptoms have been 
described, most of these being consequences of the direct action of 
the venom on the nerve centers. Nausea and vomiting, faintness, 


dizziness, tremors, loss of muscle tone, and shock are all systemic 
symptoms frequently noted. There may be speech disturbances and 
general motor paralyses of various kinds. When the respiratory 
centers are strongly affected, there follow difficulty of breathing, 
cyanosis, and prostration. 

Many different remedies have been used in the treatment of 
black-widow poisoning. Most of them have not at all changed the 
course of the symptoms, and some have undoubtedly made the con- 
dition more serious. Alcohol is now known to have a most harmful 
effect, and its use at any time during the course of the disease is a 
serious mistake. It is imperative that the patient be in the hands of 
a competent physician, and as quickly as possible following the bite. 
Ordinarily, complete rest in bed for two or more days is a necessity. 
The intense pain is alleviated by morphine sulphate, and rest is 
assured by the use of sodium amytal. The intravenous injection of 
magnesium sulphate to overcome hypertension and the spasticity 
of the muscles was a favorite remedy a few years ago. Now it has 
largely been replaced by an intravenous injection of 10 cc. of 10 
per cent calcium chloride, or gluconate. This seems to be by far 
the best method of arresting the symptoms, and is so successful that 
recourse to the serums currently available is not often necessary. 
During World War II the use of calcium gluconate for Latrodectus 
poisoning became standard practice. 

Whereas the illness following black widow poisoning is fre- 
quently grave, a fata] outcome is rare. In the average case the effects 
subside within a few hours, and virtual recovery is realized within 
a couple of days. Very young children and older people are more 
likely to be seriously affected than those in more robust condition. 
In 1794 Luigi Totti described the death of a five-year-old child in 
less than twenty-four hours following the bite of the malmignatte. 
In older people death is often due to complication rather than to 
the venom itself. The tiny wound may allow entrance to germs 
causing tetanus, erysipelas, or other dangerous diseases. The addi- 
tional strain on the circulatory system occasioned by the venom 
may cause cerebral hemorrhage. These secondary causes of death, 
however, do not minimize the importance of the spider venom in 
initiating the condition leading to the fatal consequence. 

Approximately 1 300 cases of black widow bite were reported in 
the United States from 1726 to 1943. Every state was represented 
on the list, but nearly half the total, 578, were from California. 
Virginia led the eastern states with 173 cases; Florida had 126. 


Single instances from many far northern states, such as Maine, Ver- 
mont, and Minnesota, reflect the paucity of black widow fauna in 
those areas. A total of 55 deaths was recorded, about 4 per cent of 
the total number of bites. This percentage of fatality is low, but 
would have been even lower had all the cases of spider bite been 
available for record. Many people who are bitten are not sufficiently 
affected to receive medical treatment; therefore, while fatal cases are 
usually reported, nonfatal ones do not often find their way into the 
records. It is also known that some of the deaths were the result 
of improper treatment, such as the administration of alcoholic 
potions, or even abdominal operations performed by physicians who 
erred in their diagnosis. 

Without wishing to belittle the importance of even a single 
fatality from the bite of the black widow, it is nevertheless obvious 
that the medical significance of this animal has been overemphasized. 
In 1934 the spider became notorious overnight when an intemperate 
press sank to ludicrous depths in disseminating its exploits to a 
gullible public. Ridiculous statements were made, some with a germ 
of truth but most fictional, and soon the black widow became 
Public Enemy Number One. The wave of notoriety has now sub- 
sided, and the hour-glass spider has retired to an obscurity in keep- 
ing with its slight importance in the lives of most North Americans. 

The high toxicity of the black widow's venom is now well 
established. The claim that it is the most highly toxic among all 
venomous creatures is probably correct. As compared with the 
venom of the prairie rattlesnake, which is largely a hematoxic 
poison, it is about fifteen times as potent on a dry-weight basis. 
Because of the far greater amount of venom injected into the victim, 
however, the rattlesnake is much more dangerous than the black 
widow. It is reputed to kill from 15 to 25 per cent of its victims- 
six times as high a mortality as is usually awarded to the spider. 
Each year about 1500 snakebites from all varieties are recorded in 
the United States, and approximately 5 per cent result in fatality. 
Thus, in a single year poisonous snakes account for as many bites 
as and kill more people than are credited to the black widow in 
more than two hundred. The average person's chances of dying 
from snakebite are about the same as being struck by lightning. 
The chance of dying from a spider bite is considerably less. 

The medical importance of the black widow is not sufficiently 
great to warrant its designation as a menace in any part of the 
United States. In the northern states, where the spiders are less 


numerous and only rarely found in houses, control is not a real 
problem. In southern and western states, on the other hand, there 
exists an equable climate more suitable to the needs of the spider; it 
responds by maintaining a substantial population. As is true of 
most animals, the spider becomes more abundant in certain years, 
in response to abnormal climatic or changed biotic conditions. Re- 
adjustment to the normal population is usually swift, however, and 
there need be little fear that these creatures will maintain for any 
long period a vastly increased population. In nature the black 
widow is controlled by a host of predators and various parasites 
which decimate the numbers in all the life stages. 

It is now generally believed that a periodical eradication of the 
spiders and their egg masses by mechanical means is the most satis- 
factory method of control. At night the spiders can be easily de- 
tected with the aid of a headlamp or flashlight, and destroyed by 
hand. A reasonable amount of neatness in the storage of equipment 
and disposition of rubbish will reduce the available sites for nests 
and webs. Everyone should know this brilliantly marked spider by 
sight, and avoid contact with it. A periodic examination of outdoor 
privies should be made, and the undersides of the seats should be 
painted with creosote, crude oil, or some other repellant. 


The North American Spider Fauna 



comprises much of the north temperate zone of the New World, 
the Nearctic Realm. This is one of the natural biological land areas 
of the world, and includes the part of North America north of the 
humid tropical region of Mexico and Central America. It is a vast 
land mass characterized over much of its surface by a climate that 
may, with certain reservations, be termed temperate. The present 
southern limit is a tropical climate that bars as effectively as an 
ocean the southward extension of the northern faunas. To the 
north, the faunas gradually become diminished as they approach the 
pole, being greatly reduced where conditions of extreme cold per- 
sist for long periods, and almost completely lacking on areas of 
permanent glacial ice. 

The North American region has maintained its general form 
and its separation from other major land areas of the world for vast 
periods of time, probably since the Paleozoic. Its isolation has been 
accomplished to the east and west by broad oceans, to the south by 
the tropics and transitory ocean gaps, and to the north by Arctic 
wastes. Whereas physical isolation has for the most part been com- 
plete, there have been periodic joinings to adjacent land masses by 
means of broad bands in the south and narrow bands in the north- 
ern reaches. Animals have moved northward into North America 
from centers in South America, and vice versa. Interchange of 
faunas has been effected between Alaska and Siberia by the Bering 
Strait land connection, a bridge believed always to have been a rela- 
tively narow one but that allowed animals to pass in both directions 
when climatic conditions were favorable. 

The result of this faunal intercourse during the Tertiary is re- 
flected in the great similarity of the faunas of the temperate zones 
of both the Old and the New World, which together constitute the 
Holarctic Realm. Before the ice ages, the polar region probably 
enjoyed a much milder climate, which made posible an intermin- 



gling of faunas of the whole northern belt around the world. Over 
a large part of North America the climate was subtropical, and 
many tropical forms penetrated far into the north. During Floris- 
sant time in the Oligocene, Colorado had a climate at least as mild 
as that of our southeastern Gulf states, and had as part of its fauna 
a silk spider (Nephiia) perhaps identical with the one now living 
in Florida and some of our southern states. The spiders of America 
and Europe were probably quite similar at that time, a conclusion 
that has been reached through study of a very imperfect fossil 
record, and perhaps not entirely valid. The similarity between these 
faunas, however, is not a recent one. During the Paleozoic Era, the 
same types of primitive spiders lived in Europe as those found in 
the Carboniferous slates of Illinois. The much richer spider fauna 
in Paleozoic Europe points to the derivation of American forms 
from that or some other Eurasian center of origin. In the splendid 
amber fauna of the Oligocene in Europe there is quite likely a 
picture of the wealth and variety of our own American spider 
fauna for the period, even though a close relationship on the basis 
of existing fossils cannot be demonstrated. An interchange of new 
types between the Old and the New World has gone on almost 
continuously for more than four hundred millions of years, inter- 
rupted for brief periods by transitory barriers which were not too 
great for crossing by tolerant and enterprising spiders. 

The present faunal kinship between the temperate zones of the 
Old and the New World is a striking one, which reflects itself in the 
identity or close relationship of most of the genera and many of 
the species. Unfortunately, the faunas of the two regions are not 
well enough known to make possible explicit comparisons. The 
number of known species of spiders from the entire Holarctic 
Realm is around six or seven thousand, a number far below the real 
total possibly no more than half of it. In Palearctica, only the 
European spiders have been well studied; vast expanses of temper- 
ate Asia are almost unknown. However, it is believed that the fauna 
is a very homogeneous one, and is modified longitudinally only by 
the character of the tropical genera and species, which press north- 
ward into the temperate zone for varying distances. In Nearctica 
only the spiders of the northeastern United States are well known; 
knowledge decreases progressively as one leaves that area. 

