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PSYCHE

A Journal of Entomology

Volume 90
1983

Editorial Board

Frank M. Carpenter, Editor P. J. Darlington, Jr.
W. L. Brown, Jr. H. W. Levi

E. O. Wilson Alfred F. Newton, Jr.

B. K. HOlldobler M. D. Bowers

Published Quarterly by the Cambridge Entomological Club
Editorial Office: Biological Laboratories
16 Divinity Avenue
Cambridge, Massachusetts, U.S.A.

The numbers of Psyche issued during the past year were mailed on the following
dates;

Vol. 89, nos. 3-4, for 1982, April 27, 1983
Vol. 90, nos. 1-2, for 1983, August 8, 1983
Vol. 90, no. 3, for 1983, December 9, 1983

ISSN 0033-2615

PSYCHE

A JOURNAL OF ENTOMOLOGY

founded in 1874 by the Cambridge Entomological Club

Vol. 90

1983

No.1-2

Studies on Upper Carboniferous insects: I. The Geraridae (Order Protorthop-

tera). Laurie Burnham I

Testing visual species recognition' in Precis (Lepidoptera: Nymphalidae) using

a cold-shock phenocopy. Arthur M. Shapiro 59

Defensive adaptations and natural enemies of a case-bearing beetle, Exema
canadensis (Coleoptera: Chrysomelidae). Richard B. Root and Frank J.

Messina 67

Studies on North American Carboniferous insects. 7. The structure and relation-
ships of £w6/c/;m.s r/oA7/W.v/ (Palaeodictyoptera). Frank M. Carpenter 81

The biology of Trichadenotecnum alexanderae Sommerman (Psocoptera:

Psocidae). 111. Analysis of mating behavior. B. W. Betz 97

Predatory behavior of bombardier beetles by a tabanid fly larva. Steven

Now ick i and Thomas Eisner 119

Prey selection by the neotropical spider, Alpaida tuonado, with notes on

web-site tenacity. Todd E. Shelly 123

Reproductive behavior of Claeoderes hivittata (Coleoptera: Brentidae).

Leslie K. Johnson 135

Polydomy in the slave-making ant, Harpagoxenus americanus (Emery)
(Hymenoptera: Formicidae). Maria Guadalupe Del Rio Pesado and

Thomas M. Alloway 151

Situation and location-specific factors in the compatibility in Rhytido-
ponera metallica {Uymenoplera: Formicidae: Ponerinae). Caryl P. Haskins

and Edna F. Haskins 163

Capture of bombardier beetles by ant-lion larvae. Jeffrey Conner and

Thomas Eisner 175

Reproductive plasticity in yellowjacket wasps: a polygynous, perennial
colony of Vespula maculifrons. Kenneth G. Ross and P. Kirk Visscher .... 179

CAMBRIDGE ENTOMOLOGICAL CLUB
Officers for 1982-1983

President

Vice-President

Secretary

Treasurer

Executive Committee

Frances Chew
Edward Armstrong
Margaret Thayer
Frank M. Carpenter
John Shetterly
Ronald McGinley

EDITORIAL BOARD OF PSYCHE

F. M, Carpenter (Editor), Fisher Professor of Natural History,
Emeritus, Harvard University

W. L. Brown, Jr., Professor of Entomology, Cornell University and
Associate in Entomology, Museum of Comparative Zoology
P. J. Darlington, Jr., Professor of Zoology, Emeritus, Harvard
University

B. K. Holldobler, Professor of Biology, Harvard University
H. W. Levi, Alexander Agassiz Professor of Zoology, Harvard University
M. D. Bowers, Assistant Professor of Biology, Harvard University
Alfred F. Newton, Jr., Curatorial Associate in Entomology, Harvard
University

E. O. Wilson, Baird Professor of Science, Harvard University

Checks and remittances should be addressed to Treasurer, Cambridge
Entomological Club, 16 Divinity Avenue, Cambridge, Mass. 02138.

Orders for missing numbers, notices of change of address, etc., should be sent to the
Editorial Office of Psyche, 16 Divinity Avenue, Cambridge, Mass. 02138. For previous
volumes, see notice on inside back cover.

IMPORTANT NOTICE TO CONTRIBUTORS
Manuscripts intended for publication should be addressed to Professor F. M.
Carpenter, Biological Laboratories, Harvard University, Cambridge, Mass. 02138.

Authors are expected to bear part of the printing costs, at the rate of $27.50 per
printed page. The actual cost of preparing cuts for all illustrations must be borne by
contributors: the cost for full page plates from line drawings is ordinarily $10.00
each, and for full page half-tones, $12.00 each; smaller sizes in proportion. There is
ordinarily no additional charge for setting tables of less then six columns; for tables
of six or more columns the cost is $25 per page.

Psyche, vol. 89, no. 3-4, for 1982, was mailed April 27, 1983

The Lexington Press, Inc., Lexington, Massachusetts

PSYCHE

Vol. 90

1983

No. 1-2

STUDIES ON

UPPER CARBONIFEROUS INSECTS:

I. THE GERARIDAE (ORDER PROTORTHOPTERA)

By Laurie Burnham

Department of Entomology, Cornell University,

Ithaca, New York 14853;

and Museum of Comparative Zoology, Harvard University,
Cambridge, Massachusetts 02138*

Introduction

Despite the importance of the order Protorthoptera,' little is
known about its evolutionary history. While recent workers have
emphasized morphological and taxonomic diversity in the group
(Carpenter, 1971, 1977; Wootton, 1981), no one has undertaken
serious revisionary study at the family level. As a consequence, our
understanding of relationships within the order, as well as relation-
ships of the Protorthoptera to other Paleozoic insects, is rudi-
mentary at best. Clearly, revisionary studies on this group are badly
needed.

We know that the Protorthoptera first appear in the fossil record
at the base of the Upper Carboniferous (Namurian Stage) and
apparently flourished for 80 million years before becoming extinct
at the end of the Permian. We also know that they were remarkably

'It was one of the dominant orders of the Paleozoic (exceeding all other insects
both in number of species and in number of individuals), and is considered by many
to be ancestral to the Endopterygota (the group to which 90% of all living insects
belong).

■"Present address.

Manuscript received hy the editor March 5, 1983.

Psyche

[Vol. 90

diverse morphologically, and that diversity in the group {sensu lato)
far exceeded that of any other Paleozoic order (Carpenter, 1977).
Structural modifications normally associated with more recent
insects, including brightly patterned wings, raptorial fore legs, and
thoracic extensions of various kinds, are found throughout the
group.

Despite this fascinating array of characters. Carboniferous
Protorthoptera have generated little interest among systematists.
This is due, in part, to problems common to all paleoentomological
study: an overall lack of material (rarely is a species based on a large
series of specimens); preservational quality that ranges from excel-
lent to very poor; and a taxonomy that is highly subjective.

In addition, there are problems unique to the Protorthoptera
which make their study particularly difficult. First, they are neop-
terous, and as a consequence, are most frequently found with their
wings superimposed on one another. Interpretation of the venation
under these circumstances is not only difficult, but prone to error.
Second, the vast majority of Carboniferous Protorthoptera are
known from only two localities: Commentry in France, and Mazon
Creek in the United States, and were studied primarily by turn-of-
the-century workers.- As new material has become available for
study in recent years, the accuracy of much of this earlier work has
been questioned.

Finally, there is the problem of variation. Distinguishing species-
level differences from intraspecific variation in fossils that have such
a limited array of characters is not easily resolved. How, for
instance, does one recognize sexual dimorphism in a fossil species
when there are no genitalia or secondary sexual characters to serve
as guidelines? It is not surprising under the circumstances that
paleotaxonomy rests largely on subjective reasoning. But this,
unfortunately, has its pitfalls.

Previous work on the Geraridae is a case in point. Anton Hand-
lirsch, responsible for most of the earlier work on the family, de-
scribed a new species of gerarid for every specimen he examined.

-The Permian Protorthoptera are generally much better known than their Carbo-
niferous relatives. This is attributable to the fact that there are more than eight major
Permian deposits (including two in the U.S.) at which Protorthoptera have been
found. Furthermore, intensive studies on these insects have attracted the attention of
such well-known recent workers as Carpenter, Kukalova, and Sharov.

millions of years

1983]

Burnham — Geraridae

Fig. I. Geological Time Table of the Carboniferous. Note the different ages of
the Commentry and Mazon Creek localities.

basing his taxonomic decisions on small differences in wing vena-
tion (Handlirsch, 1906b, 1911, 1922). This approach, while render-
ing the decision making easier, is nevertheless open to criticism.
Studies on intraspecific variation in some Permian Protorthoptera
have shown, for instance, that two fore wings belonging to the same
specimen will exhibit noticeable differences in venation (Carpenter,
1966). From these findings we can conclude that intraspecific varia-
tion in the Protorthoptera was high, and that the variation Hand-
lirsch saw was no greater than that seen in a single specimen.
Further evidence that suggests Handlirsch was unrealistic in his
representation of species diversity comes from the low probability of
finding only one individual per species (for all species collected) in a
random sample of living insects. Similarly, we cannot reasonably
expect to find only one specimen per species in a paleontological
sample, particularly when fossilization was catastrophic (and hence
random) as is true for the Mazon Creek biota.

Nevertheless, in spite of these drawbacks to the study of fossil
insects, the field can be immensely rewarding. This is because it
provides us with concrete evidence (in the form of fossils) of what
early insect life was like. Without such proof, we would be guided

Psyche

[Vol. 90

only by our imagination, and having this proof provides a base on
which insect phylogeny and early insect evolution can be recon-
structed.

Clearly, revisionary studies on Paleozoic insects are important.
Fortunately, recent revisional work by Carpenter has greatly in-
creased our knowledge of certain Paleozoic orders (i.e., the Paleodic-
tyoptera, Megasecoptera, Diaphanopterodea, Protodonata, and
Caloneurodea), but much work on the Protorthoptera remains.
This revision of the family Geraridae is, at least, a beginning and is
intended to be the first in a series of family-level studies on Upper
Carboniferous Protorthoptera.

Selection of the Geraridae as a starting point was influenced,
ultimately, by two factors: 1) it is typical of many of the families in
the Protorthoptera, having last been studied in the early part of this
century (despite the discovery since then of new material assignable
to the family); and 2) the Geraridae are morphologically most unus-
ual insects. They were large (up to 75 mm in body length), and had
as their single most distinctive attribute, a prothorax that was elon-
gate, flask-shaped, and adorned with long, numerous spines. These
spines gave them the appearance of walking pincushions, and pre-
sumably provided some defense against vertebrate predators.

The systematic importance of the family plus the impact this work
has on current classifications of the Protorthoptera will be discussed
in subsequent pages. The remaining sections of this paper cover (in
the following order): the systematics of the Geraridae; paleoecologi-
cal differences between the two localities at which gerarids have
been found (Mazon Creek and Commentry); and the significance of
this study relative to phylogenetic relationships within the Pro-
torthoptera.

Systematics

Materials and Methods

The fossils examined for this study occur mostly as impressions
(imprints in a sedimentary matrix devoid of organic matter) but
some occur as compressions (in these, organic matter is present, but
usually coalified). Both types of fossils were prepared by degage-
ment,^ i.e., an uncovering of the fossil by removal of the overlying
rock matrix. This is generally done using a fine pneumatic drill and

From the French verb degager meaning to disengage, extricate, or get clear.

1983]

Burnham — Geraridae

compressed air gun. The technique is particularly effective at
revealing regions of an insect’s body (wing tips, legs, etc.) that are
found beneath the bedding plane. Following degagement, specimens
were studied under a Wild M-5 stereo microscope and photo-
graphed with a Zeiss 4" by 5" format camera.

Drawings were made of each fossil by tracing a general outline
from a photographic enlargement. Verification of detail was made by
referring back to the specimens and examining them frequently
under the microscope. The most complete reconstructions (e.g., fig. 2
of G. danielsi) were possible for those species that consist of a large
series of specimens. This is because one fossil rarely displays all
characters equally well, and, therefore, the larger the number of speci-
mens, the greater the likelihood of multiple character preservation.

Type specimens, including the holotypes, for all taxa considered
in this revisionary study were borrowed and examined using the
above methods. Pre-existing taxa were synonymized whenever pos-
sible, a decision based on the assumption that (for reasons cited
earlier) intraspecific variation in the Protorthoptera is great. Char-
acters of greatest taxonomic importance were venation and body
size and shape, particularly with respect to the prothorax. In situa-
tions where clearcut characters were lacking, as is true for several of
the Mazon Creek gerarids, I relied solely on size as a criterion for
specific assignment. While this may result in the recognition of some
dubious species, it seems preferable to relegating certain specimens
to incertae sedis status.

Since wing venation is such an im.portant taxonomic tool both in
paleoentomological and extant systematic study, it is surprising that
until recently no standardized wing terminology has been adopted.
This is particularly unfortunate for the Protorthoptera, 80% of
which have been described on the basis of wings alone. Inroads
have recently been made into this problem primarily by the efforts
of Carpenter in the United States and Wootton in Great Britain.
Both have stressed (Carpenter, 1966; Wootton, 1979, 1981) the
importance of a standardized venational nomenclature and Woot-
ton (1979) has proposed a terminology modified slightly from the one
used previously by Lameere (1922) and Martynov (1924, 1938).

Wootton proposes that the following nine major longitudinal
veins be recognized: Costa (C); Subcosta (SC); Radius (R); Radial
Sector (RS); Anterior Media (MA); Posterior Media (MP); Ante-
rior Cubitus (CUA); Posterior Cubitus (CUP), and Anals. In light

Psyche

[Vol. 90

of the historical basis for the nomenclature (used extensively in the
paleoentomological literature) and its conservatism (it may be used
to homologize the wing venation of all insects) I enthusiastically
concur with Wootton’s recommendations and will employ his sys-
tem here and in future systematic work.

A total of 58 specimens were made available for study through the
loans of various institutions and individuals. These are listed here
with their abbreviations:

Field Museum of Natural History (FMNH), Chicago, Illinois,
U.S.A. (This includes specimens collected by Jerry Herdina and
subsequently acquired by the Field Museum).

Institut de Paleontologie, Museum National d’Histoire Naturelle
(IP), Paris, France.

Museum of Comparative Zoology (MCZ), Cambridge, Massa-
chusetts, U.S.A.

United States National Museum (USNM), Washington, D.C.,
U.S.A.

Yale Peabody Museum (YPM), New Haven, Connecticut, U.S.A.

Daniel Damrow, of Mosinee, Wisconsin. Private collection.
(DMRW) (Includes specimens previously in the collection of Walter
Dabasinskas).

David Douglass, of Yachats, Oregon. Private collection. (DGLS)

Francis and Terri Wolff, of Port Charlotte, Florida. Private col-
lection (Wolff).

Order Protorthoptera Handlirsch

Family Geraridae Scudder, 1885

[Nom. correct. Handlirsch, 1906a (ex Gerarina Scudder, 1885)]
Gerarina Scudder 1885:342. Type: Gerarus Scudder.

Geraridae Handlirsch 1906a:146, 1906b:701, 1911:312, 1920:151.

Sthenaropodidae Handlirsch 1906a:141, 1919:37, 1920:150; Sharov 1968:19. Type:

Sthenarupoda Brongniart. nkw synonymy.

Genopterygidae Richardson 1956:41. Type: Genopteryx Scudder. new synonymy.

Description

Fore and hind wings similar in size and shape, but markedly
different in venation.

Fore wing: length 35-55 mm, and apparently not coriaceous; cos-
tal area broad in basal region, SC simple, terminating in C; R
parallel to SC, terminating at wing apex; RS originating from base

1983]

Burnham — Geraridae

of R near midpoint of wing; M either anastomosing with RS for a
short distance or connecting to it by a cross-vein; CUA strongly
developed, arising from base of M; CUP forked, arising independ-
ently from wing base.

Hind wing; length 30-48 mm; costal area not as broad as in fore
wing; SC simple, terminating in C; R parallel to SC, terminating at
wing apex; RS pectinate, arising from R near wing base; M forked,
arising near base of RS; CUA and CUP simple and parallel to one
another; CUA arising from base of RS near M, CUP arising inde-
pendently from wing base; anal area unusually reduced; cross veins
abundant in both fore and hind wings.

Body; prothorax elongate, flask-shaped, and distinctively spi-
nose; abdomen cylindrical; antennae filamentous; head small and
probably mobile; legs cursorial, tarsi five-segmented.

Diagnosis

In many ways the Geraridae are typical Orthopteroidea, having
mandibulate mouthparts, hypognathous heads, and filamentous
antennae. But they differ from other orthopteroids in two important
characters: their well-developed prothorax which is armed with
spines (the latter reach a length of 10 mm in G. danielsi), and their
distinctive fore and hind wing venation. While gerarids can be read-
ily recognized on the basis of the prothorax alone, wing venation is
generally a better diagnostic character. Particularly distinctive are
the RS-M veins in the fore wing, and the R-RS veins in the hind
wing. In the fore wing RS is reduced and M is expanded with 5 to 6
branches. The apical branch of M either anastomoses with RS for a
short distance or is connected to it by a short cross vein. In the hind
wing, the opposite is true: M is greatly reduced and RS expanded
into 5 to 6 branches.

It is worth noting that the anal fan in the hind wing, if present,
was very small (see fig. 17). This suggests that in gerarids the fore
and hind wings may have functioned equally well in flight, unlike in
extant Orthoptera, which rely primarily on expanded hind wings for
flight propulsion. The abdomen is essentially unknown for the fam-
ily, but was probably shorter than the wings, a claim based on the
comparison of wing length to legs, thorax, and head. No cerci are
preserved, but because the Geraridae are orthopteroid, it may be
assumed that they were present.

Psyche

[Vol. 90

Fig. 2. Gerarus clanielsi, composite drawing, based primarily on specimens
FMNH PE 5276, 31973, 32027, 32029; and USNM 31973.

1983]

Burnham — Geraridae

Remarks

The family Geraridae was first established by Scudder (1885) for
several fossil insects from Mazon Creek noted for their slender
bodies, which tapered “greatly anteriorly” (Scudder, 1885:344), and
for the distinctive branching pattern of RS in the hind wing.
Scudder placed the family in the order Paleodictyoptera, section
Neuropteroidea, where it remained until 1906 when Handlirsch
erected the order Protorthoptera and transferred the Geraridae to
it.^^ Most of the subsequent work on the family was carried out by
Handlirsch who added a total of two new genera and nine new
species to it (Handlirsch, 1906a, 1906b, 1911, 1920).

This revision is the first systematic work carried out on the family
since then, and rectifies many of the taxonomic errors made by these
earlier workers. To a large extent, the mistakes made by Scudder
and Handlirsch may be attributed to the limited availability of
material at their disposal, and the preservation of most gerarids with
all four wings lying over one another. Nevertheless, their errors were
of grave consequence. To begin with, neither worker apparently
recognized the extent to which intraspecific variation occurs in the
family, and therefore each named only monotypic species. But,
more importantly, owing to the difficulties of wing overlap, neither
Scudder nor Handlirsch correctly interpreted the wing venation of
Gerarus\ both managed to interpret the venation of one wing (the
hind wing) and then assumed that fore and hind wings were identi-
cal, although neither actually saw the fore wing.

The advantage of having more material at my disposal made it
possible for me to overcome the problems that faced these workers.
Certain well-preserved specimens (especially FMNH-PE 5276,
31973, 32027; IP 5, 23) were instrumental in demonstrating the
complete venational differences between fore and hind wings. A
comparison of figs. 6a and 6b shows how strikingly different the
fore wing actually is from the hind wing. This, in itself, was quite a
revelation. But it was only later, when searching through the litera-
ture looking for venational similarities with other groups, that the

■^Prior to this, all Carboniferous insects were included in the one order Paleo-
dictyoptera in accordance with Scudder’s beliefs that ordinal differentiation had not
taken place 'n the Insecta as early as the Carboniferous. We know, of course, that this
was incorrect; a total of 1 1 orders are now recognized from that Period (Carpenter,
1977; Wootton, 1981).

Psyche

[Vol. 90

full significance of the discovery emerged. It became immediately
apparent, based on fore wing characters, that the type genus (Sthe-
naropoda) for the family Sthenaropodidae^ is inseparable from
Gerarus. The consequences of this are twofold: 1) it extends the
geographic range of the Geraridae from North America to Europe,
strongly suggesting that the family was once large and successful;
and 2) the synonymy casts serious doubts on current classifications
of Paleozoic orthopteroids such as those proposed by Sharov (1968)
and Rasnitsyn (1980). The implications of this are addressed in the
discussion section at the end of this paper.

Geological range: Carboniferous — Westphalian D to Stephan-
ian. Occurrence: Mazon Creek, Illinois, U.S.A.; Commentry,
France. Type genus: Gerarus.

Synonymies

The families Genopterygidae and Sthenaropodidae are synony-
mized here with the Geraridae, since 1 find no unique characters by
which to recognize them as independent taxa. All major veins and
body characters are in complete agreement with the definition of the
Geraridae. Although the Genopterygidae are described from the
hind wing alone, and this synonymy may therefore change as addi-
tional material is found, the venational similarities between Genop-
teryx and Gerarus are striking (see fig. 7). This, in my mind, is
sufficient reason at this time to synonymize these families. The syn-
onymy of the Sthenaropodidae with the Geraridae is based not only
on the venation of both wings, but also on the prothorax (complete
with spines) and body size. The two families are so similar in charac-
ter that synonymy at the species level could almost be justified were
it not for their separation both geologically and geographically.

