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Full text of "The book of the fly, a nature study of the house-fly and its kin, the fly plague and a cure"

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by Dr. Etienne Burnet. 
Preface by Professor E. 
Metchnikoff - - - 

Illustrated, Cr. Svo. 5/- ui-f. 

" It is one of those works which French 
authors seem to be especially skilful in 
producinR— works which, while they 
treat their subject in the broadest possi- 
ble way, and in a manner to interest the 
educated general reader as well as the 
specialist, and yet at the same time 
accurate and precise in detail."— L^ncW. 

London: William Heinemann 








With an Introduction by 



London . William Heinttnann, 1915 



Preface by E. Halford Ross, Esq., m.r.c.s., 

L.R.C.P., &c. 

I. A Product of Human Insanitation i 

II. Identification of the Common House-Fly ... 7 

III. Some other Flies and their Diverse Habits 16 

IV. Myiasis and the CEstrid^e 26 

V. General Life History 33 

VI. Structure of the House-Fly 43 

VII. Distribution and Concentration of Flies ... 49 
VIII. Natural Enemies of Flies 53 

IX. Disseminators of Disease 58 

X. Remedial Measures ; Cremation of Refuse ... 64 

XI. Control Withl\ the House 71 

XII. Service and Utility of Flies 78 

XIII. A Campaign of Effective Warfare, Con- 
clusion 84 


Description of the Wing ate Fly Chart ... 89 

Table of Wing Cells and Veins 93 

Glossary Index of Terms used 94 

Alphabetical List of Sixty Families 95 

Numbered List of Families with Descriptive 

Notes and References 108 

Analytical Table of Families ... 113 

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Fig. I. The House-Fly, Female, Enlarged 
„ 2. The Lesser House-Fly, Male, Enlarged 
„ 2a. The Stable-Fly, Female, Enlarged 

„ 3. Wing Patterns contrasted 

„ 5- Metamorphosis; Larva, Instar, Imago 

„ 6. Apparatus for the Breeding of Gentles 8i 

Plate I. External Parts and Characters, named 88 

„ II. ANTENNiE, many-jointed TYPES 97 


„ IV. Wings, Type-forms of Nemocera joi 

„ V. Wings, other Type-forms 103 

„ Details of Special Characteristics, etc. 105 

„ VII. Ditto ... 107 

NOTE. Fig. 4 has been found to be not available for this edition. 


The dangers of house-flies to tlie health of the community 
have come into such recent prominence that the appear- 
ance of Major Hurlstone Hardy's book should fill a want. 
It is written lucidly and clearly, yet in that popular style 
which is so frequently lacking in scientific works. This is 
a great advantage. Too often scientists are prone to 
bring out works couched in terms which cannot be under- 
stood by an interested public that is not versed in technical 
terms. Thus matter which is of the greatest general 
importance is passed unread by many, and is, in conse- 
quence, not acted upon. 

Major Hardy has a knowledge of these deadly insects 
which, in my opinion, is unsurpassed, because he has the 
personal experience of practical experiment combined 
with the instincts of the naturalist. The result is an 
account both accurate and interesting which should prove 
of the greatest value. 

The discovery of the transmission of disease by mos- 
quitoes required the passage of a decade before its essentials 
were grasped by the public mind ; that of the prevention 
of small-pox required a century. But the dangers of 
house-flies is rapidly becoming known in consequence of 
the popular literature, which is growing, describing the 
details of the lives of these loathly creatures. In this way 
only can such knowledge be spread — a knowledge which 
must become general before flies and the maladies they 
convey can be generally and satisfactorily dealt with. It 
is of little use to make great discoveries and then to hide 
them on the musty bookshelves of learned societies. 


Instead, lliey should be adapted to practical purposes 
applied for the good of suffering humanity ; and the best 
way to do this is to bring out well-written, interesting, and 
easily read books of this kind, so that all who run may 
read and their readings endure. This book should assist 
much to accomplish this end. Thus we may look forward 
confidently to the day when house-flies, and the diseases 
they carry, are things of the past. The " Book of the Fly " 
must take its place in the history of the events which are 
to lead up to the winning of that goal. 

Halford Ross 

{of the John Howard McFaddcn Researches at the 
Lister Institute of Preventive Medicine). 




With the present clay zeal for popularising interest 
in common things (called nature study) there has 
arisen the demand for knowledge practically useful 
and thoroughly up-to-date, yet in a form free from 
much of the technical terminology and treatment 
which are essential in the student's more fully 
developed scientific handbook. 

The ^^ House-fly" is a fit subject for a simplified 
study of this kind, and the present booklet is an 
attempt to afford information very different to that 
of the '^popular" works, which only were accessible 
to the writer's hands between fifty and sixty years 
ago; the writers of those old books all followed the 
lead of the reverend and learned contributors to the 
famous and monumental "Bridgwater Treatises." "The 
Wonders of Nature explained," "Humble Creatures" 
(a study of the earth-worm and the house-fly, in 
popularised language), "The Treasury of Knowledge," 


"Simple Lessons for Home Use," were the kind of 
cheaper works in touch with a past feneration ; 
these latter and other later well-intended publications 
will now be found to be somewhat deficient or even 
a little misleading entomologically ; they abounded 
in pious sentimentality and mostly attempted an 
aggravatingly grandiose literary style, but all have 
rather failed in teaching practical economic utility, 
in connection with which nature-knowledge can be 
rendered as interesting as any other kind of in- 
structive literature. The tribe of two-winged flies, in 
particular, has not even yet received a full and adequate 
study by scientists. A preference has ever been shown 
towards those other branches of entomology, which 
may be more interesting to the cabinet-specimen col- 
lector, but which cannot pretend to have an equal 
hygienic and economic importance to humanity. 

The presence of the house-fly in our dwellings is 
often submitted to as an irritating but an inevitable 
nuisance; yet very certain remedial measures would 
almost exterminate the creature, which is a dangerous 
and filthy peril. To many people it will seem a most 
incredible exaggeration when told that it is really 
worse than any one of the less common creatures 
universally regarded with horror and disgust as pesti- 
ferous vermin. The surmise may be true that the 
disgusting body louse carried bacteria, which spread 
the *' black death " ; and, even though the rat's flea 
has been found to be the carrier transmitting bubonic 
plague, yet amongst people living now in civilised 
communities within the temperate zones these parasites 
cannot be ranked as dangerous equally with the house- 


fly. The modern crusade against the house-fly is not 
based on any such new discovery, as is that against 
the mosquito gnats, which are the means of spreading 
zymotic diseases mainly in the tropics. The mahgnity 
of the fly is recorded in most ancient history and folk- 
lore, yet not very long ago there prevailed amongst 
certain classes opinions very difl^erent to those of old 
as well as to those of the present day. A short anecdote 
will perhaps amuse as well as explain those misplaced 
sentiments, which have not quite died out. 

In the middle of the last century there was a boy, 
thought to be too delicate to be sent to school, who 
early earned for himself the character of being a strange 
child. When barely more than nine years old he 
visited an Aunt who was a veritable exemplar of gen- 
teel breeding and propriety after the early Victorian 
pattern. There he was seriously reprimanded for the 
*^ cruelty " of feeding his secret pets, which were garden 
spiders, with flies which were, so the Aunt said, *' poor 
innocent creatures made by God for a useful purpose," 
but, she inconsequentially added, — ** Spiders were 
horrid." The strange child replied that the Devil 
made the flies, and that God made the spiders to eat 
them. The astonished Aunt then elicited the fact that 
the strange child's father had explained, during a Sunday 
Bible lesson, that Beelzebub (the Devil) meant Lord- 

This strange child was taken a walk over Doncaster 
Heath by the Aunt's maid. There a dead rabbit was 
seen from which maggots were crawling, and the maid 
explained that it was fly-blown. Next they both stroked 
and patted a patient donkey, and the strange child 


observed maggots rolling out of the donkey's nostril* 
on to the ground ; he wondered mucli that Hve animals 
should be fly-blown. He also saw with pity some 
cows, around whose eyes flies clustered. 

Pondering on these matters, one day he confided to 
the Aunt his confirmed opinion in these words — " It 
seems, Aunt, to me that people who won't kill flies 
deserve to be fly-blown." Doubtless, it would have 
been better if he had expressed himself thus — People 
who will not kill fleas deserve to be flea-bitten ; and 
people who will not wage war against flies deserve to 
be fly-tormented. However, the horrified Aunt mis- 
took the observation for insult and impudent rebellion, 
and what ensued need not be related as pointing no 
useful moral. The strange child was merely a genuine 
early nature student ahead of the times by some fifty 
or sixty years. In due course he learnt a more ortho- 
dox account of *' Creation," and the existence of mys- 
teries in fads physiological and spiritual, which can 
only be imperfectly comprehended in this world. 

His craving for nature study was not satisfied with 
the reading of most of the cheap books then published 
for the diffusion of knowledge. Collecting butterflies 
and moths sufficed for some of his schoolfellows in 
later years, but, not then having access to really good 
handbooks, he became an original investigator in wide 
fields of nature study, and thus learnt that many state- 

* Stevens' Book of the Farm and many other publications describe 
the similar affliction of sheep by (Estrus ovis but omit to notice the 
case of the donkey, which I have witnessed several times, but have 
never seen a horse or pony thus afflicted. There is a fly termed 
(Eslnis ttasalis, of which the victimised host is uncertain, for Linnaeus 
was mistaken in stating that the larvae are found in the fnitccs of 
"horses, asses, mules, slags, and goats," cutcriti^ by the nostril. 


ments and opinions, which ordinarily even at the 
present day pass current as facts, are erroneous and 
misleading. Accordingly, the reader need not be sur- 
prised at some statements in the following pages at 
variance with what may be met with elsewhere. 

The old fanciful dogma that everything existing was 
actually created "in the beginning," and "for a pur- 
pose," was once ardently championed as controverting 
aggressive Voltairean latheism, but it must be now re- 
cognised as an unwarranted assumption, deduced from 
an orthodox doctrine of " design," which in itself seems 
acceptably agreeable with the idea of unity, consistency, 
and perfection in Creation and The Creator. In fact 
the said " fanciful " dogma never really was an integral 
part of Christian Catholic doctrine. The house-fly, as 
we know it, is absolutely the developed product of 
human insanitation ; scientifically and practically it is 
a new "species" of an old "genus" established by 
a long course of breeding in man-made environments. 


Fig. I, The House-Fly, Female, Enlar^ai, 

Fig. 2. The Lesser House-Fly, Male, Enlarged, 

Fig. 2a. The Stable-Fly, Female, Enlarged. 


Although there are several other kinds of flies which 
occasionally visit the dwellings of mankind, there is 
one supti'-BhundRnt species, Musca domesitca, to which 
the name of '' house-fly " pre-eminently belongs. In 
the scientist's discriminating judgment, when viewed 
microscopically, it differs substantially from others ; but 
it differs very little in general appearance from certain 
outdoor flies and from one not uncommon indoor 
smaller companion, Fannia canicularis, which is not 
classified amongst the Muscidce but amongst the 
Anthomyidce . This latter has been fitly termed the 
^* lesser House-fly;" it has the same habit of delighting 
to pester man as much as or more than cattle outdoors. 
Both these flies join with several others in frequenting 
stables and cow-sheds. 

These two flies and the familiar "blue-bottle" (again 
it seems that we are liable to confuse two species) are 
the special subject of our present study ; but it will be 
as well to take passing notice of some few other 
mernbers of the tribe classified by scientists as belong- 
ing to the order Dipter a. The species of this order 
native to Great Britain are said to number nearly three 
thousand, of which quite two hundred of largish sizes 
are exceedingly common and widely distributed. 



This order is characterised by the fact that all the 
species are furnished with one pair of wings only: — 
dis = double, pteron = wing ; they all undergo a me- 
tamorphosis analogous to that of four-winged insects. 

The dipterid flies are apt to be popularly recognised 
as flies (with fat bodies) and gnats (with slim bodies) ; 
but they may be more intelligently classified (with a few 
anomalous exceptions) as flies {a) having a trunk-like 
mouth or proboscis (miscalled a tongue), terminating 
with bilobed suctorial lips, and as flies {b) having a 
bayonet-like trunk, or a sheaf-like tubular spike with 
skin-piercing lancets. No two-winged flies have stings; 
the tail of the female, which terminates with the 
ovipositor and is retractile in a telescopic manner, is 
very soft and quite unlike the sting of the ichneumon 
or the ovipositor of the ** saw-fly," both of which 
possess two pairs of wings like bees and wasps, and 
therefore are classified with the insect race called 

Omitting Aphides (green-flies, plant-lice, and the 
like) which are an " order" by themselves, and exclud- 
ing gnats of slim form, mosquitoes, and midges, which 
are mainly crepuscular, nocturnal, or shade frequenting, 
we might try unscientifically to sub-divide the more 
conspicuously sunshine-loving and day-flying flies 
into: — (1) flower and honey seeking flies; (2) cattle 
pestering sweat-flies ; (3) skin-piercing, blood-sucking 
flies ; (4) insectivorous flies ; (5) fungus flies ; (6) 
carrion and filth flies ; and to these must be added 
another small group (7) which comprises those of the 
wondrous family of the CEstridoey the most horrible 
though not the most injurious of the animal perse- 


cuting and torturing flies ; this last group, strange to 
say, are absolutely destitute of any mouth and feed 
only in the maggot stage. In many cases, however, 
it happens "that the males and the females differ in 
feeding habits as well as in colours and markings, 
whilst only their patterns of wing-veins and some 
less prominently apparent features are constant in the 
two sexes. These circumstances discountenance the 
above grouping. 

Again, if we tried to group our flies with adequate 
regard to their very diverse habits of life, in the larval 
stage as well as to their subsequent metamorphoses, 
we should find that these are details which are obscure 
and in many cases unknown or imperfectly recorded. 
However, after much study and many revisions, a 
scientific classification has been contrived based upon 
the minutely differentiated characteristics which are 
technically explained in the Appendix to this booklet. 

Whilst the notorious house-frequenting flies above- 
mentioned and the blue-bottle are remarkably omni- 
vorous in their feeding, the great majority of outdoor 
flies are quite otherwise inclined, and do not find much 
attraction in anything but their own individual pre- 
ferences. Indeed, the breeze-flies, and many others, 
avoid human habitations ; even the grey blow-fly, unlike 
the blue-bottle, rather seems shy of the house. In the 
above grouping, according to feeding habits, the house- 
fly must be preferably consorted with (2) sweat-flies, 
but the blue-bottle with (6) carrion flies ; however, 
the house-fly and the blue-bottle are very near akin, 
and by reason of similarity of wing-pattern both 
are included in the family of the Muscidce, 


In the entomological systematist's classification 
the primary separation of flies into two sub-divisions 
starts with a difficulty, for it is based upon circum- 
stances often obscure and in some cases at least 
imperfectly known. 

The first sub-division, Dipiera Orihorrkapka^ com- 
prises those flies which in the stage of the pupa or chry- 
salid disclose the outline of the perfect insect; in the 
other sub-division, Diptera Cyclorrhaphay there are 
grouped together all those flies of which the larvae make 
for themselves a puparium or barrel-like case out of 
their larval skin. 

The first mentioned sub-division comprises all the 
gnats, midges, and most of the slender flies which are 
outside the scope of the present work, but it also 
includes a few kinds of more stoutly built flies, to 
which some allusion will be made in the following 
pages, as for example, the breeze-flies, Tabanidce, 

The second sub-division comprises many families, 
including the muscid-like flies, of which the house-fly 
is the type. The flies of this type are to be found in 
the families of Musciduy Anihomyida, Tachinidat and 
CordyluridUy comprising nearly 700 British species, of 
which many rather closely resemble one another when 
superficially observed. 

The approved classification of flies is to some extent 
dependent upon the formation of the antennae, but the 
unique feature of the systematic differentiation is based 
upon a very intricate method of scrutinising, identify- 
ing, and numbering the vein-like strengthening ribs 
called veins, nen'ures, or nerve-lines, which, starting 
from the shoulder, mark with characteristic patterns 


the transparent tissue of the wing. We are rather 
compelled to follow something like this plan (simplified) 
for the purpose of clearly distinguishing the " lesser 
house-fly" from the common "house-fly." 

In the accompanying illustrations rather similar 
patterns of wings are shown ; these are typical of 
the Muscidce and Anthomyidce ^ which, taken together, 
comprise amongst others all the cattle and human pest- 
ering *' sweat-flies'* ; only a few really blood-sucking 
flies are included amongst the Muscidce, 

In critically comparing these four patterns, the chief 
feature to be observed is the small rib-like nervure 
called the " discal " " cross-vein," which is situate in the 
very middle of the wing, and which connects the lowest 
of a group of longitudinal nerve-lines or veins in the 
front (or upper) half of the wing to the uppermost of 
the other group of longitudinal nerve-lines in the hind (or 
lower) half of the wing. Three " main " longitudinal 
lines, technically termed " veins," are theoretically 
recognised as constituting the upper group and four 
"main " longitudinal lines the lower group ; but these 
" veins *' (numbered 1, 2, 3, 4, 5, 6 and 7) will be found 
to be varied in different families and genera, each often 
with characteristic diverging branches, whilst some 
veins may be rather inconspicuous or quite absent. 
We w'ill here devote our attention only to two such 
" veins," those respectively termed "vein 3 " and " vein 
4," which are connected in the very middle of the 
wing, as above mentioned, by the small but always 
distinct "discal" "cross-vein." The illustrated 
patterns herewith show wings divided into about twelve 
compartments or cells, to all of which learned entomo- 



logical writers give troublesome technical names, not 
nearly so intelligible as the nomenclature symbols of 
the late Rev. W.J. VVingate, explained in the Appendix 
herewith. For present purposes a simple observation 
of the (externomedial) vein " V, 4," where it is the 
lower boundary of the (subapical) cell '*0, 4^," will 

The pattern of 
the first figure illus- 
trates the wing of 
the common blue- 
bottle ;here"vein 4" 
Muscm does not run at all 
straight in the last 
part of its course, but 
curiously ben ds vei-y 
suddenly upwards 
at an angle and 
meets the margin 
very near to "vein 
3." In the wing of 
a large blue-bottle 
it will be easy to 
recognise this plan. 
The pattern of 
the second figure is 
rather similar, for 
the vein 4 likewise 

Con R)CHT has a sudden bend 
Fig. 3. Wing patterns contrasted. upwards ; it ter- 
minates practically contiguous with vein 3 at the 
margin. This pattern is characteristic of the " house- 



fly"; thus it will be easy for the reader to identify the 
common house-fly by the close resemblance of its 
wing pattern to that of the blue-bottle, with which it 
is classified in the family of the Muscidce, 

In the pattern of the next figure the vein 4 runs 
comparatively straight throughout and meets the 
margin at a spot intermediate between the third and 
fifth veins ; here all the main nerve-lines diverge more 
evenly and terminate more equi-distantly apart ; this 
latter plan is the wing pattern w^hich will suffice to 
identify the lesser house-fly, but it is shared w^ith all 
the AnthomyidcBj and more or less with some others, 
which are very common outdoor flies. 

The pattern of the lowest figure illustrates the wing 
of the common blood-sucking stable-fly, Stomoxys 
calcitrans, which only occasionally invades the house. 
Here the vein 4 is deflected upwards towards the 
margin ending near the termination of the vein 3, but 
the bend is a smoothly rounded curve and not a 
curiously abrupt angle, as in the first and second figures. 

If the reader will study the house-fly in captured 
specimens, he will be able to obsei-ve that they slightly 
differ in their inconspicuous colouration and markings. 

The male of the lesser house-fly is sometimes more 
observable than the male of the commoner house-fly, 
by reason of his being a most indefatigable dancer 
with companions in mid air around any central 
ornament, and also by reason of his possessing pale 
patches, more or less yellowish grey, on the sides of the 
abdomen ; but such markings are also in some degree 
observable in other male flies, being very conspicuously 
of a brighter yellow in the common small outdoor 


raven-fly, M, corvina. The back of the thorax of the 
house-fly is marked sometimes distinctly, sometimes 
indistinctly, with four dark lines on an ash-grey back- 
ground ; the lesser house-fly has three faintly darkish 
lines only. Quite a number of outdoor flies have 
similar markings, but these often look like closely 
adjacent or indistinct spots. The wing pattern is the 
readiest guide for distinguishing the lesser house-fly, 
both male and female. The males of the haiiy (almost 
bristly) raven-fly also indulge in the dancing habit, but 
still more so do those of the latrine-fly, Fannia scalarisy 
which may be distinguished by its uniformly ashy-grey 

These common co-inhabitants of our dwellings vary 
in size according to their nourishment when in the larval 
stage (maggots) ; after the perfect insect emerges from 
the puparium, it swells out and fattens, but does not 
grow in the real sense of the word. If looo house- 
flies will weigh an ounce, then it may be calculated that 
1600 average specimens of the other kind will likewise 
weigh an ounce. 

In representing that the house-fly exceeds the lesser 
house-fly in numbers in the proportion of twenty or 
thirty to one, it must be borne in mind that the occur- 
rence of the latter varies widely — casually according to 
the locality, and temporarily according to the time of 
the year, being more commonly observed when and 
where the other kind is scarce. 