One finds the same types of spiders in England and northern 
Europe as occur in Siberia and Japan, and in Canada and the United 
States. None of these regions shows a marked superiority in the 


number of species from comparable ecological zones; rather, they 
are essentially equal in faunal wealth, indicating that similar biologi- 
cal areas usually support quite similar kinds and numbers of animals. 
The following totals are only approximations of the present known 
numbers: In Palearctica there are about 3500 species, of which 557 
occur in the British Isles, 450 in Spain, 688 in Switzerland, 341 in 
Norway and Sweden, 391 in Greece, 1335 in France, and 3100 in 
all Europe; in Nearctica, about 2500 species, of which 50 occur in 
Greenland, 249 in Alaska, 497 in the Georgia region, 600 in New 
York State, and 650 in New England. France has long been a center 
of arachnology, so it is not surprising that its spider fa-una is so 
well known. This is also true of the British Isles, from which the 
number of known species is near the real total for the area. Inten- 
sive studies of American and Oriental spiders will ultimately bring 
the faunas of comparable regions to parity with Europe. 

More than a hundred Amercan spiders are seemingly identical 
with species from Europe, showing no differences that indicate they 
have changed sufficiently to be called subspecies. Most of these are 
long-established residents that have lived in this zone around the 
world for thousands of years. Through the medium of the balloon- 
ing threads, boreal spiders have been able to keep quite intimate 
contact with their own kind in Siberia and Alaska. Nearly one out 
of ten of the boreal American spiders occurs on the Eurasian land 
mass, and the percentage will rise as the faunas are more thoroughly 
studied. Aranea raji and nordmanni are as typical of America as of 
Europe, and the American derivation of these or any of the other 
boreal types is just as arguable as a European origin. Most boreal 
spiders are anciently American, and have not come in through 
accidental introduction by man. 

The ubiquitous spiders do not represent any special group, but 
single species from a number of different genera have become 
specialized to live all over the world without regard to differences 
in climate. The most successful is Theridion tepidariorum, a house 
spider which is the most common and most widespread of all 
spiders. The remaining cosmopolitan species are far less generally 
distributed, and are often rare or entirely lacking even in apparently 
suitable regions. Some others spiders have become widely dissemi- 
nated around the world in the tropical belts, but do not extend as 
far north as the temperate zones. Many of these tropicopolitan 
species are found in the southern portions of the Holarctic Realm. 

The cosmopolitan and tropicopolitan spiders have probably 


been transported and distributed largely by man in his ships. All 
are known to balloon, and have further distributed themselves in 
this manner. Transportation of animals by man in ships and air- 
planes is going on constantly, but relatively few kinds are able to 
establish themselves in new climatic situations. Their distribution 
by means of ballooning threads is restricted only by prevailing 
winds. There is little reason to believe that aerial spiders cannot 
cover great distances at high altitudes, and live through the ordeal 
in sufficient numbers to establish themselves. Only one successful 
flight is necessary; nature provides time for innumerable ventures. 
The fact that relatively few kinds become established demonstrates 
that mere access to a new region is not enough. The immigrant 
must be able to cope with a complex climate possessing numerous 
characteristics, any single factor of which may be capable of ex- 
cluding it from survival. 

Some immigrants into the New World are thought to have 
arrived recently. One is a handsome jumping spider, Sitticus pubes- 
cens, which has become established in Allston, Massachusetts, and 
may well expand its range in all directions from this center, since 
it seems to have habits similar to the well-known zebra spider, 
Salticus scenicus. Nesticus cellulanus and Steatoda bipunctata are 
also of relatively recent introduction; these spiders are gradually 
moving westward from their original centers in Nova Scotia and 
along the northeastern coast of the United States. Both live in 
buildings or in adjacent trash heaps, and perhaps will not find com- 
petition with our own spiders of similar habitat too strenuous. The 
only Steatoda the author found near several houses in Toronto, 
Ontario,, was the European bipunctata. Inasmuch as this is the 
normal territory for our American Steatoda bor calls (which was 
observed to be abundant two hundred miles north at Lake Tema- 
gami), it is possible that the European invader will reduce or crowd 
the native population out of particular regions as time goes on. 

The spiders known to occur both in the Palearctic and Nearctic 
regions are listed below. As has been indicated, most of the species 
are old residents and represent a panboreal or Holarctic fauna. 
Those that are cosmopolitan are identified by the letter "C," and 
similarly those that are tropicopolitan are labeled with a "T." 



T Uloborus geniculatus Olivier 


C Oecobius annulipes Lucas 
(syn. O. par let alls Hentz) 


C Amaurobius ferox Walcken- 

Dictyna arundinacea Linnaeus 

(syn. D. valuta Gertsch & 

Dictyna major Menge (syn. 

D. vincens Chamberlin) 
Dictyna borealis Cambridge 


C Scytodes thoracic a Latreille 
T Scytodes fusca Walckenaer 
T Scytodes longipes Lucas 

C Dysdera crocata C. L. Koch 


C Pholcus phalangioides Fuess- 

T Physocyclus globosus Kul- 

T Smeringopus elongatus Vinson 


Haplodrassus signifer C. L. 


Zelotes subterraneus C. Koch 
Gnaphosa muscorum L. Koch 


T Heteropoda venatoria Lin- 


Misumena calycina Linnaeus 
Philodromus aureolus Olivier 
Philodromus rufus Walcken- 
Philodromus alascensis Key- 


Thanatus formicinus Olivier 
Thanatus striatus C. L. Koch 
Thanatus coloradensis Key- 

(syn. T. alpinus Kulczyn- 

Tibellus parallelus C. L. Koch 
(syn. T. oblongus, Ameri- 
can auct.) 

Tibellus oblongus Walcken- 
(syn. T. maritimus Menge) 


Salticus scenicus Linnaeus 
Phlegra fasciata Hahn 
T Plexippus paykulli Audouin 
T Hasarius adansoni Audouin 

(syn. Sidusa borealis Banks) 
T Menemerus bivittatus Dufour 
Sitticus pubescens Fabricius 

C Tegenaria derhami Scopoli 


Tarentula carinata Olivier 

(syn. T. beani Emerton) 
Tarentula mutabilis Kulczyn- 


Pirata piraticus Olivier 
Arctosa alpigena Doleschall 
Arctosa insignita Thorell 
Pardosa tesquorum Odenwall 



Pardosa saltuaria L. Koch 
(syn. P. hyperborea Tho- 

Pardosa palustris Linnaeus 
(syn. P. andersoni Gertsch) 


Ero furcata Villers 


Lithyphantes albomaculatus 

De Geer 

T Theridion rufipes Lucas 
Theridion redimitum Lin- 
C Theridion tepidariorum Koch 

Ctenium lividus Blackwall 
T Latrodectus geometricus C. 

L. Koch 

Steatoda bipunctata Linnaeus 
C Teutana grossa C. L. Koch 
Teutana castanea Olivier 
Teutana triangulosa Wal- 


Nesticus cellulanus Clerck 
(syn. Theridion terrestre 


Argiope trifasciata Forskal 
Tetragnatha extensa Linnaeus 

(syn. T. manitoba Cham- 

berlin & I vie) 
Pachygnatha clercki Sunde- 


(syn. P. sevoardi Chamber- 

lin & I vie) 

Meta menardi Latreille 
Cercidia prominens Westring 
Cyclosa conic a Pallas 
T Neoscona nautica L. Koch 

T Neoscona theisi Walckenaer 
Aranea raji Scopoli 
Aranea diadema Linnaeus 
Aranea foliata Fourcroy 
Aranea undata Olivier 
Aranea dumetorum Villeys 
Aranea nordmanni Thorell 
Zygiella litter at a Olivier 
Zygiella atrica C. L. Koch 
Zygiella montana C. L. Koch 


Stetnonyphantes lineatus Lin- 

Microneta viaria Blackwall 
Meioneta nigripes Simon 
Lepthyphantes minutus Black- 
Lepthyphantes nebulosus 

Lepthyphantes leprosus Oh- 

Lepthyphantes audax Soeren- 


Helophora insignis Blackwall 
Bathyphantes nigrinus West- 

Eathyphantes concolor Wider 
Linyphia marginata C. L. 


Eolyphantes index Thorell 
Microerigone spitsbergensis 


Hypselistes ftorens Cambridge 
Pocadicnemis pumila Black- 
Gnathonarium dentatum 


Diplocephalus cristatus Black- 


Aulacocyba subitanea Cam- 

Caledonia evansi Cambridge 
Tiso aestivus L. Koch 
Centromerus silvaticus Black- 

(syn. Microneta quinque- 
dentata Emerton) 
Macrargus multesimus Cam- 

(syn. Microneta discolor 

Typhochraestus borealis Jack- 

Cornicidaria karpinski Cam- 

Walckenaera vigilax Black- 

Gonatmm rubens Blackwall 
Erigone dentipalpis Wider 
Erigone atra Blackwall 
Erigone arctica White 
Erigone tirolensis L. Koch 
Erigone psychrophila Thorell 

Erigone sibirica Kulczynski 
Erigone longipalpis Sundevall 
Diplocentria bidentata Em- 
Coryphaeolana holmgreni 

Coryphaeolana lapidicola 


Coryphaeolana thulensis Jack- 

Maso sundevalli Westring 
Hilaira frigida Thorell 
Hilaira glacialis Thorell 
Zornella cidtrigera Koch 
Oreonetides vaginatus Tho- 

Rhaebothorax morulus Cam- 

hlandiana alata Emerton 
Trichopterna mengei Simon 
(syn. Pelecopsis excavatum 

Microcentria rectangulata 

Missing from this list are the following species, which, long re- 
garded as the same in the two regions, must be excluded from the 
list since the original records were based on misidentifications: 
Amaurobius claustrarius Hahn, Loxosceles rufescens Dufour, Cal- 
lilepis nocturna Linnaeus, Crustulina guttata Wider, Episinus trun- 
catus Latreille, Pityohyphantes phrygianus Clerck, Linyphia 
clathrata Sundevall, Theridiosoma gentmoswn L. Koch, Aranea 
angulata Linnaeus, and Arctosa cinerea Fabricius. 