^The Sthenaropodidae, like the Geraridae, were the focus of taxonomic work
largely at the turn of the century. Brongniart first described Sthenaropoc/a (based on
S. fischeri) in 1885 and placed it with a series of other Carboniferous Protorthoptera
in the family Paleoacridiodea. Eight years later he synonymized Sthenaropoda with
Oedischia (now recognized as belonging to the Orthoptera), believing their differ-
ences too slight to warrant generic separation. In 1906 Handlirsch restored the genus
Sthenaropoda and placed it in its own family. His decision was later defended by
both Lameere (1917) and Sharov (1968), who felt that the oedischiids, by virtue of
their saltatorial legs, were true Orthoptera, and that the sthenaropodids, which
lacked well-developed jumping legs, were clearly members of the Protorthoptera.
The ramifications of this are discussed in the concluding pages of this paper.

Fig. 3. Handlirsch’s reconstructions of two species of Gerarus. a. C7. danielsi\ b.
G. collari.s (^lon^icullis). (From Handlirsch, 1920:152,153).

Psyche

[Vol. 90

Genus Gerarus

Gerarus Scudder 1885:344; Handlirsch 1906a: 147, I906b:702, 1911: 313, 1919:38.

Type: Gerarus vetus Scudder (original designation).

Sihenaropuda Brongniart 1885:59; Handlirsch 1906a: 148, 1906b: 704, 1919:30. Type:
St henaropoda fischeri (or\g\n-d\ designation), nkw synony my.'’

Genopteryx Scudder 1885:327; Handlirsch 1906a: 148, 1906b:704, 1919:30. Type:
Genopteryx constricta (original designation). Nt:w synonymy.^

Archaeacridites Meunier 1909a:39. 1909c: 145; Handlirsch 1919:39. Type: Archaea-
cridites hruesi (original designation), nhw s^ non'i my.

Rossites Richardson 1956:44. Type: Rossites inopinus (original designation).

M W SYNONYMY.

Description

Fore wing: membranous, larger than hind wing, rounded at
apex; SC long, weakly turning anteriorly to fuse with C at point
three-fourths to two-thirds the length of the wing; R parallel to SC,
terminating in C slightly anteriorad to wing apex. Fore wings differ
from hind wings in the following veins: in the fore wing, RS
branches from R in the basal third of the wing, and bifurcates two
or three times. M four- or five-branched, either connecting to RS by
a cross vein or fusing with it; CUA coalesces with M for short
distance at wing base and may be weakly branched; CUP simple,
elbowed towards CUA; network of anal veins present.

Hind wing: RS has three to six distinct pectinate branches and
does not fuse with M; M multiply branched, arising from RS; CUA

^Some doubt exists concerning the date of publication of this paper with respect to
Scudder’s 1885 article, but 1 have concluded for the following reasons that Scudder
had priority of publication: 1 ) Although we do not know the month of publication
for Brongniart’s paper, we do know that Scudder’s was published early in April,
1885. Unfortunately, attempts to obtain the exact date of publication for Brongni-
art’s article from the Museum d’Histoire Naturelle de Rouen and the Societe des
Amis des Sciences Naturelles de Rouen have met with no response. 2) Citations of
these two papers (e.g., Handlirsch, 1906a, 1922) have consistently listed Scudder’s
paper before Brongniart’s. 3) Scudder’s 1885 account of Gerarus includes a full
description, figures, and designation of a type species {G. vetus), whereas Brongni-
art’s paper only mentions Sthenaropuda and gives no formal description.

''Gerarus and Genopteryx were named and described by Scudder in the same paper
(1885). In accordance with the I.C.Z.N. procedures, and as the first reviser, I have
treated Genopteryx as the junior synonym of Gerarus, the better known and
larger genus.

1983]

Burnham — Geraridae

simple or with one bifurcation; CUP simple and parallel to CUA;
anal area slightly expanded, but unusually reduced for the Orthop-
teroidea. See fig. 17.

Diagnosis

Gerarus may be distinguished from the other genera in the
Gerandae {Nacekomia, Progenenfonium, Genentonmm and Gerarulus)
by size (members of this genus are large, fore wing is 40 mm to 55
mm in length); and the nature of the RS and M veins in the fore
wing. In Gerarus RS branches two or three times; in Progenentonium,
it branches at least four times. M in Gerarus is four- or five-branched,
and either coalesces with RS for a short distance or is connected to
it by a well-developed cross vein. In contrast, M in Naeekomia is
distinct from RS, and in Genentonium, M is only three-branched
and these branches are distinctly parallel to one another. Other
characters such as the shape of the thorax and number of prothoracic
spines may ultimately prove important in distinguishing these
genera from one another, but as yet, we lack the well-preserved
specimens necessary for separating all four genera in the family on
the basis of such additional characters.

Remarks

Handlirsch (1911:313) characterized Gerarus by its prothorax,
described as “a broad base, either provided with tubercles or
smooth, but in every case, produced into a long neck-like part bear-
ing the head.” While he was correct about the nature of the “neck,”
he was incorrect in his assessment of the “tubercles,” which were
presumably present in all adult gerarids as fully produced spines,
not tubercles. He was also slightly inaccurate in describing the pro-
thorax as “a broad base.” This study has shown the width of the
prothorax to vary from 5 mm to 13 mm depending on the species. A
better description for the genus is one based on wing venation.

Geological range: Upper Carboniferous — Westphalian D to
Stephanian. Occurrence: Mazon Creek, Illinois, U.S.A.; Com-
mentry, France. Type species: Gerarus vetus.

Synonymies

As indicated in previous pages, clarification of the venation of
both fore and hind wings has led to several important synonymies.
A comparison of Sthenaropoda with Gerarus reveals that the vena-
tional differences lie largely in the number of branches of M and

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[Vol. 90

this, in my opinion, does not justify distinction above the species
level. Similarly, Archaeacridites, lacking distinct venational charac-
ters, cannot be separated from Gerarus.

I am also synonymizing two genera from the order Caloneurodea
with Gerarus: Genopteryx and Rossites, for which Richardson
(1956) erected the family Genopterygidae. Genopteryx, originally
described by Scudder (1885), and placed in the family Homotheti-
dae, was transferred subsequently to the Geraridae by Handlirsch
(1906a). Richardson (1956:41) removed Genopteryx from the Gera-
ridae and placed it in the order Caloneurodea. He did so on the
basis of its “heavy cross veins and the close straight parallel CUA
and CUP” these being the “two characters regarded by Carpenter
(1943) as prescribing inclusion in the order Caloneurodea.” Richard-
son then states that "'Rossites has delicate cross veins and its CUA
deviates from strict parallelism with CUP, yet the venation is nearly
identical with that of Genopteryx,''" and for that reason placed the
two genera in the same family. While these genera do seem to belong
together, 1 see no reason to include them in the Caloneurodea. One
result of the present study was the discovery that CUA and CUP are
typically parallel in the hind wing of the gerarids, and that place-
ment and number of the cross veins is variable. Therefore, with the
disappearance of the supposed diagnostic venational characters that
Richardson used to justify their inclusion in the Caloneurodea and
the discovery of synapomorphies by which they may be linked to
Gerarus, 1 feel that there is every reason to include these species in
the Geraridae. It is interesting to note, however, that the parallel
positions of CUA and CUP, characteristic of this family, may ulti-
mately indicate a closer relationship with the Caloneurodea than
previously recognized.

Gerarus vetus
Figures 4 and 5

Gerarus vetus Scudder 1885:344, 1890:308; Handlirsch 1906a: 147, 1906b:702,
1919:30.

Description

Fore wing: length 45-55 mm, width 13 mm; RS two- to
three-branched, fusing with M for short distance at point where M
elbows towards RS; M three-branched; CUA simple, CUP forked.

1983]

Burnham — Geraridae

Fig. 4. Gerarus veiu.s, a. composite drawing of the fore wing, based on DGLS I
and USNM 38136. b. composite drawing of the hind wing, based on DGLS I and
USNM 38136.

Hind wing: length 42-50 mm, width 11-12 mm; RS at least
four-branched; M forked; CUA and CUP not known.

Body: prothorax much smaller in this species than in G. danielsi.
Width about 5 mm at its widest point, length 10-15 mm. Largest
measurable spine 7 mm. Unfortunately, the arrangement and number
of spines in this species is uncertain, but nine are expected in
keeping with the genus. Head small, 4-5 mm in length. Coxae
possibly enlarged; tibiae and femora long and slender.

Diagnosis

This species is distinguished from G. danielsi on the basis of its
long and slender appearance, its diminutive prothorax and narrow
wings. Unfortunately, the venation is not sufficiently preserved in
any of the specimens assigned to this species to be useful as a diag-
nostic character. Although body length is intermediate between that
of G. danielsi and G. collaris, this species is clearly more slender
than the other species in the genus. Compare fig. 5 with figs. 9 and
13.

Geological range: Westphalian D. Occurrence: Mazon

Creek, Illinois, U.S.A.

Fig. 5. Gerarus vet us, photograph of specimen FMNH PE 32024. Note the
narrow prothorax, and head, on which a compound eye is visible. Length of wing, 52
mm. e - eye; s = spine.

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[Vol. 90

1983]

Burnham — Geraridae

Holotype: USNM 38136. Specimen examined. This specimen
consists of a prothorax, including spines, and the hindwings which
overlap one another. Unfortunately, details of the venation are
incomplete.

New' material

FMNH PE 32022. Obverse and reverse halves. The prothorax
and five spines are preserved in this specimen but unfortunately, due
to overlap, venational details are obscured.

FMNH PE 32024. Obverse and reverse halves. The head is well
preserved, and complete with a compound eye, clypeus, one mandi-
ble, and a spine base. Parts of all three legs are also preserved. The
enlarged prothoracic femur is probably an artifact of preservation,
the result of lateral compression during burial.

DOES 1. Obverse and reverse halves. This is a somewhat dis-
torted specimen with the prothorax pushed into the mesothorax.
Fore and hind wings on the right side are slightly splayed apart and
reveal most of the venation of the hind wing.

Wolff 301. Obverse and reverse halves. Only a fragmentary spec-
imen with a poorly preserved prothorax and spine bases.

DMRW 2 (Dabasinskas 2). Obverse and reverse halves. An
excellent specimen showing posterior part of the head, complete
prothorax (although the spines are broken), mesothorax, meta-
thorax, and wings, which unfortunately overlap. Its long and
slender appearance and slim prothorax place it in this species.

Gerarus danielsi
Figures 2, 3, 6, 7, 8, 9, 10 and 1 1

Gerarus danielsi HandVnsch 1906a: 147, I906b;703, 1919:30.

Gerarus longus Handlirsch 1906a:147, 1906b:702, 1919:30. new synonymy.

Gerarus angusius Handlirsch 1906a:148, 1906b:703, 1919:30. new synonymy.
Gerarus laius Handlirsch 191 1:313, 1919:30. new synonymy.

Gerarus reductus Handlirsch 191 1:314, 1919:30. new synonymy.

Genopieryx constricta Scudder 1885:327; Handlirsch 1906a:148, 1906b:704, 1919:30.

NEW SYNONYMY.

Rossites inopinus Richardson 1956:44. new synonymy.

Description

Fore wing: length 53-55 mm, width 17-19 mm; SC unbranched,
parallel to C, connecting to latter by multiple cross veins; R simple,
parallel to SC, terminating at wing apex; RS pectinate with 2 to 3

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[Vol. 90

branches, originating from R in basal third of the wing; CUP
simple, originating from very base of R, connecting to RS by a short
cross vein; M four-branched, fusing for approximately 9 mm at its
base with CUA; CUA also four-branched; CUP simple, arising
independently of CUA at the wing base. CUP elbows towards CUA,
connecting to it by short cross vein. Anal veins slender and
bifurcating. Well-developed reticulation present in anal area.

Hind wing: length 40-48 mm, width 14-16 mm; SC and R same
as in fore wing; RS pectinate with five branches, arising from R near
wing base; M arising from near base of RS and deeply cleft with two
or more terminal bifurcations; CUA and CUP parallel and
independent at wing base. Anal area not well preserved, only
slightly expanded, and with reticulated venation.

Prothorax: distinctly large and swollen posteriorly. There are
nine prominent spines symmetrically arranged in the swollen region
(see fig. 8). Width at widest point 10-13 mm, length 20-22 mm;
spines 7-10 mm in length. One, possibly two, vertical spines extend
from the anterior of prothorax, posterior to head.

Body: large, ranging from 70 mm to 75 mm (tip of wing to
anterior tip of prothorax). Legs long and thin.

Diagnosis

This species may be distinguished from the other species in the
genus by the large prothorax and well-developed spines (longer in
this species than in any other); and the overall body size which is
distinctly larger than that of either G. vetus or G. collaris from
Mazon Creek. Although venational characters do vary intraspecifi-
cally, it should be noted that in the fore wing M connects to RS by a
small cross vein, and that the anterior branch of CUP connects to
CUA also by a small cross vein. This contrasts with the other species
in the genus in which one finds an actual anastomosis of these veins.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: USNM 35574. Specimen examined. Reverse half
only.^ The bulbous region and spines of the prothorax are well
preserved in this specimen. Only the costal margins of the fore wings
are present, but venation of the hind wings is clear, except in the
anal area. All evidence of the head and anterior region of the pro-
thorax has been lost.

'<The obverse half was originally in the Daniels collection, the location of which is
not known (see Carpenter, 1965, for further details on this collection).

1983]

Burnham — Geraridae

Fig. 6. Gerarus tlanielsi, a. composite drawing of the fore wing, based primarily
on FMNH PE 5276, 31973; and DMRW 1. b. composite drawing of the hind wing,
based primarily on USNM 35574, FMNH PE 32031, and MCZ 222.

Fig. 7. Gerarus danielsi, originally Genupteryx eunsiricta. Drawing of hind wing,
based on USNM 38148. Compare this with the hind wing in Fig. 6b.

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[Vol. 90

Fig. 8. Gerarus clanielsi, photograph of the prothorax, PE 32029. Total length of
prothorax, not including spines, 21 mm, s = spine.

Synonymies

Gerarus latus YPM 33. Specimen examined. Obverse and reverse
halves. This species is synonymized here with G. danielsi by virtue of
its size (hind wing as preserved is 45 mm long, but is short several
millimeters at its apex) and the shape of its prothorax. The latter,
despite some distortion, clearly has spines of the same length and
pattern as G. danielsi. A single spine base is present at the anterior

1983]

Burnham — Geraridae

Fig. 9. Gerarus cianielsi, photograph of the holotype, USNM 35574. Length ot
fore wing 42 mm, as preserved, fw = fore wing; hw = hind wing; s = spine.

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[Vol. 90

tip of the prothorax. Fore and hind wings overlap. Only the costal
area of the fore wing is visible, but most of the hind wing venation is
visible under close scrutiny.

Gerarus reductus YPM 35. Specimen examined. Obverse and
reverse halves. This is an unusual specimen in that two wings are
preserved in the same concretion, but nothing suggests that they
necessarily belong to the same specimen — or even to the same spe-
cies. The specimen is badly fractured into four distinct pieces, and
the two wings appear to be in different bedding planes. Handlirsch
(1911) described the two wings as fore and hind wings of the same
species, but expressed reservations concerning their generic assign-
ment. I am convinced that these wings do not belong to the same
specimen but believe instead that they are both hind wings belong-
ing to different species. The specimen that Handlirsch (191 1:315, fig.
20) considered to be a fore wing is here designated the lectotype of
G. reductus and it is herein synonymized with G. danielsi. The
specimen that he interpreted as the hind wing of G. reductus
(191 1:314, fig. 19) undoubtedly is a hind wing, but not sufficiently
well preserved to warrant family determination and it is placed here
in Protorthoptera incertae sedis.

Gerarus longus USNM 38822. Specimen examined. Obverse and
reverse halves. Fore and hind wings overlap but the venation is very
similar to that of the holotype of G. danielsi: RS is pectinate, with
five branches, and M is deeply cleft. Also the prothorax, although
badly preserved, does have spines, two of which are visible on the
left side. This, plus the size of the specimen (fore wing measures
approximately 55 mm, hind wing 44 mm) warrants synonymy of G.
longus with G. danielsi.

Gerarus angustus USNM 38811. Specimen examined. Obverse
half only. This is a poor specimen: all four wings overlap, and the
fossil has been weathered so the venation is only barely visible.
Nevertheless, in my opinion, the overall size of the specimen (fore
wing length is 55-57 mm) and the swollen prothorax justify its
synonymy with G. danielsi. Certainly it displays no unique charac-
ters by which it may be distinguished as a separate species.

Genopteryx constricta USNM 38148. Specimen examined. This
species was originally assigned to the Geraridae by Scudder (1885),
but later transferred by Richardson (1956) along with Rossites
inopinus (see below) to the Caloneurodea. Having examined both

1983]

Burnham — Geraridae

type specimens, I find no characters by which to separate either
genus from Gerarus. Because there are no significant differences in
venation between R. inopinus, G. constricta and G. danielsi (com-
pare fig. 6 with fig. 7), synonymy at this point seems justified.

Rossites inopinus FMNH PE 3304. Specimen examined. Obverse
and reverse halves. Only the basal half of the hind wing is preserved,
but it shows CUA and CUP very clearly. Length of the wing as
preserved measures 29 mm; actual length is estimated as 40 mm.

New material

FMNH PE 5276. Obverse and reverse halves. This specimen is,
without doubt, the most spectacular of all specimens examined for
this study. Both halves are excellent, and the obverse half gives a
particularly good three-dimensional effect (see fig. 11). The latter
also shows the entire prothorax and part of the head. The base of
the vertical spine at the anterior end of the prothorax may be seen in
the reverse half. Parts of all three legs are visible in the specimen and
unequivocally demonstrate the gracile nature of the femora.

FMNH PE 31973. Obverse and reverse halves. An almost perfect
specimen of a single G. danielsi fore wing. The apex of the wing is
missing, but the anal area is remarkably well preserved in this
specimen.

FMNH PE 31988. Obverse and reverse halves. This is a poor
specimen: fore and hind wings overlap, and are only partially pres-
ent. However, venation and size both place it in G. danielsi.

FMNH PE 32023. Obverse and reverse halves. This is not a well-
preserved specimen, but venation and size both conform to the
species description.

FMNH PE 32027. Obverse half. The prothorax, pterothorax, and
basal areas of the right hind wing and left fore wing are evident. The
prothorax bears the characteristic arrangement of nine spines and
also has a tiny lateral spine projecting from its anterior left side.
Although smaller than the other specimens in this species (width of
fore wing is 12 mm) it is included in G. danielsi because it is, in all
other respects, identical to the holotype.

FMNH PE 32029. Obverse and reverse halves. This specimen,
which has an impressive array of spines on the prothorax, and a
vertical spine at its anterior tip, is magnificent. Hind wings are pre-
served, but overlap.

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[Vol. 90

Fig. 10. Gerarus danielsi, photograph of FMNH PE 5276, obverse half. Length
of fore wing 50 mm, as preserved, s = spine; fw = fore wing; hw = hind wing.

1983]

Burnham — Geraridae

Fig. 11. Gerarus Janielsi, stereophotograph of FMNH PE 5276, reverse half.
Total length = 77 mm. Photograph by F. M. Carpenter.

FMNH PE 32031. Obverse and reverse halves. This is an excel-
lent specimen that shows the venation of the hind wing, and an
outline of the prothorax, complete with spines.

DMRW 1 (Dabasinskas 1). Obverse and reverse halves. This is a
beautifully preserved specimen, showing almost the entire fore wing,
and two-thirds of the hind wing. It differs from the holotype in the
nature of M, which has only three major branches, but is otherwise
consistent with G. danielsi. Recognition of DMRW 1 as a new
species merely on the basis of M, given that nothing is known of the
body, does not seem warranted at this time.

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[Vol. 90

Wolff 491. This specimen consists of head, thorax, and the basal
area of two wings, but nothing can be made of the venation. The
prothorax is large and bears at least seven spine bases. The head is
preserved at a slight angle to the prothorax. Labrum is visible, as are
one antenna and both eyes.

MCZ 222. Reverse half. Costal margin of the fore wings and most
of the hind wings preserved. This insect is small for the species (hind
wing measures 45 mm long, 14 mm wide) but the venation is indis-
tinguishable from that of the holotype.

Gerarus collaris
Figures 12 and 13

Gerarus collaris Handlirsch 1911:314, 1919:30.

Gerarus longicollis Handlirsch 1911:315, 1919:30. new synonymy.

Description

Fore wing: length 45-50 mm, width not known. Venation of fore
wing obscured in all specimens.

Hind wing: length 40-45 mm, width 10-12 mm; RS apparently
five-branched, M deeply forked; CUA and CUP parallel.

Prothorax: small, 1 1 mm in length and narrow (approximately 6
mm wide). Posterior, or bulbous region, 7-8 mm long. Broken
spines are present on all G. collaris specimens examined, but no
more than six can be seen on any one specimen.

Diagnosis

This is the smallest of the Gerarus species. Unfortunately, the
venation in all known specimens is not clear enough to serve as a
species level character. G. collaris is, therefore, best recognized by
its prothorax, which tapers gradually from the anterior to the poste-
rior end, and is much narrower and shorter than in other species of
Gerarus. The distinctive nature of the prothorax, and its usefulness
as a species-specific character, can be seen by comparing figs. 5, 1 1
and 13.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: Gerarus collaris YPM 34. Specimen examined.
Obverse half. Fore and hind wings overlap in this specimen, only the
costal margin of the fore wing is well preserved. The prothorax is
intact and several spine bases are visible, but the overall preserva-
tion is mediocre.