The lesser house-fly has summer broods at longer 
intervals than has the common house-fly. Towards 
the end of the summer its last brood hibernates in the 
puparium, and emerges as early as the end of March 


or early in April, whilst the common house-fly is not 
usually observable until a later date, although it is 
credited with more generally braving the dangers of 
attempting to hibernate in the imago stage. My 
attempts to test the capability of the house-fly by aid- 
ing October and November flies to hibernate invariably 
terminated in the creature's death long before spring- 
time. However, it is very apparent that under the 
shelter and encouragement of warm winter environ- 
ments in towns, amidst restaurants, bakeries, large 
hotels and certain factories, as well as and even more 
than in mews, adult flies of the latest autumn broods 
can, to some extent, survive mid- winter with very little 
or no prolonged hibernation. 


Just as the common " house-fly " and the ** lesser 
house-fly" are often in error regarded as the same 
species with an insignificantly small difference of size, 
so the identity of each in turn may be confused with 
several other species which are not uncommon, but 
they are all normally outdoor flies. 

The chief of these is the excessively common stable- 
fly, Siomoxys calcitrans^ whose generic and specific 
designations are well given, for they mean "sharp- 
mouth," ''kicking," the latter word denoting the action 
of the tormented horse ; it has a long, thin, stiff, skin- 
piercing, shining black trunk, furnished with two 
lancets. It is an eager blood sucker. In size and 
colour it rather resembles the house-fly, but anyone 
who is keen sighted will recognise it at once by its 
bayonet-like trunk, held projecting prominently in 
front of its head. It is much addicted to basking out- 
doors on sunny walls, but on the approach of darkness 
or of inclement weather it will occasionally seek 
shelter indoors. Its wing pattern rather resembles 
that of the common house-fly, as has been previously 

Round about dairy farms Hcematobia stimulanSy a 
fly slightly smaller than the stable fly, with a striped 


thorax and a blood-sucking trunk, will often leave the 
cattle to assail humanity. A still smaller, somewhat 
hairy, muscid type of fly, Lyperosia irrttans, is also a 
common aggressor of oxen throughout the summer. 

Musca corvina, the raven-fly, is smaller than the 
house-fly ; it has very distinct dark markings ; the 
abdomen of the female is chequered, but that of 
the male has a black central stripe on a yellowish 
abdomen. It frequents gardens, parks, and meadows. 
It is much less prolific than the house-fly, with which 
it shares the sweat-fly pestering habit. 

Cyrtoneura simplex is a little smaller and more 
common than the species last mentioned ; its larvae 
are bred in the dung of cows and other animals which 
it very severely pesters. However, many species of 
dung-bred flies do not in the least participate in the 
cattle-pestering habit. 

The AnthomyidcB are a family of about 250 small and 
medium sized garden frequenting and country flies, 
mainly of flower and honey seeking habits. Neverthe- 
less, some are dung-frequenting ; none are blood-suck- 
ing, but several are cattle-pestering sweat-flies, which, 
even more pertinaciously than the house-fly, will circle 
round one's head and repeatedly buzz against one's face. 
Of these, the small Hydrotcea irriians and Hy, deutipes 
are amongst the worst offenders. A few of the Antho- 
myidcB are vegetarian garden pests ; the larvae of the 
cabbage-fly, the root-fly, the onion-fly and the celery- 
fly are, in some seasons, very destructive. The so- 
called "turnip-fly" is a small striped beetle of the 
same genus, Phillotreta^ as the unstriped " flea-beetle" 
of the hop-fields. The larvae of the majority of the 


species of the family of Anthomyidcv are, more or less, 
feeders on decadent vegetable matter, but some, like 
those of the genus Fannia^ are preferentially feeders 
on dung. The female of the latrine fly, Fannia scal- 
ariSy so closely resembles the lesser house-fly that only 
the expert with a magnifying glass, after a careful 
examination, can tell which is which ; the male differs 
from the male of the lesser house-fly by being without 
the yellowish patches on the abdomen. 

There is a larger and less common muscid fly, with 
an ashy-grey body, but with reddish legs, named by 
entomologists Muscina stabulans, which not only in 
body colour, but also in the pestering habit, resembles 
the house-fiy ; its Latin specific name is rather objec- 
tionable as too suggestive of the common "stable-fly," 
which name belongs to Stomoxys calcitrans above- 
mentioned ; its larv^ae have been found in cow-dung, 
but they can also flourish on vegetarian fare. 

The common blue -bottle is now named Cal- 
liphora erythrocefhala (red -head), and it can be 
recognised by its reddish face and black hairs for a 
beard, whilst the less common blue-bottle, named 
Calliphora vomitoria, may be said to have a reddish 
beard upon a black face ; the latter has the blue colour 
more evenly distributed over the abdomen, whereon 
the former has dark markings. 

Polietes lardaria is a fly sometimes mistaken for 
the blue-bottle ; its specific name is rather too sug- 
gestive of resemblance in habit. It may be recognised 
by its having four black stripes on the thorax, by its 
large white squamae, and its tesselated glaucous abdo- 
men ; its wing pattern classifies it as belonging to the 


AnthomyidcVf whilst the true blue-bottles belong to 
the MuscidcCf and the grey blow-flies to a section 
{Sarcophagina) of the Tachinidce. 

There are some other outdoor flies which are not 
very dissimilar to the common blue-bottle, but they 
are more soberly coloured, ranging from bluish black 
to speckled and tinted greys; some of these have a 
pattern on the shiny upper surface of the abdomen \ 
which is conspicuously and beautifully chequered. 1 
Closely akin to these latter is the large grey blow-fly, O 

or flesh-fly, Sarcofhaga carnaria ; it is much referred ^ 

to in entomological books as of marvellous fecundity. 
The female deposits not eggs in a few hundreds, but 
already hatched maggots to the number of many 
thousands. Amongst half-a-dozen rarer kinds of 
smaller grey blow-flies the females differ in their 
striped markings, but their respective males seem quite 
indistinguishable apart. 

Notwithstanding the prodigious fecundity of the 
grey blow-fly, the credit of being a practically useful 
scavenger of carrion must be given only to the blue- 
bottle, which is of a more robust habit, and w^hich so 
promptly monopolises available matter that Sarco- 
phaga carnaria and her congeners are sometimes, 
perforce, compelled to give their larvae a mere vege- 
tarian diet. 

The yellow cow-dung fly, Scatophaga stercorariay is 
inoffensive, and one of the commonest flies observable 
in the course of a country-side ramble. It and its 
congeners are distinct in habits and appearance from 
any of the other flies above-mentioned. In this species 
the male is larger than the rather more smooth and 


dull-coloured female. Its body is furry but slender; 
it has small eyes and head parts. In repose it holds 
its wings parallel close above the abdomen, more 
like the "breeze-flies," or true "gad-flies," than the 
ordinary muscid flies. Although its proboscis does 
not seem as formidable as that of more insectivorous 
flies, yet it may sometimes be observed pouncing upon 
some small fly, which it holds with its powerful legs. 
This fly does not appear to be very predaceously 
inclined; perhaps it is only "acting a part," like some 
other creatures, including the amorous male of the 
common frog, which, failing to secure a more natural 
and complacent "partner in the dance," will in spring- 
time seize upon and very persistently cling to an 
astonished carp. 

Amongst many flies with bodies favoured with a 
brilliant metallic sheen, several species of green-bottle 
flies {Lucilicv) are notorious. Of these latter L, Ccvsar 
is the most common, but L, Sericaia is by far the 
worst in England, not uncommonly laying eggs upon 
sheep ; many are of a brilliant golden green, but some 
vary towards a coppery green ; all have red eyes and 
silvery faces. In summer-time these flies seize every 
opportunity of depositing their eggs upon any sores 
or skin wounds of animals ; their larvae normally feed 
on carrion and dung. The green-bottle, like the blue- 
bottle flies, are fond of both sweets and filth, but they 
do not pester wholesome animals as do the sweat-flies. 

Next to the Muscidcc the most often observed and 
easily recognisable as a distinct family of flies are the 
Syrpkida^ which include the " hover-flies," the drone- 
flies (often mistaken for the male of the hive-bee), and 



a number of other very common flies of a generally 
similar full-bodied shape, in most of which colour 
stripes and bands more or less suggest a comparison 
with wasps. The numerous species native to Great 
Britain are widely distributed, and, excepting the rare 
and very hairy Merodon narcissi^ of which the larvae 
feed on liliaceous bulbs, none is injurious and some 
are beneficial. Nearly all the flies of this family 
frequent flowers'. The habit of many to hover for 
hours about a favoured spot, as if for mere pleasure, is 
remarkable; but it is not generally recognised that 
some of these hover-flies (of the genus Syrphus) are 
hawking for winged aphides and other small insects, 
which they quickly suck dry and drop whilst still on 
the wing. Many of the flower-frequenting Syrphidce 
are great devourers of pollen ; all have strongly 
developed suctorial mouth parts. 

The larvae of the various syrphid flies differ greatly 
in appearance and habit; some are terrestrial; some 
aquatic ; some semi-aquatic ; some feed on decadent 
vegetation; some on sew^age and filth, and some are 
insectivorous. Most useful to the horticulturist are 
those of the genus Syrphus, which feed on green-fly 
and other aphides. The most curious in shape are the 
" rat- tail " maggots of the common drone-fly, Erisialis 
tenax (also others of allied genera), which can extend 
their long tubular tails and breathe atmospheric air 
through the same whilst lying under water. The larvae 
of the genus Volucella are found dwelling in the 
nests of bumble-bees and wasps ; it is rather uncertain 
how far they are commensal, or parasitic, or devourers 
of dead matter. Some of the syrphid flies are single- 


brooded, but some at least are double or treble-brooded 
in the year; records are wanting about many, and 
which, if any other than the common drone-fly, are 
multi-brooded. Anyhow, none appears to breed in 
Great Britain as rapidly as do the house-fly, the blue- 
bottle, and other muscid flies. 

The larvcC of Conops flavipes are parasitic in the 
body of the adult bumble-bee, and they pupate therein. 

The small family of the Stratiomyidcv contains a 
few fairly common species called soldier-flies ; these 
are interesting as linking Orthorrhapha w^ith Cyclor- 
rhapha ; their larvae are some aquatic (the star-tailed 
maggots), others terrestrial, and some have hard shell- 
like skins ; but they are not so curiously like a creeping 
marine limpet as are those belonging to the genus 
Microdon (of the Syrphidcv)^ which are rare and 
wonderful dwellers in ants' nests. 

There is a curiously shaped race of parasitic flies 
which cling to the host like a louse, called Hippoboscida: ; 
these have more than the usual provision of claws to 
their feet, both in the number (normally two) and size 
of the claws. The forest or spider-fly attaches itself 
to some part of the body out of reach of the horse's 
tongue. The ked, tick, or sheep louse-fly has a similai 
mode of life, and, after selecting its host, it becomes 
wingless. These flies, strange to say, nurse and nourish 
their larvae within the oviduct, and, when one might 
think that they were laying their eggs, they are deposit- 
ing pupae or larvae just ready to pupate. There are 
some species of the family of the louse-flies which 
infest birds. 

The true gad-flies of the family of Tabanida were, 


and sometimes still are called " blinden breeze-flies," 
and sometimes dun-flies ; by a very easy mistake the 
countryman's word " blinden " (blind) has got changed 
by authors in books to " blinding," which is nonsense, 
and misses a wonderful instance of old-folk knowledge ; 
the females are amongst the most inveterate blood- 
sucking flies, but the males are mere idle loiterers in 
summer sunshine on flowers; the eggs are laid on 
herbage in moist situations ; the maggots and pupae of 
many of these species are said " to be found in the 
soil," and some, if not all the larvae, are predaceous, 
attacking worms and underground larvae of various 
insects. They are more or less midsummer flies 
and are single-brooded. There are several largeish 
species (of the genera Tabanus and Therioplecies) found 
in Great Britain, and they are diversely distributed, 
being respectively woodland, moorland, lowland, and 
highland inhabitants. The great ox-gad-fly is as large 
as a bumble-bee, though more long than broad in 
body, but the term gad-fly is often wrongly given to the 
worble-fly, which is really more bee-like, being furry 
and rounder in body. The genus Hematopota com- 
prises three smaller sized extra vicious blood suckers, 
H , pluvialiSf rather common, H, italicUy very local, 
and H. crassicorniSy darker in colour and with spotted 
and dark tinted wings. Several of the large gad-flies 
have dull-tinted wings. They have large, shallow, 
brightly shining and curiously banded compound eyes, 
but no " ocelli " ; they all seem to be at least semi- 
blind, and the females are rather sluggish, except 
between the hours of 11 a.m. and 5 p.m. in bright 
midsummer sunshine. The females hunt entirely by 


scent and are easily captured when attacking human 
beings ; they alight on their victims with a stealthy 
silent approach. They appear unable to discriminate 
between clothing and bare skin as suitable spots for 
feeding. Amongst a band of mountaineering pedes- 
trians, on a sunny day, it was observable that there 
would be a dozen or more "blinden breeze-flies" 
settling on the back of one, whilst the rest of the party 
were only favoured now and then by one or two apiece. 
It was apparently the smell of the " home-spun " coat 
which attracted ; the colour of the garment did not 
seem to be the cause of the selection. Sunshine loving 
flies prefer white and pale colours. If a dog could 
speak, he would explain the smell of some ^^ finished " 
cloth, but, for the sake of the fastidious, the secret is 
not here disclosed. 

Very closely allied to the true breeze-flies in habit of 
life are the species of the genus Chrysops^ of which 
two only are often met with in England, namely 
Ch, coecutiens and Ch. relicta ; these flies are very 
keen blood suckers; they are smaller, slightly more 
slender and brighter coloured than the commoner 
Tabanidce ; it is characteristic of the genus Chrysops that 
the antennae are quite twice the length of the remarkably 
short horns of the majority of common full-bodied 
flies ; all the species possess beautiful golden glittering 
eyes (whence the name Chrysops), and their wings are 
spotted and tinted. 

One of the most horribly disgusting but serious facts 
connected with flies is observable most conspicuously 
amongst the wondrous family of the CEstridce. These 
pass the larval stage of life, not on, but inside the 


bodies of living animals ; and the perfect insect, strange 
to say, is absolutely destitute of a mouth opening. 
Much misrepresentation has been prevalent, based 
entirely upon surmise, connecting "myiasis" in man- 
kind, which is various but very rare, with the common 
infliction of horses and horned cattle with CEstrid 
maggots. Myiasis is the medical term given to all the 
various forms of animal infliction by internal parasitic 
maggots, and this subject is reserved for discussion in 
the next chapter. 

The characteristics and natures of the very numerous 
tribes and families of other kinds of flies will be found 
summarised in the Appendix of this booklet. 


The family of the CEstridcB is the most curious and 
horrific of all the different tribes of flies ; it is very 
limited in species, of which five or six are prevalent 
throughout Great Britain. The worst of these could 
be almost exterminated with ease, but unfortunately 
mistaken ideas have prevailed, and graziers commonly 
believe that though the sheep's nostril fly is con- 
spicuously harmful and dangerous, the horse's bot-fly 
and its congeners are negligible as regards the 
practical health of the host. The bot-fly and the 
worble-flies are all of a largish size, only the sheep's 
nostril fly and CEstrus hcemorrhoidaliSy which latter 
infests the throat and rectum of the horse, are of a 
medium size. 

It has been known from very ancient times that 
man himself was not exempt from some fly, which was 
imagined to resemble the horse's bot-fly, and it has 
been wrongly surmised that many different creatures 
and all ruminant animals were more or less subject to 
the attacks, each one of its own kind, of cestrid fly. It 
is undeniable that man is internally afflicted 
with dipterid larvae, but it is most certain that the fly 
to be incriminated is not a congener of the horse's 


An old illustrated French encyclopaedic work gives 
coloured pictures of the flies and larvae of CEstrus bovis 
(the worble-fly of the ox) and of CEstrus equi (the bot- 
fly of the horse), but only the larvae of a so-called 
(Estrus hominis is figured. Recently, however, new 
attempts have been made to identify the species 
causing intestinal myiasis, of which the larvae are 
observable from time to time in the course of post- 
mortem examinations and during anatomical study. 
Of recent years it has been suggested that the lesser 
house-fly is addicted to such a manner of breeding ; 
then later that another species of the same genus has 
been found to be the real culprit. However, the 
peculiar larvae of these last-mentioned flies do not in 
the least resemble the fat round larvae of the true bot- 
fly or of the worble-fly, which are correctly represented 
in the above-mentioned French work, nor the round 
and rather smooth maggots which were observed in 
Westminster Hospital nearly fifty years ago, and at other 
places from time to time both before and since, giving 
rise to much wonder and discussion, and also to very 
incredible tales. 

Another more credible surmise attributes the offence 
of human intestinal myiasis to Muscina statu lans ; if 
this be correct, the infliction would be probably due 
to the subject having eaten damaged and egg-laden 
plums or similar fruit, for M. stabulans is credited 
with being normally, though not exclusively, fruitarian 
or vegetarian. 

If any one of the above suppositions be true, it does 
not exclude any other one, amongst many, explanatory 
surmises, from being possible. Judging from the re- 


markable attractiveness of the odour of humanity to the 
common house-fly, and from the fact of the maggots 
possessing well developed tenter-hooks on their heads 
(somewhat like those which the bot-fly maggots use 
for internal attachment), it is just as likely, nay more 
likely, that this species (as the writer stated for the 
information of the authorities of Westminster Hospital 
nearly fifty years ago) is more than any other capable 
of adopting such a life-cycle existence ; these maggots 
would mature after five or six days feeding and then 
emerge. If there were a veritable '^ QLstrus hominisj" 
however rare, the hairy and peculiar female would be 
conspicuously observable, a persistent hoverer about 
the person of her victim until she had attached eggs 
to his body, from which the maggots would not emerge 
until after nine months. Most of the tropical flies, 
which are said to similarly attack humanity, may be 
rather compared to the green-bottle flies which infest 
sheep, but the latest medical records and reports profess 
to identify ten or twelve species of very different genera 
as having myiasic capabilities. 

The family of CEstrida has been fitly divided into 
three sections, namely, the Gastropkilincv (the larvae 
living in the gullet, the stomach, or the intestines), the 
Hypoder mince (worble-flies), and the CEstrincv (nasal 
or nostril flies) ; all the species are hairy or furry, and 
the gravid females fly slowly with loud buzzing, in a 
characteristic attitude peculiar by the bending down- 
wards of abdomen and tail, with a much extruded 

The sheep's nostril-fly, (Estrus ovis, has a chequered 
abdomen and is less hairy than others ; it is the type of 


the section to which the generic term Cephalomyia is 
given in some books; species of this section attack 
deer and other animals. 

The section termed Hypoder mince comprises the 
'* worble " flies or " marble " flies. One may imagine 
that the latter name indicates in the mind of the cow- 
herd the appearance of the round pustulent boils on 
the hide of the suffering animal, and that the former 
name is a corruption of "worm-hole," originating with 
the tanner, observant of the deterioration of injured 
hides. A mixing of the terms worm-hole and marble 
probably originated the name " warble." The maggots 
live under the skin on the back of oxen, and breathe 
externally through openings in the boil-like excrescences. 
The discoloured flesh of infected oxen is called 
" flecked." Two species of worble-flies are prevalent, 
one or the other, in many parts of England. 

The third section, to which the sub-family termed 
Gastrophilina is sometimes applied, comprises the 
*'bot-fly," which commonly infects the horse ; it is the 
imperfect knowledge of this latter which has led to 
erroneous surmises explanatory of the horribly dis- 
gusting fact of human intestinal myiasis. 

All the species of all the three sections are single- 
brooded. Although the flies themselves can inflict no 
immediate pain, at their mere sight all the animals out 
at grass on the farm are seized with an instinctive 
terror, conspicuously greater than when attacked and 
copiously bled by any " blinden " breeze flies, which, 
however, fly more silently and settle on their victims 
very furtively. One can understand the violent efforts 
of the horse to free himself from the exceedingly 


painful bites of a newly attached forest-fly, but one 
can only wonder at the frantic galloping of oxen and 
horses to and fro when a non-biting cestrid fly buzzes 
about like a harmless fat bumble bee and slowly 

The females of all the worble-flies, the nostril-flies, 
and the bot-fly are short-lived, appearing on the wing 
in August, possibly seen a few days earlier. In the 
act of ovipositing they make themselves very con- 
spicuous ; they lay their eggs whilst hovering in the 
air, their extruded ovipositors attaching glutinous eggs 
to their victims. The hatching of the eggs of the 
bot-flyS is assisted by the habit of animals to lick 
themselves and each other, when certainly their warm, 
moist tongues will convey into their mouths the newly 
emerged bot-fly's maggots, which many months later 
are to be found attached to the internal lining of the 
unwilling host's stomach. When fully grown in June, 
these maggots loosen their hold, are discharged with 
the dung, and pupate in the soil. 