This exclusion does not rule out the real possibility that these 
species may be listed legitimately when new evidence is available. 
No authentic specimen of Aranea angulata has ever been taken in 
the United States or Canada, and all previous records refer to one 
or several related species. Many years ago Emerton recorded Ara- 
nea quadrata from New England, but withdrew the record when 
it was found that his specimens were in reality trifolium. Several 
seemingly authentic specimens of the former have now been found 


in collections from Minnesota and Alberta. Tetragnatha extensa 
has long been recorded from the New World, but all the published 
records should be referred to a distinct species now called T. versi- 
color Walckenaer. Only recently has true extensa been found in 
North America. It is the same as the quite rare species that was 
described as manitoba in 1942. Several names are stricken from the 
list because American specimens seem at least to differ subspecifi- 
cally from European examples. In America, Pityohyphantes has be- 
come a whole complex of closely related but distinct species. At 
this time it can be noted that Loxosceles rufescens, long held to be 
virtually cosmopolitan in distribution, does not occur in the Amer- 
icas, where instead we have many quite similar but nevertheless dis- 
tinct species. 

Many of our spiders differ specifically and others generically 
from those that occur in Europe, but the relationship to Palearctica 
is nevertheless close. Neither area is noteworthy for its mygalo- 
morph fauna, except in the extreme southern portions. In each 
region is found the genus Atypus with species of very similar ap- 
pearance, three in Europe and four in the eastern United States. 
Strongly developed are such cribellate genera as Dictyna and Amau- 
robius, with many species, and each area has two species of the 
curious Hyptiotes, maker of a triangular snare. The Gnaphosidae 
are remarkably developed in the temperate zone, and many species 
of Gnaphosa, Zelotes, and Drassodes live on the ground or under 
debris. The species of Clubiona in the northern United States be- 
long to the same groups as those of Europe, but at the present time 
we have recognized none of the species as being identical. The 
crab spiders are remarkably represented by the genera Xysticus and 
Philodromus, which are largely missing from the tropics. The run- 
ning spiders of the genera Pardosa, Pirata, and Tarentula show a 
parallel growth in both regions, and again almost none of the species 
are identical. 

It is chiefly in the sedentary aerial spiders, all of which are well 
known for their ballooning propensities, that one finds many Amer- 
ican spiders identical with those from Eurasia; this is well shown 
by the list of Argiopidae and Linyphiidae common to both areas. 
If one were to name the single group largely typical of the tem- 
perate zone, it would be the Linyphiidae. This great family, which 
includes the multitudinous tiny forms that have modified their heads 
in most singular ways (Erigomnae) and the somewhat larger related 
sheet spinners (Linyphimae), has had an unparalleled development 


Lee Passmore Let Passmore 

Portrait of wandering spider, A wandering spider, Ctenus, 

Cupiennius with egg sac 

Martin H. Mu 

Portrait of jumping spider, Phidippus 


Lee Passmore 

a. Phidippus formosus stalks a fly 

b. Phidippus audax with bee fly 

Edwin Way Teale 


in the Holarctic Realm. It makes up a very substantial percentage of 
the fauna of Canada and most of our states: about 30 per cent in 
New York State, 47 per cent in Alaska, similarly high percentages 
in the north woods of Canada, and 54 per cent in Greenland. The 
representation decreases toward the south, to about 16 per cent in 
Georgia, with even smaller percentages in our southwestern states. 
In Europe the Linyphiidae are similarly abundant, with 29 per cent 
in France, 43 per cent in the British Isles, and 41 per cent in Nor- 
way and Sweden. In the tropics these spiders are largely replaced 
by other types; in Brazil only 1.2 per cent of the total fauna belongs 
to the Linyphiidae. 

The differences between the faunas of Europe and the United 
States are largely due to those species, genera, and larger groups 
that probably have been derived from the south, or represent a 
remnant of the subtropical fauna that once occupied a more sub- 
stantial portion of the temperate zone. In the United States most of 
them occur in the southern states, or in the extreme southwestern 
portion of our country; they make up what is often called a So- 
noran fauna. In Europe a very similar fauna exists in the Mediter- 
ranean subregion of North Africa. In both areas are found many 
trap-door spiders and tarantulas, many large lycosids, pisaurids, and 
ctenids, and representatives of tropical genera that have reached 
their northern limits of distribution. For the most part, the animals 
in the Sonoran region are closely paralleled by creatures of the 
same genera or families in the Mediterranean region. A very few 
major groups are represented in only one region; the families Dys- 
deridae, Argyronetidae, Urocteidae, and Eresidae are largely miss- 
ing from Nearctica; whereas the families Accatymidae, Hexuridae, 
Hypochilidae, Plectreuridae, Diguetidae, Caponiidae, and Homal- 
onychidae are almost exclusively North American. 

The following list shows graphically the similarities and differ- 
ences in the spider faunas of the Nearctic and Palearctic regions.. 
The figures for the latter are taken mostly from Eduard Reimoser's, 
checklist of the Palearctic spiders. Those for the American column 
are derived from various catalogues, but are also supplemented by 
unpublished information. These latter are for the most part ap- 
proximations of the true situation. 



American European 

Atypus 4 3 

Accatymidae 1 6 i (in Japan) 

Hexura 2 o 

Hypochilidae i o 

Eresidae o 26 

Amaurobius 40 28 

Dictyna 100 37 

Plectreuridae 8 o 

Diguetidae 5 o 

Dysderidae i (cosmopolitan) no 

Caponiidae 4 o 

Palpimamdae i 9 

Pholcidae 30 14 

Leptonetidae 12 23 

Prodidomidae 2 5 

Zodariidae 3 54 

Homalonychidae 3 o 

Zelotes (Zelotes) 26 1 18 

Zelotes (Drassyllus) ... 75 10 

Clubiona 50 48 

Anyphaenidae 43 8 

Ctenidae 4 i 

Selenopidae 4 i 

Heliophanus o 56 

Euophrys 2 45 

Phidippus 55 o 

Metaphidippus 50 o 

Habronattus 50 o 

Urocteidae o 3 

Hersiliidae i 7 

Argyronetidae o i 

Xysticus 50 79 

In summary, then, it can be said that the rich and varied North 
American spider fauna is very similar to and for the most part de- 
rived from the same sources as the temperate Eurasian fauna. A 
moderate segment comes from the American tropics, and its present 


distribution is largely limited to the extreme southern and south- 
western states. A few archaic types still persist in the Southeast 
(Hypochilus), in the Southwest (Plectreuridae and Diguetidae, 
Atypoides and Aliatypus), and even in the Northwest (Hexura and 
Antrodiaetus). Although the general character of the North Amer- 
ican spider fauna is now known, many of the details are still vague, 
and can be clarified only by considerable exploration of little- 
known regions. 

The following arrangement of spider families and higher sys- 
tematic divisions, largely based on the works of Eugene Simon, was 
adopted for use in this volume. Only those families preceded by the 
asterisk (*) have no representatives in the North American fauna. 


(The Atypical Tarantulas) (The Typical Tarantulas) 

* Liphistiidae * Paratropididae 

(*Heptathelidae) (*Pycnothelidae) 

Mecicobothriidae * Migidae 

(Hexuridae) Dipluridae 

Accatymidae Ctenizidae 

(Brachybothriidae) * Barychelidae 
Atypidae Theraphosidae 


(The Four-Lunged True * Eresidae 

Spiders) Oecobiidae 

Hypochilidae * Psechridae 

* Tengellidae 

FILISTATOIDEA * Acanthoctenidae 

(The Filistatids) Zoropsidae 

Filistatidae fT" \~A x 



(The Typical Cribellate (The Primitive Hunters 

Spiders) and Weavers) 

Uloboridae Plectreuridae 




* Thomisoididae 



(The Aerial Web Spinners) 




* Telemidae 


( Tetragnathidae ) 


( Micropholcommatidae) 


* Archaeidae 

( Micryphantidae ) 




(The Hunting Spiders) 

* Urocteidae 

* Senoculidae 


( *Argyronetidae) 





(The Running Spiders) 

* Ammoxenidae 


* Toxopidae 

* Platoridae 






(Definitions with especial reference to spiders) 

Abdomen. The posterior division of the spider body, comprising 
the pedicel and usually largely unsegmented saclike portion bear- 
ing the spinnerets. 

Anal tubercle. The small caudal tubercle bearing the anal opening; 
the postabdomen. 

Antennae. The segmented sensory organs often termed "feelers," 
borne on the heads of insects, Crustacea, etc., but missing in all 

Appendages. Parts or organs (such as legs, spinnerets, chelicerae) 
that are attached to the body. 

Arachnida. A principal division, or Class, of the air-breathing 
arthropods, the arachnids, including the scorpions, mites, spiders, 
harvestmen, etc. 