1983]

Burnham — Geraridae

Fig. 12. Gerarus col/aris, drawing of hind wing, based on holotype YPM 34.

Synonymy

G. longicollis YPM 36. Specimen examined. Obverse half. A
fragmentary specimen. Wings are poorly preserved, and only RS
and CUA/CUP in the hind wing are visible. This species is syn-
onymized here with G. collaris on the basis of its prothorax, which
is small and tapers gradually from the posterior to the anterior end,
as it does in all known members of G. collaris.

New Material

USNM 38835. Obverse half. Only the base of the wings and the
prothorax are preserved in this small specimen. The prothorax,
which bears at least six spine bases, is clearly narrow and elongate,
and is the reason for including this specimen in G. collaris.

Gerarus fischeri
Figures 14, 15, 16 and 17

Sihenaropoda fischeri ^xongmdLXi 1885:59; Handlirsch 1906a:142, 1919:38.

Oedischia fischeri Brongniart 1894:559.

Sihenaropoda lerichei Lameere 1917:178. new synonymy.

Sihenaropoda agnusi Lameere 1917:178. new synonymy.

Description

Fore wing: length 40-50 mm, width 14-15 mm; SC parallel to C
turning upward to fuse with it at point that is two-thirds length of
wing; R parallel to C, terminating at wing apex; both SC and R
connecting to C and SC respectively by numerous sigmoidal cross
veins; RS diverging from R at midpoint of wing and branching
twice; M originating at base of R, anastomosing with RS basally
before branching off and forking once; CUP forked, originating

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[Vol. 90

Fig. 13. Gerarus coUaris, photograph of holotype, YPM 34. Length of fore wing
48 mm. fw = fore wing; hw = hind wing.

1983]

Burnham — Geraridae

Fig. 14. Gerarus fischeri, a. drawing of fore wing, based on specimens IP 4, 5, 7,
and 23. b. drawing of hind wing based on specimens IP 5, 7, and 10.

separately from CUA at wing base; anterior branch of CUP fusing
with CUA for approximately 9 mm before weakly breaking away;
multiple veins and well-developed reticulation present in anal area.

Hind wing; length 39-47 mm, width 13-14 mm; SC and R same as
in fore wing; RS parallel to R and pectinate, with number of
branches varying from four to five; spacing of these branches rela-
tive to one another also variable (in one specimen IP 2 the first
branch of RS is connected to the main stem of RS by a strengthened
cross vein, forming a small oval in the middle of the wing); M deeply
cleft with one or two branches; CUA and CUP parallel. The anal
area of hind wing not known for this species, but appears to be
slightly expanded, judging by overall wing shape. See fig. 17.

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[Vol. 90

Diagnosis

G.fischeri is remarkably similar to G. danielsi in many respects:
prothorax, size, venation (compare fore and hind wings of each in
figs. 6 and 14). The only obvious difference lies in the nature of
CUA and CUP in the fore wing, \nfischeri CUA forks only once (in
danielsi it has many small branches) and the anterior branch of
CUP fuses with CUA for a distance of 9 mm. In danielsi the two are
connected by a small cross vein.

Remarks

G. fischeri was first described by Brongniart for a series of
orthopteroid insects recovered from the Commentry Coal Basin.
The series is remarkable not only because it contains a large number
of individuals, but because most of these individuals are exception-
ally well preserved. Under these circumstances it is somewhat odd
that affinities between the Commentry species and the Mazon Creek
species went unrecognized for so long. Many of the Commentry
specimens (especially IP 5, IP 7, and IP 23) have most of the body,
including the prothorax, preserved and demonstrate the same
arrangement of spine bases seen in the Mazon Creek material.
Moreover, venation of the fore and hind wings in these specimens is
unequivocally clear. Handlirsch might have recognized the similari-
ties between Sthenaropoda and Gerarus had he examined the
Commentry material himself, but this is debatable since the fore
wing for Gerarus was unknown at the time. The similarities
between G.fischeri and G. danielsi, given above in the diagnosis, are
extraordinary. While separation of the two species on siich minor
morphological differences might be subject to debate, I have chosen
to recognize the two species as distinct from one another on geogra-
phical and geological grounds. G. danielsi comes from Mazon
Creek in North America (Westphalian in age) and G.fischeri from
Commentry in France (Stephanian in age).

Geological range: Stephanian. Occurrence: Commentry,
France.

Holotype: Gerarus fischeri. IP 5. Specimen examined. Obverse
half only. This is probably the most spectacular of all the Commen-
try gerarids and of great taxonomic significance because the wings
are splayed apart and venation of both fore and hind wings is read-
ily visible. The insect is preserved dorso-laterally and the three legs

19831 Burnham — Geraridae 31

Fig. 15. Gerarus fischeri, photograph of holotype, IP 5. Total length = 75 mm.
s = spine; h = head; a = antenna, f = femur; t = tibia; ts = tarsomere; fw = fore wing;
hw = hind wing.

on the right side are preserved, as are the thorax and head. Spine
bases are present on the bulbous region of the prothorax, although
the spines themselves have broken off (see fig. 15).

Synonymies

S. lerichei. Holotype. IP 23. Specimen examined. Obverse half.

S. agnusi. Holotype. IP 19/21. Specimen examined. Obverse and
reverse halves.

I am synonymizing these species with G. fischeri as there are no
obvious specific level differences by which they may be recognized.

The specimen of 5". lerichei is a well-preserved, dorsal compres-
sion of almost the entire insect. Because the wings are separated, it is
possible to interpret the venation of both fore and hind wings, and
especially that of the fore wing. The venation, the prothorax (includ-
ing spine bases) and the size of this insect are perfectly compatible
with G.fisheri.

The specimen of S. agnusi is a single fore wing, superbly pre-
served. Although the apex of the wing is missing, the basal area.

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[Vol. 90

Fig. 16. Gerarus fischeri, photograph of IP 7. Length of fore wing = 50 mm.
f ■ femur; fw ■ fore wing; hw - hind wing.

including cross-veins, is extraordinarily well-preserved, as are all
major veins. I cannot find sufficient differences between this speci-
men and the others already included in S. fischeri to warrant sepa-
rate species status.

Several species previously included in Sthenaropoda are trans-
ferred here to family, genus indet. These are S. elegantissima Meu-
nier and Sthenaropoda minor Handlirsch, the types of which 1 have
examined, and I do not believe are similar enough to Gerarus to
warrant inclusion in the family.

New Material

IP 7. Reverse half. This specimen, although fragmentary, does
show venation of fore and hind wings. The specimen is preserved
dorso-laterally; three femora on the left side are visible, but the rest
of the body including the thorax and head is missing. See fig. 16.

IP 8. Obverse half. This insect has both fore wings, a prothorax,
complete with spine bases, a head bearing moniliform antennae, and

1983]

Burnham — Geraridae

parts of all six legs present. The hind femora are not enlarged and
demonstrate unequivocally their cursorial nature.

IP 6. Reverse half. This specimen is not particularly well pre-
served due to apparent post-burial distortion of the insect. The
pro- and mesothoracic legs on the left side are detached from the
body, and the antennae, although present, are detached from the
head. Fore and hind wings on the left side overlap, but the venation
of the fore wing is preserved, and nothing of the hind wing. The
prothorax is largely intact and shows the spine bases.

IP 4. Reverse half. The fore and hind wings on the left side are
separated, and the venation of the left fore wing is clear. Unfortu-
nately, little can be seen of the remaining three wings.

IP 2. Obverse half. A single well-preserved hind wing. Anal area is
missing but may be folded under the wing. This wing differs from
most other gerarid hind wings because the first branch of RS con-
nects to the main stem of RS by a strengthened cross vein, forming a
small triangle in the center of the wing (see fig. 17c).

IP 3. Reverse half. This is a partially preserved insect and shows
most of the right hind wing but only a fraction of the other three
wings. It is interesting, however, for one feature: the right hind wing
shows an anastomosis of the first branch of RS with the main stem
of RS as seen in IP 2. Because the anastomosis in this specimen is
smaller than in IP 2, and present in only one of the hind wings, it
may be assumed that it is a form of intraspecific variation, and not
significant at a higher level.

IP 9. Obverse half. Although the venation is virtually obscured,
this specimen is important because the insect has been compressed
laterally and all six legs are spread apart. The fore legs are only
partially preserved, but the meso- and metathoracic legs on both
sides are magnificent. This is the only specimen from Commentry in
which one can count tarsal segments. There are five tarsomeres, and
a pair of tarsal claws. The prothorax and its spine bases are also
present in the fossil.

IP 10. Reverse half. This is a single hind wing and well preserved
except at the apex and in the anal area, which is folded over.

IP 1 1. Reverse half. The specimen is a single hind wing, and so
poorly preserved that the specimen is almost useless.

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Fig. 17. Gerarus fischeri, a. photograph of fore wing, specimen IP 19. Length 42
mm, as preserved, b. photograph of hind wing, specimen IP 10. Length 40 mm, as
preserved, c. photograph of hind wing, specimen IP 2. Length 40 mm, as preserved.
Note the small triangle formed by the anastomosis of one branch of RS with the main
stem of RS.

1983]

Burnham — Geraridae

Gerarus hruesi
Figures 1 8 and 19

Archaeacridites hruesi Meunier I909a:39.

Sihenaropoda hruesi Handlirsch 1919:39.

Description

Fore wing: length 45 mm (as preserved, estimated as 48 mm),
width 15 mm; SC terminating in apical third of wing, at C; R
parallel to C, connecting to it apically by several cross veins; RS
branching twice, each branch forking once distally; M expanded,
with five main branches; CUA four-branched, fusing with M at its
base; CUP elbowed towards CUA, connecting to the latter by a
strong cross vein; anal veins present; well-developed reticulation
present in area basal to CUA.

Hind wing: unknown.

Diagnosis

This species is based on a single, but almost perfectly preserved,
fore wing from Commentry. Meunier originally described bruesi
and assigned it to the genus Archaeacridites because he felt that this
species was in some way ancestral to the extant Acrididae (order
Orthoptera). While the relationships of the Protorthoptera (including
the Geraridae) to the true Orthoptera have yet to be resolved, 1 do
believe that synonymy of Archaeacridites with Gerarus is warranted.
1 have studied the holotype, and can find no characters to justify
separate generic status for this species. However, I do think that
species separation is warranted on the basis of CUA which connects
to M only by a cross vein and does not anastomose with it as in G.
fischeri. The nature of CUA in G. bruesi is much more reminiscent

Fig. 18. Gerarus hruesi, drawing of fore wing, based on holotype no. IP 20.

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[Vol. 90

of G. danielsi, where CUA also connects with M by a short cross
vein. M, however, is more expanded (more branched) in G. hruesi
than in G. danielsi.

Geological range: Stephanian. Occurrence: Commentry, France.
Holotype: Gerarus hruesi. IP 20. Specimen examined. This
specimen is a single fore wing only, but beautifully preserved. All
veins except those at the very apex of the wing are clear and can be
interpreted without difficulty (see fig. 19).

Genus Genentunium

Genentonium Scudder 1885:329; Handlirsch 1906a: 144, 1906b:700.

Description

Fore wing: SC and R parallel to C; RS branched, originating
from R in basal third of wing; M distinctive with 3 to 4 branches, all
parallel; CUA parallel to first branch of M; CUP elbowed towards
CUA; anal area with several veins.

Hind wing: SC and R parallel to C; RS multi-branched, arising
from R near wing base; M, CUA, CUP, and anal veins not known.

Diagnosis

This genus may be distinguished from the other genera in the
family on the basis of M, which in the fore wing has the unique
branching pattern described above, and the strong topography of
the major longitudinal veins displayed by the two species assigned
here to this genus.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A. Type species: Genentonium validum Scudder.

Genentonium validum
Figures 20 and 21

Geneniomuni validum Scudder 1885:329; Handlirsch 1906a; 145, 1906b;700, 1919;40.
Genentonium Cockerell 1917:81. nhw synonymy.

Description.

Fore wing: length 45 mm (estimated), width 14 mm; SC parallel to
C, connecting to it by a series of cross veins; costal margin narrow;
R parallel to C; RS at least two-branched, originating from R in
basal third of wing; M three-branched, and distinctive for the genus;
CUA parallel to first branch of M; CUP elbowed towards CUA;
anal area with several fine longitudinal veins.

1983]

Burnham — Geraridae

Fig. 19. Gerarus hruesi, photograph of holotype no. IP 20. Length of fore wing
45 mm, as preserved.

Fig. 20. Genentonmni validunu drawings based on holotype no. USNM 38135. a.
fore wing. b. hind wing.

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Fig. 2 \ .Geneniumuni valiJuni, photographs of holotype no. USNM 38135. a. fore
wing. Length 42 mm, as preserved, b. hind wing. Length 40 mm, as preserved.

Hind wing: length 40 mm, width 14 mm; SC and R as in fore
wing; RS four-branched, originating from R near wing base.

Remarks

Originally described by Scudder as a member of the Homothetidae
(Neuroptera), this species was subsequently transferred to the family
Oedischiidae by Handlirsch (1906b) on the basis of M, which
anastomoses with RS in the fore wing. Of course Handlirsch had no
idea that this character is also found throughout the Geraridae. My
inclusion of Genentomum in the Geraridae is based on the study of
all major veins and these are completely consistent for the family.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: USNM 38135. Specimen examined. Obverse and
reverse halves. Both fore and hind wings are preserved, although the
apex of the fore wing extended beyond the edge of the concretion

1983]

Burnham — Geraridae

and was therefore lost. Base and anal area of the hind wing also
missing. Wings are separated and almost at right angles to one
another.

Synonymies

Genentomwn carri USNM 65023. Obverse half. This insect is an
impression of the wings only. Although the wings do overlap, the
fore wing on the right side and the hind wing on the left side are
visible.

I am synonymizing Genentomum carri with Genentomwn validum.
Cockerell (1917) described this specimen as a new species on the
basis of R which he figured with a single anterior branch. After close
examination of the holotype, I find that he was incorrect in his
interpretation of this vein as a branch of R. Either it is a very weak
cross vein, or a wrinkle in the wing membrane. Branching pattern of
RS in both fore and hind wings is similar to G. validum, and M is
virtually identical in both.

The following genera and species are described from single
specimens (most from single wings). Their descriptions are therefore
somewhat approximate. There seems to be no justification for
removing any of these taxa from the Geraridae at this point,
although the discovery of more nearly complete specimens may
provide characters that will alter this arrangement.

Genus Progenentomum

Progenentumum Handlirsch 1906a: 145, I906b:70I, 1919:40.

Description

Fore wing: SC terminates in C at point two-thirds distance from
wing base to apex; R parallel to anterior margin of wing, fusing with
margin just before wing apex; RS pectinate with several branches;
M more branched than RS and elbowed distally, touching RS at
that point; branches of RS and M close to one another and parallel;
numerous cross veins present; CUA, CUP, and anal region not
known.

Hind wing: unknown.

Diagnosis

Progenentomum is close to Gerarus but separated from it by RS,
which has at least four branches in the fore wing. Compare with
Genentomum.

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Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A. Type species: Progenentomum carbonis.

Progenentomum carbonis
Figures 22 and 23

Progenentomum carbonis Handlirsch 1906a:145, 1906b:70l, 1919:40.

Description

Fore wing: length 30 mm preserved (estimated as 50 mm), width
15 mm; RS pectinate with four branches; distal branch of M elbows
up to touch RS. A distinct cross vein connects branches two and
three of M, and probably acted as a brace vein.

Diagnosis

This species differs from all others in the family in having a linear
series of punctations between R and RS. These may or may not
have been pigmented, but because this specimen is only an impres-
sion, no organic material remains.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: USNM 35580. Specimen examined. Obverse half.

Genus Nacekomia
Nacekomia Richardson 1956:33.

Description

Fore wing: SC terminates in C two-thirds from wing base; R
parallel to SC; RS two-branched; M four-branched; CUA and CUP
simple.

Hind wing: unknown.

Diagnosis

Nacekomia differs from Gerarus only in the nature of M, which is
separate from RS, and not connected to it except by several very
small cross veins. This, in my opinion, warrants separate generic
status but not separate family status.

Remarks

This monotypic genus was originally included in the family
Cacurgidae (order Protorthoptera), but is here transferred to the
Geraridae on the basis of its fore wing venation. While one cannot

1983]

Burnham — Geraridae

Fig. 22. Progeneniumuni carhonis, drawing of fore wing based on holotype no.
USNM 35580.

Fig. 23. Progenentomum carhonis, photograph of fore wing, based on holotype
no. USNM 35580. Length 30 mm, as preserved.

be certain that this genus belongs in the Geraridae until a more
nearly complete specimen is found, the fore wing is so similar to that
of Gerarus that I do not hesitate to include it in the family. 1 cer-
tainly can see no justification for the inclusion of Nacekomia in the
Cacurgidae, where it was placed by Richardson (1956). The vena-
tion of Nacekomia differs considerably from that of Cacurgus. In
the latter, R is branched, RS simple, M is reduced, CUA simple, and
CUP many branched. In the former, R is simple, RS branched, M
has many branches, and CUA and CUP are simple.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A. Type species: Nacekomia rossae.

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Nacekomia rossae
Figures 24 and 25

Nacekomia rossae Richardson 1956:34.

Description

Fore wing: length 43 mm, but apex is missing; SC terminates in C,
two-thirds distance from wing base; R parallel to SC, terminating at
wing apex; RS two-branched, diverging from R at midpoint of
wing; M with four well-developed branches; CUA strongly convex
and fused at base with M, nature of CUP uncertain.

Hind wing: unknown.

Diagnosis

It is impossible to designate specific characters when the genus is
based on a single specimen, but in all probability the nature of RS
(with only two branches) may be important.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: Nacekomia rossae FMNH PE 791. Specimen exam-
ined. Obverse half.

Genus Gerarulus
Gerarulus Handlirsch 1911:318, 1919:30.

Description

Fore wing: SC parallel to C, terminating on it; R simple, RS
branched; M with multiple branches, anastomosing briefly with RS;
CUA simple, CUP elbows towards CUA.

Hind wing: SC and R same as fore wing; RS pectinate; M simple;
CUA and CUP independent from one another and parallel.

Fig. 24. Nacekomia rossae, drawing of fore wing based on holotype no. FMNH
PE 791.

1983]

Burnham — Geraridae

Fig. 25. Nacekomia russae, photograph of fore wing of holotype no. FMNH PE
791 . Length 43 mm.

Diagnosis

Although the prothorax is unknown, venation of fore and hind
wings is typical for the family. I have retained this as a distinct genus
only on the basis of the diminutive size of its one species, and this
may change as more material is found.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A. Type species: Gerarulus radialis.

Gerarulus radialis
Figures 26 and 27

Gerarulus radialis Handlirsch 1911:316, 1919:30.

Description

Fore wing: length 25 mm as preserved (estimated as 35 mm),
width 1 1 mm; SC parallel to C, terminating on it; R simple, RS
branched (at least two or three times); M anastomosing briefly with
RS, appearing to be four-branched; CUA simple, CUP elbowed
towards CUA; two anal veins visible, each forking once.

Hind wing: length 21 mm as preserved (estimated as 30 mm),
width 10 mm; SC and R simple and parallel to C; RS pectinate,
although the number of branches is unknown; CUA and CUP inde-
pendent from one another and parallel; anal area slightly enlarged;
abdomen, although indistinctly preserved, appears to be rather
slender; prothorax missing.

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Fig. 26. Gerarulus racUalis, drawings based on holotype no. YPM 37. a. fore
wing. b. hind wing.

Diagnosis

This is the smallest of all the gerarids and its size seems, at pres-
ent, to be the most distinguishing feature of this species.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: YPM 37. Specimen examined. Obverse and reverse
halves. This specimen is somewhat unusual in that both fore and
hind wings are stretched out on one side of the body and do not
overlap at all. The abdomen appears to be rather slender. The pro-
thorax is missing.

Genus Anepitedius
Anepiteciius Handlirsch 1911:318, 1919:30.

Description

Owing to the poor state of preservation of the type specimen, it is
impossible to describe diagnostic characters for this genus.

1983]

Burnham — Geraridae

Remarks

It is clear that this genus belongs in the family Geraridae: the
prothorax is distinctively shaped, and the limited venational charac-
ters are in accordance with the family. Unfortunately, since this is a
monotypic genus and based on a single, poorly preserved specimen,
it is impossible to assess its relationship to other taxa in the family.
Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A. Type species: Anepitedius giraffa.

Anepitedius giraffa

Anepiiedius giraffa HancUirsch 1911:318, 1919:30.

Description

Fore wing: length 40 mm, width 10 mm; M converges with RS,
connecting to it by a short cross vein before diverging.

Hind wing: apical half of wing missing and only costal margin
visible.

Remarks

This species deviates from the other species in the family by hav-
ing a combination of narrow wings and a robust prothorax. Unfor-

Fig. 27. Gerarulus raclialis, photograph of holotype no. YPM 37. Length of fore
wing 25 mm, as preserved.

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tunately, the poor preservation of the one specimen known
pjecludes a more detailed species description.

Geological range: Westphalian D. Occurrence: Mazon Creek,
Illinois, U.S.A.

Holotype: YPM 38. Specimen examined. Obverse and reverse
halves.

Depositional Environment

For most of this century, Mazon Creek and Commentry have
reigned as the two major localities of Upper Carboniferous insects (a
third locality has just been added to this list; see Burnham, 1981).
Both have provided large numbers of superbly preserved specimens
and have contributed greatly to our understanding of early insect
evolution. Because the family under consideration is represented at
both places, a comparison of their geological history is warranted.