No satisfactory account has yet been given as to the 
early stages of the maggots of the worble-flies. The 
eggs, having been attached to hairs on the host's hide 
in August, the prominent round pustulent swellings, 
called worbles, wherein the maggots dwell, do not 
become conspicuous until the following months of 
April and May. It is a reasonable surmise that the 
obscure and long first-period of the maggot's existence 
may more or less conform to that of some of those 
flies which are also single-brooded but are predaceous 
or parasitic on insects. The newly hatched maggot 
perhaps can crawl, but does not feed until after several 


moults ; at each moulting the strange creature becomes 
smaller and smaller, but probably at the same time is 
provided with a new head well suited for the purpose 
of that period ; firstly, with a burrowing or grappling 
head, and in due time with a feeding suctorial mouth, 
and then only does practical growth begin. No dip- 
terid flies, at all events, known to be native to Great 
Britain, possess skin-piercing ovipositors. 

I have been astonished to read in current literature 
much about cestrid flies which is not in agreement 
with my long course of personal observation ; for 
instance, one high authority (F. R. S.) writes that cestrid 
** flies" appear from May until October, and hints that 
their egg-laying aggressions upon their victims are not 
conspicuously observable. I feel confident that the 
facts are quite otherwise. 

That the bot-flies normally (and a few others abnor- 
mally, but for short periods only) pass a very long 
larval stage in the stomach and alimentary canal of 
herbivorous animals is one of the greatest marvels 
of insect life. All other growing creatures, which 
normally breathe in free air, require a certain large 
amount of breathable oxygen; and they would be 
stupefied or killed by a much smaller percentage of 
carbonic dioxide and other fermentive gases of diges- 
tion than undoubtedly exist in the strange abode 
wherein the bot-fly maggots dwell during the entire 
period of their feeding career. It has been stated that 
fly maggots artificially ingested into the human system 
have emerged alive in a normal condition, but the 
repulsive and objectionable experiment is not stated 
to have procured well nourished and full grown nor- 


mally pupating larvae. Some of the maggots of human 
intestinal myiasis are not perhaps amenable to artificial 
culture up to the stage of final metamorphosis ", and 
they do not appear to have developed a breed or new 
species with a distinct habit of life. All the credible 
accounts of human intestinal myiasis point towards 
some fly which is plural-brooded, and of which the 
larvae develop rapidly and promptly quit the body all 
at once ; otherwise more than one infection must have 
occurred. The tales of prolonged continuous breeding, 
with slow and prodigiously copious emergings at 
intervals, should be altogether discredited. 

It is an amply warranted criticism to say that recently 
published records by authorities, in an endeavour to 
comprise every reported instance of myiasic infection, 
seem to countenance mere coarse Gargantuan jokes. 
On the other hand, it is painful to read such a " cock- 
and-bull " story as that of the doctor about his elderly 
lady patient, up whose nostril a gravid female blue- 
bottle flew and successfully performed the prolonged 
and delicate operation of laying therein a large batch 
of eggs, in spite of all attempts to expel the invader 
by violent sneezing. Day by day the said doctor 
observed the terrible injury, and the symptoms accom- 
panying the growth of the feeding maggots, whilst the 
injection of a spoonful of paraffin would have effected 
an instantaneous cure. 


Whereas the bkie-bottle rarely enters the dwellings 
of mankind, except gravid females led by the sense of 
smell in search of fish, or flesh meat, and (less eagerly) 
sweets, both species of house-fly and both sexes seem 
to delight in the mere odour of humanity ; breeding 
females will seek the larder and the dust- bin, but others 
will very provokingly pervade all quarters. Although 
avoiding a dark or deeply shaded room, the house-fly 
seems to like partial shade ; it will be content to re- 
main indoors and to rejoice in a warm kitchen, even 
on a hot summer's day, whilst all the other kinds of 
flies are enjoying the outdoor sunshine. It may be 
said of nearly a dozen other species, occasionally ob- 
servable crawling on w^indow panes, that they are " out- 
door" flies, and that their occurrence indoors is acci- 
dental. In fact, they are mostly observed when trying 
to escape. 

Next after human habitations, stables, cow-sheds and 
pig-sties are the delight of the breeding female house- 
fly. Round about and in these latter resorts she 
associates with an immense host of rather small sized 
flies, and amongst a few others of equal size with the 
skin-piercing and blood-sucking stable-fly ; but many 
stablemen are ignorant of the difference of the two 


kinds of flies and of the serious suffering of their horses 
from the bites of the stable-fly. This lamentable ig- 
norance was shared by the joint authors of " Humble 
Creatures," published in 1858, when Neo-Darwinism 
was in vogue, and many books were published for 
popularising a knowledge of common things and 
spreading an interest in nature-study ; this publication, 
which is still (19 14) in print and very little revised, has 
probably led some later would-be nature-study teachers 
to follow suit in confusing the characteristics of the 
two species. Very often the fly most numerously 
breeding in the manure heaps of the mews will be 
Borborus equinus, or some other of the same family, 
which are characterised by a very simple pattern of 
wing nervures and by the absence of squamae or scales 
behind the wings ; also the ankle joints of the feet are 
most peculiarly short and broad. B. equinuSy and a 
great host of other dung breeding flies of a still smaller 
size, may be considered beneficial insects ; they do not 
pester cattle, and their larvae make food more scarce 
for injurious flies. 

The breeding habits of the blue-bottle are very con- 
spicuous by reason of its haste and boldness in taking 
possession of dead animals. It is incapable of breed- 
ing in horse or cow dung, to which latter the green- 
bottle fly often resorts. 

The blue-bottle deposits her eggs, 500 or 600, pre- 
ferably on dead fish, or flesh, and sometimes on the 
sores or the flesh of wounded animals, but both the 
house-flies preferably affect dung, carrion, garbage, and 
all kinds of fermenting vegetable matter. It has been 
commonly but not truly said that the principal breed- 


ing places of the house-fly are the mews and the farm- 
yards where manure is allowed to accumulate ; the 
house-fly has a preference for horse dung before cow 
dung, which is preferred by some other kinds of flies ; 
however, near towns, the domestic dust-bins, heaps of 
market garbage, and deposits of town refuse give rise 
to a worse plague of house-flies than stables. All these 
flies deposit batches of white eggs, and are careful to 
place them as much as possible in crevices and shielded 
from exposure to strong light, or from draughts. 

The two house-flies and the blue-bottle have similar 
larval stages, but their larvae, called maggots, differ. 
The larvae avoid daylight and cannot withstand dryness. 
As the larvae feed, they have the power of ejecting or 
excreting a juice, which dissolves the food before they 
imbibe the material ; their mouths are suctorial and 
are destitute of teeth or biting jaws. 

The larva of the house-fly is an eyeless and legless 
maggot, one half inch long when full grown and ex- 
tended ; twelve cylindrical segments may be counted 
in its body, or even thirteen if we separately distinguish 
the small head segment, which may be withdrawn, and 
but little observable ; five or six rear segments are of 
nearly equal stoutness when only half grown ; after- 
wards counting from the three stoutish rear seg- 
ments, the others taper towards the very small head. 
The middle and rear segments have pad-like bristly 
processes underneath, which aid the maggots in 
creeping, in which action they also make much use 
of the head segment's grappling hook. The maggots 
feed voraciously, but they seem, like the larvae of the 


honey bee, to pass out very little anal excreta ; some have 
thought that, like what is said of bee larvae, no excre- 
ment is discharged until after the imago has emerged 
from the puparium ; but such conduct seems altogether 
incredible. In the bee-hive doubtless the assiduous 
workers ever wash their babies clean and lick up all 
matter, just like domestic cats and dogs, when nursing 
their young. 
^ I The larva of the blue-bottle, called a gentle, is pro- 
portionately larger but very similar, except that the 
rear segment possesses a ring of tubercles, which may 
have some useful function in connection with two 
breathing tracks, which have their orifices at that part 
of the body. 

The larva of the lesser house-fly is very peculiar ; 
all its segments have projectmg tubercles ; its whole 
body is rather louse-shaped, having not cylindrical 
but somewhat flattened segments, of which the middle 
are the broader, and those near the head and tail the 

The transformations in the case of the blue-bottle 
are typical of the house-fly and others of closely related 
families and genera which are many-brooded within 
the year; these creatures develop very rapidly immedi- 
ately after emerging from the egg. Some other kinds 
of dipterid maggots, which are single-brooded, pass a 
very prolonged and obscure early period of skin- 
shedding and non-feeding, a preparatory sort of baby- 
hood metamorphosis ; then at last they begin to feed 
voraciously and to follow the general habits of other 
maggots. Some maggots curiously refuse to feed 
except in company ; probably some are unable to feed 


on dung except where other species are providing the 
necessary dissolving juice. 

When the common maggots or gentles have ceased 
feeding, they burrow into the ground or crawl away, 
often to a considerable distance, apparently seeking a 
secluded, a more wholesomely clean, and a dryer spot. 
During this migrating time, they are palatable food 
for many birds, which would not eat them in their 
former food-loaded or unscoured state. Indeed, it is 
doubtful whether either a vulture or a raven could eat 
a fly-blown carcase without danger of myiasic punish- 
ment. The skin of the larva whilst growing is trans- 
parent, but, when about to pupate, it thickens and 
becomes an opaque creamy white. 

The most marvellous part of the metamorphosis of 
the blue-bottle is concealed, when the gentle becomes 
the pupa ; according to Reaumur the embryonic fly 
develops most curiously inside the puparium by a 
procedure not exactly like the change from the cater- 
pillar to the chrysalid in the case of the butterfly. 
After a pause of a day or two, the front segments of the 
fully fed maggot contract, so that the body assumes a 
barrel-like shape ; the skin then hardens, and turning 
a reddish brown it becomes a much contracted shell 
or case called the puparium. However, the long 
slender maggot has done something more than merely 
shrink and shape itself conformably to the case; it has 
withdrawn its embryonic head, so small as to be hardly 
distinguishable microscopically, together with its 
embryonic legs, wings and thorax into its embryonic 
abdomen ! As the development proceeds, and the 
embryonic members of the future perfect insect acquire 


their destined shape, the immensely increased head 
and the thorax with its appendage members slowly 
emerge, and the partly inverted integument of the 
abdomen rolls back, disclosing the shape of a fly not 
before recognisable. 

Other naturalists would have it believed that the 
true account of the transformation is as follows, — when 
the maggot has shrunk and freed its body inside its 
skin which forms the case or puparium, all its pre- 
existing internal organs become absolutely dissolved ; 
then out of the fluid mass a new growth ensues, con- 
stituting the pupa with its recognised shape. This 
account is the one represented in most modern 
entomological books, and is based partly upon B. T. 
Lowne's monographic work on the blow-fly. 

The comparative embryologist of our day is inclined 
to be a hyper-theorist, and so it seems that some have 
not remained content with either of the above accounts ; 
to them, apparently, the production of the large and 
complex head of the imago out of a single small 
anterior segment of the maggot requires a more recon- 
dite explanation, and must be brought into harmony 
with analogous facts. To this end some degree of 
linked support is found by the investigations of micro- 
scopic anatomy, and it has been conjectured that not 
one or two head segments, but five are lying blended 
and embryonically hidden in the larvae, all ready to 
bud forth. However, for fear of wearying too much 
with the theories of advanced erudite scientists, the 
following jeu d! esprit is presented, instead of a more 
elaborate and sober attempt, to lure the unscientific 
lay reader to an extreme hypothetical conception of 



the "essential unity" underlying the apparent diversi- 
ties of Nature within that vast domain of the Kingdom 
of Fauna, which is obviously outside the later creation 
of a vertebrate Animalia. 




Fig. 5. Illustrating the debatable continuity of a l2-segmented 
structure throughout the metamorphosis. 

The futurist's dogmatic CREDO of creative progress, 
For him who would meritoriously pass his histo- 
logical examinations, and qualify as a Professor and 
Doctor of Science, above all it is necessary that he 
should acknowledge the unicellularity of the primae- 
val OVUM (or e^), whence proceeds the seventeen- 
segmented boneless ANNELID (or worm), out of 
which there develops the quadrangular articulated 


"crustacean INSTAR (or shell-encased aurelian), which 
" metamorphosises into the winged IMAGO (the an- 
Vgelic ? or diabolic ? fly) ; in the contemplation of this 
'^ knowledge alone is there supreme Darwinian Modern- 
"ismal salvation and felicity." Amen. 

In view of the prosaic illustration of transmutation, 
figure 5 above, the futurist disciple w^ill have to accept 
the seventeenness of segmentation by something like 
faith without sight. 

The quadrangularity of the crustacean stage is based 
upon the idea that the wings bud out from the two 
upper corners, whilst the legs develop from the lower 
corners of the transmuting instar. 

Perchance the reader will desire information about 
the use of this curious word " instar," which has not the 
honour of notice in Dr. Sir J. Murray's New English 
Dictionary. One might well feel proud of the oppor- 
tunity of adding the smallest item to such a stupendous 
and monumental work, but I fear I am only qualified to 
venture a fair guess. Virgil, I believe, used this term 
in allusion to the legendary wooden horse of the 
Greeks at their siege of Troy. Some time less than 
one hundred years ago entomologists recognised that 
the words aurelian, chrysalis, and pupa were none of 
them an inherently fit term of general application to 
the stage of insect life to be indicated. After many 
attempts, this latest proposed substitute seems to be 
gaining favour. 

The fly emerges after bursting apart the first four 
segments of the puparium ; this it does by a curious 
provision, whereby it can inflate a chamber in its head 
in a queer, balloon-like fashion, making a bag-like 


extrusion, which it uses as a punching and pushing 

After emerging from the ground, the fly withdraws 
the bag-Hke extrusion and cleans itself. Its body soon 
grows fit and it becomes very active, as long as day- 
light and warm w^eather favour it ; otherwise it seeks 
shelter and becomes quiescent ; however, artificial 
light and heat will awaken it to nocturnal activity. 
Sweets, carrion, and filth are all attractive to the blue- 
bottle, but the house-fly and the lesser house-fly also 
find extraordinary attraction in both man and his 

Considering the superfluity of other flies, and the 
multitude of other insects ever ready to do duty as 
devourers of carrion, garbage, and filth, the scavenging 
services of the larvae of the house-fly can be well 
dispensed with. 

In civilised communities cremation in a refuse 
destructor is the only'sanatory method of treating town 
refuse. The economic value of the fly is very little, 
and consists merely in its food value for certain birds. 

In warm w^eather the scavenging capabilities of all 
the carrion and filth feeding maggots are very remark- 
able, and there appears no exaggeration in the state- 
ment by Linnaeus, that the progeny of three flesh flies 
can eat up the carcase of a horse sooner than it could 
be devoured by a lion. 

When a batch of eggs has matured in the abdomen 
of the female, she is most careful in the location and 
manner of their disposal. Guided by the sense of 
smell, she will not lay her eggs except in contact with 
food, or in places securing her progeny access to their 


intended food. By the use of her soft, slender ovipositor, 
which is telescopically extensile and flexible, the eggs 
are deposited in shaded and concealed situations. 

The house-fly is credited with laying batches of eggs 
at intervals, perhaps four or more times, and about 1 50 
on the first occasion, then 100, and less on subsequent 
occasions. Under favourable circumstances the eggs 
may hatch within a few hours of their being laid. 
The maggots of midsummer broods may be full grown 
and pupate in six days, and the perfect insect may 
emerge from the puparium in another ten days of warm 
weather, but in cold weather the pupae of autumnal 
broods may remain dormant for several weeks, or even 
months. When nine or ten days old the mature fly may 
begin to lay eggs ; hence, with such a life-cycle, in a 
month of very favourable weather the progeny of a 
single pair may number, say, 500 ; in two months' 
time the number may become 250 times 500 ; and in 
three months' time many millions ! 


The house-fly has quite the typical insect form, inas- 
much as there are three well defined sections of body 
— the head, the chest or thorax, and the abdomen ; 
also it has three pairs of legs, each with nine joints, of 
which five joints constitute what may be called the 
foot. The twelve segments of the maggot are observ- 
able as twelve rings in the puparium, but in the fly the 
three which form the thorax look like one, whilst the 
eight which should theoretically exist in the abdomen 
look like four or five, until the rings of the ovipositor 
are counted. 

The illustration on page 39 will make plain how 
the permanence of the twelve-segment structure (con- 
spicuous in the larval stage) has been thought to persist 
throughout the life-cycle, but at the same time will 
disclose how great is the change in the relative 
proportions of these segments. 

The prominent features of the hemispherical head 
are the two large compound eyes and the proboscis or 
trunk-like mouth. The antennee or horns are very short 
appendages with three joints ; small plume-like 
projections, called arista, are attached to the third 
segment ; the horns hang down over a hollow in the 
middle of the face, and are insignificant in size when 


compared with those of other kinds of insects ; but 
their structure viewed under the microscope is intricate, 
and they may be efficient organs of sense perception, 
probably in part auditory. The really unique feature 
is the retractile and suctorial proboscis, which is often 
incorrectly regarded as the tongue ; it is normally held 
doubled up and withdrawn towards a hollow under the 
head, whence it is from time to time extruded. The 
structure of this member is characteristic of the entire 
tribe to which the house-fly belongs ; it is a fusion or 
'combination of mouth parts, which in other insects are 
used more or less separately for the various functions 
of inspecting, biting, masticating, drinking and 
"SvVallowing. In the house-fly the proboscis is 
absolutely suctorial, and is not provided with the 
lancets used by the blood-sucking flies for piercing the 
skin. Two maxillary palpi are attached to the upper oi* 
basal part of the proboscis, which is called the rostrum 
(a snout) ; the lower part is called the haustellum (a 
pump), and it has at the end a pair of soft cushion-like 
lobes or lips, which, when spread apart, form a heart- 
shaped pad with an opening in the centre. The max- 
illary palpi are used for feeling and probably smelling. 
Each mouth-lobe has amain collecting central channel 
and thirty subsidiary cross channels of a wonderfully 
complex character. Imbibed fluids pass from the 
mouth-lobes to the gullet along a passage in the 
haustellum and the rostrum. 

As with many other flies and other insects, there are 
on the top of the head very small simple and rather 
inconspicuous eyes called ocelli, three in number, 
between the large and prominent compound eyes. 


which latter are said to possess each four thousand 
facets. The compound eyes of the male fly are 
proportionately larger than those of the female ; it ife 
quite observable that they approach each other more 
closely at the top of the head, a feature of sex differenti- 
ation which is shared with bees, wasps, and many 
other insect creatures. It is thought that a single 
brain image arises from the combined views of the 
four thousand facets of the compound eyes blending 
with the view conveyed through the "ocelli." How- 
ever, it is a most curious fact that it is the inconspicuous 
ocelli which are of supreme importance visually. The 
compound eyes have doubtless some special function, 
but throughout the insect world the size of compound 
eyes is not a certain indication of keenness of sight. 
The vision of the fly is good for distinguishing the 
movement of any broad mass, but it is rather in- 
effective for observing a thin line, as may be proved 
by slowly lowering a knife blade, with a steady hand, 
when its body may be severed before the fly takes 
alarm. It is a remarkable fact that the family of 
Tabanida (blood-sucking breeze flies), which are 
destitute of "ocelli," are the dullest sighted of all flies; 
in fact, at least semi-blind. Moses Harris observed 
that a blue-bottle became practically blindfolded when 
its ocelli were covered with an opaque pigment. 
Probably this is the case with other insects. Bees, 
which require long distanced sight for home returning, 
are well provided with ocelli. Butterflies, however, 
without the use of ocelli have a distinct faculty of day- 
light vision for a moderate distance. The investigation 
of sight by blindfolding is very difticult in flies. 


There are two cephalic ganghons, which are regarded 
as the brain ; these are situated in the upper part of 
the head close to the neck. There are also ganglions 
in the thorax with connections extending into the 

The thorax is mainly occupied with the powerful 
muscles which actuate the attached wings, the legs, and 
the small appendages called halteres or balancers, which 
are supposed to be obsolete hind wings. There are 
three unequal segments in the thorax ; the pair of front 
legs belong to the first segment, the wings and the pair 
of middle legs are attached to the second larger segment, 
whilst the third is connected with the hind legs and 
the halteres. 

The breathing apparatus of the fly is distributed in 
portions over the head, thorax, and abdomen ; it con- 
sists of a number of internal air-sacks with membranous 
ducts ramifying everywhere ; the largest air-sacks are 
in the abdomen near the waist. There is a pair of 
external spiracles to each segment of the body, and 
these lead to the air-sacks. 

The lines on the wings of the house-fly called 
nervures have already been alluded to in Chapter II, 
These nervures are strengthening ribs to the trans- 
parent tissues of the wings. The tissues are double 
Xtop and bottom) enclosing the nervures, which are so 
united to the connections called trachae of the air-sacks, 
that the newly emerged fly helps to extend its limp and 
crumpled wings by a process of inflating the nervures. 

The stomach is located partly in the thorax and 
partly in the abdomen. A passage from the gullet 
passes through the neck into the lower part of the 


.thorax, where are the entrances to two long capacious 
chambers, of which the upper one is the true stomach 
and the lower one a store pouch, which latter may be 
likened to the honey bag of the bee. The fly habitually 
regurgitates liquid food stored in this pouch, and, 
somewhat after the manner of the cow chewing the 
cud, passes the same back into the true stomach, 
whence it proceeds onwards through the digestive track. 

The abdomen holds all the other ordinary internal or- 
gans including that which may be called the heart, and 
which lies above the stomach ; it consists of a long 
muscular tubular vessel with four contractile chambers. 