Arachnologist. One who studies the arachnids. 

Araneae. The ordinal name of all spiders; same as Araneida. 

Araneology. The branch of zoology that treats only of the spiders. 

Arthropod. The jointed-legged animals, such as centipedes, milli- 
pedes, insects, crustaceans, spiders, scorpions, and many other less 
well-known types; the members of the Phylum Arthropoda. 

Attachment disc. The series of tiny lines that serve to anchor the 
draglines of spiders. 

Autophagy. The eating of an appendage shed from the body by 
autotomy or otherwise. 

Autotomy. The act of reflex self-mutilation by dropping append- 
ages; unknown in the arachnids. 

Autospasy. The loss of appendages by breaking them at a prede- 
termined locus of weakness when pulled by an outside form; 
frequent in spiders and arachnids. 

Ballooning. Flying through the air on silken lines spun by spiders. 

Book lungs. The respiratory pouches of the arachnids, filled with 
closely packed sheets or folds to provide maximum surface for 
aeration; believed to be modified, insunk gills. 



Calamistrum. The more or less extensive row of curved hairs on 
the hind metatarsi, used to comb the silk from the cribellum. 

Carapace. The hard dorsal covering of the cephalothorax in the 

Cephalothorax. The united head and thorax of Arachnida and 

Chelicerac. The pincerlike first pair of appendages of the arachnids; 
in spiders two-segmented, the distal portion or fang used to 
inject venom from enclosed glands into the prey. 

Chorion. The outer covering or shell of the spider or insect egg. 

Coxa. The basal segment of the leg by means of which it is articu- 
lated to the body. 

Claw tufts. The pair of tufts of adhesive hairs present below the 
paired claws at the tip of the tarsi of many spiders. 

Colulus. The slender or pointed appendage immediately in front of 
the spinnerets of some spiders; in other greatly reduced or seem- 
ingly missing; the homologue of the anterior median spinnerets 
or cribellum. 

Coxal glands. The excretory organs of arachnids, in spiders located 
opposite the coxae of the first and third legs, that collect wastes 
into a saccule and discharge them through tubes opening behind 
the coxae; homologous with the nephndia of Peripatus, etc. 

Cribellum. A sievelike, transverse plate, usually divided by a deli- 
cate keel into two equal parts, located in front of the spinnerets 
of many spiders; the modified anterior median spinnerets. 

Cuticle. The hard outer covering of an arthropod. 

Deutovum. The resting, spiderlike stage following the shedding of 
the chorion of the egg; the second egg. 

Dorsum. In general, the upper surface. 

Ecdysis. The process of casting the skin; molting. 

Endite. The plate borne by the coxa of the pedipalps of most spiders, 
used to crush the prey; the maxilla. 

Epigynum. The more or less complicated apparatus for storing the 
spermatozoa, immediately in front of the opening of the internal 
reproductive organs of female spiders. 

Femur. The thigh; usually the stoutest segment of the spider's leg, 
articulated to the body through the trochanter and coxa and bear- 
ing the patella and remaining leg segments at its distal end. 

Genitalia. All the genital structures. 

Hackled band. The composite threads of the cribellate spiders, spun 
by cribellum and combed by the calamistrum. 


Integument. The outer covering or cuticle of the spider or insect 

Instar. The period or stage between molts in the postembryonic de- 
velopment of arthropods. 

Labium. The lower lip of spiders forming the floor of the mouth 

Maxillae. In spiders, used as a synonym of the endites or coxae of 
the pedipalps. 

Metatarsus. A principal segment of the legs, the sixth from the base, 
with tibia at its base and tarsus at its apex. 

Molting. The periodic process of loosening and discarding the 
cuticle, accompanied by the formation of a new cuticula. 

Mygalomorph. The members of the suborder Mygalomorphae, the 
tarantulas, trap-door spiders, and all their kin. 

Nephridia. Tubular structures used as excretory organs in annelids, 
mollusks, etc. 

Ocelli. The simple eyes of insects. 

Ostia. The slit-like openings into the heart of spiders and insects. 

Palpus. The segmented appendage of the pedipalp, exclusive of 
coxa and endite; in female spiders, simple; in males, bearing a 
reproductive organ. 

Patella. A segment of the leg between the femur and tibia in the 

Pedicel. The attenuated first abdominal segment, or waist, of 
spiders, which joins the abdomen to the cephalothorax. 

Pedipalps or Pedipalpi. The second pair of appendages of the head 
of spiders, consisting of a coxal portion to aid in crushing prey 
and a distal appendage or palpus. 

Postabdomen. In spiders, the anal tubercle; the fused vestigial seg- 

Receptors. The sense organs; specialized structures of the integument 
that respond to external stimuli. 

Segment. A ring, somite, or subdivision of the body or of an append- 
age between areas of flexibility. 

Scales. Flattened, modified setae of spiders. 

Setae. The slender hairlike or spinelike appendages of the body. 

Sclerotized. Hardened by deposition of sclerotin or other sub- 
stances in the cuticule. 

Scopula. A small, dense tuft or more extensive brush of hairs or 


Sexual dimorphism. A difference in form, color, size, etc., between 

sexes of the same species. 
Spermathecae. The vessels or receptacles in the epigyna of female 

spiders that store the spermatozoa of the males. 
Sperm web. A web of few or many threads on which male spiders 

deposit the semen preparatory to taking it into the palpus. 
Sperm induction. The process of transferring the spermatozoa from 

the genital orifice beneath the base of the abdomen into the 

receptacle in the male palpus. 
Spermatozoa. The mature sperm cells. 
Spiderling. A tiny, immature spider, usually the form just emerged 

from the egg sac. 
Spinnerets. The fingerlike abdominal appendages of spiders through 

which the silk is spun. 
Spiracle. A breathing pore or orifice leading to tracheae or book 

Stadium. The interval between the molts of arthropods; instar; a 

period in the development of an arthropod. 
Sternum. A sclerotized plate between the coxae marking the floor 

of the cephalothorax. 
Tarsus. The foot; the most distal segment of the legs, which bears 

the claws at its tip. 

Tergites. Dorsal sclerites on the body; the hard plates on the ab- 
domen of the atypical tarantulas that indicate the segmentation. 
Thorax. The second region of the body of insects that bears the 

legs; in spiders, fused with the head to form the cephalothorax. 
Tibia. The fifth division of the spider leg, between the patella and 

Tracheae. The air tubes in insects; in spiders, tubular respiratory 

organs of different origin; by many thought to be modified book 

Zygote. The fertilized egg. 


The following references will be found useful to those readers 
who wish to delve more deeply. For the most part, they are books 
of general interest, likely to be available in larger libraries; many 
are furnished with acceptable bibliographies. Advanced students 
can find a complete list of spider literature current to 1939, sys- 
tematically classified by subject, in the first volume of the Bibli- 
ographia Araneorum by Pierre Bonnet. 

BERLAND, L., Les Arachnides. Encyclopedie entomologique, 

XVI, pp. 1-485, Paul Lechevalier & Fils, Paris, 1933. 
BONNET, P., Bibliographia Araneorum, Vol. i, Toulouse, 1945 

(pub. by author). 
BRISTOWE, W. S., The Comity of Spiders, Vols. i and 2, The 

Ray Society, London, 1939 and 1941. 
COMSTOCK, J. H., The Spider Book, Doubleday & Co., New 

York, 1912; revised ed., 1940, by W. J. Gertsch. 
EMERTON, J. H., The Common Spiders of the United States, 

Ginn & Co., Boston, 1902. 
FABRE, J. H., The Life of the Spider, Dodd, Mead & Co., New 

York, 1913. 
MOGGRIDGE, J. T., Harvesting Ants and Trap-Door Spiders, 

L. Reeve & Co., London, 1873. 
McCOOK, H. C, American Spiders and Their Spinningivork, Vols. 

1-3, Philadelphia, 1889-1894 (pub. by author). 
McKEOWN, K. C., Spider Wonders of Australia, Angus & Robert- 
son, Ltd., Sydney, 1936. 
NIELSEN, E., The Biology of Spiders, Vol. i (in English), Vol. 2 

(in Danish), Levin & Munksgaard, Copenhagen, 1932. 
PETRUNKEVITCH, A., A Synonymic Index-Catalogue of Spiders 

of North, Central and South America, etc., Bui. American Mus. 

Nat. Hist., Vol. 29, pp. 1-791, New York, 1911. 
SAVORY, T. H., British Spiders, Their Haunts and Habits, The 

Clarendon Press, Oxford, 1926. 



SAVORY, T. H., The Biology of Spiders, Sidgwick & Jackson, 

London, 1928. 
SAVORY, T. H., The Arachnida, Edward Arnold & Co., London, 


THORP, R. W. and W. D. WOODSON, Black Widow, Univer- 
sity of North Carolina Press, Chapel Hill, 1945. 