Roughly three hundred million years ago, in the Stephanian
Stage of the Upper Carboniferous, the Commentry Coal Basin was
a shallow lake — 9.6 km long, 3.2 km wide, and encircled by moun-
tains (Fayol, 1887; Stevenson, 1909). Two principal streams de-
scended from the surrounding mountains into the lake, where deltaic
swamps formed from the deposition of fine-grained sediments.
These were, in many respects, typical coal swamps, characterized by
Cordaites, and, in lesser numbers, other coal swamp flora such as
Lepidodendron and Stigmaria. Fossilization at the site was almost
instantaneous, the result of flooding that deposited massive amounts
of sediment in the lake and bordering swamp. The remarkable pres-
ervation of the Commentry insects would not have been .possible
without their immediate burial under these catastrophic conditions,
and it is assumed that they were buried with minimal post-mortem
transportation.

The first fossils at Commentry were discovered in the mid-
nineteenth century as a result of extensive coal exploration in the
central region of France, and were made accessible to collectors
only because of intense mining activity in the area. Once the coal
supply began to diminish, about 1915, the mines were closed down
and filled in, and further fossil collecting prohibited. For an histori-
cal account of the Commentry collections and a review of the litera-
ture on Commentry insects, see Carpenter (1943).

1983]

Burnham — Geraridae

Mazon Creek, in contrast, was once part of a major delta on the
edge of the Illinois Basin Sea. Periodic floodings in this area
resulted in the burial and preservation of a wide diversity of organ-
isms, both plant and animal. Two assemblages are recognized: the
Essex fauna (mostly marine organisms); and the Braidwood assem-
blage (freshwater to brackish flora and fauna). According to
Richardson (1956:1 1-12) the Braidwood fossils “represent the fauna
that lived on an aggrading plain, [just] above sea-level” and con-
sisted of “more than 200 species of small animals, including insects,
arachnids, mussels, and amphibians.” Over 140 species of insects
have so far been described from this locality (Richardson, pers.
comm.) and many of the specimens show exceptionally fine detail.

Unlike the Commentry fossils, which are preserved in shale,
Mazon Creek fossils are found primarily in iron carbonate or side-
rite concretions. These concretions (also called nodules) form due to
decay of the organism contained within them, but will do so only
under the right conditions (iron-rich sediments, high pH, rapid bur-
ial). They are characteristic of certain Upper Carboniferous coal-
bearing strata and have been recorded from localities in the United
States, France, England, and Germany. Nodules are shaped roughly
according to the dimensions of the organism they contain and can
be split along the bedding plane to reveal their fossilized contents.
Preservation is generally good, although appendages (particularly
legs) are frequently lost due to insufficient chemical reaction in the
extremities. For a more detailed account of concretion formation
see Woodland and Stenstrom (1979).

The Mazon Creek biota has been known since the middle of the
nineteenth century (Nitecki, 1979), but their initial discovery (unlike
Commentry) was due to the erosion of fossil-bearing strata by
stream action rather than by mining exploration. Concretions
washed out by the stream (Mazon Creek) accumulated along its
banks, and were found there by local collectors. Eventually the area
became the focus of extensive mining exploration and several pit
mines were dug in an effort to obtain coal. This was enormously
beneficial to paleontologists because it exposed great numbers of
concretions that then became available for study. Although most of
the mining has now ceased, at least one mine remains open (pit
eleven) from which fossils are still being collected, primarily by an

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avid corps of amateur collectors, many of whom have made their
finds available for scientific study.

The presence of the Geraridae at both Mazon Creek and at
Commentry may seem somewhat surprising,*^ The Mazon Creek
locality is roughly 5 to 10 million years older than that at Commen-
try and the two formed under quite different circumstances. How
can the presence of Gerarus at both be explained?

To find an answer, one must look at land mass movements during
the Carboniferous, and at their influence on climatic patterns and
continental distributions (see fig. 28). The collision of the continents
Gondwana and Laurasia during this period had two major conse-
quences. These were 1) the formation of the Allegheny Mountain
range in North America; and 2) the alignment of eastern North
America and western Europe so that they were contiguous at zero
latititude. The significance of these events for the family Geraridae
is twofold. One, the separate land masses were fused into a single
continent, and two, their new position along the equator resulted in
the formation of extensive coal swamps throughout North America
and Europe. These events made dispersal of insects from one region
to the other relatively easy. Although the creation of the Allegheny
Mountain chain may have acted as a barrier to dispersal for some
insects (and other animal and plant species), this was probably not
so for those that were strong fliers. It is likely, therefore, that the
Geraridae were able to cross the barrier, and in so doing, passed
from one coal swamp habitat to another. It is assumed, being
orthopteroids, that they were herbivores, and probably restricted in
their feeding habits to plants found in these swamps. It is not sur-
prising, then, that they should have been so widespread and success-
ful during the Upper Carboniferous. For the same reason, it is not
surprising that they died out by the end of the Carboniferous when
climatic changes led to the drying up of the great coal swamps and
the concomitant extinction of the coal swamp fauna and flora.

“^Three other genera common to both these localities have previously been
reported. They are Honialoncura (Carpenter, 1964) and Spilaptera (Carpenter and
Richardson, 1971) in the order Paleodictyoptera, and Mischoptera (Carpenter and
Richardson, 1968) in the order Megasecoptera.

1983]

Burnham — Geraridae

Fig. 28. Geographic map of the Upper Carboniferous. Stippled areas represent coal swamps. Note location of Mazon
Creek relative to Commentry. (After Bambach, et al, 1980).

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[Vol. 90

Discussion

Recognition of the Protorthoptera has had a varied and unsettled
history. Despite the unquestioned importance of the order in the
evolution of the higher Insecta (as ancestors to extant Orthoptera
and possibly to the Holometabola) there is as yet little agreement
about affinities within the group. Our understanding of relation-
ships within the order is still rudimentary. This is well documented
by the present study in which the families Sthenaropodidae and
Geraridae (previously assigned to two distinct orders) are synony-
mized. Many attempts have been made to separate the Paleozoic
Orthopteroidea into more “natural lineages,” but it is currently pro-
posed (Carpenter, 1966) that recognition of one order Protorthop-
tera {sensu lato) is preferable until a better understanding of the
group’s true phylogeny emerges. While this forces acknowledgement
of the Protorthoptera as a “taxonomic wastebasket” and the group
“as thus constituted is almost certainly polyphyletic” (Carpenter,
1966), adoption of a presumably phylogenetic classification would,
at this time, only misrepresent the actual evolutionary relationships
of these insects. 1 believe that previous work on the Protorthoptera
(particularly the Sthenaropodidae) is a good example of how such
misrepresentation can occur as the result of inadequate study of a
given fossil group.

The Protorthoptera were first recognized in 1906 when Hand-
lirsch split the Paleozoic orthopteroids into three orders: the Protor-
thoptera, Protoblattodea, and Protorthoptera vel Protoblattodea
(for species that seemed to merge the characteristics of the first two).
In 1938 the Soviet scholar Martynov made an alternative sugges-
tion: that the fossil Orthopteroidea be divided into the two orders
Protorthoptera and Paraplecoptera according to whether they pos-
sessed saltatorial legs, as in the Protorthoptera, or cursorial ones, as
in the Paraplecoptera. The Geraridae were placed at this time in the
Paraplecoptera, and Martynov considered them, on the basis of size
and cursorial legs, to be typical representatives of that order. Sharov
(1960, 1962) originally suggested that these orders be reorganized
into the Protorthoptera, Paraplecoptera, and Protoblattodea, but
later (1968) expressed agreement with Carpenter that the Paraple-
coptera and Protoblattodea cannot be recognized as distinct orders.

1983]

Burnham — Geraridae

Convinced that the Protorthoptera should reflect direct relation-
ship to the Orthoptera, Sharov narrowed the order to include only
a single family, the Sthenaropodidae, synonymized here with the
Geraridae. Unfortunately, not having had the opportunity to
examine the Commentry types, he erroneously believed that the
family consisted entirely of saltatorial forms and used this to justify
its placement in the Protorthoptera. The various families previously
assigned to the Protorthoptera were placed in the Paraplecoptera
(containing the Geraridae), and the true Orthoptera. More complete
accounts of these various classifications are given by Carpenter
(1966, 1977) and Sharov ( 1968).

The most recent classification of Orthopteroidea was proposed by
Rasnitsyn (1980) in his work entitled The Historical Development
of the Insecta. Here he distributes the Paleozoic orthopteroids
among ten separate orders and proposes a new order Gerarida for
which Geraridae is the type family. The order Gerarida includes six
Mid to Late Upper Carboniferous families (previously assigned to
the Protoblattodea and Paraplecoptera), which Rasnitsyn consid-
ered related to one another on the basis of their elongate protho-
races and free, highly mobile heads. He includes in this order the
Eucaenidae, Spanioderidae, Dieconeuridae, Ischnoneuridae, Cne-
midolestidae, and Geraridae.

Rasnitsyn ( 1980: 165) admits that recognition of the Gerarida and
its division into these families is “extremely provisional owing to
insufficient study of its members.” Inasmuch as this revision of the
Geraridae has shown the degree to which detailed study of a particu-
lar taxon can affect higher levels of paleoentomological classifica-
tion, it would seem premature to accept Rasnitsyn’s ordinal
classification at this time. In my opinion, it is preferable to continue
to recognize the Protorthoptera sensu lato until we have valid syn-
apomorphies by which the true monophyletic groups in the Protor-
thoptera can be recognized.

The relationship of the Geraridae to other Carboniferous Protor-
thoptera must consequently remain unresolved. Nevertheless, there
are several interesting possibilities to consider. The first of these is
that Rasnitsyn may be correct in grouping together those families
with elongate prothoracic segments. It is perfectly possible that they

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[Vol. 90

represent a monophyletic offshoot of the Insecta that left no
descendants."^

Other possible relationships, however, may be construed on the
basis of venational characters, particularly the nature of M in the
fore wing. This vein is distinctive in that it either anastomoses with
RS for a short distance, or is connected to it by a cross vein. Because
a similar trend is seen in other groups of Protorthoptera, it may
suggest common descent. Families, aside from the Geraridae,
known to possess this anastomosis between M and RS are the
Streptocladidae, Oedischiidae, Nugioneuridae, and Tococladidae.
While many of these families (particularly the Streptocladidae) have
a much more complex venation than the Geraridae, it may be that
they represent an earlier stage in the evolution of the group — one
that led eventually to the saltatorial forms represented by the oedi-
schiids. Because the oedischiids were clearly saltatorial as far back
as the Carboniferous, it is reasonable to speculate that the gerarids
fall into a proto-saltatorial complex of Upper Carboniferous Pro-
torthoptera and may represent a line of evolution quite distinct from
that of the cursorial orthopteroids living today.

Summary

The family Geraridae, previously thought restricted to North
America, and known only from Mazon Creek, was apparently a
widespread and fairly successful group in the Upper Carboniferous.
Careful examination of Commentry Protorthoptera has resulted in
the synonymy of Sthenaropoda with Gerarus from Mazon Creek
and illuminates the problems inherent in the classifications pro-
posed by several recent authors. Recognition of the family Sthena-
ropodidae as the sole family of the order Protorthoptera and the
Geraridae as members of the order Paraplecoptera or Gerarida is no
longer tenable.

While further study is required to determine whether the Gerari-
dae are more closely related to the Mazon Creek families considered

"’Rasnitsyn is not the first to propose that the elongate prothorax is a
synapomorphic character. Others, especially Handlirsch, have already suggested that
the Geraridae are close relatives of the Spanioderidae on this basis. An argument
against this relationship, however, is the fact that they have distinctly different
patterns of venation. (In the Spanioderidae CUA is multiply branched and R
branches only once. Neither character is true for the Geraridae.)

1983]

Burnham — Geraridae

by Rasnitsyn as belonging to the “Gerarida,” or to the oedischiid
complex of true Orthoptera, at least monophyly for the family is
now established. What remains is the task of clarifying the relation-
ships of these other families; not only in terms of their relationships
to each other, but to their extant descendants as well.

TABLE I. Past and Present Classifications of the Geraridae.

Classification proposed Classification proposed

by previous workers by Burnham in this article

Order Paraplecoptera
Family Geraridae
Gerarus
vet us
danielsi
longicollis
longus
angustus
talus
rectucius
coUaris
niazonus
Genopieryx
constricta
Gerarulus
radialis
Anepitedius
girqffa

Order Protorthoptera
Family Sthenaropodidae
Sthenarupoda
fischeri
elegantissima
hruesi
minor
a gnu si
lerichei

Order Orthoptera
Family Oedischiidae
Genentomuni
validuni
carri

Prugenentomum

carhonis

Order Protorthoptera

Family Geraridae (= Genopterygidae,
Sthenaropodidae)

Gerarus (— Sthenaropoda, Rossites,
Genopieryx, A rchaeacridiies)
veius

danielsi (= talus, reducius,
tongus, angusius, consirieius,
inopinus)

cottaris (= tongicottis)
fischeri (= terichei, agnusi)
hruesi

Genenioniuni
vatiduni (=carri)

Progeneniomum
carhonis
Nacekomia
rossae
Gera rut us
radiatis
A nepiiedius
girqffa

Psyche

[Vol. 90

Acknowledgements

Many persons have contributed in varying ways to this paper. I
would like to begin by thanking Professor Frank M. Carpenter for
his superb advice and guidance. 1 thank him for his demanding
sense of scholarship, his never failing encouragement of my re-
search, and his incredible ability to understand even my most pecul-
iar idiosyncrasies. In honor of his 80th birthday, and in recognition
of his role as friend, mentor, and adviser, I dedicate this paper to
him.

Robert Mawhinney is a special person and Harvard colleague
who deserves thanks for his keen, theoretical mind and inspirational
nature, both of which he has so willingly shared with me. I thank
him for the spirit with which he has gauged my progress and has
offered many helpful, insightful, and nonambiguous suggestions.

Professor James Wilkinson of the History and Literature De-
partment at Harvard has shown strong interest in the Geraridae and
provided encouragement and editorial assistance whenever needed.
His enthusiasm for paleoentomology and his support of my work
have meant a great deal to me.

Dr. E. S. Richardson, Jr., of the Field Museum was particularly
helpful in sending unidentified material to me for examination;
without this material this revision would have had little significance.
His warm and enthusiastic support of my research is gratefully
appreciated. His premature death is a great loss to many of us.

Professors W. L. Brown, J. L. Cisne, and G. C. Eickwort of
Cornell University read an earlier draft of this manuscript and
offered many excellent suggestions for its improvement.

Beverly Strassmann, Dr. Naomi Pierce, and Professors Ruth Tem-
ple and Geneva Sayre are colleagues and friends who provided en-
couragement and support at the right times. They are appreciated in
many ways.

Dean John Wootton of Cornell University offered assistance and
advice when they were most needed. I am grateful to him for this.

K. M. Horton provided invaluable typing and editing skills. Her
standards of excellence have greatly improved this manuscript and I
am grateful for her support.

The staff at the Institut de Paleontologie in Paris were warm,
helpful, and hospitable during my visit there. In particular, I would
like to thank Dr. J. C. Fischer (Directeur), Mme. Yvette Gayrard,

1983]

Burnham — Geraridae

Dr. Daniel Heyler, and Dr. Agnes Lauriat-Rage for their wonderful
assistance.

The following individuals very kindly supplied the specimens on
which this study depended: Mr. F. J. Collier of the United States
National Museum; Mr. David Douglass of Yachats, Oregon; Mr.
Daniel Damrow of Mosineee, Wisconsin; Mme. Y. Gayrard of the
Institut de Paleontologie; Mrs. J. S. Lawless of the Yale Peabody
Museum; and the late Dr. E. S. Richardson of the Field Museum of
Natural History.

Partial financial support of this research is gratefully acknowl-
edged to National Science Foundation Grant no. DEB 82-05398 (F.
M. Carpenter, Principal Investigator), the Society of the Sigma Xi,
Cornell Chapter, and to Sigma Xi, the Scientific Research Society,
for a Grant-in-Aid of Research.

Literature Cited

Bambach, R. K., C. R. Scotese and A. M. Ziegler.

1980. Before Pangea: The geographies of the Paleozoic world. Amer. Sci.
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Brongniart, C.

1885. Les insectes fossiles des terrains primaires. Bull. Soc. Amis Sci. Nat.
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1894. Recherches pour servir a I’histoire des insectes fossiles des temps pri-
maires. These Fac. Sci. Paris, no. 821: 1-494.

Burnham, L.

1981. Fossil insects from Montceau-les-Mines (France): A preliminary report.
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Carpenter, F. M.

1943. Studies on Carboniferous insects from Commentry, France: Pt. 1. Intro-
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Bull. Geol. Soc. Amer. 54: 527-554.

1964. Studies on North American Carboniferous insects. 3. A spilapterid from
the vicinity of Mazon Creek, Illinois (Palaeodictyoptera). Psyche 71(3):
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1965. Studies on North American Carboniferous insects. 4. The genera Met-
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175-190.

1966. The Lower Permian insects of Kansas. Pt. 11. Psyche 73: 46-88.

1971. Adaptations among Paleozoic insects. Proc. N. Amer. Paleo. Conv.,
Chicago, 1969, vol. I, pp. 1236-1251.

1977. Geological history and evolution of the insects. Proc. 15th Int. Congr.
Ent., Washington, D.C., 1976, pp. 63-70.

Psyche

[Vol. 90

Carfentj r, F. M. and E. S. Rkhardson, Jr.

1968. Megasecopterous nymphs in Pennsylvanian concretions from Illinois.
Psyche 75(4): 295 309.

1971. Additional insects in Pennsylvanian concretions from Illinois. Psyche
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COCKHRHLL, T. D. A.

1917. Fossil insects. Ann. Ent. Soc. Amcr. 10(1): 1-22.

Favol, H.

1887. Etudes sur le terrain houiller de Commentry. Premiere partie: Litholo-
gic et stratigraphic. Bull. Soc. Ind. Min. XV(3 & 4). Synopsis [in] Bull.
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Handlirscii, a.

1906a. Die fossilen Insekten und die Phylogenie der rezenten Formen. Ein
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1906b. Revision of American paleozoic insects. Proc. U.S.N.M. 29: 661-820.
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1919. Revision der palaeozoischen Insekten. Denkschr. Akad. Wiss. Wien
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1920. Geschichte, Literatur, Technik, Palaeontologie, Phylogenie, Syste-
matik. Handb. Ent. 3: 1 18-306.

1922. Insecta palaeozoica [in] Fossilium Catalogus. 1. Animalia, pars 16, C.
Diener, ed.. pp. 1 230.

Lamhhrh, a.

1917. Revision sommaire des insectes fossiles du Stephanien de Commentry.
Bull. Mus. Paris 23: 141 200.

1922. Sur la nervation alaire des insectes. Bull. Class. Sci. Belgium, 1922:
138 149(transl. Psyche 30: 123 132, 1930).

Martynov. A. V.

1924. Sur rinterpretation de la nervation et de la tracheation des ailes des
Odonates et des Agnathes. Rev. Russd’Ent. 18: 145-174 (transl. Psyche 37:
245-280, 1930).

1938. Etudes sur I’histoire geologique et de phylogenie des ordres des
insectes (Pterygota). Trav. Inst. Paleont. Acad. Sci. URSS 7: 1-150.
Meunter, F.

1909a. Nouveaux insectes du Stephanien de Commentry. Bull. Mus. Hist. Nat.
Paris. 15: 37-49.

1909b. Nouveaux paleodictyopteres du Stephanien de Commentry. Ann. Soc.
Sci. Bruxelles. 33: 139-140.

1909c. Nouvelles recherches sur les insectes du Terrain Houiller de Commen-
try. Ann. Paleont. 4: 125-152.

Nite:cki, M. H.

1979. Mazon Creek fauna and flora: a hundred years of investigation [in]
Mazon Creek Fossils, M. Nitecki, ed.. Academic Press, pp. 1-13.

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Burnham — Geraridae

Rasmtsvn, a. P.

1980. The historical development of the insects. Trans. Paleont. Inst. 175:
1-268.

Richardson, E. S., Jr.

1956. Pennsylvanian invertebrates from the Mazon Creek area, Illinois.
(Insects). Fieldiana Geol. 12: 15-56.

Sri DDKR, S. H.

1885. Palaeodictyoptera: on the affinities and classification of Paleozoic
Hexapoda. Mem. Boston Soc. Nat. Hist. 3: 319-351.

1890. The fossil insects of North America, vol. 1. The pretertiary insects.
Sharov, A. G.

1960. On the system of the orthopterous insects. Int. Congr. Ent., Wien, 1960,
vol. 1, pp. 295-296.

1962. The order Protorthoptera [in] Osnovy paleontologii, B. Rohdendorf,
ed., Moscow, pp. 145-146.

1968. Phylogeny of orthopteroid insects. Tr. Paleontol. Inst. Akad. Nauk
SSSR 1 18: 1-218. (In Russian. English transl. 1971, Israel Program Sci.
Transl. Ltd., 251 pp.)

Stevenson, J. J.

1909. The coal basin of Commentry in central France. Ann. N. Y. Acad. Sci.
19(2): 161-204.

Woodland, B. G. and R. C. Stenstrom

1979. The occurrence and origin of siderite concretions in the Francis Creek
Shale (Pennsylvanian) of northeastern Illinois [in] Mazon Creek Fossils,
M. Nitecki, ed.. Academic Press, pp. 69-104.

Wootton, R. j.