Although the organ called the brain is located in the 
head, and although that called the heart is in the 
abdomen, yet some sense of control over bodily motions 
curiously exists separately in the ganglions of different 
parts of the body. This fact seems to make it possible 
for one extremity of the body to continue performing 
a pleasurable action (say, the head drinking honey) 
after the other extremity has endured a painful catas- 
trophe (say, amputation of the abdomen). However, 
it may be fairly surmised that no creatures of a lower 
grade than warm-blooded vertebrate animals feel 
pleasure and pain in any way at least after the manner 
of mankind. 

The most vital part of the fly is not the head but the 
thorax. A severe squeeze on the thorax will effectually 
paralyse and kill the creature. Muscular movements 
of different parts of the fly's body, which continue after 
severance or other fatal injury, cannot be regarded as 
visible proof of a slow death and prolonged sensibility. 

Possessed of six legs, each with nine joints, the fly 


exercises a unique capability of walking ; the legs are 
moved three at a time, a front and a hind leg on onb 
side advancing simultaneously with the middle leg on 
the other side ; thus the fly proceeds most securely 
always poised on three feet, which are so well furnished 
with pads, claw-like hooks, and hairs, that it can walk 
over polished glass and can even walk upside-dowh 
along comparatively smooth surfaces. 

In comparison with the more heavily constructed 
wasp, with its four wings, the house-fly, with its two 
wings, is the more alert and active flier. The wasp is 
more robust than the fly and will be active in weather 
too inclement for the latter ; however, some of the 
frail and slender gnats will brave cold temperatures 
impossible for the wasp. 


It might be supposed that a strongly developed house 
haunting proclivity would not be consistent with a 
disposition to roam far afield from the locality of birth. 
Many clever experiments have been made with marked 
flies released and recaptured within measured distances 
and times. After an immensity of pains taken, very 
little profitable knowledge has been arrived at thereby. 
Little of what we really want to know is indicated by 
such a fact as that, out of hundreds or of thousands of 
marked flies released, one per cent was recaptured at 
spots as remote as a mile within two or three days, or 
by such a fact as that a large percentage should be 
observed to remain within a more limited home circuit. 
The variable factors of temperature, wind, sunshine 
and rain inevitably tend to discredit the reliability of 
the observed results following any such experiments. 

' Close observations of the habits of the house-fly re- 
veal the very appurtenant fact that the movements of 
newly-hatched flies, for their first six or seven days' 
active life, differ from those of a more mature age, when 
the breeding instinct has grown strong. The latter 
are disposed to locate themselves for the rest of their 
lives in and about one attractive spot, and they areMn- 
disposed to fly high above ground or to travel far. 


unless it be with the object of leaving an unsatisfying 
locality and discovering a better place. However, the 
younger flies seem to feel no such restrictive influence, 
for, as soon as they have become fit and the weather 
suits, they show an inclination to fly high and thus may 
travel to very remote places. It is just the same with 
peacock, red admiral, and tortoise-shell butterflies, 
which I have often reared and released for adding 
to the interest and beauty of a flower garden. In 
sunny weather many or most will soon wander never 
to return ; those which have remained a few days 
continue residence close round about, especially if 
nettles, the food plant, grow in the neighbourhood. 

It would be of great interest if we could discover 
how far a plague of flies arising from unsanatory 
surroundings in one locality is liable to spread to the 
injury of other localities. 

On this subject nothing useful can be said other 
than can be safely surmised from the known habits of 
the fly. The female has none of the attachment of the 
honey-bee to its hive and community ; she is not 
moved by an instinct like that of the wandering bumble- 
bee in spring to found a colony ; she is indeed very 
solicitous about the disposal of her eggs, but she is not 
impelled by any desire to place successive deposits in 
one locality. 

The lesser house-fly has proclivities similar to those 
of the common house-fly, but probably she travels less 
far afield although a little more inclined to outdoor 

Very little is known about most of the common out- 
door sweat- flies. Some breed in dung, and may be 


many-brooded and otherwise resemble the house-fly in 
proHfic increase ; others are more consistently vegetarian 
in the larval stage and slower in development ; and 
some are possibly even single-brooded, like certain 
foreign large sized flies which fortunately appear only 
for a few weeks of summer weather, for they have a 
curious semi-bloodsucking habit of feeding after or 
alongside the skin-piercing flies, and their suctorial 
mouths are capable of further inflaming wounds and 
carrying infection from one animal to another. 

The robust blue-bottle very closely resembles the 
house-fly in an inclination to spread the brood. 
Mature females, however, do sometimes show a slight 
temporary kind of " homing " instinct ; having secured 
a cosy corner and a well sheltered retreat in a sunny 
wall, the occupant will battle for its possession, buffet- 
ing new^ comers. 

Some of the smaller filth flies and many of the fungus 
flies hav'e their lives, in the imago stage, influenced and 
shortened by their extra early sexual maturity; the 
females are fertilised whilst newly hatched and their 
wings limp and unfolded. This fact accounts for our 
seldom seeing some kinds of these flies abroad except 
females ; and these are never seen to indulge in dances, 
flirtations, and games of chasing and buffeting each 
other, after the manner of so many kinds of flies. 
They habitually fly low ; nevertheless they travel very 
great distances, for, though short, their flights arc 
incessant when searching for their special kind of food. 

The most disinclined to roam of all common flies 
is the stable-fly. None other is a more eager seeker of 
sunshine, but when basking on a sunny wall it seems 


unwary and sluggish ; it is seldom to be seen far from 
where horses or cattle are stationed or stabled ;. how^ 
iever, it will make very long journeys hovering about a 
driven horse or reposing on the car. 

A plague of flies of local origin will not take many 
weeks of summer weather to spread, but it is generally 
observable that plagues of flies, like many other occur- 
rences, are simultaneous co-incidences distributed over 
wide areas and at places remote from each other. 


Flies, which are such insidious and pertinacious 
persecutors of man and beast, are themselves the prey 
of innumerable enemies ; many species are much 
sought for by birds, they are devoured by lizards 
and toads, and they are equally preyed upon by 
predaceous insects. Those flies which have bodies 
with banded colours, and which otherwise somewhat 
resemble bees and wasps, probably escape being the 
victims of some birds ; but the tribe of flies does not, 
like the beetles, the lepidopterae, and some other 
insects, furnish instances of other common protec- 
tive devices, such as bearing and voiding offensive 
secretions, or attempted concealment in repose by 
mimicry of environment. 

All insectivorous birds are fond of a diet of flies, 
and we may largely attribute the spring-time immigra- 
tion of the beautiful swallow tribe to the fact that 
in the northern parts of the temperate zone swarms of 
soft bodied dipterous insects abound, and there re- 
place the hard cased and more chitonous insects of 
hotter countries. The true swallow, the house martin, 
and the sand martin, all require a special food for theii 
nestlings; and they also then require the longer 
summer days and the prolonged twilight of our 


northern clime for the frequent feeding of their young. 
The prevalence of flies near houses partly accounts for 
the partiality of the swallow for nesting under the 
eaves of our dwellings, where unfortunately the 
aggressive, the pampered, and the demoralised sparrow 
in towns generally prevents successful breeding by 
appropriating its nest and sometimes by eating its 
eggs. People who desire to favour the breeding of 
the swallow should destroy the nests immediately 
after the migratory departure of the builders. Their 
retention until the following spring is in no way an 
enticement for rehabitation ; on the contrary, it favours 
the objectionable habit of the sparrow to use them for 
a night resort, whereby they become very foul with 
bird vermin. The cleanly swallow annually desires a 
newly built habitation, and a bare peg projecting two 
inches from the house-wall will much encourage swal- 
lows to start the foundations of a nest thereon. 

Ground feeding birds of many kinds eagerly search 
for flies, their pupae, and their larvae ; even some 
finches wmII add flies to their diet in the nesting 
season. Chaffinches are very fond of the house-fly 
at all times. 

The wasps are assiduous hunters of flies, and, though 
possessing less agility than their prey, they manage to 
pounce upon many victims. Very common enemies 
are the predaceous EmpidcVf of which numerous 
species are native to Great Britain. Less common, 
but very observable w^hen met with, are the closely 
related robber-flies, Asilida\ which are hardly ever 
to be seen on a hot midsummer day w^ithout a captured 
fly held between their strong front legs. The largest 


of the robber-flies, A. crabroniformis, is a conspicuously 
fine insect. It equals the hornet in length, but is 
more slender in body, tapering throughout the abdo- 
men towards the tail ; it resembles the queen hornet 
in colour. The dragon-flies also eat flies, but they 
mostly feed upon winged aphides, gnats, and the like 
small game. 

More secret destroyers of the fly brood are a few 
rather obscure creatures akin in their nature to the 
ichneumon flies, which are parasitic mainly but not 
exclusively on lepidopterce. Likewise, certain insec- 
tivorous beetles share in the good work of fly 

Flies are often observable encumbered with minute 
vermin ; some of these are true lice, and some are 
allied parasites called false-scorpions or chelifers. 
These are acquired whilst frequenting dung and refuse 
heaps, where they abound ; thus, probably cheese- 
mites and the like are conveyed by flies into our 
larders and warehouses. 

It is not only the web-weaving spiders which prey 
upon the proverbially "silly" flies; there are also 
roving spiders which do not contrive webs, and some 
of these are nocturnal feeders ; the latter can only be 
seen in daylight by looking for them underneath stones 
and in other hiding places. 

Other fly destroyers are internal parasites, and these 
include thread worms {N ematoidea) y as well as Proto- 
zoa of obscure kinds. These are being scientifically 
studied by experts, and their life-history is as curious 
as that of others of the same order, in that they pass 
from one host to another, which fact for long helped 


to baffle investigation. Some have now been proved 
capable and others are suspect of baneful possibilities. 

The house-fly fungus, Empusa musccc, which is pre- 
valent in autumn, has ever attracted popular wonder 
and much scientific attention. It has been much 
written about and plentifully illustrated, but the 
complete life-cycle of this peculiar parasitic growth 
is not yet understood ; much that has been published 
as of fact is mere "copy" repeated in one book after 
another, originally in fact rather a matter of conjecture, 
based upon the idea that fungic propagation must be 
on exactly parallel lines with known biologic processes 
of a botanic order. 

The house-fly fungus seems to have a superficial 
resemblance to some of the common "moulds," but 
mycologically examined there is good reason for 
classifying it with a family {Eniomopkthorecv)^ which 
may be capable of an alternative form of fructificative 

The originating germ somehow at some time must 
be supposed to have effected a lodgment in the body 
of the fly or possibly that of the maggot. Later on, 
one cannot say when, fungic spawn (a pulpous 
mycelium) starts a course of development, invades 
every part of the body, quickly kills the fly, and fixes 
it to the spot to which in its last moments it has 
crawled, often a window-pane. Its corpse is now 
swollen with the spawn developed into masses termed 
hyphal ; but these should not be called hyphal (thread) 
but quasi-sclerotia, bodies intermediate in a process of 
normal development between the mycelium and the 
fruiting stage ; fungic fructification ensues with great 


rapidity; and the corpse becomes suffused with an 
appearance of white mouldy excrescences, fiHforra 
conidiophores, of which the club-Hke tips make a 
copious aerial discharge of white spores ; when these 
adhere to a glass or window-pane they imprint thereon 
a remarkable halo. Attempts to artificially infect other 
flies with these spores are common failures or have led 
to contrary conclusions. 

The period from the first symptoms of distress to 
the death of the fly, and from that time to the spore 
discharge is wonderfully short. The infectious germs 
may have been long dormant in the fly, and very likely 
may have been acquired in the maggot stage. In the 
absence of exact knowledge, w^e can only make con- 
jectures from observations of some kindred fungic 
parasites, which are not very uncommon amongst the 
chrysalids of certain moths, beetles, and the pupae of 
some annual wild bees. In these cases it Seems very 
unlikely that the infection was incurred otherwise than 
in the caterpillar or larval feeding stage. Dampness 
and insanitary conditions seem to favour the spreading 
of such disease, especially amongst artificially reared 
larvae when crowded together and closely confined. 

Other kinds of flies do not, so often as the house- 
fly, perish from Empusa musccVy but I have seen a 
common yellow cowdung-fiy, as early as June, thus 

In spite of all antagonists the brood of the house- 
fly flourishes and multiplies, but this is because great 
opportunity and encouragement is provided by the 
neglect of good sanitation by mankind. 


The house-fly may seem at first much less to be 
dreaded than any one of the painfully ** biting " or (to 
be correct) skin-piercing and blood-sucking flies ; yet 
it should be regarded as a much greater enemy to 
humanity and a more dangerous peril than any of 
those other flies, of which some short mention and 
description has now been given. Its life-history and 
its fecundity have been already alluded to ; its rapid 
growth and maturity counterbalance the fact that it is 
short lived. 

From ancient times there has been a consensus of 
opinion that there was in some way a connection of 
cause and effect between swarms of flies and the 
spread of disease. In the plagues of Egypt, in the 
reign of Pharaoh of the Exodus, it will be remembered 
how, after " the land was corrupted by reason of the 
swarms of flies," Exodus viii, 24, there came "a 
very grievous murrain " upon cattle. Exodus ix. 3, 
followed by a "plague of boils and blains" upon man 
and beast. 

In our present day insect life is being scientifically 
investigated with the view of establishing the con- 
nection, and of discovering fully the serious rdle of 
disseminating disease, of which the house-fly has long 


been suspect. The microscope reveals much, and the 
art of bacterial culture now explains how it is true that 
the superabundant creature, which has persistently 
followed civilised man into every quarter of the globe, 
has ever had a share in conveying contagion beyond 
that of any other household pest. 

That the house-fly is bred in filth matters not much. 
After emerging from the puparium its first voidance of 
faecal matter may be contaminated with live baneful 
germs, but it voids itself before its first flight. Having 
six legs it stands upon two pairs, whilst with the other 
pairs, at one time the front pair and at another time the 
hind pair, it works frequently and vigorously at 
brushing and stroking down every part of its body. 
Though it starts its new life quite a wholesome new- 
born creature, and though it must be credited with 
being a most assiduous remover of dirt from its own 
body, yet from the human point of view its subsequent 
life is a persistently disgraceful career. 

It is the evil course of the newly-hatched and self- 
cleaned fly not to restrict its diet to the honey of 
flowers, as do some of its relations. Its food includes 
excrement, sputum, and eveiy kind of putrefying 
organic matter likely to be swarming witlr micro- 
organisms of a character deleterious to humanity. It 
is certain that, when only a few^ days old, a fly will 
practically abound internally and externally (on the 
feet) with dangerous germs, as amply proved by 
methods of laboratory culture , As it feeds, it walks 
over the food ; and the hairy joints of its feet, when 
microscopically viewed, appear conspicuously liable to 
carry germs in spite of frequent attempts at self- 


cleaning. Wherever it alights and walks, it prospects 
with a touch of its trunk, which is the main instrument 
of evil. It has a very filthy habit, from time to time, of 
depositing pale vomit spots as well as dark-coloured 
faecal droppings. These defilements are visible, 
wherever it may alight on walls, windows, ceilings, 
and especially on pendent ornaments, whereon the 
males delight to rest. 

Its manner of feeding upon solid food is to pour 
forth a copious supply of saliva, to regurgitate some 
previously imbibed fluid draught, and then to re- 
imbibe ; thus, besides devouring soft food, it dissolves, 
befouls, and feeds on crystalline sugar and other hard 
di*y food materials. 

Its regurgitated fluid commonly swarms with bacteria, 
microbes, and the like. Imbibed bacteria are not 
inevitably killed in the digestive process of the fly, for 
its excrement has been found to abound with well 
recognisable infective germs. Iji the mar ket, the shop, 
the larder, and on our tables, the house-fly seeks ev ery 
opportunity of befouling and contaminating human 

The varieties of micro-organisms are multitudinous, 
doubtless many more in number than the microscopist 
and the bacteriologist expert have yet isolated and 
registered as capable of identification. Granted that 
the majority of these are non-pathogenic to humanity, 
still a formidable number, including some which are 
very generally disseminated, are virulently pathogenic, 
and many are suspect. There is no need to give a list 
of all the infectious diseases which man and beast are 
liable to contract, but the germs of nearly all may be 


/ carried from place to place, from creature to creature, 
/ and from person to person, through the intervention or 
\ agency of the house-fly. The medical profession are 
( convinced that infantile mortality from epidemic 
\ ^ dia rrhoea must be attributable to summer flies. 

In the matter of food which becomes fly-infected after 
having been cooked, or of food like milk, butter, and 
fruit, which are consumed raw, it should be known 
that a single pathogenic germ of ultra-microscopic 
dimensions, having obtained lodgment in the body, 
may there multiply and originate a fatal disease. On \ 
the other hand, raw meat which has been infected may, 1 
after the bacteria have been all killed by cooking, J 
contain excreted poison in deleterious quantity. / The 
decomposition of infected meat begins ten or twelve 
hours before the bad odour is perceptible. 

Fortunately the omnipresent germs which most 
commonly deteriorate our food are not very actively 
deleterious, or are only slightly debilitating; yet 
wherever such less obnoxious germs get lodgment, 
there the ready prepared and most favourable breeding 
place for the worser kind is to be found. The various 
species of these evil things are not always exterminating 
competitors ; they sometimes flourish in company, and 
dwell together, like the seven devils within the exorcised 
and sane man after his relapse, as mentioned in the 

That food gets fly-blown and maggot-infected is a 
very disgusting fact, but the plainly visible result is 
of little hygienic significance apart from the more 
concealed facts of the fly-borne conveyance of zymotic 
diseases. '- ■ '" - " ' 


Internal protozoal parasites and parasitic worms 
breed in and are disseminated by the house-fly ; so also 
are the fungic spores of fermentive yeasts, of moulds, 
and the like, but these latter are mainly disseminated 
by mere air currents. The eggs of tape-worms and 
the like are carried by dung-frequenting flies to food, 
especially to semi-putrid food devoured by dogs and 

Some of the skin-piercing and blood-sucking flies 
are pestiferous in a more direct way than any of the 
tribes of filth and sweat-flies. They are the usual or 
suspected agents whereby anthrax, cattle-plague, swine 
fever, glanders, and other diseases are spread far and 
wide. Some of these last blood-sucking flies will 
travel with and on the bodies of transported animals 
for long distances ; of course there can be no doubt 
also as to the capability of disease dissemination by 
the direct independent flight of flies to long distances 
with favouring weather and breeze. Such evils are 
prevalent throughout the temperate zones, but cir- 
cumstances are far worse in the tropics, where Glossina 
morsitans^ considered by some to be a near relation of 
our Stomoxys calcitrans^ transmits the microscopic 
trypansomes which cause the devastating ** sleeping 
sickness" of mid-Africa. This last reference, and 
other discoveries of the fly-borne germs of recurrent 
fevers, should bring into prominent notice a very 
pertinent fact, which has not yet received adequate 
scientific investigation. All the bites of our common 
blood-sucking insects, flies, gnats, midges, fleas, etc., 
are each kind of them wounds, sometimes very in- 
flammatory, sometimes but little or not at all so ; 


furthermore, the worst inflammatory wounds not 
uncommonly show feverish symptoms of a well marked 
periodic character, quiescent intervals being followed 
by revived inflammation in the same spot. These facts 
almost prove, or at least strongly suggest, an explana- 
tion that in the latter cases the source of pathogenic 
trouble is of a microbic character, and that periodic 
recurrence of feverish and inflammatory symptons is 
the time of the spore-swarming of breeding microbes ; 
the difl^erence between these latter and those of a more 
severe and often fatal kind in the tropics being that 
the one class finds the human body a fit host in which 
to multiply but the other class does not, and accord- 
ingly the latter grow weaker until their breed dies out. 
Similar effects can be observed in cattle and other 
animals, but all creatures, after suffering much from fly- 
bites at first, afterwards become for a time more or less 



We have seen in Chapter VIII that the checks' 
which Nature has imposed upon the prolific breeding 
of the house-fly have been insufficient to protect 
civilised mankind from ancient times continuously up 
to the present day. This defect need now no longer 
be endured ; but, alas, communities and individuals 
are ever slow to be warned, and averse to practise 
newly advised methods of sanitation. In few other 
directions is there greater promise of advancement in 
general public health and comfort than by preventive 
measures against the breeding of the house-fly. 
Effective measures comprehensible to all who consider 
the subject are so easy of application, that, if universally 
carried out, the house-fly might become a rare insect 
in a very few years' time. It is, however, of funda- 
mental importance that the public should be made to 
comprehend the case ; else the power necessary for 
enforcing suitable regulations by the local authorities 
will not be obtainable. 

Preventive measures must constitute the supreme 
objective of an anti-fly crusade. The habits of the 
house-fly and its life-history make it clear how 
successful breeding may be prevented. The breeding 
places are local and accessible ; the food substances 
of the larvae are capable of being put under control ; 


and the maggot stage is the opportune period wherein 
the fly plague is most obviously open to attack. 