WARBURTON, C, Spiders, The University Press, Cambridge, 


Abbot, John, 133 

abboti, 133, 136 

Abdomen, 12, 24, 105, 127 

Abraham, Nendick, 209 

Acantboctenus, 146 

Acari, 15 

Accatyma, 130 

Accatymidxe, 127, 130, 263 

Accessory claws, 159 

Ackerman, Conrad, 148 

Actinoxia, 114, 117 

acuminata, 173 

Aerial fauna, 30 

Aerial hackled band weavers, 146 

Aerial web spinners, 157 

major groups of, 159 

walking in the web, 159 
Aeronautic spiders, 30, 173 
Agelena, 217 

pennsylvanica, 89 
Agelenidae, 216 
albineus, 207 
aleatorms, 227 
Aliatypus, 127, 130, 131, 132, 265 

calif ornicus, 132 
Allepeira, 178, 184 

conferta, 184 
alter anda, 172 
Amanrobius, 137, 142, 143, 149, 262 

bennetti, 142 

ferox^ 143 

socialis, 143 
Ambushers, 225 
Ambushing crab spiders, 226 
Ambushing spiders, 224 
American tarantulas, 247 
americana, 222, 231 
americanus, 34, 151 
Amphibious spiders, 4 
Amputation, 48 
Ancestral spiders, 100 
Anelosimus, 167 

eximius, 167 
angulata, 261 
annulipes, 144, 146 

Ant mimics, 220, 230 
Antennae, 15 
Anthracomarti, 99 
Anthrobia mammouthia, 174 
Antlike spiders, 24, 34, 85, 220 
Antrodiaetus, 3, 26, 127, 130, 131, 132, 


Anus, 14 
Anyphaena, 229 
Aphonopelma, 120 
Aquatic spider, 214 
Arachne, 52 
Arachnida, 15, 21, 52 
ara?Zij capulina, 248 
araiJa del lino, 248 
arana homicida, 242, 246 
aranas de caballo, 119 
Aranea, 94 

angulata, 261 

cornuta, 35 

diadema, 60 

displicata, 30 

dumetonmi, 60 

foliata, 60 

gemmoides, 190 

nordmanni, 190, 257 

pegnia, 30, 189 

quadrat a, 261 

r*#, 190, 257 

thaddeus, 189 

trifoliwn, 190 
Araneae, 15, 52 
Araneid copulation, 96 
Araneid mating, 96 
Araneid a, 52 
Araneinae, 188 

Araneoworphae, 101, 102, 103, 107 
Archaeidae^ 175 
Arctosa littoralis, 202 
argentata, 187 
argentea, 169 
Argiope, 37, 38, 186 

argentata, 187 

aurantia, 35, 60, 91, 187 

trifasciata, 187 



Argiopidae, 182, 262 
Argiopids, 189 
Argiopinae, 186 
Argyrodes, 168 
Argyroneta, 4, 206, 214 
Argyronetidae, 263 
Ariadna, 194, 231, 232, 233 

bicolor, 233 
Ariamnes, 167, 168 
arizonicus, 34, 151 
Arthrolycosa, 102 
Arthrolycosidae, 102 
Arthropoda, n, 12, 15 
Arthropods, 11 
Ascyltus pterygodes, 238 
aspersa, 202 

Atkinson, George F., 133 
Atrax, 240 
atrica, 60 

Attachment disks, 57, 59 
Attitude toward spiders, 4 
Atypical tarantulas, 126 
Atypidae, 126 
Atypoides, 127, 130, 131, 265 

river si, 131 
Atypus, 26, 127, 131, 134, 136, 262 

abboti, 133, 136 

bicolor, 134, 136 

European species, 134 

Immune to spider wasps, 135 

piceus, 30 
audax, 219 
audouini, 113, 247 
aurantia, 35, 60, 91, 187 
Autonomy, 46 
Autophagy, 46, 48 
Autospasy, 47 
Autotomy, 47, 48 
Aysha, 229 

Baerg, W. J., 31, 120, 246 
Ballooning, i, 28, 30, 224 

distance and duration of, 29 
Baltic amber, 103, 108 
Banana spider, 224 
Banded argiope, 187 
Banfield, E. J., 64 
Bank wolves, 202 
Barbour, Thomas, 209 
Barking spider, 223 
Barrier web, 186 
Basilica spider, 178, 184 
bicolor, 134, 136, 233 
Big-jawed spiders, 183 

bilineata, 82 

Biological control, 237 

Biotic importance, 236, 237 

bipunctata, 258 ' 

Bird spiders, 3, 1 19 

bis ho pi, 249 

Biting apparatus, 241 

bituberculata, 173 

Black widow spider, 6, 164, 248, 249, 


Black wolf, 248 
blackwalli, 229 
blondi, 33 

Bolas spiders, 3, 188, 190 
Bombyx mori, 54 
Bon de Saint-Hilaire, 61 
Book lungs, 12, 25 
borealis, 258 
Bothriocyrtum, 117 

calif ornicum, 113 
Bothrops, 125 
Bowl and doily spider, 172 
Brain, 14 
Breathing, 13 
Bridal veil, 80 
Bridge lines, 59, 178 
Bristowe, W. S., 77, 173, 198, 236 
britcheri, 230 
Browne, Patrick, 1 1 o 
Burrows, 200, 201 

of carolinensis, 202 

tarantula, 121 

typical, in 

Caddis, flies, 54 

Calamistrum, 27, 137 

Calcium gluconate for Latvodectus 

poisoning, 252 
calif ornicum, 1 1 3 
calif ornicus, 205 
Calisthenics, 44 
Calommata, 136 
calycina (or vatia), 227 
Camponotus planatus, 222 
Camouflage, in 
cancellata, 169 
cancer aides, 33 
cancriformis, 188 
ccmcroides, 17 
Cannibal spiders, 175 
capitatus, 85 

Caponiidae, 231, 232, 263 
Caponina, 232 
Capture of birds, 184 



of fish, 209, 210 

of mouse, 165 

of vertebrates, 164 
carabivorus, 31 
Carboniferous Era, 99, 100 
carolinensis, 202 
Castianeira, 230 
Castianeirae, 229 
cavatus, 152 

Cave spiders, 162, 174, 230 
cellulanus, 174, 258 
Centruroldes, 16 
Cephalothorax, 21, 22 
Ceratinopsis, 171 
Characteristics, 52 

of atypical tarantulas, 1 27 
Chelicerae, 22, 23, 79, 107, 241 
Chelifer cancroides, 17 
Cherokee myth, 7 
Chiggers, 18 
chiritatlabua, 6, 248 
Chiracanthium, 229 
Chorion, 32 
Chorizops, 116 
Circulatory system, 13 
Citharoceps, 233 
clavipes, 185 
Claw tufts, 142, 195, 219 

of the psechrids, 142 
Claws, 23 
Clubiona, 229, 262 
Clubionidae, 229, 230 
Clubionids, 229 
Goad, B. R., 30 
Cobwebs, 218 
Cocoons, 34 

Coenothele gregalis, 145 
Colonization, 30 
Color change, 4, 226 
Color differences, 71 
Colulus, 26, 27 
Comb-footed spiders, 57, 162 

capture of mouse, 165 

capture of vertebrates, 164 

comb of, 163 

commensal habits of, 167 

feeding of young, 164 

size or, 70, 166 

Commensal spiders, 145, 167, 168 
Communal web, 167 
communis, 172 
Complete orb, 190 
conferta, 184 
Conophista, 94, 163, 167, 168 

cancellata, 169 

nephilae, 169 

trigona, 168 

Control agents, 237, 238 
convictrix, 145 
Coriarachne, 226 
Cork door, no 
Cork nest, 1 1 3 
Cornicularia, 173 
cornuta, 35 

Cosmopolitan spiders, 257, 258 
Courtship, 68 

aggressiveness of certain web build- 
ers, 89 

antics of, 83 

by sight, 74 

by touch of threads, 74 

explanation of, 75, 77 

finding the female, 74 

of Angelena pennsylvanica, 89 

of Argiope aurantia, 91 

of Atypus, 135 

of crab spiders, 79 

of Drassodes, 79 

of Euophrys monadnock, 88 

of Habrocestum pulex, 86 

of HabronattuSj 87 

of harvestmen, 95 

of hunters, 75 

of jumping spiders, 83 

of long-sighted hunters, 81 

of Lycosa gulosa, 82 

of Mastophora, 91 

of Metaphidippus capitatus, 85 

of Metepeira labyrinthea, 91 

of mites, 96 

of naeviaj 89 

of Pachygnatha, 79 

of Pardosa emertoni, 81 

of Pardosa milvina y 81 

of Pardosa modica, 81 

of Pardosa saxatilis, 81 

of Peckhamia picata, 85 

of Phidippus, 85 

of Pis aura mirabilis, 83 

of pseudoscorpions, 95 

of Schizocosa bilineata, 82 

of Schizocosa crassipes, 82 

of scorpions, 95 

of solpugid, 95 

of Theridion tepidariorum, 90 

of Tutelina elegans, 84 

of web spinners, 88 

of Xysticus, 80 

2 7 6 


of Zelotes, 79 

of Zilla x-notata, 91 

specialization for grasping female, 71 

specialization of the female, 69 

specialization of the male, 69 

tolerance of certain web builders, 89 

Coxa, 22, 23 

Coxal glands, 14, 26 

Crab spiders, 4, 79, 195, 222, 225 
size, 70 

crassipes, 73, 82 

Cremastogaster lineolata, 230 

Cribellate spiders, 137 
origin of the, 139 

Cribellum, 27, 57, 104, 137 

croc at a, 232 

Cryptic coloration, 225, 226 

Ctenidae, 230 

Ctenizidae, 109 

Ctenus, 246 

cul rouge, 248 

Cucullus, 19 

Cyclocosmia, 3, 116 
truncata, 115, 116, 117 

Cyclosa, 189 

Daddy-long-legs, 17 
decipiens, 227 
Deinopidae, 146 
Deinopis, 147 

spinosus, 148 
de Reaumur, R. A., 61 
derhami, 240 
Derivation of word, 52 
Deutovum, 40 
Development of spiders, 39 
diadema, 60 
Diameter line, 179 
Dictyna, 143, 149, 262 

annulipes, 144 

sublata, 145 

voktcripcs, 144 
Dictynidae, 142 
Dictynids, mating of, 144 
differ ens, 166 
Digestive fluid, 23 
Digestive system, 13 
Digger wasps, 203 
Diguetia, 231, 234 
Diguetidae, 234, 263, 265 
Dipluridae, 117, 127, 130 
Diplurids, 1 18 
Dispersal device, 30 
duplicate, 30 