1979. Function, homology and terminology in insect wings. Syst. Ent. 4:
81-93.

1981. Palaeozoic insects. Ann. Rev. Ent. 26: 319-344.

TESTING VISUAL SPECIES RECOGNITION IN PRECIS
(LEPIDOPTERA; NYMPHALIDAE) USING A COLD-SHOCK

PHENOCOPY

By Arthur M. Shapiro'

Department of Zoology, University of California
Davis, California 95616

There have been many studies of the role of color and pattern in
mating and species recognition in butterflies. For example. Crane
(1955) manipulated the bold color pattern of Heliconius spp. (Heli-
coniidae), affecting mating success; Burns (1966) claimed on the
basis of spermatophore counts that differential attractiveness of
female morphs helped to maintain a mimetic polymorphism in Papi-
lio glaucus L. (Papilionidae); and Silberglied, Aiello, and Lamas
(1980) found that modifying the pattern of Anartia (Nympha-
lidae) affected mating success but not survivorship.

Recently Hafernik (1983) demonstrated that the conspicuous pale
dorsal forewing band serves as a visual species-recognition charac-
ter, contributing to reproductive isolation between the partly sym-
patric buckeye butterflies Precis {=Junonia) coenia Hubner and P.
nigrosuffusa (Barnes & McDunnough). In hybridization experi-
ments these entities are quite compatible genetically and develop-
mentally; Hafernik concluded that differences between them “are
probably not associated with major genomic reorganization, but are
rather the result of allelic differences at a few loci,” including pre-
sumably those that control the presence or absence of the forewing
band.

The experiments done by Hafernik to test the hypothesis of visual
reproductive isolation were modeled on the work of Scott (1972),
involving presentation of reared virgin females to wild patrolling
males afield. There were four sets of experiments (i) actual combina-
tions of nigrosuffusa and coenia; (ii) coenia painted to resemble
nigrosuffusa; (iii) “wing transplants” (wings of one type glued onto
the wings of a living animal of the other; (iv) paper models. All of
these tended to indicate that coenia males discriminate against

^Manuscript received hy the editor January 6, 1983

Psyche

[Vol. 90

bandless females, and that species-specific pheromones need not be
invoked to account for reproductive isolation. None of Hafernik’s
females actually mated, but Scott (1972) showed that darkening the
wings of male coenia does not lower their courting success with
conspecifics, as it does when females are darkened.

Despite the consistency of these results, there are possibly con-
founded variables whenever one tests using entire genomes (as in i
above, in which pheromonal and subtle behavioral cues cannot be
controlled for), or altered phenotypes (as in ii and iii, where the
“similarity” to the other species is questionable, and wing loading
and odor may be altered by glues or paints). However, another test
is available, not exploited by Hafernik: pure coenia genomes can be
induced to produce nigrosuffusa-WkQ phenotypes, which may then
be presented to coenia males afield. This situation arises from the
sensitivity of coenia to temperature shocks applied shortly after
pupation.

A named aberration of coenia, “schracleri, ” figured in color by
Comstock (1927, plate 43), resembles nigrosuffusa in lacking the
band. Other characters, including the hindwing ocelli, are in the
^ coenia rather than the nigrosuffusa state. Schrader’s specimen was
reared, but similar individuals do occur in nature. One shown in fig.
If has the hindwing ocelli and distal pattern obsolescent; others are
normal for these pattern elements. The actual frequency of bandless
buckeyes is unknown. 1 have taken two at the same locality in eleven
years, during which time I must have seen hundreds of thousands of
individuals. No clear-cut genetic basis for bandlessness has been
established, but the same phenotypes are readily inducible by
subjecting wild California pupae to sustained low temperatures. Fig.
2 shows chilled individuals from three different families. The
extensive variation in individual response to treatment is character-
istic of such experiments. The involvement of the ocelli and distal
pattern is partly controllable by age of the pupa at onset of chilling,
but even very precise timing can only reduce, not eliminate, the
variation. Such indeterminacy was characterized as early as 1913 in
Pictet’s “law of melanization and albinization of parts,” which is a
statement of the partial independence of different pattern-deter-
mining processes during wing development.

Several broods of pure coenia from Solano County, California
were reared and subjected to a potent cold-shock treatment (3 weeks

1983]

Shapiro — Species recognition

Fig. I. Phenotypes of wild-collected Precis. A,C, male, B,D, female P. nigro.suf-
fusa from Arizona, USA and Sinaloa, Mexico. E, normal female P. coenia, Solano
Co., California. F. "\schraJeri'\ Suisun Marsh, Solano Co., CA. viii.28. 1978.

Psyche

[Vol. 90

at 3°C beginning 8 hr after pupation). The usual spectrum of
phenotypic response was observed. About one-third of the animals
which eclosed were seriously crippled and unusable for mating tests.
The remainder — 46 females in toto — were classified into three more
or less arbitrary phenotypic categories: (i) essentially unaltered (fig.
2e), (ii) bandless but with ocelli unaltered (figs. 2a-d), and (iii)
bandless and with ocelli obsolete (fig. 20- These were used in
experiments modeled on Scott’s and Hafernik’s, carried out on a
total of 9 days at Suisun City, Solano County, and Rancho
Cordova, Sacramento County, in urban vacant lots and annual
grassland from late September to early November 1982. Wild male
coenia were common throughout this period.

My methodology differed from Hafernik’s in a few points. Virgin
females were held, unfed and unflown, in the dark at 3°C for 3 to 1 1
days before use. This treatment did not diminish their attractiveness
relative to Hafernik’s females. They were transported in a cooler in
the dark to the study sites and allowed to warm in the sun (air
temperatures 14-24° C). After a test they were usually recaptured,
rechilled for at least 15 min, and re-used. A few were lost, and about
one-fourth mated successfully and were not re-used. As in Hafer-
nik’s work, only releases in which the male at least investigated the
female were scored. Females were considered to have elicited a
courtship if the male either attempted to copulate or remained
oriented toward the female for at least 20 sec. The durations of
about a third of the courtships were recorded.

The percentages courted were overall higher than seen by Hafer-
nik. For Point Richmond, California female coenia X male coenia
at Point Richmond, Hafernik had 64% courtship. When female
nigrosujfusa from Texas were used, this dropped to 10%. My corre-
sponding figures (table 1) are 74% and (pooled classes ii and iii)
49%. The difference remains highly significant, however, and the
discrepancy in frequency may be due to differences in weather
conditions or to the torpidity of my females. For timed courtships,
bandless females elicited less persistence than banded ones, but the
difference was not statistically significant. Most of the actual
copulations were essentially instantaneous, regardless of phenotype.

This experiment does not rule out pheromones in Precis court-
ship, but as in previous work indicates that visual cues are impor-

1983]

Shapiro — Species recognition

Fig. 2. Phenotypes of female P. coeniu from northern California, induced by
chilling the young pupa. A— D, grade ii (bandless, ocelli unaltered). E, grade i
(essentially unaltered). F, grade iii (bandless, ocelli obsolete).

Psyche

[Vol. 90

tant and possibly adequate to account for reproductive isolation. (It
is conceivable that pheromones could be physiologically coupled to
phenotypes such that the most phenotypically deviant females
would also be pheromonally abnormal.)

The control of pattern in Precis has been studied by Nijhout
(1980a, b), who has shown that all of the wing pigments in P. coenia
are melanins and that the ocelli are determined by well-defined foci
in the early pupal wing. His work does not permit a causal analysis
of how pupal chilling phenocopies the normal phenotype of nigro-
suffusa, though the phenocopy “straw” has been linked functionally
to its genocopy in Drosophila (Seybold, Meltzer, and Mitchell,
1975). In Shapiro’s (1981) model of the evolution of phenotypic
plasticity, a genetic basis for bandlessness could be established by
selection of modifiers bringing the latent ''schraderr response to the
surface under normal developmental temperatures. The derivative
character of bandlessness is shown clearly by its variable penetrance
(especially in females) in pure nigrosuffusa populations. But how
did it become virtually fixed? Discrimination by male coenia against
bandless females, even genotypicaly normal ones with intact wings,
should lead to selection against any bandless allele, however ori-
ginated. Under the conventional model for enhancement of pre-
zygotic reproductive isolating mechanisms in secondary sympatry,
one could rationalize bandlessness as a device protecting the gene
pool of nigrosuffusa. This, however, presupposes a disadvantage to

Table 1. Success of cold-shocked female Precis coenia in attracting courtships by
wild males in field tests in northern California.

Type of female

Number of

Total

releases

Number of
$9 mated

Number of
courtships

(i) essentially

unaltered

phenotype

(ii) bandless, ocelli

unaltered

(iii) bandless, ocelli

obsolete

Totals

1 14

1 1

'-test for courtship proportions, (i) \’.v. (ii + iii): z

= 2.7845 (significant at 0.01)

1983]

Shapiro — Species recognition

hybridization which outweighs the discrimination against bandless
females, and no such disadvantage has been found. Bandlessness
may be quite incidental to hybridization, but that still leaves the
question of why it persists.

Acknowledgements

This research was supported by the Department of Zoology, UC
Davis, to which 1 express my thanks. This paper is dedicated to the
memory of Robert E. Silberglied, who would no doubt have had
great fun with shock phenotypes in behavioral studies.

References

Burns, J. M.

1966. Preferential mating \’.v. mimicry. Science 153: 551-553.

COMSTOC K, J. A.

1927. Butterflies of California. Publ. by author, Los Angeles. 335 pp.

Crane, J.

1955. Imaginal behavior of a Trinidad butterfly, Heliconius erato hydara
Hewitson, with special reference to the social use of color. Zoologica 40:
167-196.

Hafernik, j. E., Jr.

1983. Phenetics and ecology of hybridization in buckeye butterflies (Lepi-
doptera: Nymphalidae). Univ. Calif. Pubs, in Ent., 96: 1-109.

Nijhout, H. F.

1980a. Pattern formation on Lepidopteran wings: determination of an eyespot.
Devel. Biol. 80:267-274. 1980b. Ontogeny of the color pattern on the

wings of Precis coenia (Lepidoptera: Nymphalidae). Devel. Biol.
80: 275-288.

Pic tet, A.

1913. Recherches experimentaies sur les mecanismes du melanisme et de
I’albinisme chez les Lepidopteres. Mem. Soc. Physique et Hist. Nat. de
Geneve 27: 1 1 1-278.

Scott, J. A.

1972. Comparative mating and dispersal systems in butterflies. Unpubl. Ph.D.
thesis, Univ. Calif. (Berkeley).

Seybold, W. D., P. S. Meltzer and H. K. Mitc hell.

1975. Phenol oxidase activation in Drosophila: a cascade of reactions. Biochem.
Genet. 13:85-108.

Shapiro, A. M.

1981. Phenotypic plasticity in temperate and subarctic Nymphalis antiopa
(Nymphalidae): evidence for adaptive canalization. J. Lepid. Soc. 35:
124-131.

Silberglied, R. E., A. Aiello, and G. Lamas.

1980. Neotropical butterflies of the genus Anartia: systematics, life histories,
and general biology (Lepidoptera: Nymphalidae). Psyche 86:219 260.

DEFENSIVE ADAPTATIONS AND NATURAL ENEMIES
OF A CASE-BEARING BEETLE,

EXEMA C/lA/4D£A5^/N(COLEOPTERA: CHRYSOMELIDAE)

By Richard B. Root and Frank J. Messina*

Section of Ecology and Systematics,

Corson Laboratory, Cornell University
Ithaca, New York 14853, U.S.A.

Introduction

The larval habit of constructing and carrying a portable case has
evolved many times in the Holometabola. It is a widespread trait
of the Trichoptera and Lepidoptera (e.g. the Coleophoridae and
Psychidae). Among the Coleoptera, casebearing is found in four
related subfamilies of the Chrysomelidae, the so-called camptoso-
mates: Clytrinae, Cryptocephalinae, Chlamisinae, and Lamproso-
matinae (Boving and Craighead 1931). The larval case of many
insects is thought to function primarily in defense by providing
armor or camouflage (Otto and Svensson 1980). Here we describe
the uses of the case and other defenses in a chlamisine beetle, Exema
canadensis Pierce, and speculate briefly on the evolution and conse-
quences of the case-bearing habit.

The genus Exema Lacordaire contains nine species in North
America (Karren 1966). All of the species appear to be univoltine
and to feed on a fairly restricted range of herbaceous or shrubby
genera in the Asteraceae (Jenks 1940; Karren 1966, 1972). In central
New York E. canadensis is commonly found on goldenrods {Soli-
dago spp.) and asters {Aster spp.). Its life cycle was summarized by
Messina and Root (1980). Le Sage (1982) recently described the
immature stages.

Methods

We observed the life history and natural enemies of E. canadensis
during 1979 and 1980 at Whipple Farm, 8 km N.E. of Ithaca, New

*Present address; Boyce Thompson Institute for Plant Research, Tower Road,
Ithaca, New York 14853, U.S.A.

Manuscript received by the editor January 24, 1983.

Psyche

[Vol. 90

York. Field-collected larvae and pupae were reared to measure the
incidence of parasitoids. Voucher specimens of E. canadensis and its
enemies were placed in the Cornell University Insect Collection (Lot
no. 1068).

The morphology of E. canadensis was examined with the scan-
ning electron microscope. Larval cases and adults were air-dried
and mounted on metal stubs with double-sided tape. Larvae and
pupae were dehydrated in an ethanol series and critical-point dried
with COt before mounting. All specimens were sputter-coated with
gold-palladium (ca. 200A). Measurements of larvae and cases were
made with an ocular micrometer.

We did experiments on the protective functions of the case by
exposing beetles to three predaceous insects: Podisus maculiventris
(Say) (Pentatomidae), Nahicula suhcoleoptrata (Kirby) (Nabidae),
and Hippodamia glacialis (F.) (Coccinellidae). For these experi-
ments we carefully extracted 4th-instar larvae from their cases; this
procedure did not appear to harm the larvae. “Exposed” and
untreated (“encased”) larvae were placed in petri dishes containing
moist filter paper and a few goldenrod leaves. In trials using P.
maculiventris, two 5th-instar nymphs were taken from a vigorous
lab culture and added to dishes containing three exposed and three
encased E. canadensis larvae (a choice situation). We recorded the
number of each prey type that were consumed by the stink bugs
after 6 and 24 h. In trials using A. suhcoleoptrata and El. glacialis,
field-collected adults were starved for 24, 48, or 72 h before being
added to dishes containing either exposed or encased E. canadensis
larvae (a no-choice situation). Each dish held three predators and
five prey. We recorded prey consumption hourly for up to 5 h.

Results

The larval case and adaptations associated with its use

In chlamisine beetles the female parent provides the initial larval
case in the form of an egg case or “scatoshell” (Hinton 1981). The
female deposits a single yellow egg that is attached to the plant on a
smooth, yellowish stalk (Figs. 1-3) that appears to be continuous
with the egg chorion. The attachment is shaped into the contours of
the leaf or stem surface (Fig. 3), suggesting that the base of the stalk
is extruded in a plastic state. The female then systematically sur-
rounds the egg with strips of green fecal material. She starts around

1983]

Root & Messina — Exenia canadensis

Figs. 14: Cases of E. canadensis. F Egg case with egg stalk attached to stem. 2,
View from top of case before cap has been added (egg was removed). 3, Close-up of
egg stalk and base. 4, Case of 1st instar larva. Arrow indicates juncture between
original egg case and larval additions. Scale bars = 500 (Fig. 4), 200 (Figs. 1-2), or
100 (Fig. 3) /um.

Psyche

[Vol. 90

the stalk and periodically twists the egg with her hind legs as she
builds up the sides until the egg is enclosed in a cuplike case with a
flared ridge (Figs. 1-2). A flat top is then added to seal the egg in the
case. The flexible egg stalk often remains twisted beneath the case
(Fig. 3). The entire deposition process takes 20-30 min in the labor-
atory. The egg case turns a drab brown color as it dries.

The larva emerges by chewing through the flat top of the case. It
then flips the case over, presumably after severing the connection
with the egg stalk (Karren 1972). Inside the inverted egg case, the
larva assumes the characteristic folded posture of the camptoso-
mates with the mouth and anus both adjacent to the single case
opening.

The larva begins to feed and gradually enlarges the case by adding
its own fecal material to the rim around the opening. The juncture
between the contributions of the mother and the larva remains dis-
tinct (Figs. 4-5), and the original egg case eventually appears as a
small nipple projecting from the tail of the larval case. A larva
passes through four stadia, always molting within the enlarging case
(Le Sage 1982). Case length is a moderately good predictor of larval
instar, as determined by the width of the head-capsule (Table 1).

Larvae of E. canadensis possess several morphological features
that are probably related to the case-bearing habit. The legs are
unusually long; each coxa is movable and so elongated that it
exceeds the length of the femur (Fig. 6). The legs can extend later-
ally beyond the rim of the case when the larva is walking. If dis-
turbed, the larva retracts its legs and pulls the case down so that the
rim is appressed to the foliage (Wallace 1970). The strongly recurved
tarsal claws (Fig. 7) may facilitate this maneuver by providing a
firmer grip on the substrate. The larval cuticle, which is normally
covered, is sclerotized in only a few areas (Le Sage 1982). Setae
(usually tricoid sensillae) are sparse, but spiny or rounded protuber-
ances are scattered over much of the surface. These protuberances
serve may to increase traction between the larval cuticle and the
case. The larval spiracles are uniforous and annular (Fig. 8). The
requirements for spiracular closure and moisture retention may be
reduced in a case-bearer; Karren (1964) reports that artificially
exposed Exema larvae are highly vulnerable to desiccation.

The prepupa seals the case rim to a leaf or stem with a layer of
frass. It then reorients itself so that the posterior end is against the

1983]

Root & Messina — Exema canadensis

Table I: Head capsule widths and case lengths (in mm) ol the immature stages of
E. canailensis.

Egg

111

Head width

x(SE)

0.29(±.01)

0.37(±.02)

0.50(±.02)

0.67(±.02)

Case length'

x(SE)

1.05(±.05)

1.62(±.38)

2.69(±.33)

3.55(±.32)

4.34(±.26)

Range

0.96 1.12

1.04 2.32

2.16 3.36

2.80 4.08

3.84 4.80

'As measured from case opening to tip of original egg case.

substrate and the anterior end faces the nipple at the tail. Fully
sclerotized adults cut a circular cap in the tail of the case with their
mandibles; this cap is pushed off as the beetles emerge. The barrel-
shaped, tuberculate adults (Figs. 9 10) can be easily mistaken for
caterpillar frass by humans (Jenks 1940; Karren 1964; and our per-
sonal experiences). It may be that vertebrate predators overlook
them in the same way. The adults exhibit the widespread chryso-
melid trait of quickly withdrawing the legs and dropping off the
substrate when they are disturbed. This escape mechanism is elabo-
rated in Exenia\ the deep sternal grooves (Fig. 10) allow the adult to
retract its appendages so completely that the falling beetle bounces
and rolls off the foliage. The compact adults also slide deeply into
the litter beneath the plant and often come to rest in a deep recess
where they are extremely difficult to find.

Natural enemies

No predators were seen to attack the larvae of E. canadensis
during the many hours that we and our associates, E. W. Evans and
J. A. Gowan, have spent observing the goldenrod fauna in the field.
The three species of predaceous insects used in our experiments,
however, were frequently observed to kill the larvae of other chry-
somelid species that are associated with Solidago in central New
York (Evans 1982; Messina 1982). In the laboratory, exposed E,
canadensis larvae were readily captured and eaten by these preda-
tors (Table 2). In contrast, few encased larvae were consumed even
though the confined space in the petri dishes must have increased

Psyche

[Vol. 90

Figs. 5-8: Case and larval morphology of E. canadensis. 5, Case of 3rd instar larva.
6, 3rd instar larva, lateral view. 7, Tarsal claw. 8, 2nd abdominal spiracle. Arrow
indicates juncture between original egg case and larval additions. Scale bars = 500
(Figs. 5-6) or 10 (Figs. 7 8) yum.

the frequency of encounter between predator and prey far above the
usual conditions in nature. The coccinellid, H. glacialis, never suc-
ceeded in capturing an encased larva and nine of the ten encased
prey consumed by the pentatomid, P. maculiventris, were taken
only after all of the exposed larvae in the dish had been eaten. The
rate that exposed larvae were consumed by N. subcoleptrata and H.
glacialis was increased by starvation (Fig. 1 1).

The protective function of the larval case is further illustrated by
its influence on predator behavior. The predator appeared to
approach in response to prey movement with the outcome that
attacks were launched, without apparent discrimination, on both
exposed and encased larvae. Attacks on exposed larvae were
quickly and invariably successful. Upon encountering an encased
larva, the predators with sucking mouthparts {N. subcoleoptrata
and P. maculiventris) touched the case with their forelegs and
extended their beaks. They were never able to penetrate the case

1983]

Root & Messina — Exenia canadensis

Figs. 9-10: Adult E. c anadensis. 9, Dorsal view. 10, Ventral view. Scale bars = 500
/urn.

even though they made repeated probes. In those instances when
these hemipterans did consume encased prey, they fed through the
case opening on the few occasions when a larva had been knocked
on its side. This is an unlikely event in nature because dislodged
larvae fall from the plant. The chewing predator, H. glacialis,
attacked the encased larvae by attempting to insert the mandibles
under the rim of the case; we never observed success in this
endeavor.