In all town and suburban parishes a house to house 
collection of domestic refuse and garbage must be 
made, not weekly, but bi-weekly in summer, and the 
material must be cremated in a dust destructor furnace 
within a few days of its collection ; thus neither larv^ae 
nor pupae therein would survive ; no alternative 
disposal otherwise than by cremation should be 
attempted. Furthermore, and above all else, only 
refuse collecting bins of an authorised pattern should 
be employed. Contrary to the prevalent idea these 
should not be fly-proof and not have air-tight 
covers ; they should freely admit air all round 
and should encourage the access of breeding flies. 
They should stand preferably in open daylight places 
and should be egg- traps for flies which, thus encour- 
aged, w^ould hardly ever deposit their eggs elsewhere ; 
the result would be that all maggots and pupae would 
be inevitably cremated. 

It may be objected that, if open dust-bins are used, 
house-flies after visiting the same may return to the 
house and subsequently contaminate food in the larder. 
There will be such a possibility, but the danger thereof 
can be minimised, and would in fact be nearly auto- 
matically cured, as prospective fly progeny perished. 
Furthermore, there are circumstances which indicate 
that the said danger would not be great, and anyhow 
nothing comparable to the baneful effects which are 
now endured. The worst germs are not those of 
newly discarded food remnants ; the commonest and 
well-known bad smelling germ of ordinarily " tainted " 


meat, which is exceptionally attractive to the house- 
fly and the blue-bottle, is fortunately, after cooking, not 
so dangerous as some of those other deleterious micro- 
organisms mentioned in the last chapter. Taking one 
thing with another the balance of benefits and dis- 
advantages will incline overwhelmingly in favour of 
open dust-bins, wherein food remnants may purposely 
become fly-blown. An improved dust-bin lid has been 
contrived which combines with the cover a centrally 
held wire-gauze ** balloon" fly-trap, wherein flies will 
congregate and be imprisoned when attempting to 

Unfortunately air-tight dust-bins have been very 
generally recommended as a giand device of hygienic 
value ; hence it is most necessary that unthinking people 
at large should be informed how much better it is to use 
open bins which can catch and secure for destruction 
prospective fly-broods. It may be asked — why not 
trap and kill the breeding females ? The reply is that 
to do so will be good, as is to be explained in the next 
chapter ; but contrivances for the latter procedure are 
apt to be less effectively put into general operation. 

The fly swarms of mews, arising from accumulations 
of stable manure, will be difficult to alleviate without 
stringently enforced measures, but it is a mistaken 
notion to believe that town flies are bred in stables to 
such an extent that the invaders of our dwellings and 
town restaurants, shops, and markets, are merely or 
mainly the overflow of the mews. The concentration 
of many kinds of flies is very dense around ill-kept 
mews, and in midsummer-time a large percentage will 
be true house-flies. Frequent removal and cremation 


of stable manure would be quite effectual, but there is 
reason to think that, if proper care be taken, no such 
drastic procedure as cremation will be absolutely 
necessary, unless perhaps for the months of July and 

There are two matters involved in sanitary stable 
reform — one is the proper structure of the stable floor 
and the treatment of the litter whilst in use for 
bedding ; the other is the disposal of the horse 
droppings and the discarded litter called stable manure. 
If the floor be good and the bedding be well kept and 
fairly dry, which is often not the case, then the effective 
breeding of flies will be in the dung-pit and the 
external manure heap. From a sanitary point of view 
these latter are indeed almost everywhere ill-kept. 

The general fate of maggots living on the floor of 
well-kept horse-boxes is to end their lives drowned in 
the drains to which they descend, when or before they 

In these days of motor-cars and fewer horses the 
horticulturist everywhere is eager to buy good stuff ; 
now stable manure to be good must be fresh and free 
from the garbage with which stable men wantonly 
corrupt the same, instead of consigning such extraneous 
refuse to a proper separate dust-bin for collection and 
cremation. So much can be done remuneratively with 
a regular supply of clean fresh manure, that it seems 
almost worth while transgressing the proper limits of 
this booklet and writing chapters on mushroom culture 
and on the intensive hot-bed cultivation, with the aid 
of "cloches" or bell glasses, called French gardening. 
It may be thought that such cultures will of themselves 


breed swarms of flies. Though such is not necessarily 
the case, the liabiHty by common carelessness is very 

The expert horticulturist has a special preparatory 
treatment for fresh manure intended for hot-beds ; new 
manure in heaps rapidly ^^ heats," and is aerated by 
being turned over two or three times on separate days 
before being packed close for the hot-bed. This 
process of treatment rather disagrees with the breeding 
of the house-fly. Mushrooms and all the fungus tribe 
breathe by inhaling oxygen and exhaling carbon di- 
oxide ; and so it happens that even insects which 
delight to feed on mushrooms, are somew^hat repelled 
by the special atmosphere of very actively growing 
mycelium or spawn. 

The amateur entomologist and the nature-student 
will observe that the flies which pester the gardener at 
work are mainly other than the common house-fly. 
The reader, nevertheless, will like to know if something 
more cannot be done to stable manure for exterminat- 
ing maggots, whether of house-flies or the many various 
filth flies, already hatched and growing therein. Well, 
^'something" indeed can be done by the use of some 
insecticide. Hitherto chloride of lime has been em- 
ployed, but the most approved insecticide for the 
purpose is a solution of iron sulphate — two pounds in 
one gallon of water ; this is said not to deteriorate 
the horticultural value of stable manure. However, 
in fine weather, the spreading out and drying of freshly 
received manure practically rids it of fly maggots, which 
cannot survive this simple procedure. The mere burial 
of fly-blown dung and stable litter without prior treat 


ment is quite inefficient. Insanitary heaps of neglected 
manure, which terribly swarm with maggots, much 
deteriorate in horticultural value. :: •: .: :. . 

Farmyards and the scattered dwellings of rural 
districts remain to be considered, and no doubt 
herein the difficulty is great, but not hopeless. The 
latter will be persuaded to follow suit when the 
good effects of town and suburban policy become 
apparent. -- 

Something more than usual is desirable for the pro- 
tection of cattle from the breeze and the oestrid flies 
at midsummer. The latter, at all events, could be 
easily exterminated by giving butterfly nets and en- 
couragement to children, who would enjoy the fun. 
Although the close approach of strangers may alarm 
grazing animals, after the latter have galloped away a 
very good chance will occur of capturing the slow 
flying gravid female worble-fly with a butterfly net, 
or of felling her to the ground with a suitable instru- 
ment; if missed on the first attempt, other chances 
can be got again and again by waiting until the said 
same fly has returned to threaten her intended victims. 
The writer has often succeeded in felling the slow 
flying gravid female worble-fly with a mere walking 
stick. It is strange that no farmers' entomological 
friend has hitherto suggested so common-sense a 
remedy as butterfly nets, which should be of a dark 
green colour. A company of our popular boy scouts, 
marching in a skirmishing line on an August Bank 
Holiday (or a preceding Saturday), over ground where 
grazing animals are observed showing behaviour con- 
spicuously indicative of attacks by oestrid flies, would 


enjoy doing grandly useful execution. Every capture 
should be substantially rewarded. 

In an organised campaign of house-fly extermination 
it may rather be expected that the principal trouble 
will be with the stable men of unsanatory mews. 
In the United States of America very stringent bye- 
laws have been made and enforced. Some of these, 
perhaps, deserve consideration for adoption, with 
judicious improvements, in England, but the policy 
of the OPEN DUST-BIN and CREMATION raises new 
hopes of success far beyond any advantages hitherto 
obtained in America. 


Many minor plans have been proposed for obviating 
or alleviating the perils and plague of invading fly 
swarms ; several such plans may be well carried out on 
a private domestic scale, but one cannot expect any of 
them to be adopted universally. In domestic methods 
people will prefer some one plan, some another, whilst 
some will not personally aid in the work of fly 
destruction in any single way perseveringly. This 
latter circumstance emphasises the necessity of a 
dominant control by local authority for the safeguard- 
ing of all inhabitants, including the delinquents them- 
selves in spite of themselves. 

The plan, as detailed in the last chapter, of enticing 
breeding females to lay their eggs within depositories 
of discarded food remnants and garbage, can be 
practised on a smaller scale with great advantage every- 
where. Kitchen refuse of many kinds, not neglecting 
potato and turnip parings, cabbage leaves, or even 
tea leaves, should all be collected in brown paper bags, 
which should be left open for a few days in suitable 
places round about the house for the free access of 
gravid female house-flies. Every such collection 
should be cremated on the third day. In a paper, read 
at a recent congress of the Royal Sanitary Institute, on 


" Destruction and Prevention of Household Pests," 
Dr. Gay advised rich and poor, in every household, 
whether ornot a sanitary dust-bin was in use, instantly 
to wrap up in paper all such fly-breeding materials in 
readiness for cremation. However, to do so would be 
missing the much more effectual course of applying 
my ^' egg-trap" plan of collections in exposed open 
bags for cremation on the third day. 

For indoor use insecticide methods are more suited ; 
and the best of these are immensely more effective than 
some popular devices, which make a remarkable dis- 
play and sell well, but which the purchasers soon 
become neglectful to keep in constant use. Traps in 
the form of wire-gauze cages, and glass non-return 
bottles belong to this latter class of contrivances; when 
seen crowded with struggling victims, the employment 
of such articles captivates many observers ; but their 
real efficiency will be found to fall far short of general 
expectation. The explanation will be apparent when 
the use of the wire-cage trap is contrasted with the 
success of a good fly poison. Given, say, a dwelling 
room on a midsummer day containing ten female flies 
and ten idle dancing male flies ; in such cases not 
more than half the females and one quarter of the 
males will get imprisoned within four or five hours by 
the employment of the wire-cage trap, but with a good 
method of setting poison nine-tenths of the females 
and half the males may be killed within the same 
period. In the case of poisoning, the dead have to 
be swept up, whilst fly traps have the advantage of 
collecting the victims ; but, unless the inmates are 
carefully destroyed, a few will manage sometimes to 


escape from the traps, especially as side window light 
changes and daylight fades. In these fly traps it is 
only the perseverance of the prisoners in struggling 
towards outer light which prevents their exit by the 
entrance aperture. 

Stickfast adhesive papers and suspended tapes and 
strings look very effective when seen crowded with 
accumulated captures ; but, again, these " exhibition " 
appearances are as deceptive in suggestions of real 
efficiency as are the crowded cage traps last mentioned ; 
moreover, sticky messes are not commendable or con- 
venient articles for placing w^here most wanted. 
Truly, suspensory strings are attractive resting resorts 
for dancing males, but the worst agents of Beelzebub 
are the females, which have a keener appetite for food 
and for pestering humanity. 

There remain for consideration insecticide poisons. 
A great choice of materials can be supplied by the 
chemist's shop, and various methods of using them 
have been recommended. In old times country people 
prepared decoctions of Amanita muscariay the fiy toad- 
stool, a large orange-scarlet, or crimson, mushroom- 
shaped fungus commonly appearing in autumn in 
woods where birch trees abound. Strange to say, such 
decoction will poison flies of many kinds, although 
they, and many different creatures, feed with impunity 
on other fungi which are more deadly poisonous to 

Effective poisons are such good exterminators of 
flies, that the main consideration is how to safely and 
most suitably employ them. There are some people 
who have an invincible aversion to the mere thought 


of poison purposely administered by way of food or 
drink, though possibly they do not have an equally 
strong repugnance to the use of insecticides used for 
stifling. However, one cannot help running counter 
to much misplaced sentimental humanitarianism in 
some people on some subjects ; reasons and arguments 
will not move them, for they do not wish to think 
otherwise than as their prejudices influence them. 
The house-fly is itself a poisoner of our food, and it, 
or rather she (the offender being nearly always female), 
is a more dangerous and a more subtilely baneful 
enemy than, for instance, the human flea, which even 
the Brahmans or the disciples of Buddha may kill. 

Fumigatory insecticides, though occasionally useful, 
may be left out of consideration in discussing the rival 
merits of means in a warfare against the house-fly. 

A liquid or moist food poison employed in a safe 
and effective way will excel every other weapon of 
warfare within the house. One of the newest recom- 
mended substances is formalin, which has the advan- 
tages of being a disinfectant, a strong fly-poison not 
avoided by flies, and not dangerous or attractive to 
domestic animals. A tablespoonful of (40 per cent.) 
formalin should be mixed with one half pint of milk 
and water ; this, when exposed in saucers or shallow 
dishes, is said to be an attractive and a fatal bait. It 
would be evidently dangerous and objectionable to 
use some other commoner poisons in the same way ; 
but it is the opinion of some users that formalin and 
milk is not sufficiently alluring. 

Contrary to a generally prevalent idea a powerful 
odour is not required as an indoor allurement for the 


common house-fly ; again, a saucer or shallow dish 
with liquid contents is not a good method of presenting 
the fatal bait. Placed on a table, or on a window sill, 
or on a shelf, a saucer is liable to be tipped up and its 
contents spilt ; moreover, the form of such receptacles 
is radically faulty by reason of the strenuous w^alking 
habits of the fly on the level. Out of many flies walk- 
ing over a table ten or twelve may pass by, or round, 
an overhanging saucer's rim to one fly that will mount 
the same and sip inside. However, let such a saucer 
or plate be placed on a table upside-down, and let 
a slightly moist substance be placed in the shallow 
central depression, which ordinarily is the base, then 
the said ten or twelve flies will all mount and sample 
the moist substance, even though it be not apparently 
attractive in smell ; an inclined plane is ever an irre- 
sistible invitation to mount and prospect the summit. 

It is another great mistake to suppose that an extra 
tasty food material is desirable as a bait. The same 
kind of mistake is made by people baiting a mouse 
trap with toasted cheese, whilst a bit of dry bread, or 
better still, a green pea, would much better entice a 
common mouse. Strong smelling and saccharine 
foods immensely attract the blue-bottle and the wasp, 
which are thus enticed indoors and induced to become 
occasional visitors to our tables ; but the house-fly 
requires little of such lures ; indoors she is an inquisitive 
prospector, who will never pass by any moist material 
without testing its quality. Moreover, the use of 
poisoned milk, or even jam, should be rather avoided 
for fear of injury to dog or cat ; furthermore, it is 
dangerous to place a piece of bread in a saucer of 


liquid fly-poisan, as is sometimes done, to serve as a 
sop and as a standing stage. However, there is one good 
lure well worth mentioning ; it is beer-dregs with or 
without a little sugar ; moistened yeast is good, and the 
advantage of beer-dregs with just a little sugar is due 
to the mild yeast-like odour of slow fermentation, 
which may fail if formalin be the insecticide ingredient. 

The handiest and safest preparation of fly-poison is 
that sold in the form of a dry flypaper, which is said 
to contain arsenic as the deadly ingredient. A very 
small piece of one of the sheets ordinarily sold should 
be placed on the summit of an inverted saucer ; a mere 
spoonful of water now and then will suffice to moisten 
the same ; there is little or no advantage in sprinkling 
a little sugar thereon, unless beer-dregs are added. 
This plan of using moistened poison paper is clean ; it 
is safer than using a more fluid bait, and the ingredient 
is certainly efficient ; the slightest taste thereof by an 
inquisitive fly ensures its speedy death. Another 
poison which has been recommended is a strong 
decoction of tea-leaves, to which a little sugar and 
beer may perhaps be added. 

It is said that the smell of geraniums is odious to 
the house-fly, and so pots of these plants may be grown 
beneficially on window-sills. Certain other odoui*s 
and scents are believed to be likewise more or less fly 
deterrent, but their use is not effective warfare against 
fly propagation. Paraffin painted on window-sills is 
said to be very efficient. 

Flies may be easily prevented from entering the 
open windows of any room, which has windows only 
on one side, by the use of Venetian or louvre blinds or 


shutters, or of many kinds of screens, although the 
apertures thereof may allow of ample room for flies to 
pass to and fro. If, however, there be windows on 
two sides of a room, then Venetian blinds and the like 
will be useless, and window screens must have very 
close meshes to be effective. The house-fly will pass 
through netting only when there is light shining on the 
further side. A knowledge of this fact is very important 
in the planning of hospital wards. In a sick room, if 
there be windows on two sides, one in summer time 
should be darkened when the other is open for 

The protection of the larder and the screening of 
food should never be neglected, but what is of even 
greater importance is the prevention of access by flies 
to fcecal matter, or to pumlent and all unhealthy dis- 
charges from the sick room. 


It is often asked — have not house-flies some use in 
Nature ? The only true answer is that they are warn- 
ing signals. 

They certainly do join with a multitude of other 
flies in promiscuous scavenging services, and they can 
be very active agents therein ; but this work only 
aggravates the fact of their dangerous partiality to 
mankind, together WMth all his belongings and sur- 
roundings. These creatures may well be imagined to 
have developed out of some primaeval species by reason 
of the increase of mankind upon this planet. The mere 
presence of the house-fly denotes some nuisance more 
or less remote ; the local density of the brood indicates 
the degree and the proximity of unsanatory conditions. 
Under present circumstances the visitation of the 
house-fly is Nature's intimation that peril of a very 
insidious character is about. Very properly, Nature's 
messenger will not be denied, and pertinaciously mani- 
fests herself to us indoors ! 

It has already been explained that the scavenging 
service of the house-fly can be altogether dispensed with, 
inasmuch as there is a sufficiency of other less noxious 
flies and creatures devoted to such work. Reflecting 
on the Story of Creation, and the mission of man as 



first a gardener, and then, when expelled from Para- 
dise, destined to more laboriously cultivate the earth, 
it may be held to be man's allotted duty not only to 
wage war against weeds, but likewise to distinguish 
friends and foes of all kinds, and treat accordingly 
creatures even of all branches of the animal kingdom, 
whether insects, reptiles, birds, or mammals, favouring 
one and exterminating another. This will be to 
rule the earth and "subdue it " (Genesis i. 28). Neme- 
sis will inevitably chastise man unless he rectifies the 
consequences of his own delinquencies, whether they 
be direct or indirect. The **good service" of the 
house-fly is comparable with that of the flea, which 
performs an unwelcomed and indirect "sei*vice," 
inciting the housewife to have well-swept floors and 
clean bedding. 

The unalloyed good service of insectivorous flies is 
quite apparent. The details of their life-history and 
a description of their different characteristics would 
make an interesting volume, but the limitations of the 
present work preclude such enlargement of its scope. 

It certainly stands to the credit of the blue-bottle 
that she is by far our best native scavenger of carrion; 
so good, indeed, that none other as an assistant is 
needed. She may just possibly sometimes convey 
germs and contaminate food, but she does not so 
directly assail man. Her larger size makes her easy for 
exclusion from the domestic food store. So eager and 
alert is the female in searching for meat, dead animals, 
and fish, that our other native carrion-feeding flies are 
at a great disadvantage in the struggle for existence ; 
so prompt is she in monopolising carrion, that would- 


be competitors often have to be content with laying 
their eggs in less rich food materials. The blue-bottle 
can withstand temperatures a few degrees colder than 
can those flies to which she is nearest akin ; and she 
seems capable somehow of sheltering herself better. 
Even as late as the middle of winter, sometimes, a dead 
bird may be found to be fly-blown under circumstances 
which indicate that the eggs must have been laid in 
frosty weather, when flies are not seen at large. The 
explanation is that the blue-bottle will for a short time 
awake, and venture outside her retreat in a sheltered 
south wall, warmed by a few hours of winter sun. She^ 
does not hibernate in early winter in such a continuous 
state of rigid torpor as, for instance, does the queen 
wasp ; probably few or none survive the winter by a 
real hibernation, the progenitors of the first spring 
broods emerging at a date no earlier than do their 
rivals and congeners. 

As a bird food or a fishing bait gentles are superior 
to the maggots of any other dipterid insect. So-called 
ants' eggs and meal-worms are more highly appreciated 
by the fancier for bird food, but they are expensive. 
The pupa2 called " ants' eggs " can only be had fresh 
for a short period of summer, and dried stock for the 
rest of the year requires much labour to obtain and 
prepare. Meal-worms are the cleanest and the easiest 
to propagate of all similar larva3 ; but they are very slow 
growing compai*ed with gentles ; in the natural state 
the life-cycle from the egg to the feeding worm, then 
the pupa or chrysalid, and finally the bettle, Tenebrio 
molitorj occupies a twelvemonth's time ; but, like many 
other insects which have accommodated themselves to 


human surroundings, they can increase more rapidly. 
By rearing a number of broods, each in a separate 
vessel, and by hastening the development and propaga- 
tion of some broods more than others, meal-worms 
may be obtained fresh throughout the year ; the amount 
of trouble and attention required is accordingly great. 

The artificial rearing of gentles is easy, rapid, and 
cheap. Generally it is not well or methodically 
managed, and consequently it is then a horribly mal- 
odorous nuisance. However, with proper care the 
process can be managed without offensiveness, and it 
will immensely repay all trouble. 

A more restricted variety of birds relish gentles, but 
no insect food is more wholesome for any of the 
galinaceous tribe. 

A spot in the open air, preferably 
sheltered from the north or east wind 
and from mid-day sun, should be 
chosen. There an inverted earthen- 
ware sea-kale pot or a similar vessel 
should be fixed on a stand or table 
twenty inches high from the ground ; jj 
the table should have a central hole ij 
corresponding to that in the sea-kale ^ p "^ 
pot. The hole in the pot should be ^~ -^ 
obstructed with a wire-cage strainer, or ^'S- ^- 

a piece of perforated wood or metal, ^Pr^jr^r^ding 
above which a few sticks or a bunch of gentles, 
of straw may be placed. 