Distribution, 258 

of Atypus, 136 

of Calommata, 136 
Diving belt, 215 
Dolomedes, 4, 206, 207 

albineus, 207 

fimbriatus, 34, 208 

okefenokensis, 207 

triton, 34, 207, 208 
Dooming bag, 64 
Double-door branched nest, 114 
Dragline, 53, 57, 59 

composition of, 59 

habit, 104 

Drapetisca alter anda, 172 
Drassodes, 79, 229, 262 
Drassyllus, 229 
Dufour, Leon, 98 
Dugesiella hentzi, 78 
dumetorum, 60 
Dwarf spiders, 172 
Dysdera, 92, 93, 232 

croc at a, 232 
Dysderidae, 232, 263 

Earth wolves, 204 

Eo, 225 

Ecdysis, 42 

Economic importance, 236 

biotic importance, 236 

control agents, 237 

food for Laos, 238 

number of spiders, 236 
Ectatosticta, 139 
Egg sac, 33, 35 

of Amaurobius, 143 

of Ero, 175 

of Fictilia, 168 

of Lycosa, 199 

of the green lynx, 213 

opening of the, 28 
Egg tooth, 40 
Eggs, 3 2 

number of, 33, 34, 35 
Eggs or spermatozoa, 4 
Elasticity, i 
elegans, 84 
elongata, 183 
Embolus, 97 
Emerton, J. H., 30 
emertoni, 81, 184 
Enemies, 203, 222, 254 
Engineering skill, 164 
Engraving on glass plates, 61 



Epigynum, 25, 68, 94, 97, 232 

Eresidae, 142, 263 

Erigone, 173 

Erigonids, 173 

Erigoninae, 172, 262 

Ero, 38, 175 

Esophagus, 13 

Euophrys monadnock, 88 

Euprosthenops, 210 

European tarantula, 243 

Euryopis, 163, 169 

argentea, 169 

junebris, 169 

spinigerus, 169 
Evagrus, 118 
Evolution, 99, 194 

of orb web, 176, 177 

of webs, 158 
Excretory organs, 14 
eximius, 167 
extern a, 262 
External gills, 12 
Eyes, 14, 22 

Fabre, 176, 182 

Fall, 49 

False hackled band spinners, 234 

Fang, 23 

fasciculatus, 223 

Faunas, 49 

Featherfoot spiders, 150 

Fecundity, 222 

Feeding, 23 

of young, 164 
Femur, 23 
ferox, 143 
fictilia, 1 68 
Filistata, 149 

hib emails, 140 
Filistatidae, 241 
Filistatids, 140 
Filmy dome spider, 171 
fimbriatus, 35, 208 
Fisher spiders, 4, 194, 205, 206 

capture of fish, 208 

capture of tadpoles, 208 

food of, 208 

funnel webs of, 210 

sheet webs of, 210 
Fishing nets of the Papuans, 64 
flavidus, 237 
florem, 173 
floridanus, 205 
Florissant, 108 

Folding-door tarantulas, 130, 133 

foliata, 60 

Folklore, 126 

Food for Laos, 238 

Food of spiders, 17, 23, 124, 125, 208, 


fordum, 166, 175 
Foregut, 13 
formica, 221, 230 
Fossil spiders, 99 
Foundation lines, 179 
Four-lunged true spiders, 139 
foxi, 183 
frondeum, 166 
Frontinella communis, 172 
fimebris, 169 

Funnel- web spiders, 194, 216 
Funnel webs, 210, 216 

Gabritschevsky, Eugen, 227 
Ganglia, 14 
Gasteracantha, 70, 188 

cancriformis, 188 

size, 70 

G aster acanthinae, 187 
gasteracanthoides, 246 
genmioldes, 190 
Genital opening, 4, 32 
Geolycosa, 204 
geometricus, 249 
gertschi, 152 
Giant crab spiders, 223 
giganteus, 20 
Glands of spiders, 56 

aciniform, 57 

aggregate, 58 

ampullate, 57 

cribellar, 57 

cribellum, 58 

cylindrical, 57 

lobed, 57, 58 

maxillary, 23 

poison, 23 

pyriform, 57 

types of, 57 

venom, 108 
Glenognatha, 183 

emertoni, 184 

foxi, 183 
Gnaphosa, 262 
Gnaphosidae, 228, 262 
Gnathonargus unicorn, 173 
Gossamer, 31, 59 

in the Yosemite Valley, 31 

2 7 8 


gracilis, 162, 188 
Grammostola, 125, 247 
Grass spiders, 217 
Gray widow, 249 
gregalis, 145 
guina, 248 
gulosa, 82 
Guppy, H. B., 65 

Habrocestum pulex, 86 
Habronattus, 87 
Hackled band, 137 

of Filistata, 141 

orb weavers, 149 
Hadrotarsus, 169 
Hairs, 24 

Hapalopus pentaloris, 33 
Harvestmen, 15, 17 

mating of, 95 
Hase, A., 237 
hasselti, 248 
Hatching, 39 
Head, 12 
Headdress, 64 
Hematodochae, 93 
Hematoxic venom, 245 
Hematoxins, 242 
hentzi, 78, 200 
Heptathela, 26, 128 
Heptathelidae, 241 
Herpyllus vasifer, 229 
Heteropoda venatoria, 224 
Heteropodidae, 223 
Hexathele, 118 
Hexura, 127, 130, 265 

p/cetf, 130 
Hexuridae, 263 
hib emails, 140 
Hindgut, 14 

Hingston, R. W. G., 30, 220 
hirsutus, 87 
Holm, Ake, 40 
Homalonychidae, 231, 262 
Homalonychus, 231 
Horizontal platform, 170 
House spiders, 162, 224, 257 
Household remedies, 239 
Hub, 179 

Hunting spiders, 193 
Huntsman spider, 224 
Hypochilidae, 108, 263 
Hypochilus, 139, 140, 265 

thorelli, 139 
Hypomma bituberculata, 173 

Hypselistes florens, 173 
Hyptiotes, 147, 152, 153, 154, 262 

cavatus, 152 

gertschi, 152 

Incomplete orb, 189 
Indian legend, 6 
indistinctus, 248 
Instincts, 5 
Intelligence, 2 

Jumping spiders, 3, 83, 194, 195, 218, 

juniperi, 94 

Karakurt, 248 
Kaston, B. J., 81 
katipo, 6, 248 
Kite, 65 
Kite lures, 65 
knoppiespmnekop, 248 

Labium, 22 

laboriosa, 183 

Labyrinth spiders, 178, 189 

labyrinthea, 34, 91 

Landing nets of Papuans, 66 

Larva, 18, 40 

Lasiodora, 119, 125, 247 

Latrodectus, 6, 247 

bishopi, 249 

geometricus, 249 

hasselti, 248 

indistinctus, 248 

mactans, 248 

menovadi, 248 

tredecim-guttatus, 248 
Lattice spider, 189 
Legend, 6, 7 
Legs, 23 
lent a, 23 

Leptonetidae, 162 
Leucauge, 184 
Line weavers, 160 
Hneolata, 230 
Linyphia marginata, 171 
Linyphiidae, 90, 170, 171, 262 
Linyphiids, 171 
Linyphiinae, 262 
Liocranoides, 229 
Liphistiidae, 102, 126 
Liphistiids, 102, 107, 126, 128 
LiphistiuSj 26, 127, 128 
littoralis, 202 



Lock and key principles, 98 
Locket, G. H., 91 
Longevity, 3, 49, 51, 107, 121 
Long-legged cellar spider, 161 
Long-sighted hunters, 80 
Lorando, N. T., 237 
Loxosceles, 234 

rufescens, 262 
Loxoscelidae, 234 
lucacha, 248 
Lutica, 231 
Lycosa, 92, 199 

aspersa, 202 

carolinensis, 202 

gulosa, 82 

hentzi, 200 

rabid a, 200 

raptor ia, 242, 245 

tarentula, 244 

tenta, 203 
Lycosidae, 195, 200, 206 

burrows of, 200, 201 
Lynx spiders, 194, 212 

color and habitat of, 2 1 3 

gray, 213 

green, 212 

striped, 213 

madams, 248 

Madagascar, 62 

Major groups of aerial spiders, 159 

malmignatte ', 244, 248, 252 

Malpighian vessels, 14 

mammouthia, 174 

manitoba, 262 

marginata, 171 

Mastigoproctus giganteus, 20 

Mastophora, 38, 70, 91, 190, 246 

gasteracanthoides, 246 

size, 70 

matacaballos, 119, 126 
Maternal devotion, 211 
Maternal solicitude, 196 
Mating, 4, 68, 91, 96 

araneid, 96 

Dysdera embrace, 92, 93 

genital structure union, 93 

Lycosa embrace, 92 

of Dictynids, 144 

of harvestmen, 95 

of mites, 96 

of pseudoscorpions, 95 

of scorpions, 95 

of solpugid, 95 

principal embraces, 92 

role of female during, 92 
Maxillae, 23 
McAtee, W. L., 236 
McCook, H. C., 116, 179. 182, 224 
Mecicobothriidae, 127, 130 
Mecicobothrium, 130 
Median claws, 159 
Medical importance, 238 

spiders as remedies, 239 
medicinalis, 240 
menardi, 184 
Menge, Anton, 72, 75 
Menneus, 147, 148 
menovadi, 248 
Merian, Maria Sibylla, 124 
Meta, 184 