The case is an ineffective barrier to certain adapted paraSitoids.
Larvae at both field sites were parasitized by a Tetrastichus sp.
(Eulophidae); this was possibly T. chlamytis Ashmead, a species
that is only known to attack chlamisine beetles (Burks 1979). Rates
of parasitism ranged from 16 to 42% (Table 3). We obtained an
average of 8.6 Tetrastichus adults/ infested host (range, 5-14 wasps;
n = 37 hosts). Parasitoids emerged from larvae that were collected in
the field as both early (I-Il) and late (III-IV) instars. The cuticle of a
parasitized larva turns from white to black and the host dies shortly
before the time it would normally pupate. The wasps usually
emerged from the case opening, but a small exit hole was observed

Psyche

[Vol. 90

Table 2: Consumption of exposed and encased larvae of E. canadensis by three
arthropod predators in laboratory arenas.

% available prey consumed

Predator

Exposed

Encased

Podisus niaculiventris

.001

nymphs

Nahicula subcoleoptrata

.001

adults

Hippodamia glacialis

.001

'Number of each prey type offered.

-Chi-square test, where expected values assume equal consumption of each prey type.

in the case of a larva that had cemented the opening to the substrate
before it died. We could not determine if Tetrastichus females ovi-
posit through the case wall or under the rim. In the field, however, we
commonly observed Tetrastichus adults that remained perched on
the side of a larval case for prolonged periods. Perhaps these wasps
were waiting for the larva to move and thus expose a vulnerable
spot for oviposition.

^ N. subcoleoptrata H. glacialis

Hours after release
Predator starvation ;• 24,° 48, ° 72 h

Fig. 1 1: Consumption of exposed E. canadensis larvae by Nahicula subcoleoptrata
and Hippodamia glacialis in the laboratory. Predators were starved for 24-72 h
before release. Ten prey were offered per trial.

1983]

Root & Messina — Exenia canadensis

Six of 22 pupae that were collected on August 21, 1979, were
parasitized by Spilochaleis albifrons (Walsh) (Chalcidae), a species
that has previously been reported from Exenia dispar Lacordaire
(Burks 1979). One chalcid emerged from each host. No S. albifrons
were found in E. canadensis that were collected as larvae. If this
chalcid attacks only pupae, it must be able to oviposit through the
case wall because the case rim is sealed to the substrate by the
prepupae. In this regard, it is interesting to note that S. albifrons has
been taken from a broad range of unrelated case-bearing and leaf-
mining insects. Moreover, at least four of the seven species in the
side group, to which S. albifrons belongs, parasitize case-bearing
chlamisines and coleophorids (Burks 1979). These observations
suggest that the evolution of specializations in Spilochaleis is more
closely linked to the abilities required to penetrate materials that
cover the host than it is to factors that are more narrowly associated
with the host’s taxonomic affinity.

Larval mermithid nematodes were found in dissections of a few
field collected E. canadensis larvae. These parasites are functionally
similar to parasitoids, killing the hosts as they exit the body follow-
ing development (Nickle 1974).

Larvae of an erythraeid mite, Leptus sp., were found attached at
several locations on beetles. In a survey done in late August 1979,
67% of the 43 adult beetles sampled bore at least one mite. There
was an average of 1.7 mites on the infested beetles and as many as
five mites were found on a single host. Nothing is known about the
influence of these mites on the beetles.

Table 3: Per cent of E. canadensis larvae parasitized by a Tetrastichus sp. in 1979
and 1980. (Sample sizes in parentheses.)

Site

Collection date

Brooktondale 1979

3 July

29 July

21 August

21 August'

17(107)

16(57)

38(21)

27(22)^

Whipple Farm 1980

28 June

1 July

4 July

16 July

23(61)

42(19)

40(55)

31(13)

'These cases contained pupae; the larvae had cemented the case rim to the substrate
prior to collection.

-An additional 27% of the pupae were parasitized by Spilochaleis albifrons.

Psyche

[Vol. 90

Discussion

The defensive adaptations of the immature and adult stages of E.
canadensis are quite different even though they occur in the same
microhabitats, overlap in their seasonal occurrences, and encounter
similar predators. The cases that cover the eggs and larvae appear to
deter most, if not all, of the several invertebrate predators that
forage on goldenrods (see Messina 1982 for a list). Wallace (1970)
has found that the case of another chlamisine, Neochlamisus gibbo-
sus (F.) (= Anthrochlamys plicata F.), protects the larvae from
imported fire ants. The defenses of adult chlamisines require further
investigation. Nevertheless, it seems obvious that a variety of escape
mechanisms are derived from the adults’ morphology. As a conse-
quence of their hard, compact body form, adults are well-armored
against the initial thrusts of predators and they are more likely to
tumble into a refuge after dropping from the foliage. Furthermore,
because of their resemblance to caterpillar frass, adults may be over-
looked by many predators that rely on vision (Jenks 1940).

Many chrysomelids are chemically defended against predators
(e.g. Meinwald et al. 1977; Howard et al. 1982). Adults in the camp-
tosomate group, however, lack the defense glands found in most
chrysomelid subfamilies (Deroe and Pasteels 1982). This suggests
that chlamisine adults must rely primarily on the mechanical and
behavioral defenses discussed above.

The major enemies of E. canadensis are the parasitoids, S. albi-
frons and T. chlamytis. Specialized parasitoids have been highly
successful in overcoming most of the defenses (e.g. reflex bleeding,
fecal shields, glandular secretions) employed by chrysomelid larvae
to deter predators (Eisner et al. 1967; Wallace 1970; Matsuda and
Sugawara 1980).

Several characteristics of E. canadensis can be grouped into an
adaptive syndrome that is associated with the case-bearing habit.
This coordinated set of traits includes the bowed posture, long legs,
and other morphological adaptations that accommodate the larvae
to life within the confinement of a case. In addition, casebearing
probably influences other aspects of the natural history. For
instance, the time and case-building material that the female must
invest in each egg may result in a lowered reproductive rate. We
observed that 30 females laid an average of only 1.2 eggs per day
over a six-day period; Karren (1972) reports similar oviposition

1983]

Root & Messina — Exenia canadensis

rates. This low output is reflected in the females’ reproductive mor-
phology. In dissections we found that females of E. canadensis have
only four or five ovarioles per ovary and that each ovary never
contains more than one fully mature oocyte. Camptosomate beetles,
in general, have relatively few ovarioles per ovary (Robertson 1961 ;
Suzuki 1974; Mann and Singh 1979). Beetles may compensate for
gradual egg production by ovipositing over an extended period. In
central New York, overwintered females begin egg-laying in early
May and continue until mid-July.

The low fecundity of E. canadensis may be related to its normally
low and relatively stable population size. Over a three-year period,
the population densities of five other chrysomelid species that feed
on goldenrod fluctuated by at least an order of magnitude (Messina
and Root 1980). During this same period the population of E. cana-
densis varied less than twofold. Furthermore, during the course of
our long-term investigations on the goldenrod fauna at several local-
ities in central New York, we have yet to observe a host plant that
was significantly depleted by E. canadensis. Karren (1964) has also
noted the stable densities of Exenia populations. Le Sage (1982),
however, reported that during 1980-81, populations of E. canaden-
sis increased greatly over a large area in southern Canada.

The evolutionary steps that produced the case-bearing habit are
unclear. Since the larval case is added to the egg case, it can be
argued that the defense originated with the female’s habit of cover-
ing the eggs with fecal material (this may be mixed with secretions
from the anal gland; Hinton 1981). This initial step is exhibited by
other chrysomelids, e.g. the eumolpine, Chrysochus auratus (Fabri-
cius). The extant species of camptosomate beetles differ in their
manner of oviposition and egg case deposition. Some clytrine bee-
tles lay eggs in clusters (a typical trait of non-camptosomate chry-
somelids), with each egg connected to the substrate by a separate
stalk (Hinton 1981). A cryptocephaline, Pachybrachis bivittatus
(Say), apparently does not connect the egg to the substrate at all.
Instead, the female covers the egg with fecal material while holding
it with her hind legs, and then simply drops the egg to the ground
(Lawson 1976). Further comparative data on the details of egg-case
provisioning are needed to trace further the evolution of the case-
bearing habit and the often enigmatic phylogeny of the camptoso-
mate line (Mann and Crowson 1981).

Psyche

[Vol. 90

Acknowledgements

We thank E. W. Evans and M. K. Hausmann for technical
assistance. N. F. Johnson and B. M. O’Connor identified the parasi-
toids and mites respectively. The research was supported by NSF
grant DEB77-25120.

Summary

Morphological and behavioral defenses of Exema canadensis are
illustrated with scanning electron micrographs. In laboratory exper-
iments, the fecal case was shown to protect larvae from three pre-
daceous insects (a nabid, a pentatomid, and a coccinellid) that occur
in the same microhabitats with E. canadensis. Exposed larvae were
readily consumed by predators. The case did not deter parasitoids;
larvae were heavily parasitized by a eulophid, Tetrastichus sp., and
pupae were attacked by a chalcid, Spilochalcis albifrons. Other
enemies include mermithid nematodes and erythraeid mites. The
adaptive syndrome associated with the case-bearing habit and its
possible evolution are discussed.

Literature Cited

BOving, a. G. and F. C. Craighead

1931. An illustrated synopsis of the principal larval forms of the order Coleop-
tera. Entomol. Amer. 11: 1-351.

Burks, B. D.

1979. Chalcididae, pp. 860-873 and Eulophidae, pp. 967-1021. In K. V.
Krombein, P. D. Hurd, Jr., O. R. Smith, and B. D. Burks (eds.). Catalog
of Hymenoptera in America north of Mexico. Washington, D.C.,
Smithsonian Institution Press.

Deroe, C. and J. M. Pasteels

1982. Distribution of adult defense glands in chrysomelids (Coleoptera: Chry-
somelidae) and its significance in the evolution of defense mechanisms
within the family. J. Chem. Ecol. 8: 67-82.

Eisner, T., E. Van Tassell, and J. E. Carrel

1967. Defensive use of a “fecal shield” by a beetle larva. Science 158:
1471-1473.

Evans, E. W.

1982. Feeding specialization in predatory insects: hunting and attack behavior
of two stinkbug species (Hemiptera: Pentatomidae). Amer. Midi. Nat.
108: 96-104.

Hinton, H. E.

1981. Biology of insect eggs, vol. II. Oxford, Pergamon Presss. 778 pp.

1983]

Root & Messina — Exenia canadensis

Howard, D. F., M. S. Blum, T. H. Jonks, and D. W. Phillips

1982. Defensive adaptations of eggs and adults of Gastrophysa cyanea (Coleop-
tera: Chrysomelidae). J. Chem. Ecol. 8: 453-462.

Jenks, G. E.

1940. Dwarfs that live in their hats. Nature Mag., pp. 337-340.

Karren, J. B.

1964. Protective coloration and form in the North American genus Exema
(Chrysomelidae, Coleoptera). Proc. North Central Branch, Entomol.
Soc. Amer. 19: 77-79.

1966. A revision of the genus Exema of America, north of Mexico (Chrysome-
lidae, Coleoptera). Univ. Kansas Sci. Bull. 46: 647-695.

1972. A revision of the subfamily Chlamisinae of America north of Mexico
(Coleoptera: Chrysomelidae). Univ. Kansas Sci. Bull. 49: 875e988.

Lawson, F. A.

1976. Egg and larval case formation by Paehyhraehis hivinatus. Ann. Ento-
mol. Soc. Amer. 69: 942-944.

Le Sage, L.

1982. The immature stages of Exema eanadensis Pierce (Coleoptera: Chry-
somelidae). Coleop. Bull. 36: 318-327.

Mann, J. S. and R. A. Crow.son

1981. The systematic positions of Orsudaene Latr. and Syneia Lac. (Coleop-
tera, Chrysomelidae), in relation to characters of larvae, internal anat-
omy and tarsal vestiture. J. Nat. Hist. 15: 727-749.

M ANN, J. S. andJ. B. Singh

1979. Ovariole number in the family Chrysomelidae (Coleoptera: Polyphaga)
from northern India. J. Entomol. Res. 3: 217-222.

MATStIDA, K. AND F. SUGAWARA

1980. Defensive secretion of chrysomelid larvae Chrysomela viginiipunetata
eosteUa (Marseul), C. populi L., and Gastrolina depressa Baly (Coleop-
tera: Chrysomelidae). Appl. Entomol. Zool. 15: 316-320.

Meinwald, j., T. H. Jones, T. Eisner, and K. Hicks

1977. New methylcyclopentanoid terpenes from the larval defensive secretion
of a chrysomelid beetle {Plagiodera versieolora). Proc. Nat. Acad. Sci.
U.S.A. 74: 2189-2193.

Messina, F. J.

1982. Comparative biology of the goldenrod leaf beetles, Trirhahda virgaia Le
Conte and T. borealis Blake (Coleoptera: Chrysomelidae). Coelop. Bull.
36: 255-269.

Messina, F. J. and R. B. Root

1980. Association between leaf beetles and meadow goldenrods. (Solidago
spp.) in central New York. Ann. Entomol. Soc. Amer. 73: 641-646.

Nickle, W. R.

1974. Nematode infections, pp. 327-376. In G. E. Cantwell (ed.). Insect dis-
eases, vol. II. New York, Marcel Dekker.

Otto, C. and B. S. Svensson

1980. The significance of case material selection for the survival of caddis
larvae. J. Anim. Ecol. 49: 855-865.

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Robertson, J. G.

1961. Ovariole numbers in Coleoptera. Can. J. Zool. 39: 245-263.

SnzoKi, K.

1974. Ovariole number in the family Chrysomelidae. J. Coll. Lib. Arts,
Toyama Univ. 7: 53-70.

Wallace, J. B.

1970. The defensive function of a case on a chrysomelid larva. J. Georgia
Entomol. Soc. 5: 19-24.

STUDIES ON NORTH AMERICAN CARBONIFEROUS
INSECTS. 7. THE STRUCTURE AND RELATIONSHIPS OF
EUBLEPTUS DANIELS/ (PALAEODICTYOPTEKA)*

By Frank M. Carpenter
Museum of Comparative Zoology
Harvard University, Cambridge, Mass. 02138

Eubleptus danielsi was described by Handlirsch in 1906 from a
single, poorly preserved specimen in a concretion from the Francis
Creek Shale, Illinois (Middle Pennsylvanian). The systematic posi-
tion of the insect has been controversial. It was placed by Hand-
lirsch in a new family, Eubleptidae, in the order Palaeodictyoptera.
However, Martynov, in 1938, expressed doubt about its assignment
to that order, and in 1952 Laurentiaux transferred it to a new order,
Eubleptidodea, which Rohdendorf accepted in the Osnovy Paleon-
tologii in 1962. Neither Laurentiaux nor Rohdendorf gave a diagno-
sis of the new order, although vague reference was made to the
presence of large eyes and to the absence of pronotal lobes. From
my study of the reverse half of the holotype (all that is now known) 1
came to the tentative conclusion (1965) that the insect was a member
of the Palaeodictyoptera, probably related to the family Spilap-
teridae.

During the past decade, many additional specimens of Eubleptus
have been found in a strip-mine pit on the Will-Kankakee County
line, Illinois, mostly by private collectors. These new specimens,
some of which are exceptionally well preserved, have been loaned to
me for study. The purpose of this paper is to present the results of
my examination of these specimens and to discuss the relationships
of the insect, as it is now known.

I am grateful to Mr. Frederick J. Collier of the Department of
Paleobiology, National Museum of Natural History, Washington,
for the loan of the holotype of Eubleptus danielsi; and to Mrs. J. S.
Lawless of the Peabody Museum of Natural History, Yale Univer-
sity, for the loan of the holotype of Athymodictya parva, a synonym

♦Partial financial support of this research is gratefully acknowledged to the National
Science Foundation, Grant No. DEB 82 05398, F.M. Carpenter, principal investi-
gator.

Psyche

[Vol. 90

of danielsi. 1 am especially grateful to the following private collec-
tors for the opportunity of studying their specimens: Mr. Paul Harris,
now of Mountain Home, Arkansas; Helen and Ted Piecko, Chicago;
Mr. and Mrs. Francis Wolff, now of Port Charlotte, Florida; Mr.
Daniel Damrow, Mosinee, Wisconsin; Mr. Raymond Bandringa,
Willow Brook, Illinois; Mr. Joseph Pohl, Belgium, Wisconsin; and
Mr. Richard Rock, Crest Hill, Illinois. As will become apparent from
the account below, our present extensive knowledge of Eubleptus has
resulted mainly from their fossil collecting and their cooperation in
making the specimens available for study.

1 am deeply indebted to the late Dr. Eugene S. Richardson, Jr.,
formerly of the Department of Geology, Field Museum of Natural
History, for his unfailing cooperation and his assistance over the
past fifteen years in the course of our investigations on the insects in
the concretions from the Francis Creek Shale.*

Order Palaeodictyoptera

Family Eubleptidae Handlirsch
Eubleptidae Handlirsch, 1906a, p. 679; 1906b, p. 1 1 1.2
Eubleptidae Laurentiaux, 1953, p. 423.

Eubleptidae, Carpenter, 1965, p. 178.

Small species, with slender, pointed wings. Fore wing; SC extend-
ing nearly to wing apex, terminating on the costal margin; RS dichot-
omously forked, with 4 (rarely 5) terminal branches; M forking just
basad of the origin of RS; MA with a long fork; MP with 3 terminal
branches; CUA with a short fork; CUP with 3 (rarely 2) terminal
branches; 3 short anal veins present; relatively few cross veins,
unbranched, and forming a distinct pattern; archedictyon absent.
Hind wing: similar to the fore wing in venation but slightly broader
near or before mid-wing, the hind margin strongly curved. Body:
moderately slender; antennae very long and thin; head apparently

'Shortly before his death in January, 1983, Dr. Richardson and I completed a joint
paper on the Archaeognatha (Insecta) in the concretions. This will be published in
the next issue of Psyche.

2The family, genus, and species were described and designated as new in both of
Handlirsch’s 1906 publications; the 1906a article obviously has priority, since ijiany
of its pages are cited by number in the 1906b work.

T\gmt\.Eublep,usdanielsi. Photograph of specimen PH 1 5 (reverse) in the Paul Harris collection. Length of fore wing, 13 mm.

Psyche

[Vol. 90

small in dorso-ventral view, but eyes prominent and protuding;
beak well developed; prothorax short, with small and weak pronotal
lobes; mesothorax and metathorax subequal; abdominal segments
apparently with small lateral lobes; cerci very long; female with
short, curved ovipositor.

The family is known only from the Francis Creek Shale.

Genus Euhleptus Handlirsch
Euhlepius Handlirsch, 1906a, p. 681; 1906b, p. 111.

Athynwciictya Handlirsch, 191 1, p. 298. nhw synonymy.

Fork of MA at nearly the same level as the first fork of RS; first
fork of MP well before mid-wing, its posterior branch forked near
the wing margin.

Type-species: Eubleptus danielsi Handlirsch; by monotypy.

Euhleptus danielsi Handlirsch
Figures 1-8

Euhleptus danielsi H-dxxdWx^cK I906a:681; I906b:112; 1920:137. Rohdendorf, 1962:

54. Carpenter, 1965: 180.

Athyniodictya parva Handlirsch, 191 1:298. new synonymy.

Fore wing: length 13-14 mm; maximum width, 3. 5-3. 8 mm; hind
wing: length 13-14 mm; maximum width, 4-4.3 mm; length of
antennae (complete), 1 1 mm. The venational pattern is shown in
figure 2. Only slight individual variations seem to occur: RS usually
with four terminal branches, but a fifth, short branch may be pres-
ent; CUP usually with three branches, though the shortest one may
be absent. Head about 3 mm wide across the eyes, and about 1.5
mm long as seen from above (i.e., not including the beak, which is 3
mm long). Pronotum about 1 mm long and 2.5 to 3 mm wide,
including the small pronotal lobes; meso- and metathoracic seg-
ments apparently subequal, although the compression of the body
has probably altered the true proportions of both segments; the
abdomen is about 13 mm long and 2 mm wide at mid-length.

Holotype: no. 38731, U.S. National Museum of Natural History,
Washington (L.E. Daniels, collector). This is a poorly preserved
specimen, showing the proximal three-fourths of a fore wing and
very little of the hind wings and body. Handlirsch described the
species from both obverse and reverse halves, but when I examined

1983]

Carpenter — Euhleptus

Figure 2. Euhleptus danielsi. Venational diagram of fore and hind wings. SC,
subcosta; R, radius; RS, radial sector; MA, anterior media; MP, posterior media;
CUA, anterior cubitus; CUP, posterior cubitus; A1 and A2, anals. Drawing based
mainly on specimen PH 15 Paul Harris collection, with some details from specimens
PE32046 and PE32045.

the specimen in 1965 only the reverse half could be found."* Having
now examined many additional specimens, I am convinced that
both Handlirsch and I incorrectly interpreted several of the vaguely
indicated structures in the type. Most of the cross veins that I de-
scribed and figured are obviously wrinkles in the wing membrane; in
the well-preserved specimens discussed below the cross veins are as
strongly developed as the longitudinal veins. Also, the structures
that 1 considered to be pronotal lobes are, in part, the large eyes to
which Handlirsch referred. The pronotal lobes are indeed present
but they are small.

Handlirsch’s Athymodietya parva, described in 1911 from a sin-
gle, poorly preserved specimen (YPM 18ab) in the Peabody Museum

^According to the records of the National Museum, counterparts of some of the
Daniels specimens were kept by Mr. Daniels after Handlirsch had studied them;
their present location is unknown.