Fly-blown dead animals, fish, offal, or suitable food 
remnants should be placed from time to time in such 
a receptacle, which should be surmounted with a 


removable rain-proof cover and shade of ample size. 
The latter should allow a two-inch space or a little more 
underneath all around the rim of the pot for ventilation. 
Underneath the table or stand a wide and more or less 
shallow pan or dish should be placed, and a little clean 
sharp sand placed therein. 

The gentles, whilst growing and feeding, are called 
*' green" gentles ; their skin is transparent, and in this 
state chickens do not like eating them ; and it is as 
well so, for then the half-grown gentles would be 
capable of temporarily becoming deleterious internal 
parasites in the birds' crop. As soon as they are full 
grown they crawl away from the food material and will 
fall through the strainer-like obstruction in the bottom 
hole of the pot into the pan on the ground underneath. 
They are then termed clean or *' scoured" gentles and 
are lit for bird-food or for tishing-bait. 

If taken out of the pan and placed in boxes with a 
little sand, they will keep three days, more or less, 
according to the weather ; they then pupate, and in a 
few days, or weeks, or months, accordingto temperature, 
emerge as blue-bottles. As pupa^ they are good and 
convenient food for domestic fowls, and for all 
pheasants and like game-birds. 

If receptacles as above directed are situate in a fowl- 
run, the hens will never leave the ground dish 
unwatched as long as full fed gentles are maturing. 
Hens thus fed are prolific layers of eggs, but of course 
they must be otherwise fairly fed with farinaceous and 
suitable other food and healthy grit. The maggots of 
no other flies are worth similarly cultivating ; those 
that feed on vegetable refuse are more offensive in 


smell than common gentles ; the maggots of the fungus 
flies are comparatively clean creatures and free from 
bad smell, but the largest are small. 


Several authors of recent books, and lately also able 
lecturers, have done much to awaken people to a realisa- 
tion of the dangers of our ever recurrent summer plague 
of flies. The advent of the petrol motor-car and other 
automobile vehicles has at the most but very slightly 
improved the state of affairs within town areas, where 
mews were formerly much more numerous. The 
public press has followed suit, but something more in 
the way of a sustained effort for hygienic reform is 
desirable. The terrible European war should not pre- 
clude consideration of the subject, for the scourges of 
fly-borne contagion have ever followed armies and 
rivalled the casualties of the very battlefield. Bands 
of enthusiasts everywhere should keep going a verit- 
able anti-fly campaign as one of the most urgent needs 
of practical sanitation. Otherwise active support of 
the cause will soon languish and be obliterated amongst 
the multitudinous ever-changing questions of the day, 
political and other, which, as newspaper editors are 
persuaded, have the attention of the public for the 
time being. In spite of the incontestible prospects of 
universal benefit it may not be easy to engage a large 
body of public support without something like an 
organised propagandist movement. 

If any readers of this booklet are disposed to join 


and form a central body with a view of ultimately 
founding an association for promoting the work of fly 
extermination, the writer will be glad to find or meet 
with an honorary secretary and helpers who will work 
in the cause and economise in the necessary expendi- 
ture of all contributions received. After the preliminary 
efforts of starting such an association, its work will be 
not only to urge the local sanitary authorities every- 
where to adopt the best possible course of action, but 
also to incessantly move public opinion to compel 
Parliament to pass laws, capable of administration, for 
the public welfare in this matter. 

The present booklet had its origin very many years 
ago in the author's idea of writing an account of the 
house-fly and its kindred, which would be interesting 
and more truthful than much then to be found in 
current literature. Such off-hand inconsiderate writing, 
as appears in the " Elements of Entomology," by 
W. S. Dallas, F.L.S., requires to be controverted ; 
therein it is stated that the house-fly, which is " trouble- 
some, does very little actual damage, for our only 
real grounds of complaint are to be summed up in 
the tickling sensation which its feet cause," &c. " In 
its larvae state, however, it lives inoffensively enough 
in dung." It has now seemed timely to publish my 
long-delayed work, re-written with the object of more 
urgently interesting the general public, in the cause of 
the anti-fly campaign. Still, the author trusts that both 
the deeper and the less entomologically inclined nature 
students will find therein not only useful, but also some 
novel information, given with not too much entomo- 
logical technicality. 


There is no English work sufficiently modern and 
comprehensive for a study of our native flies. In 
1776, Moses Harris, who originated or elaborated the 
study of wing patterns, published his ** Exposition of 
English Insects," in which more than 300 flies are 
figured and described ; they have the old Linnaean classi- 
fication and nomenclature, of course, and the work is 
scarce. All later attempts by English authors in the way 
of a more comprehensive student's guide book have been 
left incomplete. Another excellent, but expensive work, 
Curtis's "Genera of British Insects," contains about 
250 illustrations and descriptions of flies ; but most of 
these are rather rarities, and the amateur in search of 
a facile guide to the commoner objects of the country- 
side will be apt to be disappointed. For the sake of 
readers possibly eager of advancing further in the study, 
and in the absence of any commendable guide book, 
a short appendix has been added to the present work, 
for help in identifying more numerous species and 
those of many families and genera not mentioned in the 
foregoing pages. With the leave of the Northumber- 
land, Durham, and Newcastle-upon-Tyne Natural 
History Society some valuable plates of illustrations 
are herewith reprinted, and explanatory notes are 
added, mainly from the volume of the Society's trans- 
actions for 1906, a most valuable work and compilation 
by the late Rev. W. ]. Wingate, of Bishop Auckland. 
This learned entomologist has succeeded in giving a 
marvellously comprehensive amount of clear condensed 
guidance. It is a great privilege that the present 
booklet has been allowed to borrow from such a source 


of knowledge, valuable far beyond the locality of its 

Other illustrations which have been borrowed appear 
with the leave of His Majesty's Office of Works, out 
of Reports to the Local Government on Pubhc Health 
and Medical Subjects. 

g [ FLY CHART.] 


^neitMtffif A,Bl A-A <■■ I n-^OOli C ( 

Plate I. (appendix) 





This Index, together with the following "Table of Wing-cells and 
Veins," the " Glossary," and plates, II, III, IV, V, VI and VII, will 
explain the theoretical Diagram entitled The Fly Chart, illustrating 
characteristic features and exterior parts, by the study of which the 
reader may learn to differentiate all the sixty families which con- 
tain species native to Great Britain. 

^ A = the Head, comprising nine regions and parts (A, I to A, IX). 

A, I, the Vertex, which contains (I) the Ocellar Triangle; (2) 
the Ocelli; (3) the Vertical Triangle, a coloured patch 
surrounding the ocellar triangle; (7) the Vertical Orbit, the 
sides of the vertex close to the compound eyes. The 
Bristles hereabouts are (4) the Vertical (inner and outer) ; 
(5) the Post-vertical; and (6) the Ocellar. 

A, II, the Compound Eyes, large and often hairy. 

A, III, the Frons is the forehead between the eyes; it contains 
(I) the Frontal Stripe; (2) the Frontal Orbits at the sides 
of the frontal stripe ; (3) the Frontal Lunule {plate VII, 5) 
a crescent immediately above the antennas. The Bristles 
hereabouts are (4) one pair of Frontal ; a row, or rows of 
(5) Fronto-orbital ; and (6) Lower Fronto-orbital. The (7) 
Eye Margin is a narrow, often glistening, white line close 
to the eye. 

A, IV, Antenna?, jointed processes springing from between the 
eyes just below the frons ; those with numerous joints are 
illustrated in plate II, others in plate III. The Frontal Su- 
ture in the middle of the face is a little pit in which short 
antennae often lie close together. The (I) Basal Joints are 
the two next the head; (2) theFlagellum, all the joints, when 
numerous, taken together; (3) the First Joint is next the 
head; (4) the Second Joint; (5) the third Joint (/»/</ /c III, 1-9) 
is sometimes ringed ; (6) the Arista, or Seta, is a plume, spine, 
or bristle springing from the third joint at some point of its 
upper surface between the base and the tip. 


A, V, the Face is the region above the so-called mouth and be- 
low the antennae; the ridges bounding the face on each side 
are (I) the Facialia ; here are (2) the Facial Bristles; (3) the 
Mystax {pi. VI, /i,il. 28) is peculiar. 

A, VI, the Cheeks, spaces at the sides between A, II and A, V(I). 

A, VII, the Jowls, parts below A, VI and the so-called mouth. 

A, VIII, the Mouth, more or less of a cavity into which (3) the 
Proboscis (the jointed sucking trunk) can be sometimes 
partly withdrawn; the proboscis has a basal joint called the 
Rostrum (a snout) ; the other joint is called the Haustellum 
(a pump) and has the tip variously adapted as for mere sur- 
face suction, or for deep insertion, or for piercing, (i) the 
Peristome is the region surrounding the mouth ; (2) the Vi- 
brissas are strong bristles close to the sides of the mouth, or 
A, V(I); (4) the Palpi, two feelers (or perhaps smelling 
organs) attached to the proboscis. 

A, IX, the Back of the Head; here (I) Post-orbital Bristles are 

sometimes found, that is to say, behind the eyes. A, II. 

B — the Thorax, the middle portion of the fly bearing the organs 
of locomotion. 

B, I, the Dorsum. The diagram on plate VI, .//.;<. 40 illustrates 

the upper surface of this region; this part is bounded in 
front by (a) the Neck; behind by (h) the Scutellar Suture 
(15) or Seam; at the sides by (c) the Dorso-pleural Sutures 
(9-9) running from the front corners to the front of the 
Wing Bases; by (d) the Wing Bases (lO-lO) ; and by (e) the 
Scutellar Bridges, which are ridges (il-ll) runnini? with 
right and left inclines to ihe root of (6) the Scutellum. 
The Dorsum is crossed by (8) the Dorsal Suture, behind 
which are the Alar Regions (5-5); here on each side is a 
ridge (12-12) the Alar Frenum; rows of minute bristles on 
the centre are termed Acrostichal. 

B, II, the Sides, or Pleurae, specified separately in connection 
with — 

B, III, the Brest, or Sternum; (l) the Prothorax is below the 
shoulder and above the fore-leg ; (2) the Meso-pleura is 
contiguous to the prothorax and the shoulder; here in the 
upper front corner is the "Stigma," a prominent respiratory 
orifice, below which the large Stigmatical Bristle may be 
found; the (3) Ptero-pleura is below the wings and behind 
the meso-pleura; (4) the Meta-pleura is "a more or less 
tubercular piece below the region between the root of the 
wing and the haltere"; (5) the Sterno-pleura is above the 
middle leg and below the Sterno-pleural Suture, where it 


bounds the meso-pleura ; (6) the Hypo-pleura is behind the 
sterno-pleura and above the hind leg. 

B, IV, the Meta-Notum is the part of the thorax behind and be- 

neath B, I (6), the scutellum. 

C = Appendages of the thorax. 

C, I, Fore-legs, Mid-legs, and Hind- legs; every leg has nine 

joints [particularised illustrations on flate VII] ; (i) Coxas 
are the joints attached to the body ; (2) Trochanters very 
small and inconspicuous; (3) Femora or Thighs; (4) Tibiae 
or Shins; (5) First Tarsal Joint or Metatarsus; (6) Second 
Tarsal Joint; (7) Third; (8) Fourth; (9) Fifth Tarsal Joint; 
(10) the Knees are where the Thighs and Shins join; (II) 
Claws, Foot-pads, and Empodium are appendages of the fifth 
tarsal joint. 

C, II, Wings [sec Table of wing-cells and veins] ; the quarters 
of the wing are the Fore and the Hind Basal Regions and 
the Fore and the Hind Apical Regions. The Stigma is a 
thickened portion of the wing at the middle of the fore 

C, III, the Halteres. 

C, IV, Squamae are scale-like appendages beneath the wings 

and above the halteres ; they seem to have some attachment 
to the roots of the wings ; a small inner lobe is called the 
antisquama, but it is a feature not of much use in classifying 
and differentiating species. 

D= the Abdomen has numerous ringed sections ; in the Sub-order, 
Cyclorrhapha in eight segments, but commonly divided into 
four or five conspicuous segments and three or four more 
smaller, less visible, and much modified in the sexual 
terminal segments. 

D, I, the first abdominal segment is the Basal Segment. 

D, II, the last of those more visible is the Anal Segment or Anus. 

D, III, the abdominal termination, sec flatc VI, fig. 17. 

D, IV, the chief segments consist each of an Upper Plate joined 
to an Under Plate by Membranous Sides, often concealed. 

D, V, Abdominal Bristles, see plate VI, fig. 41. 

E = Bristles, Hairs, etc.; fine short furry hairs are called Pubes- 
cence; " Hairs " are longer and stronger; Bristles are still 
stronger ; but a very thick bristle is called a Spine, if on the 
costa, and a Spur, if on the leg ; the larger bristles on B or 
on D are called Macrochaeta?. 


F = Stripes and Bands; a long marking, when parallel (or nearly 
so) to the major axis of the body, leg, or wing, is called a 
Stripe ; when lying at right angles (or nearly so) it is called 
a Band. For " frontal stripe " see A, III (I). 

0= Cells of the wing [sec the following Table]; the rib-like 
nervures are termed Veins; these divide the area of the 
wing into more or less twelve compartments called Cells or 

V = Longitudinal Veins [see the following Table] ; two groupings 
within the margin can be recognised ; the principal veins 
of the Fore Region are numbered, 1,2, and 3, whilst those 
of the Hind Region are numbered, 4, 5, 6 and 7 respective- 
ly ; some have branches, n, h, c, etc., when sections (separ- 
ately referred to) may have index numerals attached. 

X = Cross- Veins [see the following Table] ; one very significant 
X-vein termed X, 4 (or the Discal X) in the middle of the 
wing connects the longitudinal V, 4 to the V, 3, which are 
thus to be identified even in very abnormal patterns. 

The cross-veins and cells are symbolised by having attached to the 
letters X and O respectively the indicative and qualifying figures 
and letters belonging to the V upon which they rest, that is to say, 
the V (or part of V) which is the lower boundary. 


O, I.— Costal Cell (undivided), or Costal Areolet. 

O, laK—The Humeral Cell ] 

O, la^— Second Costal Cell ]■ Costal Cell, when divided. 

0, 1 6.— Subcostal Cell J 

O, 2.— Marginal Cell (resting on V, 2). 

O, 3.— Submarginal Cell (resting on V, 3). 

O, 4^.— Cell resting on 4^ (the 1st part of V, 4), a "basal " cell. 

O, 42.— Cell resting on 4^ (the 2nd part of V, 4). 

O, 4&.— Cell resting on 46 (a lower branch of V, 4). 

O, 5^.— Cell resting on 51 (the 1st part of V, 5), a "basal" cell. 

O, 5^.— Cell resting on 52 (the 2nd part of V, 5), a "discal " cell. 

O, 53.— Cell resting on 5^ (the 3rd part of V, 5), a "marginal" cell. 

O, 6.— The Anal Cell. 

O, 7.— The Axillary Cell. 

0, 8.— The Subaxillary Cell. 

O, 9. — The Alula, or Axillary Lobe. 

V, c (or C). — The Costal Vein, or Costa, bounding the front Margin. 

V, cia. — Part of the Costa (often ciliated and spined) reaching to the 

end of V, la. 
V, in. — The upper branch of the V, I. 
V, lb. — The lower branch of the V, I. 
V, 2. — Second (longitudinal) Vein. 
V, 2b. — Lower branch of V, 2. 
V, 3.— Third or Cubital Vein. 
V, s. — The "Vena Spuria," a thickening of the wing (characteristic 

of Syrphidae), an imperfect V between V, 3 and V, 4 crossing 


V, //.— A "Hang" V (or Appendix) a more or less irregular in- 
complete V. 

V, 4. — Fourth Vein, often much branching. 

V, 5.-Fifth Vein. 

V, 6.— The Anal Vein. 

V, 7. — The Axillary Vein. 

X, la. — The Humeral Cross-vein, connecting V, la to V, r. 

X, lb. — The Subcostal X-vein, connecting V, lb to V, la. 

X, 2. — Cross-vein connecting V, 2 to V, lb. 

X, 4. — Discal, Middle, or Central X-vein. 

X, 5^.— Lower Cross-vein, connecting V, 5^ to V, 4. 

X, 5*^.— Lower Marginal Cross-vein, connecting V, 5;^, to V, 4 (or to 
some branch of V, 4). 

X, 6. — Anal Cross-vein. 







C, I (10) 




B, III (2) 

Alar frena 

B, I (12-12) 

Meta Notum 

B, IV 

Alula, or Axillary 


B, III (4) 




C, I (5) 

Anal Vein 



A, VllI 

Antennas, or Horns 

A, IV 





0-- Cell of wing... 


Apical Region 



A, I (2) 

Arista, or Seta 

Ocellar Triangle... 

A, I (I) 

[pialc III] ... 

A, IV (6) 

Orbits ... A, I (7) and A, III (2) 

Axillary Vein 



A, VIII (4) 

Basal Region 



A, VIII (I) 

Breast, or Sternum 


Pleurae, or Side 

Bristles, Spines, 



Hair, etc. 



A, VIII (3) 

Calcar, Spur, or 


B, HI (I) 




B, III (3) 

Cells of Wings, or 


B, I (6) 


Scutellar Bridges... 


Cheeks or Genas ... 

A, VI 

Shoulders or Humeri 



[//a/. VI, 40]... 

B, I (I-I) 

Coxas, or body- 

Squamae, or Calyp- 


C, I (I) 



Cubital Vein 



B, III (5) 

Dorsum [plalc VI J 


Stigma of Pleura... 

B, III (2) 

Empodium, claws 

Stigma of Wing ... 


and pads 

C, I (II) 

Stripe or Band ... 


Eye Margin 

A, III (7) 

Sutures ... A, 

IV, and B, I 

Face and Facialia 


Tarsi, or Tarsal 

Femora, or Thighs 

C, I (3) 

(foot) Joints ... 

C, I (5-9) 

Forceps [plalc Yl,fi 


Tibias, or Shins ... 

C, I (4) 





Frontal Lunula 


C, I (2) 



V = longitudinal 

Frontal Stripe 

A, III (I) 


C, II 

Frontal Suture ... 

A, IV 

Vena Spuria 




Vertex, or Crown... 

A, I 

Hang Vein, or 

Vibrissas, or Mouth 


V, /I 


A, VIII (2) 


B, III (6) 

X = Cross- Veins of 



Wings ... 

.. C,II 




Family Analytic 









..LIII ...] 





Anthomyidae . 




..III ... 


Asilidae ... 




..LX ... 



..LV ... 






..IV ... 









..VII ... 



..LVI ... 




87, 104 







Cecidomyidas . 

..II ... 

•.. 3 



89, 116 

Chironomidae ■ 

-VI ... 




68, 125 


..LI ... 











Cordylurid^ . 







..IX ... 


Psilidae ...XXXIX ] 

[01, 135 

Cyrtidas ... 




..VIII ... 


Dixidae ... 

..X ... 



..XI ... 


Dolicopodidae . 




..I ... 


Drosophilidas . 

..L ...I 

14. 131 



... 8 

Empidae ...XXIII 45, 














Sciomyzidae XXXVIII 





Sepsidae...XLVI 83, 102, 

121, 136 



[ ...78 


..V ... 


Hippoboscidae . 




..XV ... 







[ ••59 


..XII ... 















..XX ... 



..XL ...103, 109 





..LII ... 







Family Type- Forms of Antenna' in the first section, or Flies 
with many-jointed Antenna- — NEMOCERA 


1. Epidosis longipes, s 

2. Asphondylia sarothamni 


13. Mochlonyx velutinus 

14. Corethra plumicornis, ? 


3. Sciara thomag 

4. Mycetophila cingulum 

5. Mycetobia pallipes 

6. Macrocera lutea 


15. Limnophila dispar 

16. Rhipidia maculata, J 

17. Erioptera flavescens 

18. Trichocera hiemalis 


7. Bibio marci, ? 

8. Scatopse notata 


9. Simulium reptans 


19. Ptychoptera conlaminata 


20. Tipula gigantea 

21. Ctenophora pectinicornis 


10. Chironomus plumosus 

11. Ceratopogon femoratus, 

12. Clunio marinus 

22, Rhyphos cinctus 



2 Asphond/li&. 

P* 4.Myce^ophila. S.MycePobI* 


^^''"<'- SScafops. 9.Simulium 



ll.Ccra^opo^on.^ 12 Clonio 


IS.Mochlooyx../ l4.Corerhra.* 



22 Rhyphus. 

Plate II. (appendix). 