Metaphidippus capitatus, 85 
Metatarsus, 23 
Metepeira, 178, 189 

labyrinthea, 34, 91 
Metinae, 1 84 
Miagrammopes, 147, 155 
Micaria, 230 
mico, 248 
Micrathena, 70, 188 

gracilis, 188 

saghtata, 188 

size, 70 

Microhexura, 37, 107, 118 
Micro- whip scorpions, 15, 20 
milvina, 81 
Mimetidae, 174 
Mimetus, 175 
Mimicry, 221, 230 
mineata, 94 
mira, 35, 210 
mirabilis, 83 
rmssottfiensifj 204 
Misumena, 226 

calycma (or vatia), 227 
Misumeninae, 225 
Misumenoides, 226 

aleatorius, 227 
Misumenops, 226 
Mites, 15, 1 8 

mating of, 96 
modica, Si 

Moggridge, J. Traherne, no 
Molting, n, 42 

calisthenics, 44 

changes, 46 

details, 41 

duration of, 44 



fluid, 43 

of tarantulas, 43 

of true spiders, 43 

symptoms, 42 

time intervals, 45 
monadnock, 88 
Montgomery, T. H., 75, 76, 77, 81, 90, 


mori, 54 
mosquero, 145 
Moths, 54 

Multiple cocoons, 35 
muraria, 144 
My gale truncata, 115 
Mygalomorph spiders, 101, 102, 107 

venom glands of, 108 
Mygalomorphae, 101, 102, 107, 108, 


Myrmecophiles, 230 
Myrmekiaphila, 114, 115, 117 

torreya, 114 
Myths, 7 
naevia, 89 
Navajo legend, 7 
Necrosis, 242 
Nemesia, 110 
Nephila, 62, 63, 185, 256 

capture of birds, 184 

clavipes, 185 
nephilae, 169 
Nephilinae, 184 
Nephridia, 14 
Nervous system, 14 
Nest of masquer o, 145 
Nesticinae, 174 
Nesticus cellulanus, 174, 258 
Nesticus pallidus, 174 
Nets of New Guinea natives, 63 
Neurotoxic reaction, 16 
Neurotoxins, 242, 243 
New Hebrides, 64 
niger, 136 
Nopsides, 232 
nordmanni, 190, 257 
notatum, 164 
Notched zone, 179 
Number of molts, 44 
Numbers of spiders, 236 
Nursery, 211 
Nursery web weavers, 206 

Ochyroceratidae, 162 
Oecobiidae, 142, 146 
Oecobius annulipes, 146 

Ogre-faced spider, 147 

retiarius of, 149 
okefenokensis, 207 
Oligocene, 108 
Olios, 223 

fasciculatus, 223 
Oonopidae, 34, 232 
Oonops pulcher, 34 
Opiliones, 15 

Orb weavers, 175, 180, 181, 190 
Orb web of Uloborus, 150 
Orb webs, 2, 158, 175, 176 
Orchestina saltitans, 233 
oregonense, 87 
Omithoscatoides, 227 
Orthonops, 232 
osborni, 16 
Ovum, 32 

Oxyopes salticus, 213 
O^op^ scalaris, 213 
Oxyopidae, 212 
Oxyptila, 226 

Pachygnata, 79, 183 
Pachylomerus, 113, 115, 117 

audouini, 113, 247 

carabivorus, 31 
Paleocteniza, 99 
Paleodictyna, 103 
Paleozoic fauna, 101, 256 
pallidus, 174 
pallu, 248 
Palpigradi, 15 

Palpus, 5, 23, 48, 68, 94, 95, 96, 231 
Pardosa, 36, 38, 198, 262 

emertoni, 81 

milvina, 81 

modica, 81 

purbeckensis, 198 

saxatilis, 146 
parietalis, 146 
Parthenogenesis, 32 
Patella, 23 
Pearse, A. S., 226 
Peckham, G. W. and E. G., 75 
Peckhamia americana, 222 - 
Peckhamia picata, 34, 35, 85, 221, 222 
Pedicel, 21, 24 
Pedipalpi, 4, 23 
Pedipalpi, 15 
pegnia, 30, 189 
peninsulanus, 237 
penmylvanica, 89 
pentaloris* 33 




Peripatus, 100 
pernix, 225 
Peucetia, 94 

viridans, 212 
phalangiaides, 161 
Phanetta subterranea, 174 
Pharynx, 13 
Phidippus, 85 

audax, 219 
Philodromus, 225, 262 

pernix, 225 

rufus, 225 

virescens, 225 
Pholcidae, 160 
Pholcids, 37, 161 
Pholcus, 37, 72 

phalangioides, 161 
Phoneutria, 246 
PhormictopuSj 33 

c oncer oideS) 33 
Phrurolithus, 230 
Phrynarachne decipiens, 227 
Phyrnarachne rugosa, 227 
Phylogeny of spiders, 100 
/wVata, 34, 35, 85, 221, 222 
picea, 130 
piceus, 30 
pikei, 204 
Pirata, 199, 262 
Pirate spiders, 174 
Pisaura ?nirabilis ) 83 
Pisauridae, 206 
Pisaurids, 206 
Pisaurina mira, 35, 210 
Pityohyphantes, 262 
plcmatus, 222 
Platinum filaments, 61 
Plectreuridae, 231, 234, 263, 265 
Plumb line, 179 
p/to, 169 
Pododora, 246 
Poecilochroa, 229 

convictrix, 145 
Poison glands, 23 
po-ko-moo, 6 
Polygamy, 94 
Pompilid wasps, 222 
Pompilidae, 112 
Predigestion, 23 

Primitive hunters and weavers, 231 
Prodidomidae, 229 
Prodidomus rufus, 229 
Properties of silk, 55 

Protective device, 32 

of tarantulas, 124 

of trap-door spiders, 117 
Protective resemblance, 225, 226, 227 
Proscorpio osborni, 16 
Psechridae, 142 
Pseudomyrma, 221 
Pseudoscorpiones, 15 
Pseudoscorpions, 15, 16 

mating of, 95 
pterygodes, 238 
pubescent, 258 
pulcher, 34 
pulex, 86 
punctulata, 200 
purbeckensis, 198 
Purse-web spiders, 3, 30, 107, 126, 133 

capturing prey, 135 

courtship of Atypus, 135 

distribution of, 136 

European species, 134 

immunity to spider wasps, 135 

spinning of purse web or tube, 134 
Purse webs, 2 

quadrat a, 261 
Queensland, 64 

rabida, 200 
Radii, 179 
radiosa, 185 
rafaelana, 204 
Raft spider, 208 
mji, 190, 257 
raptoria, 242, 245 
Ray spiders, 185 

web of, 185 

Receptaculum seminis, 96 
Receptors, 14 
Red spiders, 53 
Red-back spider, 248 
Redbugs, 18 
Red-legged widow, 249 
Regeneration, 46, 49 
Relatives of spiders, 15 
Remedies, 252 

calcium gluconate for Latrodectus 
poisoning, 252 

household, 239 
republic anus, 34 
Reputation, 9 
Respiration, 4, 12 
Respiratory organs, 12 
Retiarius, 149 



of Menneus, 148 

of ogre-faced spider, 149 
Retreat, 189, 228, 233, 234 
Rhomphaea, 94, 167 

fictilia, 1 68 
Rice, Lucile, 236 
Ricinulei, 15 
Ricinuleids, 15, 19 

Rocky Mountain Spotted Fever, 19 
rubronitens, 247 
rufescens, 262 
rufus, 225, 229 
rugosa, 227 
Running spiders, 227 

sagittata, 188 
saltabunda, 79 
Salticidae, 218 
salticus, 213 

Salticus scenicus, 220, 258 
saltitans, 233 
Sand wolves, 203 
Sawflies, 54 
saxatilis, 81 

Scaffolding spiral, 180 
scalaris, 213 
scenicus, 220, 258 
Schizocosa bilineata, 82 
Schizocosa crassipes, 73, 82 
Scorpiones, 15 
Scorpions, 15, 16 

mating of, 95 
Scotinella, 230 

britcheri, 230 

formica, 230 
Scotinoecus, 118 
Scotophaeus blackwalli, 229 
Scytodes, 233, 235 

thoracic a j 235 
Scytodidae, 233, 235, 241 
Sedentary spiders, 50, 157 
Sedentary wolves, 205 
Seed ticks, 18 
Sege stria, 40, 231, 233 
Segestriidae, 233 
Segmentation, 12, 24, 127 
Selenopidae, 223 
Selenops, 233, 224 
Semi-marine spider, 198, 999 
Sensation, 14 
Sergiolus, 229 