Psyche

[Vol. 90

at Yale University, is without question a synonym of cianielsi. Hand-
lirsch mentioned a fine archedictyon on the wings and he placed the
insect in the family Dictyoneuridae, but I can find no suggestion of
it in the fossil. The matrix of that particular concretion is unusually
granular and I surmise that Handlirsch interpreted the granulation
as an archedictyon. If the fossil is moistened with alcohol, the char-
acteristic cross veins of Euhleptus are discernible. The venational
pattern, even as shown in Handlirsch’s drawing, is identical with
that of danielsi, although his figure incorrectly depicts some of the
veins with pectinate instead of dichotomous branching. The type of
parva is about the size of that of danielsi, the fore wing being 13
mm. long, with a maximum width of 4 mm.

Specimens of Eubleptus danielsi Studied

I have been able to examine seventeen specimens of danielsi dur-
ing this investigation. For convenience of reference, I include here
an annotated list of these:'*

1. National Museum of Natural History, Washington, No. 38731
(reverse half only). Mazon Creek. Holotype of danielsi. Poorly pre-
served, showing about three-fourths of a fore wing, but virtually
nothing of the body and hind wing. Fore wing, as preserved, 13 mm.
long.

2. Peabody Museum of Natural History, Yale University, No.
18. Mazon Creek. Holotype of Athymodictya parva. Poorly pre-
served, showing proximal portions of fore and hind wings, as well as
pronotum, pterothorax, and parts of abdomen.

3. Paul Harris collection, no. PH 15. Pit Eleven. Excellent pres-
ervation of entire insect, except end of abdomen; the best specimen
known. Especially good are the wings (which include the color
markings), the pronotum, and the head, which shows the antennae,
and eyes, and the location of the beak.

^There are apparently only two exposures of the Francis Creek Shale at which
specimens of danielsi have been found: Mazon Creek, the bed of the stream about 4
miles west and a mile north of Coal City; and Pit Eleven, a strip mine of the Peabody
Coal Co., in Will and Kankakee Counties, Illinois.

1983]

Carpenter — Eu hie plus

Figure 3. Euhleptus cianietsi. Photograph of specimen PH 15 (obverse), Paul Harris
collection. Dorsal view of head and thorax; a, antenna; h, head; e, eye; p, pronotum;
ms, mesonotum; mt, metanotum; cv, small cavity in the matrix of the concretion,
several millimeters deep and partially filled with kaolinite; cavity originally occupied
by the beak. Width of mesonotum, 3 mm.

Psyche

[Vol. 90

Figure 4. Euhleptus danielsi. Photograph of specimen 236, Daniel Damrow collec-
tion; dorsal view of thorax, but frontal view of head: b, beak; e, eye. The three
thoracic segments are partially covered by kaolinite. Maximum width of fore wing in
photograph, 3.5 mm.

4. Field Museum, No. PE32046 (J. Herdina collection, no.
H424). Pit Eleven. Very good preservation of all wings, especially of
basal parts; also, thorax and abdomen, including proximal part of
cerci. Head crushed.

5. Field Museum, No. PE32045 (J. Herdina collection, no.
H540). Pit Eleven. Good preservation of basal parts of all four
wings; body very poorly preserved.

6. Francis and Terri Wolff collection. No. 229. Pit Eleven. Good
preservation of basal portions of all wings; poor preservation of
body, but good view of head from above; one fore leg present.

1983]

Carpenter — Euhleptus

Figure 5. Euhleptus danielsi. Photograph of head of same specimen shown in
figure 4, with greater magnification and different illumination. Scale line is 1 mm
long.

7. Francis and Terri Wolff collection. No. 233. Pit Eleven. Good
preservation of basal two-thirds of wings; most of body not
preserved.

8. Raymond Bandringa collection. No. 66-PBSM-l l-(3). Pit
Eleven. Good preservation of basal parts of wings, part of antennae,
eyes, and thorax.

9. Field Museum collection. No. PE22016 (from Dwayne Stone
collection). Pit Eleven. Excellent preservation of whole insect in
lateral view; wings overlapped but venation clear; shows abdomen,
including cerci; head, including eyes; beak, in side view.

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[Vol. 90

10. Daniel Damrow collection. No. 236. Pit Eleven. Good
preservation of basal part of wings; thorax strongly compressed;
entire head well preserved in front view, showing beak, with excel-
lent preservation.

1 1. Joseph Pohl collection. No. MPH8. Pit Eleven. Good preser-
vation of basal parts of all four wings, with general features of body.

12. Helen and Ted Piecko collection. No. 402. Pit Eleven. Fair
preservation of basal parts of all wings, but body not clear.

13. Helen and Ted Piecko collection. No. 422. Pit Eleven. Good
preservation of most of all four wings and parts of thorax and
abdomen.

14. Helen and Ted Piecko collection. No. 432. Pit Eleven. Fair
preservation of body and of basal portions of all wings.

15. Helen and Ted Piecko collection. No. 436. Pit Eleven. Poor
preservation of wings and body.

16. Richard Rock collection, no. 729. Pit Eleven. Good preserva-
tion of body and of basal parts of fore and hind wings.

17. Richard Rock collection. No. 817. Pit Eleven. Good preserva-
tion of basal parts of wings, poorly preserved body.

A composite drawing of Eubleptus danielsi is given in figure 8.
The general habitus of the insect, as drawn, is based on the Paul
Harris specimen, PH 15 (see figures 3 and 4), but details from other
fossils have been added, as follows (the numbers refer to the speci-
mens in the above lists): head, PE22016, Wolff 229, Damrow 236;
beak, PE22016, Damrow 236; pronotum, YPM 18; mesothorax and
metathorax, PE32046,YPM 18; fore leg, Wolff 229; abdomen, PE32046,
PE22016; ovipositor, PE22016; cerci, PE32046,PE22016; wings,
PE32046,PE32045, Wolff 229, HTP 422. All structures shown in the
composite drawing are present in one or more of the fossils studied.^

Discussion of the Structure of Eubleptus danielsi.

Head: The head of danielsi was obviously hypognathous. In the
specimens preserved in dorsal view (i.e., PH 15, figure 2) there is a
distinct hole in the matrix, at about the center of the insect’s head,
marking the point at which the beak penetrated the matrix; and in

^Handlirsch’s restoration of Eubleptus, based on the unique type (1920), bears little
resemblance to the insect in this composite drawing.

1983]

Carpenter — Euhleptus

Figure 6. Euhleptus cianielsi. Photograph of specimen YPMI8 (holotype of Athy-
mudictya parva Handlirsch. Dorsal view (reverse); pr, pronotal lobes, maximum
width of left fore wing in photograph, 4 mm.

the one specimen preserved in lateral view (PE22016, figures 4 and
5) the head is clearly hypognathous. The antennae are extraordinar-
ily long and thin (PH 15, Wolff 229; Bandringa specimen 66-
PBSM); for most of its length it is .04 mm in diameter and the
segments are about .1 mm long. The antennae of PH 15 include
about 1 10 segments and are almost certainly complete. The beak, as
preserved in lateral view in PE22016 is 3 mm long and slender;
several stylets project from its end. In specimen Damrow 236, the
beak is 2.8 mm long and as seen in front view (figure 4) is triangular
in shape, relatively broad basally, and bears long striae, as has been
noted in other species of Palaeodictyoptera (Kukalova, 1970). The
eyes are large and bulging, as shown in PH 15, Wolff 229, Bandringa
specimen 66-PBSM, and especially in PE22016, in which the eye, in
lateral view, is preserved in strong relief.

Thorax. The prothorax is very small and, as Handlirsch showed
in his drawing of parva, bears small lateral lobes about 1 mm wide
(YPM18); the folded and twisted condition of the lobes in some
specimens suggests that they were thin and weak. The legs ae known

Psyche

[Vol. 90

Figure 7. Eubleptus danielsi. Photograph of specimen PE22016. Lateral view: b, beak; c, cerci; o, ovipositor. Length of
ovipositor as preserved, 10 mm.

1983]

Carpenter — Eubleptus

only from a single fore leg in Wolff 229; the preserved part, appar-
ently consisting of the femur, tibia, and tarsus, has a total length of
3.5 mm; the tarsus appears to have five subequal segments. The
wing venation, as previously noted, shows only a slight amount of
variation among the 17 specimens examined. The shape of the wings
is more diverse, but that has undoubtedly been determined to some
extent by the process of preservation and the amount of movement
of the sediment in which the specimens were entombed. The degree
of variation in wing shape in the specimens of danielsi seems to be
comparable with that reported by Kukalova-Peck (1971) for the
Permian Dunbaria faseiipennis. The wing markings, consisting of
four triangular spots along the anterior margins of both wings, are
similar in both specimens in which they are preserved (PH 15 and
PE32046).

Abdomen. The segmentation of the abdomen is nearly homo-
nomous, except for the 9th and 10th segments, which are slightly
smaller than the others. The lateral margins of the tergites are
extended posteriorly only slightly (YPM 18), about as in the Spilap-
teridae. The ovipositor, preserved only in PE22016, is strongly
curved and only 2.5 mm long, not extending beyond the end of the
abdomen. The cerci (PE22016, and PE32036) are preserved to a
maximum length of 10 mm, but since they end at the edge of the
concretion, that is almost certainly not their full length. Segmenta-
tion of the cerci is clear at intervals; the segments are .3 mm long
(beyond the basal segments) and .3 mm wide, and covered with
short hairs. The largest piece of a cercus includes about 34 segments.

Relationships of Eubleptus

Study of the new specimens of Eubleptus danielsi provides no
evidence to justify the recognition of the order Eubleptidodea. On the
contrary, all the evidence supports Handlirsch’s assignment of the
family Eubleptidae to the Palaeodictyoptera. Furthermore, both the
wing venation and the newly acquired knowledge of the body struc-
ture of Eubleptus show a close relationship to the family Spilapter-
idae of the Palaeodictyoptera. The wings of Eubleptus have the
same general shape as those of the spilapterids, the hind wings
being slightly broader than the fore wings. The only significant
difference between the venational patterns of the two families is the
reduction of CUA in the family Eubleptidae: it has only a small

Psyche

[Vol. 90

Figure 8. Eubleptus danielsi. Reconstruction based mainly on specimen PH 15, in
the Paul Harris collection, with some details from specimens PE32046,PE32245,
PE22016, YPM18, USNM35576,FTWolff 229 and 233, HTP 422, and Bandringa
66-PBSM. All structures shown are preserved in at least one of these fossils. Length
of fore wing, 13 mm.

1983]

Carpenter — Euhleptus

terminal fork, whereas in the spilapterids CUA has several long
branches. This difference serves to justify the separation of Eublep-
tus into its own family, but does not have any significance at the
ordinal level. The body structure of Eubleptus turns out to be very
similar to that of the spilapterids. The pronotal lobes are small in
both, the beaks are relatively small and of similar shape in both, the
legs (so far as they are known) are short in both, and the ovipositors
are similarly formed. Eubleptus danielsi is the smallest known spe-
cies in the Palaeodictyoptera, but it is not much smaller than the
Permian Dunbaria faseiipennis of the family Spilapteridae.

Literature Cited

Carpenter, F.M.

1965. Studies on North American Carboniferous insects. 4. The genera Met-
rupator, Eubleptus, Hapaloptera and Hadentomum. Psyche, 72: 175-
190.

Handlirscii, Anton

1906a. Revision of American Palaeozoic insects. Proc. U.S. Nat. Mus., 29
( 1 44 1):66 1-820.

1906b. Die fossilen Insekten und die Phylogenie der rezenten Formen. II.
Abschnitt: Palaeozoische Insekten, p. 53-393. Engelmann, Leipzig.

I91 1. New Paleozoic insects from the vicinity of Mazon Creek, Illinois. Amer.
Journ. Sci. (4) 21:297-326,353-377.

1920. Palaontologie, in Handbuch der Entomologie (ed. C. Schroder).
3:117-306.

Kukalova-Peck, J.

1971. The structure of Dunbaria (Palaeodictyoptera). Psyche, 78: 296-305.
Laurentiaux, D.

1953. Classe des insectes. In Traite de Paleontologie (ed. Piveteau), p. 397-527.
Martynov, A.V.

1938. £tudes sur I’histoire geologique et de phylogenie des ordres des
insectes. Trav. Inst. Paleont., Akad. Nauk USSR, 7 (4): 1-148.
Roiidendorf, B.B.

1962. Osnovy Paleontologii: Tracheata, Mandibulata. Akad. Nauk USSR., p.
1-374.

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THE BIOLOGY OF TRICHADENOTECNUM ALEXANDERAE
SOMMERMAN(PSOCOPTERA: PSOCIDAE).

III. ANALYSIS OF MATING BEHAVIOR

By B. W. Betz'

Introduction

Several authors have described mating behavior in species of Pso-
coptera (Pearman 1928, Sommerman 1943a, 1943b, 1944, 1956,
Badonnel 1951, Thornton and Broadhead 1954, Klier 1956, Mock-
ford 1957, 1977, Broadhead 1961, Eertmoed 1966). Only one or at
most a few matings in a species were observed. This paper presents a
comprehensive analysis of pre- through post-copulatory behavior in
Trichadenotecnum alexanderae Sommerman. Evidence is presented
for a sex-attractant pheromone, produced only by females that were
receptive to mating.

Trichadenotecnum alexanderae is a relatively common psocid in
eastern United States (Betz 1983a). The species inhabits trees and
rock outcroppings providing its principal food source, pleurococ-
cine algae. Betz (1983a) found that T. alexanderae is capable of
facultative thelytoky. Formerly, the species was confused morpho-
logically with three other species, all obligatorily thelytokous, which
have been identified and described as T. castum Betz, T. merum
Betz, and T. innuptum Betz (Betz 1983a).

This paper is part of a series (cf. Betz 1983b, c, d) detailing the life
history of T. alexanderae.

Materials and Methods

Cultures of T. alexanderae were obtained from three populations
in Illinois: at Moraine View State Park (McLean County), along the
Sangamon River at Lake of the Woods (Champaign County), and
along the Salt Fork River at Champaign County Forest Preserve
District — Homer Lake (Champaign County).

Specimens were collected from tree trunks with an aspirator and
kept with pieces of bark in cotton-stoppered test tubes. Cultures
were transported to the laboratory over ice-water in a cooler.

MOOO North Lake Shore Drive, Chicago, Illinois, 6061 1.
Manuscript received by the editor August 16. 1982.

Psyche

[Vol. 90

Laboratory cultures were kept in cotton-stoppered test tubes.
Each tube was supplied ad libitum with food in the form of pleuro-
coccine algae on bark. Culture tubes were stored in closed, glass
desiccator jars over a saturated potassium chloride (KCl) solution to
maintain a relative humidity of 80 ±5%. The temperature regimen
for rearing was 23.3° : 1 8.0° C light:dark, and the photoperiod was 1 5
h light:9 h dark. Illumination was 4300 lumens/ m^, supplied by
incandescent and fluorescent lamps.

Because the other species of the T. alexanderae complex are oblig-
atorily thelytokous and often occur sympatrically with the biparental
species, I began a laboratory culture of T. alexanderae from each
locality with females mated in the laboratory to assure the identity
of the culture as the biparental species. Several breeding pairs
were used to begin a culture, an attempt to represent the genetic
diversity of the original sample from the field population. 1 also
examined the morphology of the original breeding pairs to verify
that they were T. alexanderae. 1 used bark obtained only from the
original field locality in cultures; bark was examined for eggs before
it was placed in a culture.

Mating behavior was studied in adults from Lake Dawson, Lake
of the Woods, and Salt Fork cultures. Adults were isolated as late
stage nymphs and reared in shell vials (four dram size). Each vial
was supplied with a flat piece of bark which lessened the interference
of the substrate on mating behavior. Females were 2-3 days old and
males were 2-5 days old when brought together, the times when they
were the most receptive to mating (Betz 1983c). Isolated specimens
were brought together by the following method. The cotton stopper
on each vial was removed, the open ends of pairs of vials were
apposed, and the vials were tilted carefully until the piece of bark in
the vial containing a male contacted the bark in the vial containing a
female. The open ends of pairs of vials were kept together and the
vials were not moved during observation of the insects. The method
I used to bring together isolated specimens did not appear to disturb
the insects greatly, and thus probably provided accurate observa-
tions of courtship behavior.

Results

Precopulatory Behavior

The behavior of male and female T. alexanderae was somewhat
variable among the successful matings (N = 99) and the unsuccessful

1983]

Betz — Biology of Trichadenotecnum

attempts (N = 45) I observed. Most precopulatory behavior fol-
lowed the patterns outlined in Figure 1.

When bark bearing an isolated, receptive female was brought
together with bark bearing a sexually active male, the male always
ran onto the female’s bark. A male displayed a higher level of activ-
ity under these conditions than if his piece of bark was brought
together with bark bearing a nymph, a female of T. alexanderae in
an unreceptive state, or a piece of bark without an insect (N = 7). In
five of the mating encounters I observed, the male flew onto the
female’s bark before the two pieces of bark were touching.

This higher level of activity in males occurred even if females were
placed out of the males’ sight. Almost immediately after a male ran
onto the bark of a female, he began a search over the substrate.
Sometimes a female remained motionless during this search, even
though she might have been active prior to the introduction of a
male. The manner in which males elicited this reaction of females
remains unknown, although the reaction may have resulted from
the slight disturbance caused by the introduction of pieces of bark
into the females’ vials.

A male searched in the direction of a female, often stopping
momentarily to flick his antennae and adjust his course.

When a male approached within about 1 cm of a receptive female
he began a quick, sideways gait while moving toward her, even
though she may have remained hidden from the male’s view. The
sideways gait lasted about 1-2 seconds. Occasionally a male ap-
proached a receptive female, or courted her, without the sideways
gait (N= 12). Females always fled from these encounters. When a
female fled, a male remained in the vicinity of the encounter and
spun completely around one or more times flicking his antennae.
Then a male usually ran off in the general direction of a female’s
flight. Unless unsuccessful courtship occurred many times (usually
the result of a male not performing the sideways gait), a female
would always acquiesce at the next courting.

After performing the sideways gait, a male ran up to a female’s
side, about midway along her length; a male approached a female
almost perpendicularly from her side. If features on the substrate
made a male’s approach difficult, his contact with a female was as
perpendicular to her as the substrate permitted. When a male ran up
to a female, he touched her briefly (less than a second) with both his
antennae. A male’s antennae usually struck a female’s thorax or
head and the distal end of her forewing because his antennae were

100

Psyche

[Vol. 90

Figure 1. Schematic diagram depicting precopulatory behavior in Trichadenotecnum alexanJerae. Typical behavior is indicated by bold
face arrows. Female behavior coinciding with male behavior is indicated by dashed arrows.

1983]

Betz — Biology of Trichaclenotecnuni

101

usually held about 90° apart and at about 45° off the substrate at
rest and also during the search for a female. Directly after contact-
ing her, a male backed away slightly, then rapidly fanned his wings
over his body. The wings were fanned at such a rapid rate and at
such a small angle (never more than 90°) that they became blurred.
As a male continued to fan his wings, he began to move anteriorly
along a female’s side, while still remaining perpendicular to her. A
male continued this motion until he was almost facing a female.
When this occurred, a male stopped fanning, dropped his wings
slightly, turned about 180°, and backed underneath a female
between her legs. The genitalia were apposed in this manner.

Occasionally a male stopped fanning when he was only laterally
apposed to a female’s head, then turned about 90°, and tried to back
under her. Of the 14 mounting attempts I observed progressing
in this way, only two of them led directly to copulation. Of the failed
attempts, eight were unsuccessful because males were blocked from
backing in by females’ legs; in the remaining four attempts, males
turned around farther than necessary and kept moving backward
beside the females rather than beneath them.

When a female remained hidden from a male’s view, he some-
times approached her directly from the front (N = 3). In two encoun-
ters, the female assumed the receptive posture (see below) as the
male fanned his wings. However, both of these males were unable to
locate the female after they turned around and began to move
backwards. One of the males approached the female on her left,
turned counterclockwise about 240°, and finally stopped after mov-
ing 8 mm away from her. He then tried to mount her end-to-end
(i.e., facing away from her), but this failed. The pair remained
motionless in the end-to-end position for about 30 seconds with
their genitalia nearly touching, then the male courted the female
from her side and was able to orient himself correctly.

The male of the third encounter courted frontally, but the female
turned her body slightly instead of assuming the receptive posture,
and the male was unable to move far enough backward for their
genitalia to come together. The courtship did not lead to copulation.

Most (73.7%) courting attempts were successful on the first try
(Table 1, A). When an attempted mounting failed, a male and
female always remained motionless for about 10-30 seconds. After
this period, if a male and female remained within about 1 cm after

102

Psyche

[Vol. 90

Table 1. Precopulatory behavior in TrichaJenoiecnum alexanderae

% of Total

Number of courting attempts

1. One

73.7

by a male (including the one

2. Two

15.2

leading to copulation)

3. Three

10.1

4. Four

0.0

5. Five

1.0

N=99^ 100.0

B. Length of time between the x

introduction of a male s.d.

and the beginning of mating range

(i.e., genitalic contact) N

C. Stage in courtship when a female
assumed the receptive posture

1. During the approach of a male

2. When touched by a male’s antennae

3. Just before a male backed underneath

N=96

1.1 minutes
1.3

0. 1-9.0 minutes
62

15.6

83.3

1.1

100.0

^The number of mating pairs for which the states of this behavioral character
were recorded.

they separated, a male courted again by approaching a female on
her side, touching her with his antennae, and fanning his wings.
Once either sex had fled from an unsuccessful courtship, males
always began further courtship with a sideways gait.