Family Type-Forms of Antennae in I he second section, or Flies 
with three or few-joinicd Antenna' 


1. Pachygaster atra 

2. Oxycera pulchella 

3. Stratiomys chamasleon 

4. Sargus cuprarius 

5. Beris chalybeata 

6. Nemotelus uliginosus 


7. Chrysops caecutiens 

8. Haematop6ta pluvialis 

9. Tabanus bovinus 


10. Chrysopilus auratus 

11. Leptis scolopacea 

12. Atherix ibis 

13. Symphoromyia melaena 

14. Spania nigra 


15. Leptogaster cylindrica 

16. Dioctria oelandica 

17. Isopogon brevirostris 

18. Laphria marginata 

19. Asilus crabroniformis 


20. Anthrax hottentota 

21. Bombylius major 


22. Thereva annulata 

23. Scenopinus fenestralis 

24a. Empis livida 
24b. „ borealis 

25. Ardoptera irrorata 

26. Ocydromia glabricula 

27. Stilpon lunata 

28a. Clinocera stagnalis 
28b. „ lota 

29. Hybos grossipes 

30. Tachista arrogans 

31. Chersodromia hirta 

32. Cyrtoma spuria 

33. Psilopus wiedemanni 
34a. Dolicliopus loiigicornis 
34b. „ discifer 

35. Chrysotus gramineus 

36. Rhaphium longicorne 

37. Medeterus diadema 


38. Lonchoptera lutea 

39. Platycnema pulicaria 

40. Platypeza picta 


41. Chalarus spurius 

42. Pipunculus campestris 


43. Volucella bombylans 

44. Xylota sylvarum 

45. Orthoneura elegans 

46. Chrysotoxum arcuatum 


47. Myopa buccata 

48. Physocephala rufipes 


49. Zophomyia temula 

50. Sarcophaga carnaria 


51. Calliphora vomitoria 

52. Coniosternum obscurum 

53. Scatophaga stercoraria 


54. Tetanocera ferruginea 


55. Borborus nitidus 


56. Hypoderma bovis 


57. Phora incrassata 



PdchygssUr. 2,0xycera. 



4,S4r3u» S.Bcris^ 

O.Hatmaropora Q.Tabanus. 

lS.L(protfa»UK 16, 

15, Symphoromyia 


oJa»^c>^ 16, Dieetrla. I7,l$epogon. 18,Laphria. 19,At)luk. 



iO--— ^:> — 

3a, LonchopUra. 39^Pla^y enema. 


^'([Ml/ijl/// 40, Plaryp«2a. ^ 

43,Voluce1la!* V.) "^ 

4*.Xylola. ♦^Omh^..^ ♦*-"'>"'«''"^;t:^ocepha.a 

y > ^'af* ' 

JTTJ^ SO.barcopnaga. v;^ | i 

54.T«Unoccra. Xt, """^'X^' 53,Sca>oph»^a. 

56,M/pod«rm» 57, Phora. 

Plate III. (appendix). 


Family Type-Forms of the IViugs of NEMOCERA 


1. Cecidomyia rosaria 

2. Lasioptera rubi 

3. Catocha latipes 


4. Sciara thomas 

5. Mycetophila cingulum 

6. Macrocera lutea 


7. Bibio pomonae 


8. Simulium reptans 


9. Ceratopogon illustris 

10. Chironomus plumosus 

11. Tanypus monilis 


12. Psychoda sexpunctata 

13. Culex arinulatus 


Dixa maculata 


15. Ptychoptera contaminata 


16. Rhyphus cinctus 


17. Dicranomyia stigmatica 

18. Rhipida maculata 

19. Symplecta punctipennis 

20. Erioptera fuscipennis 

21. Limnophila nemoralis 

22. Trichocera hiemalis 


23. Nephrotoma dorsalis 

24. Dolichopeza sylvicola 

25. Pachyrrhina crocata 

26. Tipula gigantea 



25.Pathyrrhina. ''^ * 26. Tipula. 

Plate IV. (appendix). 


Family Type-Forms of the Wings in the second section, or 
Flies with few-jointed Antenna' 


1. Sargus cuprarius 


2. Tabanus bovinus 



3. Leptis scolopacea 


4. Asilus crabroniformis 

5. Isopogon brevircstris 


6. Bombylius major 

7. Anthrax hottentota 


8. Thereva nobilitata 

9. Scenopinus fenestralis 


10. Empis livida 

11. Ocydromia glabricula 

12. Stilpon lunata 


13. Acrocera globulus 

14. Dolichopus plumipes 

15. Medeterus diadema 


16. Lonchoptera lutea, male. 

The dotted line shows V, 6 
in the female. 


17. Platypeza picta 

18. Verralia aucta 


19. Syritta pipiens 

I9i. Eumerus sabulonum 

20. Eristalis tenax 

21. Brachyopa bicolor 

Physocephala rufipes 


22. Gastrophilus equi 

23. Oestrus ovis 


24. G>mnosoma rotundatum 

25. Cercomyia thoracica 

26. Dexiosoma caninum 

27. Sarcophaga carnaria 


28. Calliphora erythrocephala 

29. Mesembrina meridiana 


30. Anthomyia pluvialis 


31. Scatophaga stercoraria 


32. Tetanocera ferruginea 


33. Psila fimentaria 


34. Tephritis comiculata 


35. Phora rufipes 


36. Micropeza corrigiolata 


37. Center cereris 


38. Chromatomyia affinis 


39. Limosina fontinalis 


40. Hippobosca equina 








niTvplili^. fifUN'^UL"'*- 


26.Dexioboma. 27.Sartophaga. 

3I.Scatophaga TR YPETID/E. aiT^anocera 

psiLiD/E. ' rAiL-t ^^aaw PHORID/E. 




CHL0R0P1£5l S 

35 Phora. 

^^ S 


40 Hippobo&ca 

Plate V. (appendix). 




Head of Mycetophilato show 


Dorsum of Culex— no cross- 

the position of the two 




Dorsum of Tipula— cross- 


Fore-leg of Dilophus 

seams (a— a), (disregarding 



characters other than cross- 


Palpus of Limnobia 





Dorsum of Muscid (disre- 


„ Anopheles 

garding characters other 



than cross-seams) 


Foot of Dilophus 

34. Extremity of abdomen of 


„ Leptis 

Pedicia rivosa 


„ Asilus 


Head of Stenopteryx sunk 


„ Thereva 

in shoulders 


Profile of Eumerus 


Foot and claws of Hippo- 


„ Syritta 



„ Helophilus 


Puparium of Calliphora 




T-shaped emergence-orifice 



in the pupa of Dixa— dorsal 


End of abdomen of Doli- 




A mummy-pupa (Tipula) 

(a) the forceps 


Diagram of the Dorsum 

(b) the pennis 

(l-l) Humeri or Shoulders 

(c) the lamellae 

(2) Prae-sutural Central 


Head of Psarus, viewed from 


above, showing frontal pro- 

(3) Post-sutural Central 




Shape of the proboscis in 

(4-4) Post-humeral Region 


(5-5) Alar Regions 


Shape of the proboscis in 

(6) TheScutellum 


(7) The Neck 


Shape of the proboscis in 

(8) Dorsal Suture 


(9-9) Dorso-pleural Sutures 


Shape of the proboscis in 

(10-10) Wing bases 


(II-II) Scutellar Bridges 


Hind leg of Ramphomyia 

(12-12) The Alar Frena 


(13-13) Inner rows of 


Hind leg of Sphcerocera 

Dorso-central Bristles 


(14-14) Outer rows of 


. Palpus of Lispe tentaculata 

Dorso-central Bristles 


Leg of Limnophila— tibia 

(15) The Scutellar Suture 



Diagramatic Chsetotaxy of 


Leg of Erioptera— tibia not 

an Abdominal Segment 


(I-I) Side Fore-marginal 


Head and double-jointed pro- 


boscis of Myopa 

(2-2) Side Hind-marginal 


Head of Asilus— front view 


{(i) the hollowed vertex 

(3) Central Fore-marginal 

(6) the mystax 



. Head of Drymia 

(4) Central Hind-marginal 


Head and proboscis of 


Stomoxys calcitrans 

(5) Discal bristles 




21 Ocydromia y ^/ 

22.Eu'iSs==^ 25.i.«.iophi,a 
27 Myopa. .vkdl^ i^ ,<<M^2g,trlopl«r* 


58.Dixa. 39.TipwM 

13 ^^_-^ i3 

Plate VI. (appendix). 



1. Profile of Doryceragraminum 

2. Profile of Trigonometopus 


3. Profile of Platystoma semi- 


4. Profile of Ceroxys crassi- 


5. Head ofChilosiamaculata 3 

6. Fore-leg of Platychirusmani- 

catus, <j (5 should be 6). 

7. Fore-leg of Platychirus pel- 

tatus, <? 

8. Fore-leg of Platychirus scu- 

tatus, <? 

9. Fore-leg of Platychirus albi- 

manus, s 

10. Fore-leg of Platychirus 

clypeatus, s 

11. Platychirus, c? and ?, quad- 

rate spotting 

12. Melanostoma mellinum, ? 

triangular spotting 

13. Larva of Microdon 

14. Wing of Helomyza pallida 

15 & 16. Diagram of a fly's leg. 
Vide C, I, on page 91. 

15. As viewed from behind 

16. As viewed, horizontal section 

(through A-B) 
{b.f.) base of femur 
(/./.) tip 

(bj.) base of tibia 
(/./.) tip 

(1) upper or outer side 

(2) under or inner „ 

(3) hinder 

(4) fore side 

(5) upper fore side 

(6) upper hind „ 

(7) under hind „ 

(8) under fore „ 

17 & 18. Base of wing, illustrat- 
ing the difference in O, 6^ 
respectively in 

17. Urophora 

18. Trypeta 

19. Profile of Drosophila 

20. Profile of Ceratomyza denti- 


21. Profile of Tichomyza fusca 

22. Antennae of Notophila cin- 

erea; note the "thorn" on 
second joint 

23. Antennae of Hydrellia gris- 

24. Antennae of Tichomyza fusca 

25. Profile of Hydrellia griseola 

26. „ Ochthera mantis 

27. Wing of Borborus equinus 
, Limosina sylvatica 



Section of a collector's net, 


{a) the small end of a large 

{b) a detachable muslin 

(c) elastic closing the bag ; 
(</) transparent celluloid 


A small bag, closed and de- 

31. Box for carrying bags 



S.Chiletia Maculat'a 

. AS^^'^-^^iS^ 11 pla^ychirus 12.Melar»o»roma 



Plafychiru*. Halt /ote Ugi 

bt ^j_ 13,UrvaMicrodon. 

!♦ Htlomy/a, 

16 $«ch»n>».fl t/^ 15. M^-^"***- 

19 Drosophila. 20.Cera^om)rxa 


V>^ ( V 22 Noriphila. ^^^^^ , 

17, Urophora. ^ /(R.«!»'-^^ , . ^>«/\ i 


27. Borborus 



Plate VII. (appendix). 


Together with referenced to the Analytical Table and Notes, 

The sequence of the numbering indicates some proximity of relation- 
ship, in most cases at least, in respect of some particulars. 

Nos. Refs. Families— Notes 

I... — . PULlClDyE: fleas regarded as flies with atrophied or un- 
developed wings. About 30 native species. 

II ... 3. CEClDOMYiDiE : mostly gall-gnats, minute and midge-like, 

or very frail, slender and gnat-like. Cccidomyia destructor is 
the notorious Hessian-fly, injurious to cereal crops. 

III ... 10. Mycetophilid^ : fungus-gnats; 34 genera; many com- 

mon species. The marvellous "army-worm," the larvae of 
Sciara militaris, which (being not a feeder on fungi) may be 
classified either separately or as belonging to this family, has 
been observed travelling in Continental forests in millions, 
described as massed together with a viscous mucus in bands 
said to be as large as 5 or 6 inches wide, I inch deep, and 50 
or more feet long ! 

IV. ... II. BlBTONlD^ ; 40 species of small and medium sizes; 
commonly the males are black, but the females of some 
species coloured; Bibio marci, ofa largish size, pubescent, and 
black, sometimes appears in great numbers on fine spring 
days, as likewise do some smaller black species of the same 
genus; ocelli absent ; semi-blind. 

V ... 13. SiMULiDiE: midge-like flies, mostly with wings, limbs, and 

bodies of short length; the largest, Sm/7///;/«/ reptatis, only 
2-3 mm., is common; its larvae are aquatic. Some foreign 
species are called sand-flies and are much dreaded poisonous 

VI ... 14. ChironomiD/E : midges and many small, slender and gnat- 

like flies ; Ceratopoflon fulicaris, C. bipuiictatiis, and C. varius are 
our commoner native blood-sucking midges, of which the 
larvae have been found under the damp bark of decadent 
trees ; the larvae of some others are aquatic, as also are all 
those of the long slender non-blood-sucking species, including 
those of the very common harlequin-fly, Chirouowus plutvosus, 
as also of several congerers, including C//. dorsal is, of which 
the larvae are known as "pond blood-worms." 


Nos. Refs. Families— Notes 

VII ... 196. Orphnephilid^ (darkness-loving): all foreign flies, 
except one rare. 

VIII ... 16. PSYCHODID.E : minute moth-like flies; they have been 
named owl-raidges from a peculiar manner of holding their 
wings in repose. 

IX ... 18. CULICID^ : the true gnats or mosquitoes ; 5 genera, 18 

native species; three common, including Culex pipiens; 
larvae abundant about marshy land and everywhere in water 
from which _^s/i are absent, even inbrackish water, but particu- 
larly in the stagnant water of small pools and vessels. 

X ... iga, DixiDiE: a few small and gnat-like flies; larvae aquatic. 

XI ... 21. PTYCHOPTERlDiE : larvae in shallow muddy pools. 

XII ... 23. LiMNOBlD^: 32 genera and more than 100 species; 

generally marsh and fen slender flies, large and small, rather 
resembling "crane-flies"; the larvae live some in decaying 
vegetable matter, some in fungi, some are aquatic, and some 
are unknown; two species called "winter-gnats," genus 
Trichoccra, are very common. 

XIII ... 24. TiPULlDiE : true crane-flies or daddy-long-legs; about 

60 species; larvae (leather-jackets) underground in turf, or in 
decadent matter. 

XIV ... 8. Rhyphid^: three native species; slender and of medium 

size ; larvae in rotting vegetable matter. 

XV ... 28. Stratiomyid^ : 12 genera, 40 or more species; pro- 

boscis imperfect ; wings rather small in comparison with the 
body, which is free from hairiness; a few are those large and 
conspicuously bright-coloured flies, which are called "soldier- 
flies"; the larvae of the genus Strationiys are known as "star- 
tailed" maggots. 

XVI ... 30. TABA^^[DiE: breeze-flies; ocelli absent; the short well- 

developed proboscis of the blood-sucking female pierces the 
skin of mammalia; the abdomen is somewhat pubescent, 
never hairy ; semi-blind ; larvae in damp earth, predaceous. 

XVII ... 31, 37. LEPTlDiE ; a family of few species resembling some 
Empidae rather than the flies of any preceding family. Lcptis 
scolopacca is a large fly, common in meadows, yellowish body 
with black spots. 

XVIII ... 40. AsiLlDiC: the "robber-flies," which are more boldly 
voracious than any other raptorial flies, preying on winged 
insects, large and small ; terrestial predaceous larvae. 

XIX ... 42. BOMBYLID/E: furry, hovering, bee-like flies, mostly very 

long-tongued; bodies very rotund but with legs singularly 
thin ; larvae, some parasitic on the larvae of ground bees, some 


Nos. Refs. Families— Notes 

XX ... 43. Therevid/E: non-raptorial flies; smaller, shorter, and 

more feeble than Asilidas ; though differing much in wing- 
pattern superficially like some Leptidae or some Empidae. 

XXI ... 44. SCENOHNID.E: a very limited family of smallish flies. 

Sccuopimisfcucstralis, the " window-fly " was formerly thought 
to breed amidst old carpets and musty neglected clothing, 
but its larvas have been found to be therein predaceous 
devourers of the larvae of clothes-moths and fleas; larvae of 
other species feed on fungi. 

XXII ... 38. Cyrtid^ : quite unlike any of the preceeding or suc- 
ceeding families; flies with diminutive heads and large rotund 
abdomens ; proboscis very short or obsolete ; the larvae of 
some are said to be parasitic on spiders. 

XXIII ... 45, 49, 66a. Empid^: an extensive family; about 200 
species, mostly of small sizes ; of slender habit, and of dull 
colours; there are 30 genera and the characteristics of some 
are peculiar; the life-history and habits of most are un- 
recorded; though with bodies of feeble appearance, some 
have the proboscis well devolped and are predaceous on small 
insects. Amongst the most curious are some species of the 
genus Hilar a, of which the males have the first tarsal joint of 
the fore-leg thickened and flattened; some species of this 
genus, not very uncommon, fly and float about carrying 
"veils" or small cob-web-like attachments. 

XXIV ... 50, 65. DOLICHOPOUID^: long-legged; alargefamily of 42 
genera; some species of medium size but mostly small, 
amongst which latter bright metallic colours, often golden 
green, are common. The life-history of only a few is known. 

XXV ... 51. LONCHOPTERID^ : a few small slender flies with long 
pointed wings. 

XXVI ... 53. PLATYPEZID.E : small flies; the peculiar broad flat 
larvae of some of the genus Platyfeza have been found in 

XXVII ... 58. PiPUNCULlD^: small and uncommon flies with abnor- 
mally large eyes 

XXVIII ... 59. Syrphid^: a most interesting group of 51 genera; 
"hover-flies," and other various, conspicuous, large and med- 
ium sized flies (only a few small), very distinctly characterised 
and differentiated; the wings show the "vena spuria," and 
the face is without a "frontal suture." The larvae are very 
diversified; some are terrestrial, some aquatic, some insecti- 
vorous, some parasitic or commensal in the nests oi Hymen- 

XXIX ... 54, 60. CONOPID^: the wings show no "vena spuria"; the 
known larvae are parasitic on Hymcnoptera and Orthoptcra. 


Noa. Refs. FAMILIES— Notes 

XXX ... 62. CEsTRlDiE : a few very distinct species; proboscis and 
mouth parts atrophied ; very hairy except one very rare ; 
parasites of mammalia. 

XXXI ... 72. TACHiNlDiE: 100 genera, more than 250 native species; 
with great difficulty classed in divisions, which may rank as 
separate families; stoutness of body and abundance of strong 
hairs, or rather bristles, are so generally apparent that many 
species may be guessed to belong to this family rather than 
to the closely related Muscidae. Many of the larvae are 
parasitic on various insects. 

XXXII ... 73. MusciDiE: 15 genera, comprising 36 native species, 
mostly very common, and many superabundant throughout 
summer by reason of rapid breeding. 

XXXIII ... 74. ANTHOMYlDiE: 4 sub-families (MYDiElN/E, AnthO- 
MYIN^, HOMALOMYlNyE, CCENOSIN^), 36 genera, and nearly 
300 native species ; difficult to characterise, but many rather 
resemble the lesser house-fly in size, and more or less in 
appearance, habit, and life-history, but some seem attracted 
rather more to flowers and others drawn only towards dung. 

XXXIV ... 82. CORDYLURID^: 29 genera; absence of squamae 
apparent ; otherwise generic features and general sizes and 
bodily shapes of species vary considerably. The yellow cow- 
dung fly, Scatophaga stercoraria, is the commonest species of 
this large family. 

XXXV ... 89, 116. Phycodromid^ : sea-shore flies. 

XXXVI ... 80. Helomyzid^ : 8 genera; the costa of wings very 
"pectinate "; wings large and abdomen small. 

XXXVII ... 78. Heteroneurid^: 3 native species; smallish 
elongated wings ; the larvae, which live in rotten wood, can 
jump, somewhat like the cheese-hopper maggots. 

XXXVIII ... 86, 95. SCIOMYZID.E: II genera; slender flies with 
tinted brownish wings; larvae aquatic. 

XXXIX ... lOl, 135. PsiLlDiE: 4 genera. 

XL ... 103, 109. MiCROPEZlD/E: 6 native species. 

XLI ... 87, 104. Ortalid^: about 20 species; smallish flies; some 

common in pastures; legs short and stout. 
XLII ... 97. Tripetid^: numerous small species; larvae in stems 

of plants, or galls thereon, some leaf-miners. 
XLIII ... 92. LONCH/ElDiE: some are of a plump figure and a dark 

metallic blue or green, others more slender and yellow, grey, 

or black. 
XLIV ... 93. SAPROMYZlDiE : 21 species. 
XLV ... 139. Opomyzid^: 5 species; life-history unknown. 
XLVI ... 83, 102, 121, 136. SEPSID.E: several are common small 

dung-flies, with black bodies, somewhat ant-like. 


Nos. Refs. Families— Notes 

XLVII ... 120. PlOPHlLlDyC: the "cheese-hopper" maggots are 
larvae of Piophila casei ; seven other species. 

XLVIII ... 132. GEOMYZID.E : 12 species.; 

XLIX ... 113. Ephydrid^: nearly lOO species; life-history of few 

L ... 114, 131. DROSOPHlLlDyE : larvae leaf-miners. The pale 
yellow "fruit-fly,'' Drosophila fcnestrannn, loves the cider- 
press and fermenting fruit. 

LI ... III. Chloropid^: numerous family; in the genus Chlorops 
are many beautiful little flies. 

LII ... 129. MlCHlLlD^: 2 native species. 

LIII ... 127, 138. AGROMYZlDyE: some are leaf-miners. 

LIV ... 68, 125. PHYTONfYZlDiE : leaf-miners. 

LV ... 126. AsTlADiE: 2 species; life-history unknown. 

LVI ... 106. BORBORID^: first tarsal joint (C,l, 5) of hind leg con- 
spicuously thick and short; small species of the genera 
Borbonis and Sfhcrocera often abound in the dung-pits of 
mews. The larvae of some have been found on rotting 
potatoes and on confervae. 