Sericopelma rubromtens, 247 
Serum, 245, 252 
Setae, 24 

sexpunctatus, 208 

Sexual characteristics, 4 

Sexual dimorphism, 69, 70, 171, 188 

Shamrock spider, 190 

Sheet weavers, 90, 160 

Sheet web atypical tarantulas, 1 27, 1 30 

Sheet web tarantulas, 109, 117 

Sheet web weavers, 170 

sheet of, 170 

Sheet webs, 2, 118, 170, 210, 217 
Shoe-button spider, 248 
Short-sighted hunters, 78 
Short-sighted vagabonds, 193 
Shuttling, 161 
Sia Indians, 7 
Sight, 228 
Silk, 17, 53, 55, 239 

dependent on, 53 

fineness of, 56 

for reticules, 60 

for textiles, 61 

in industry, 61 

in optical instruments, 60 

of Aranea diadema, 60 

of Aranea dumetorum, 60 

of Aranea foliata, 60 

of Argiope aurantia, 60 

of black widow, 60 

of insects, 53 

of mites, 53 

of Nephilia, 57 

of pseudoscorpions, 53 

of red spiders, 53 

of silkworm, 62 

of Tetranychidae, 53 

of Zilla atrica, 60 

paintings on, 218 

properties of, 55 

strength of, 56 

use by primitive peoples, 63 
Silk glands, 56 
Silk spiders, 184 

capture of birds, 184 
Silkworm, 54, 62 
Silver argiope, 187 
Simon, Eugene, 102, 265 
Single-line snare, 155 
Sitticus pubescent, 258 
Six-eyed hunting spiders, 195 
Size, 3, 70, 107, 167 
Small bags, 64 
Smothering cap, 64 
Snare of Miagrammopes, 155 
Snare of the comb-footed spiders, 163 



Social spiders, 34, 142, 143, 151, 167 
socialis, 143 
Solpugida, 15, 19 
Solpugids, 15 

mating of, 95 
Sossipus, 195 

calif ornicus, 205 

floridanus, 205 

Specialization for grasping female, 71 
Specialization of the female, 69 
Specialization of the male, 69 
Sperm, 32 

Sperm induction, 68, 72, 73 
Sperm web, 5 

types of, 72 

Spermatozoa or eggs, 4 
Spider hole, 8 
Spider wasp, 112, 135 

paralyzing the spider, 112 
Spider woman, 7 
Spiderling, i, 28, 41 
Spiders as remedies, 239 
Spider's bite, 238 
Spinder, 52 
Spines, 24 
spinigerus, 169 
Spinne, 52 
Spinnerets, 21, 26, 58, 132, 231 

anterior median, 104 

of Aliatypus, 132 
Spinning of an orb web, 178 
Spinning of orb web of Uloborus, 150 
Spinning of orb weavers, 178 
Spinning of purse web or tube, 1 34 
spinosus, 148 

Spiny-bodied spiders, 187, 188 
Spitting spider, 235 
Spring, 49 
Stabilmenta, 180 
Stabilmentum, 186, 189 

of Uloborus, 151 

two-banded, 187 
Steatoda, 258 

bipunctata, 258 

borealis, 258 
Stegodyphus, 142 
Stemmops, 169 
Stercoral pocket, 14 
Sternum, 22 
Stick spiders, 147, 155 
Stilt spiders, 183 
Storena americana, 231 
Strength of Nephila web, 66 
Stridulation, 235 

Striped wolves, 200 
Structure of spiders, 21 
sublata, 145 
subterranea, 174 
Sucking stomach, 13 
Superstitions, 9 
Swathing band, 57 
Swathing film, 57, 58 
Symbionts, 167 
Symptoms, 251 
Synema viridans, 226 
Synemosyna, 221 

formica, 221 
Syspira, 229 

Tailed whip scorpions, 20 
Tailless whip scorpions, 20 
Tangled maze, 231 
Tangled webs, 2 
Tapetum, 22, 196 
Tarantism, 243, 245 
Tarantula burrows, 121 
Tarantula hawk, 122 
Tarantula versus tarantula hawk, 123 
Tarantulas, 3, 73, 101, 107, 109, 119, 
1 20, 243, 246 

American, 247 

capture of birds by, 124 

chelicerae of, 107 

defensive attitude of, 123 

European, 243 

food of, 124, 125 

longevity of, 107, 121 

protective device of, 124 

size of, 107 

survival without food, 124 

urticating hairs of, 124 

wandering of males, 122 
tarentula, 244 
Tarentula, 262 
Tarsus, 23 

Tegenaria derhami, 240 
Tegenaria medicinalis, 240 
Telema tenella, 34, 162 
Telemidae, 160, 162 
tenella, 34, 162 
Tensile strength, i 
tepidariorum, 90, 162, 164, 166, 257 
Tergites, 24 
terrestriSy 30 
Tetragnatha, 183 

elongata, 183 

extensa, 262 

laboriosa, 183 

28 4 


versicolor, 262 
Tetragnathids, 183 
Tetragnathinae, 183 
Texas Fever of cattle, 19 
thaddeus, 189 
Thalassius, 209 
Thanatus, 225 

flavidus, 237 

peninsulanus, 237 
Theraposa, 119 

blondi, 33 
Theraposidae, 118 
Theridiid web, 164 
Theridiidae, 57, 58, 162 
Theridiids, 163 
Theridion, 166 

differ em, 166 

frondeum, 166 

notatum, 164 

tepidariorum, 90, 162, 164, 166, 257 

zelotypum, 163 
Theridiosoma, 39 

radiosa, 185 

Theridiosomatinae, 185 
Thick-jawed spiders, 183 
Thomisidae, 224 
Thomisoididae, 235 
thoracic a, 235 
thorellii 139 
Tibellus, 225 
Tibia, 23 
Ticks, 1 8 
Tidarren, 48, 166 

fordum, 175 
Tiger wolf, 202 
torreya, 114, 115 
Totri, Luigi, 252 
Toxicity, 253 
Trabea, 199 
Tracheae, 12 
Tracheal spiracles, 25 
Trachelas tranquillus, 34 
tranquillus, 34 
Trap door, 202, 203 
Trap-door spiders, 3, 107, 109, no, 

"5, 2 47 

protective devices of, 117 

rake of, no 

true, 109 

types of, 113 

types of nests of, 1 10 
Trap line, 190 
Trapeze line, 191 
Treat, Mary, 203 

Trechona venosa, 247 
tredecim-guttatus, 248 
Triangle spiders, 152 

spinning of the web, 152 
trifolium, 190, 261 
trigona, 168 
triton, 34, 208 
Trochanter, 23 
Tropic Days, 6, 64 
Tropic Day, 64 

Tropicopolitan spiders, 257, 258 
True spiders, 101, 102, 107 

abdomen of early, 105 

emergence of, 102, 103 

evolution of, 103 

features of, 105 

habits of, 105 

simplification of organs, 104, 105 
truncata, 115, 116, 117 
Tube webs, 2 
Turret, 202, 204 
Turret spider, 131 
turricola, 204 
tusti-bowl, 7 
Tutelina elegans, 84 
Typical crab spiders, 224 
Typical hackled band weavers, 141 
Typical tarantulas, 109 
Typical wolf spiders, 199 

Ubiquitous spiders, 257 
Uloborid, 150 
Uloboridae, 141, 146, 241 
Uloborus, 150 

americanus, 34, 150 

arizonicus, 34, 151 

republicanus, 34 

spinning of orb web of, 150 
unicorn, 173 
Urocteidae, 263 
Usofila gracilis, 162 

Vagrant linyphiid, 172 
Vagrant theridiids, 169 
vancoho, 248 
vasifer, 229 
vatia, 227 

veinte cuatro boras, 248 
venatoria, 224 
Venom, 16, 23, 241, 253 

hematoxic, 245 
venosa, 247 
versicolor, 262 
Vertebrate as food, 125 

INDEX 285 

Vertebrate prey, 209 Web repair, 182 

virescens, 225 Whip scorpions, 15, 20 

viridans, 212, 226 Whirling, 161 

viridipes, 87 Wilder, B. G., 62, 152 

Viscid spirals, 180 Williams, Eliot C., 236 

Viscid threads, 58 Wind scorpions, 19 

viuda negra, 248 Winnebagos, 8 

volucripes, 144 Wolf spiders, 4, 194, 195, 242 

Wormlike spiders, 168 

Wafer door, no ivrighti, 204 

Waist, 24 Wulfila saltabunda, 79 

Walckenaerae acuminata, 173 

Walking appendages, 24 x-notata, 91 

Walking in the web, 159 Xysticus, 80, 226, 262 
Wallace, A. R., 76 

Wallace, H. K., 116 Zebra spider, 220, 258 

Warning threads, 231 Zelotes, 79, 229, 262 

Wash-Ching-Geka, 8 zelotypum, 163 

Water spider, 4, 206, 214 Zilla atrica, 60 

Web builders, 88 Zilla x-notata, 91 

Web of Allepeira conferta, 184 Zodariidae, 231 

of black widow spider, 169 Zorocrates, 146 

of marginata, 172 Zoropsidae, 142, 145 

of Nephila, 185 Zwwi, 8 

of ray spider, 185 Zygiella, 189 

of triangle spider, 152 Zygoballus terrestris, 30 



Released fr@m library 
tfCGK institute of Sri^