LVII ... 140. Phorid^e: a numerous family of small flies; 6 genera. 

LVIII ... 144. HlPPOBOSClD^ : the females of some shed their 
wings, and all live a lice-like life attached to animals. 

LIX ... 143. BRAULlDiE: eyeless and with strangely atrophied body 

appendages ; found in bee-hives. 
LX ... 145. Nycteribid^: wingless parasites on bats ; with small 

heads held in a curious posture. 


Order — Diptera 

1 (141). Insects with the head distinct from the thorax, with one pair 

of wings, one pair of halteres, 5-jointed tarsi, proboscis not 
spirally coiled ; with a well defined pupal stage intermediate 
between the larval stage and the perfect insect, 
li (52^)* Frontal lunule absent. 

Sub-order I. ORTHORRHAPHA (comprising 25 families); 
flies with "mummy-pupas," see plate VI, figs. 38 and 39. 

2 (25). Antennas many-jointed (plate II). 

NEMATOCERA (thread-horns)— 

3 (4). Vein endings round the margin {plate IV, figs. I, 2, 3) not 

more than 6. 


4 (3). Vein endings more than 6. 

5 (20). Thorax (plate VI, 31) without B, I, 8 conspicuous. 

6 (15). Costa ending at apex of wing (plate IV, 4-II). 

7 (12). Ocelli as in plate I, or as in plates VI, I and II, 4, 

8 (9). Discal cell (O, 46 or O, 5^) present (plate IV, 16). 

Rhyphid^e, XIV 

9 (8). Discal cell absent (plate IV, 4-7). 

10 (II). Antennae long (plate II, 3-6) ; or, if short, coxae elongated. 


11 (10). Antennae as in plate II, 7 and 8 ; coxae not elongated. 


12 (7). Ocelli absent. 

13 (14). Antennas (plate IL 9) shorter than B; wings (plate IV, 9) 



14 (13). Antennae (plate II, 10, li) longer; wings narrow (plate IV 


Chironomid^, VI 

15 (6). Closta (plate IV, 12-14) around hind margin. 

16 (17). Wings held roof-like, hairy ; X only at base (plate IV, 12). 



17 (16). Wings flat over D ; X on middle of wing. 

18 (19). Veins hairy {plate IV, 13). 


19 (18). Veins bare. 

I9'i (196). Antennae long ; V, 4 and V, 2 forked ; X, 4 (plate IV, I4) 
ending in V, 2. 

196 (19a). Antennae very short but ll-jointed ; no veins forked. 


20 (5). Thorax {plate VI, 32) with a strong cross seam. 

21 (22). V, 6 absent {plate IV, 15). 

Ptychopterid^, XI 

22 (21). V, 6 present. 

23 (24). V, la ending in costa and {plate IV, 17-22) united to V, 16 

by X, 16; last joint of palpi {plate VI, 4) never whip-like. 


24 (23). V, la ending in V, 16 ; and, except for X, la at its base, not 

united by X {plate IV, 23-26) ; palpi {plate VI, 5). 


25 (2). Antennae short, 3-jointed {plate III) ; 3rd joint sometimes 


BRACHYCERA (short-horns)— 

26 (140). Wing veining normal ; X-veins present. 

27 (32). Third antennal joint ringed ; A, IV, 6, if present {plate III, 

1-9) apical. 

28 (29). Costa ending at apex of wing {plate V, I). 


29 (28). Costa around the hind margin {plate V, 2). 

30 (31). Squamae very large. 


31 (30). Squamae very small. 

Part of LEPTID.E, XVII (genus Xylophagus) 

32 (27). Third joint of antennae {plate III, 10-55) not ringed. 

33 (55). Arista terminal or wanting (/>/rt/c III, 10-26,28-32,35-40,48) 

34 (46). V, 3 forked {plate V, 3-10, 13). 

35 (45)' O, 61 long, extending (or nearly) to hind margin, or entire- 

ly wanting {plate V, 3-9, 13). 


36 (39). C, I, (II) much enlarged, appearance of 3 foot-pads (plate 

37 (38). Squamae small, not covering C. Ill ; O, 6^ long and distinct 

(plate V, 3) ; long bodied flies, head of normal proportions. 

Part of LePTID^, XVII 

38 (37)- Squamas very large, hiding the halteres ; O, 61 absent (plate 

V, 13) ; short round-bodied flies with very small heads. 

Cyrtid^, XXII 

39 (36). Empodium small, only 2 foot-pads apparent (/>/fl/c VI, 10, 1 1)» 

40 (41). Vertex hollowed out between the eyes (plate VI, 28). 


41 (40). Vertex flat or raised, eyes not protruding. 

42 (43) (44)- V, 4 ending in 3 branches (plate V, 6, 7) between V, J 

and V, 5. 


43 (42) (44)- V, 4 ending in 4 branches (plate V, 8) between V, 5 

and V, 5. 


44 (42) (43). V, 4 ending in 2 branches (plate V, 9) ; antennae (plate 

III, 23) without A, IV, 6. 


45 (35)' O, 6^ short (plate V, 10) not nearly reaching hind margin. 

Part of EmPID^. XXIII 

46 (34). V, 3 not forked (plate V. 11-12, 14-17). 

47 (52). Alulae absent or rudimentary. 

48 (51). Apex of the wing rounded. 

49 (50). X, 4 placed generally beyond X, 5Sat most only a little 

before it ; V, 5 with 2 X-veins bounding a discal cell (plate 
V, II) ; or, if only one, then X, 5 is placed before, or, at most 
(plate V, 12) only a little beyond X, 4. 


50 (49). X, 4 placed very near the base of the wing ; V, 5 with only 

one X-vein placed far beyond X, 4 ; no discal cell (plate V, 

14, 15). 


51 (48). Apex of the wing (plate V, 16) pointed. 


52 (47). Alulae present. 

52^ (li). Frontal lunule (plate VII, 5) present. 

SUB-ORDER n. CYCLORRHAPHA (families XXVI— LX) ; flies 
which escape from a puparium, formed of the indurated 
larval skin, through a circular orifice made by pushing off 
its head end (plate VI, 37). 



53 (54). Antennae {plaie III, 39, 40) with a long seta or bristle 

Platypezid^, XXVI 

54 (53)» Antennae {plate III, 48) with a short seta or spine 


55 (33). Arista dorsal {plate III, 27, 33, 34, 41-47, 49-55). 

56 (61). O, 6^ long {plate V. 18-21J) extending nearly to hind mar- 

gin : D without strong bristles (macrochaetas). 

57 (60). Proboscis of moderate length {plate VI, 12-16) generally 


58 (59). Vena spuria (plate V, 18) absent ; A, II very large ; O, 4'^ 



59 (58). Vena spuria present {plate V, 19-21); O, 4^. closed ; A, II 


Syrphid^, XXVIII 

60 (57). Proboscis projecting far in front, very thin and long, often 

double-kneed (plate VI, 27) ; no vena spuria {plate V, 21^). 


61 (56). O, 6' short, not nearly reaching margin, or absent {plate V, 

12, 22-39) abdomen often with strong bristles. 

62 (63). Proboscis and palpi atrophied. 


63 (62). A, VIII, 3 and 4 distinctly present. 

64 (67). X, 5^ absent, X 52 present, i.e., only one^X-vein on V, 5 and 

that beyond X, 4. 

65 (66). X, 4 very near base of wing {plate V, 14, 15) ; X, 5 far 

beyond X, 4, 


66 (65). X, 4 more towards middle of wing {plate V, 12, 36, 37) 

nearer X, 5. 
66a (666). Proboscis directed straight downwards. 

Part of EMPlDiE, XXIII (genus Stilpon) 
666 (66a). A, VIII, 3 retracted [ordinary Muscid type] pass on to 
108 of this table. 

67 (64). X, 5' present, that is, a X-vein on V, 5 before, or under X, 4; 

or no X- veins on V, 5. 

68 (69). No X-veins on V, 5. 


69 (68). At least X, 5' present, generally also X, 52. 

70 (75). Squamae distinctly present though sometimes small. 



71 (74). V, 4 angled or bent towards V, 3 {plate V, 24-29). 

72 (73). D with E (macrochsetae and hairs) on middle segments; 

otherwise A, IV, 6 is bare or bare on the tip-half {plate III, 


73 (72). D without macrochaetae though often with rather strong 

' hairs ; A, IV, 6 fully plumed or combed {plate III, 51). 


74 (71). V, 4 going straight or nearly straight to margin {plateV, 30). 


75 (70) • Squamae absent or rudimentary. 


76 (105). V, la distinctly present, nearly as thick as V, lb, which 

generally ends in the fore margin at or beyond the middle of 
the wing {plate V, 31, 32, 34)- 

77 (84). Vibrissas present {plate VIII, 2) together with more or less 


78 (79), V, 44 four or five times as long as V, 43 (/.c, X, 52 nearer 

X4 than to wing margin). 

Heteroneurid^, XXXVII 
79l(78)- V, 44 about equal to V, 43, or only a little longer. 

80 (81). Costa with spines in addition to the ciliation {platcVII, I4). 

Helomyzid^, XXXVI 

81 (80). Costa without a row of spines, only ciliated. 

82 (83). A, III (5) present, or, if absent, then body never shining 


83 (82). Fronto-orbital bristles absent ; body always shining black. 


84 {77)- Vibrissas absent; mouth with short hairs or bare {plateVll, 

I, 3, 4); or, if the hairs are strong, all of same length and 

85 (88). A, IV very long and horizontal ; A, IV (4) as long or longer 

than A, IV (5) of which the upper edge is concave {plates 
111,54; VII, I). 

86 (87). Profile not triangular; face perpendicular or slightly re- 


87.(86). Profile triangular; A, V retreating {plate VII, I) almost 




88 (85). Antennas not long, or. if long, drooping; A, IV (4) shorter 

than A, IV (5) of which the upper edge is straight or convex. 

89 (90). Brown or black shore flies with flat horny thorax and with 

strong mouth hairs. 


90 (89). Otherwise than 89. 

91 (94). O, 51 and O, 61 very small and indistinct. 

92 (93). Only one fronto-orbital bristle on each side ; tibiae all with- 

out the pras-apical bristle. 


93 (92). A, III (5) on each side; the prae-apical E on some of the 

C, I (4). 

Sapromyzid^, XLIV 

94 (91). O, 51 and O, 61 fairly large and quite distinct. 

95 (96). Hind tibiae with a prae-apical bristle. 


96 (95). Hind tibiae without the prae-apical bristle. 

97 (98). A, III (6) present and close to A, II ; V, la [sharply bent 

up at its end (plateV, 34). Wings usually spotted ; ovipositor 

TrypetiDvE, XLII 

98 (97). Lower fronto-orbital bristles absent ; V, la gently bent up. 

99 (104). Legs long ; abdomen narrow and long, contracted at base. 

100 (103). V, 4 straight or nearly so. Shining black species. 

101 (102). V, 6 reaching to the wing margin; abdomen narrow, 

more than twice as long as the thorax. 


102 (lOl). V, 6 not nearly reaching margin ; D rather broad. 

Part of Sefsidm, XLVI 

103 (100). V, 4 much bent towards V, 3. Brown species. 

Part o/MlCROPEZlD^, XL (genus Calobata) 

104 (99). Legs normal ; D comparatively short and broad, never 

contracted at base. 


105 (76). V, la absent or rudimentary, much thinner than V, lb, 

which latter ends at or before the middle of the fore margin. 

106 (107). Hind C, I (5) thickened and shorter than the next joint. 


107 (106). Hind metatarsus longer than and not thicker than C, I(6>. 


108 (115). X. 51 absent, X, S'^ present (i.e. only one X-vein on V, 5 

and that placed beyond X, 4 {plate V, 36). 

109 (no). Legs long and thin ; abdomen very long. 

Part q/"MlCROPEZlD^, XL (genus Micropeza) 

110 (109). Legs short and strong; D oval or elliptical. 

111 (112). A, III (6) absent ; A, IV (5) round, or, if lengthened, then 

A in profile is triangular. 

Chloropid^, LI 

112 (III). A, III (6) present ; A, IV (5) generally long or oval ; A 

in profile never triangular. 

113 (114). Head square ; face strongly convex (plate VII, 21) ; 

O, 61 absent. Not orange coloured species. 


114 (i^S)- Head round or semi-circular; face not arched (plate 

VII, 19) ; O, 61 present, or, if absent, then the species orange 


115 (108). X, 51 present, or, if absent, then X, 52 also absent (Lc, 

either two X-veins or no X-veins on V, 5) (plate V, 33, 38). 

116 (117). Scutellum of the male extraordinarily long and squared 

off behind ; costa thickened from the end of V, I to the wing 

Part of Phycodromid^ (genus Thyreophora) 

117 (116). B, I (6) usually short, and somewhat triangular; costa 


118 (133). Mouth bristles present. 

119 (122). Fronto-orbital bristles absent. 

120 (121). Wings without a black spot near the tip. 


121 (120). Wings with a black spot near the tip. 

Prtr/t)/SEPSlD^, XLVI 

122 (119). Fronto-orbital bristles present. 

123 (128). X, 52 before middle of wing (both X, 4 and X, S- near the 

base and exceedingly near together) or no X-vein on V, 5. 

124 (127). X, 5"^ immediately under X, 4 (or nearer the base), or 

X, 51 and X, 52 both absent (plate V, 38). 

125 (126). Arista bare or nearly so. 


126 (125). Arista with long hairs on one side. 



127 (124). X, 52 present and placed further from base than X, 4. 


128 (123). X, 52 at or beyond the middle ; X, 4 and X, 52 neither 

very near to the wing base nor to one another. 

129 (130). Arista bare ; body short and broad. 


130 (129). Arista plumose, combed, or pubescent, or, if bare, then 

the body always narrow and long. 
13 [ (132). Arista thinly but long haired, plumose, or combed. 


132 (131). Arista thickly and short haired, pubescent, or bare. 

Geomyzid^, XLVIII 

133 (118). Mouth bristles absent. 

134 (137)- O, 51 and O, 61 large and very prominent. 

135 (136). Antennae moderately long or very long, male genitalia 

not prominent. 


136 (135). Antennas short ; male genitalia prominent, and club- 


Part of SEPSlDiE, XLVI (genus Tetanura) 

137 (I34)« O, 5i and O, 61 small and not very prominent. 

138 (139). Light grey or silvery species. 


139 (138). Orange or brownish-red species. 

Part of OpOMYZID^, XLV 

140 (26). Wings with two short very thick veins (in fore-basal re- 

gion) whence spring a few very fine unbranched veins. X~ 
veins absent (plate V, 35). 


141 (I) (52:1). Body of a horny or leathery nature ; head sunk into a 

hollow in the thorax {plate VI, 35). No proper proboscis or 
palpi ; claws very large (plate VI, 36). Perfect insect parasitic. 


142 (145). Head fairly large; wings sometimes shed or absent. 

143 (144). Eyes, ocelli, scutellum, halteres, and wings all absent ; 

last tarsal joint combed with bristles. 


Braulid^, LIX 

144 (143). Eyes and scutellum present ; last tarsal joint with well 

developed claws. 


145 (142). Head small, when at rest thrown back upon the dorsum ; 

always wingless. 



Air-sacks, breathing by, 46 
Anthomyida, 10, 17 
Asilns crabroiiifontiis, 55 
Aphides, plant-lice, etc., 8 

Beelzebub, Lord-of-flies, 2 
BlBiONlDi^, semi-blindness of, 

Birds, food for, 80 
Black death, 2 

Blood-sucking flies, kinds of— 
genus, chrysops, 24 
„ hcvmatobia, 16 
„ hcemaiopota, 23 
„ lyPero%ia, 1 7 
„ tabanjts, 23 
„ thcrioplcctcs, 23 
Blood-sucking midges and gnats 
— common species — 
ceratopo^oii piilicai ts, 108 
„ bipunctatiis, 108 

„ van lis, 108 

(also others of the same genus 
and of the allied genus, 
culex pipicns, 108 
Blue-bottles, 12, 18, 33, 36, 51 
Horboriis cqiiiniis, 34 
Bot-fly of the horse, 26 
Breeze-flies, "blinden," 10, 23, 

Bridgewater Treatises, I 

Cabbage-fly, 17 

CalUphora crythroccpUala\ see 
^ ., . \ blue- 

vomitorui j bottles 

Celery-fly, 17 
Chelifers, 55 
Chrysops ccvcntiens, 24 

„ rclicta 24 
Coiwpsflavipcs, 22 
Contagion, fly-borne, 84 

Cow-dung fly, the yellow, 19 
Crane-flies, or Daddy-long-legs, 

Cremation of refuse, 41, 61, 65, 

Cyrtoneura simplex, 17 

DiPTERvE, nearly 3,000 species, 10 
Dragon-flies, 55 
Drone-flies, 20. 22 
Dun-flies, sec Gad-flies 
Dust-bins, preferably open, 65, 70 
Dust destructor furnace, impera- 
tive, 65 

Economic value of the fly, 41 
Egg-traps, domestic refuse as, 

EMPID.E, 54 
Empnsa miisccv, 56 
Eristalis tcnax, 21 
Exclusion from rooms, 76 

Fauiiia canicnlaris, 7 
„ scalar is, 14, 18 
Filth-flies, 51 
Fleas, 108 
Flecked flesh, 29 
Fly chart, the Wingate, 88 
Fly-traps, 66 
Forest (or spider) fly, 22 
Fungus-flies, 51 
Futurist's Credo, 39 

Gad-flies, 23 

Garden pests, vegetarian, 17 
Gargantuan jokes. 32 
Gastrophilits, see Gisinis 
Gentles, apparatus for breeding, 

Gentles, green, 82 



Glossina morsitana, 62 
Green-bottle flies, 20 
Grey blow-flies, 19 

Hcematobia stimulans, 16 
Hcematopota crassiconiis, 23 

„ itdlicn, 23 

„ fhtvialis, 2$ 

Hibernation, 15, 80 
Horse-flies, sec Forest-flies 
House-fly fungus, 56 
House-fly, larva of, 35 
House-fly, wing pattern of, 12 
Hover-flies, 20 

Human intestinal myiasis, 25, 26 
Humble Creatures, I, 34 
hydrotcea dcntipcs, 1 7 

„ irritans, 1 7 

Instar, pupa, or chrysalid, 40 

Larvae, see Maggots 
Lesser house-fly, larva of, 36 

„ „ wing pattern, 12 

Louse-fly, tick, or ked, 22 
Liicilia Ca'sar, 20 

„ sericata, 20 
Lyferosia irritans^ IJ 

Maggots, feeding in company, 36 
„ insectivorous, 21 
„ jumping or hopping, 

III, 112 
„ myiasic possibilities, 

28, 37, 82 
„ parasitic on hpuiop- 

tcra, etc, III 
„ predaceous, 109 
„ " rat-tail," 21 
„ "star-tail," 109 

Meal-worms, 80 

Mcrodon narcissi, 21 

Messengers of peril, 78 

Metamorphosis, 37 


Mttsca corvina, 14, 17 

Muscina stabulans, 18, 27 

Nostril-fly of the sheep, 4, 26, 28 

Ocelli, visual importance of, 45 

Odour of humanity, attracted 

^ by, 33 

CEstrid flies, egg-laying aggres- 
sions, 31, 69 

Gistrus Itominis, discredited, 28 

Qistnts {Gastroplfliis) cqiii, 27 
„ „ hivmorrhoidalis, 


(Estnis nasalis 

Oestrus ovis, 28 

„ (hypodcnita) bovis, see 

„ ,, Uncatnm, see 


Onion-fly, 17 

Owl-midges, moth-like, 109 

Pestering flies, commoner kinds 
cyrtoneura simplex, 17 
fannia canicularis, 7 

„ scalaris, 18 
niHSca dowcstica, 7 

„ corviiia, 17 
muscina stabulans, 18 
and other ANTHOMYlDiE 
Poisons, eS"eciive insecticide, 73 
Polictcs lardana, 18 
Pond blood-worms, 108 

Robber-flies, 54. 109 
Root-fly, the, 17 

Sarcopha^a carnaha, 19 
Scatophafia stercoraria, 19 
Scavenging services, 78 
Sccnopinus fcncsfralis, 1 10 
Sex differentiation, 45 
Soldier-flies, 22, 109 
Spiders, flies parasitic on, HO 
Stable-fly, 12, 13, 16, 51 
Stable manure, 67 
Stomoxys caUi trans, 12, 1 3, I6, 5 1 

Swallow, attracted to breed, 53 
Syrphid^, 20 
Syrphus, 21 

TabaniD/C, 10, 22, sec also blood- 
sucking flies 

124 INDEX 

Tlicnoplcctcs, sec blood-sucking 

fiies Warning signals, flies as, 78 

TiPULiD^E, 109 Westminster Hospital and myia- 
Traps for flies, some ineffective, sis, 28 

72 Window-fly, the, 1 10 

Turnip-fly, a beetle, 17 Window screens, 77 

Wingate's nomenclature sym- 
Veins of wings, II bols, 12 

Voltairean atheism, controversy Wing patterns contrasted, 12 

of, 5 Worble-flies, 26, 28, 69 

Woods & Sons Ltd., Punters, LoNix>N, K.