I observed the behavior of females that had fled from a failed
courtship (N = 4). Each female eventually stopped moving, and at
this time I observed each female flexing her valvulae dorsoventrally
in a pairwise manner, and making about ten contractions of her
abdomen.

The time required by males to establish genitalic contact after
they were introduced to females varied among mating encounters
(Table 1, B). This period was usually less than 1 minute if the first
courtship was successful. A male ran directly to a female in some
encounters, and the time between introduction and the beginning of
copulation was usually less than 30 seconds. Some males (N = 5)
were slower to find females because each remained within a small

1983]

Betz — Biology of Trichaclenotecnum

103

area on a female’s bark. Even though a female was not nearby, three
males exhibited sideways gaiting, wing fanning, and backward move-
ment, while two others only displayed a higher level of activity. All
five males were active, and each found a female about 10 minutes
after introduction to the female’s bark.

A female had to raise the anterior part of her body for a male to
be able to fit beneath her. Females always assumed a characteristic
appearance for this purpose that I here term the receptive posture.
In the receptive posture, the fore- and midlegs were moderately
extended, the hindlegs were slightly extended, and the antennae were
swept back along a female’s body (Fig. 2b). Most (83.3%) females
assumed the receptive posture when males touched them with their
antennae (Table 1 , C). Some ( 1 5.6%) females assumed the receptive
posture when males performed the sideways gait. One female waited
until a male was backing underneath her.

Females assuming the receptive posture early in courtship (i.e.,
before antennal contact was made by a male) elicited less wing
fanning from males. Males exhibited all of the actions involved in
courtship, but performed them more rapidly. On the other hand, the
female not assuming the receptive posture until a male began to
move beneath her did not appear to inhibit the male from courting
normally.

After a courtship failed, a male often fanned his wings around a
female for a longer period of time during the next one, regardless of
whether a female assumed the receptive posture when a male was
approaching or courting (N=10). These prolonged courtships
always led to copulation.

A male had to crouch slightly just prior to moving beneath a
female, even though she had assumed the receptive posture. This
position is shown in Figure 2a. Males remaining in a standing posi-
tion were blocked from moving past the coxae of the females’ legs
(N = 2). Furthermore, at this time a male’s abdomen became slightly
arched along its length, raising the posterior end.

A male’s wings were kept extended over his body as he backed
underneath a female, and she rested her fore- and midlegs on him.
When the genitalia of a pair were apposed, the head of a female was
positioned between and slightly caudad of a male’s raised hindwings.

As a male moved under a female, the shelf of his epiproct, which
normally rested in a posterodorsal position, struck a female’s sterna

104

Psyche

[Vol. 90

Figure 2. Typical precopulatory behavior in Trichadenotecnuni alexanderae.
a. A male in position to move beneath a female. b. The receptive posture of a
female.

and was brought anteriorly. This flattened the shelf against the
male’s abdominal terga, and caused his paraprocts to extend slightly
posteriorly. When fully beneath a female, a male’s epiproctal shelf
was brought into apposition with the basal arms of a female’s sub- i
genital plate and the sterna of her posterior abdomen.

I studied how males orient themselves with females to produce a
successful mounting. Individual females (N = 18) that had been
freshly killed (by pressure from a forceps) from a Lake of the Woods
culture were placed in a standing position on the substrate. Males
always courted and mounted the females without losing orientation
(N = 5). When I reoriented a female while a male was turning
around after touching her with his antennae, he did not reorient to
mount successfully (N = 3). If a female was moved as a male
approached (that is, prior to antennal contact), a male was always
able to orient and mount in the proper direction (N = 10). Hence,
antennal contact by males appeared to be important for a successful \
mounting.

When I placed a teneral male with a receptive female (N = 1), he
ran to her, paused briefly at her side, but then did not exhibit any \
other courting behavior (e.g., antennal contact, wing fanning, etc.).
Instead, he repeatedly climbed over her for about 10 seconds until '
she fled. The male made no attempt to mount, and the female did not ,
assume the receptive posture. ^

1983]

Betz — Biology of Trichaclenotecnum

105

Copula lory Behavior

When a male was fully beneath a female, the posterior end of his
abdomen probed for hers. The valvulae of a female dropped
ventrally somewhat, and moved until contact was made with a male.
The genitalia of male and female T. alexanderae interlocked strongly
together during copulation.

When their genitalia became locked, a male lifted a female off the
substrate by extending his legs, which were still crouched from back-
ing beneath her.

A normal copulatory position for a pair of T. alexanderae is
shown in Figure 3. The hind legs of most (67.8%) males were
extended slightly more than the other pairs of legs, causing a male’s
head to be lowered, and raising and slightly arching his abdomen
(Table 2, A). Males greatly extending their hindlegs usually also had
greatly arched abdomens; males extending all pairs of legs about

I 1

1.0 mm

Figure 3. Trichadenotecnum alexanderae in copulation.

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equally had no abdominal arch. Because the degree of abdominal
arching and the extension of the legs compensated for each other,
the overall position of a male, and thus the relative positions of a
male and female, generally differed little among the matings 1
observed. A male’s abdomen became slightly more arched and his
head dropped lower as copulation progressed. Some males lowered
their heads so much during copulation that their maxillary palps
touched the substrate.

After a female was raised off the substrate, a male’s abdomen
contracted more or less rhythmically. A female contracted her
abdomen in synchrony with a male. Her paraprocts were periodi-
cally flexed medially during copulation.

At the beginning of copulation, the wing pairs of a male were
usually extended high over his body, forming a small angle between
them (Table 2, B). As copulation progressed, the angle formed by
the wing pairs increased; the angle of the wings at the end of copula-
tion was about 60° greater (Table 2, C). 1 found 45.7% of all males
had both wing pairs locked at the nodus (Table 2, D). Wing pairs
remaining free were in a position as though they were locked, and
thus did not interfere with copulation.

Table 2 (E and F) shows that a male’s antennae generally remained
in a normal resting position during copulation.

A female was lifted off the substrate until the angle formed by
her body and the substrate was about 3 1°-60° (Table 2, G). Females
whose bodies inclined more than 60° (7.4%) had been pushed up
into this position when males mounted beneath them.

A female placed her fore- and midlegs on a male when he moved
beneath her. Table 2 (H and I) shows the distribution of the place-
ment of a female’s fore- and midlegs, respectively. Most (41.3%)
forelegs were placed on males’ hindwings and most (50.0%) midlegs
were placed on males’ anterior abdominal pleura. However, as
reflected in Table 2, the first two pairs of legs were positioned in
many other ways.

Table 2 (J) shows the distribution of the placement of a female’s
hindlegs. Most (93.3%) females kept their hindlegs on the substrate.
The rigidity of the hindlegs indicated that they were supporting
some of a female’s weight.

The forewing tips rested lightly on the substrate in 84.8% of the
females (Table 2, K). This contact did not appear to support much
of a female’s weight.

1983]

Betz — Biology of Trichadenotecnuni

107

Table 2. Copulatory behavior in TrichaJenoiecnum alexamierae

% of Total

Position of a male

A. Extent of the arch of
the abdomen

B. Angle formed by the forewings
at the beginning of mating

C. Angle formed by the forewings
at the end of mating

D. Number of wing pairs locked
at the nodus

E. Angle formed by the antennae

F. Angle formed by the antennae
and the bark substrate

1 . Not arched

21.9

2. Slightly arched

67.8

3. Greatly arched

10.3

N = 87

100.0

1. 0°-30°

52.3

2. 3l°-60°

38.5

3. 6l°-90°

6.1

4. 9I°-I20°

3.1

N=65

100.0

1. 0°-30°

5.6

2. 3l°-60°

II. 1

3. 6l°-90°

37.0

4. 9I°-120°

40.7

5. I2I°-150°

0.0

3.7

7. I8I°-2I0°

1.9

N=54

100.0

1. None

35.7

2. One

18.6

3. Both

45.7

N=70

100.0

1. 0°-30°

5.2

2. 31°-60°

32.8

3. 61°-90°

56.9

4. 91°-120°

3.4

5. 121°-150°

0.0

6. 151°-180°

1.7

N=58

100.0

1. 0°-30°

40.5

2. 31°-60°

59.5

N=74

100.0

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Table 2. (continued)

% of Total

Position of a female

G. Angle formed by the body of a
female and the bark substrate

H. Placement of a foreleg on a male

I. Placement of a midleg on a male

J. Placement of a hindleg on a male

0°-30°

1.90

3P-60°

90.7

7.4

N=54

100.0

Forewing

5.6

Base of forewing

29.1

Hindwing

41.3

Base of hindwing

3.1

Metanotum

8.7

Anterior abdominal

terga

6.6

Anterior abdominal

pleura

4.6

Hind tibia

1.0

N=196^

100.0

Hindwing

3.7

Hindwing base

3.1

Metanotum

17.7

Anterior abdominal

terga

6.3

Anterior abdominal

pleura

50.0

Anterior abdominal

sterna

0.5

Hind tibia

13.5

Hind femur

0.5

Bark substrate

4.7

N=192^

100.0

Anterior abdominal

pleura

1.0

Anterior abdominal

sterna

0.5

Hind tibia

5.2

Bark substrate

93.3

N=194^

100.0

1983]

Betz — Biology of Trichadenotecnum

109

Table 2. (continued)

% of Total

Position of a female

K. Position of the forewing tips

On the bark substrate 84.8

In the air

15.2

N=92

100.0

L. Angle formed by the antennae

0°-30°

25.0

51.7

61°-90°

18.3

9I°-120°

5.0

N=60

100.0

M. Angle formed by the antennae and

the bark substrate

0°-30°

88.3

11.7

N=60

100.0

General Features

N. Relative positions of a male

and female

Both in-line
Female skewed

55.3

right or left

44.7

N=47

100.0

O. Duration of copulation

14.3 minutes

s.d.

2.2

range

8.3-19.9 minutes

^Recorded for both legs.

In contrast to the position of a male’s antennae, a female’s anten-
nae were swept back along her body when she assumed the receptive
posture. Usually the antennae were held close to her sides, and the
angle formed by the antennae was between 31° -60° (Table 2, L).
Most (88.3%) antennal pairs were slightly raised from the substrate
(Table 2, M).

Copulation did not always proceed uneventfully. The number of
positions among the pairs reflects the incidence of minor problems
that were encountered during mating. The conformations occurring

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with lower frequency were usually the result of some difficulty dur-
ing copulation. The relative positioning of a male and female (Table
2, N) generally indicates whether a problem occurred during copu-
lation. If the bodies of a male and female were in-line, copulation
usually had proceeded normally. A female was skewed left or right
in 44.7% of the matings. Some of the complications that occurred
during mating are discussed below.

Sometimes a male lifted a female far off the substrate, so her head
was almost over his. Other males pushed females backward during
mounting, then locked genitalia, causing females to be inclined
almost vertically and males to have greatly arched abdomens.
When events such as these occurred, the positioning of a pair, espe-
cially a female’s legs, changed to maintain her balance. For exam-
ple, the hindlegs of a female typically rested on the substrate.
However, when a male lifted a female relatively far off the substrate,
copulation proceeded with more stability when her hindlegs were
placed on a male’s abdomen. When a male’s abdominal contractions
increased to an amplitude that caused his hindwings to strike a
female on the head, she placed one (N = 8) or both (N = 3) forelegs
about midway up on a male’s fore- or hindwings. This response
lessened the force of a male’s contractions. Sometimes a mating pair
fell on their sides (N = 3), but their genitalia remained locked. These
pairs never regained a normal copulatory position, yet they did not
break off copulation because of this problem.

Except for the abdominal contractions and adjustments for stabil-
ity, other movements by a mating pair were uncommon. Occasion-
ally the maxillary palps of a male or a female moved or pulsed
rapidly.

1 observed courtship and mating on a vertical bark substrate in
the laboratory (N = 3). When a male courted a female, she oriented
herself so her head faced downward, then she assumed the receptive
posture. A male lifted a female off a vertical substrate during copu-
lation. A female was positioned dorsally and posteriorly on a male,
similar to mating on a horizontal surface, but in a vertical orienta-
tion a female balanced directly above a male. On a vertical substrate
the fore- and midlegs appeared to have supported more of a female’s
weight.

The duration of copulation varied considerably (Table 2, O),
although it was never less than eight or more than 20 minutes.

1983]

Betz — Biology of Trichadenotecnum

Postcopulatory Behavior

The final stage of copulation was indicated by a slowing of the
rate of abdominal contractions and by contractions of a slightly
more spasmodic nature. Males suddenly became active and broke
off copulation (Table 3, A) by quickly running forward, dragging
along the females for about 1 second until their genitalia unlocked.
Of the 60 pairs I observed for this behavioral character, only two
females (3.3%) appeared to break off copulation. In each of these
matings, the female became active during copulation and tried to
dismount laterally, but her genitalia were locked with the male’s and
this caused her to fall on her side. One female successfully dis-
mounted, thus terminating copulation. The other female failed to
dismount, and instead tried to assume a normal mating position
three times, but because the genitalia were locked she was kept
off-balance. Copulation continued with the female supported tenu-
ously off a side of the male.

A spermatophore was passed in all copulations, including the one
broken off by a female.

Table 3 (B) shows the reactions of males after copulation was
broken off. Most (53.5%) males ran forward about 1 cm, then
remained motionless for at least 5 minutes. Some of these males had
their wings parted slightly and held laterally along their bodies, but
most males brought the wings back to a normal resting position.
Some (28.2%) males were highly active after copulation, and ran
over the substrate without stopping for over 5 minutes. Other
(12.7%) males broke off copulation and remained almost at the
place where copulation occurred. A few (5.6%) males courted the
females they had just mated, but this always caused the females to
flee.

The reactions of females after copulation (Table 3, C) were
somewhat different than those of males. Most (60.0%) females
remained in the area where copulation occurred; almost all of these
females spun around about 90°, some females spun around about
180°. If a female ran off, she usually ran in the direction of a male
because both faced in the same direction during mating. Females
that ran, even for 1 cm, never spun around more than 90°.

Unless disturbed by another insect, once females stopped walking
after mating they rarely moved until the contents of the spermato-
phore that they held had been transferred. Even the antennae did

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Table 3. Postcopulatory behavior in Trichadenoiecnuni alexanJerae

A. Identity of the sex
breaking off copulation

B. Reaction of a male
after copulation
was broken off

C. Reaction of a female
after copulation was
broken off

% of Total

1. Male

96.7

2. Female

3.3

N=60

100.0

1. Ran off ( > 1 cm)

28.2

2. Ran about 1 cm.

then remained still

53.5

3. Stayed in the area

where mating

occurred

12.7

4. Tried to court the

female again

5.6

N=71

100.0

I . Ran off ( > 1 cm)

8.6

2. Ran about 1 cm,

then remained still

31.4

3. Stayed in the area

where mating

occurred

60.0

N=70

100.0

not change position during this time. Only one of three postcopula-
tory females 1 observed at length changed her location once, about 2
minutes after copulation, but did not move after this.

Initially, a spermatophore had an appearance of a whitish, semi-
opaque, hemispherical droplet, protruding between the terminalia
of a female. A female manipulated her terminalia so its contents
passed her genital opening. When it was first visible on a female, a
spermatophore seemed adhesive and somewhat fluid in shape,
allowing it to be manipulated on a female’s terminalia. During the
transfer of its contents, a spermatophore covering seemed to lose
adhesiveness and harden, allowing a female to dispose of it easily.

1983]

Betz — Biology of Trichaclenotecnum

113

A female manipulated a spermatophore between her paraprocts
and valvulae. These movements were accomplished by a rhythmical,
medial flexion of the terminalia. Contractions were spaced about
1-2 seconds apart, and each contraction lasted about 1-2 seconds.
The epiproct was less active in this respect; it was flexed once about
every 30 seconds. Epiproctal flexion probably forced the contents of
a spermatophore into a female’s genital area. The abdominal con-
tractions were pronounced for about the first 4-5 minutes after
copulation, then slowly decreased in rate and intensity.

The females I observed (N = 3) required about 10-25 minutes to
transfer the contents of a spermatophore and discard it. A spermato-
phore either fell from a female’s genital area when she ran (N = 2),
or a female dragged the posterior end of her abdomen along the
substrate for about 1 mm to discard it (N = 1 ). A female sometimes
intermittently flexed her terminalia after a spermatophore had been
discarded.

Evidence for a Sex-attractant Pheromone

The following observations present evidence indicating that the
attraction of males to females of T. alexanderae was mediated by a
pheromone. All females discussed here were unmated, receptive
females from cultures of all three field localities unless noted
otherwise.

Males introduced to bark bearing receptive females often became
more active than when they were introduced to pieces of bark
which had no exposure to receptive females. Some males became so
active they flew across the gap between the pieces of bark before I
could join these together. A male was usually able to find a receptive
female, even though she may have remained hidden from his view.
Additionally, males would court females of T. castum and T.
merum, two obligatorily thelytokous species of the T. alexanderae
species complex, if vials containing these females had previously
contained receptive females of T. alexanderae (Betz 1983a).

Females of T. alexanderae which had just mated ceased rapidly to
be a source of attraction to males, although males occasionally tried
to court females engaged in mating. Teneral females, or females in
the stage of oviposition, failed to attract males (Betz 1983c).

In one mating encounter involving a male and female from a Lake
of the Woods culture, when the male was introduced into a vial

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[Vol. 90

containing the female, she deposited a clear droplet from her genital
area on the bark. The droplet was absorbed rapidly. The male was
highly active and quickly found the female, who was still in the area
where she deposited the droplet, and mated with her. In another
encounter, the female deposited a droplet about 3 minutes after a
failed courtship attempt. This pair mated eventually. Another
female intermittently dragged the tip of her abdomen over the sub-
strate after the male was introduced into her vial. In two encounters,
each involving a male and female from a Lake of the Woods culture,
two from a Lake Dawson culture, and one from a Salt Fork culture,
the male persistently courted a particular place on the female’s sub-
strate, even though she was not nearby. Eventually, after about 10
minutes, males stopped courting these areas.

I have not observed females of T. castum or T. merum depositing
any type of droplet in the above manner, or observed males courting
places on a substrate bearing females of T. castum or T. merum.

In the orientation experiment, it was important to use freshly
killed females because after about 5 minutes they lost attractiveness
to males. Anesthetizing females with ether (N = 3) or carbon dioxide
(from dry ice) (N = 3) caused an immediate loss of interest by males.

From the evidence cited above it appears the females of T. alex-
anderae produce a pheromone that attracts males. It appeared to be
highly volatile; a loss of mating receptivity in a female was almost
immediately evident, as indicated by the lack of attractiveness to
males.

The area around a female in which the pheromone was effective in
attracting males was rather small, having a radius of about 1 cm. 1
determined this by placing individual receptive females (N = 10) in
uncovered petri dishes (standard size), then introducing sexually
active males.

Discussion

Mating behavior in T. alexanderae followed a pattern outlined by
Pearman (1928) for “winged Psocids.” This courtship pattern, which
has since been categorized (Badonnel 1951) and further documented
(Klier 1956), is the one found in most species of Psocoptera that
have been studied. This pattern differs from those in other species in
two details: males do not run over the dorsum of females prior to
mounting, and the duration of copulation is relatively long.

1983]

Betz — Biology of Trichadenotecnum

115

A receptive posturing by females has been noted in several other
species of Psocoptera (Pearman 1928, Sommerman 1943a, 1956,
Schneider 1955, Broadhead 1961). Apparently only females of T.
alexanderae have been observed assuming the receptive posture
before males began backing underneath them.

The receptive posture appeared necessary only to permit males to
fit beneath females during mating. Lifting the anterior end of a
female’s body did not communicate a female’s orientation to a male.
Males courting one of the freshly-killed females always moved ante-
riorly along her body, even though she was not in the receptive
posture. However, the contact made by a male’s antennae after the
sideways gait probably was important in discovering how a female
was oriented because a male was unable to adjust his course to find
a reoriented female after antennal contact was made. Also, males
that had difficulty moving beneath females began the next courtship
with wing fanning, but males not contacting females recourted with
a sideways gait and antennal contact. A differential concentration of
pheromone along a female’s body may have informed a male of her
orientation. A perpendicular approach to a female allowed maxi-
mum extension of a male’s antennae along her body, thus perhaps
facilitating a determination of her relative position.

1 found that the receptive posture was assumed by some females
of T. alexanderae when males approaching to court began a side-
ways gait. Largely auditory cues, rather than visual ones, were proba-
bly given by a male to signal his approach, thereby eliciting the
receptive posture in a female. The sideways gait may cause stridula-
tion of a male’s Pearman’s organs because a male approaching a
female in this way never caused her to flee, even though he may have
remained hidden from her view during the sideways gait.

The purpose of the females’ genital movements and abdominal
contractions after failed courtship is unknown. These motions were
only observed in females involved in some phase of the mating
process. Perhaps this action released more pheromone to attract
males again.

The role of the droplets (apparently containing pheromone)
which were deposited by females is also uncertain. This behavior
would assist a male in locating a female only if she remained in the
area where a droplet was deposited. Because the pheromone appears
to be highly volatile, to have any effect on males a female probably
must deposit many of these droplets during her receptive period.

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[Vol. 90

The epiproctal shelf of a male played an important role during
mating in T. alexanderae: the shelf and a female’s hindlegs on the
substrate supported almost all of a female’s weight. A male’s epi-
proctal shelf and the basal arms of the subgenital plate of a female
are structures apparently functioning to distribute her weight
because both structures are well-sclerotized and have large surface
areas.

The support given by the epiproctal shelf and the interlocking
genitalia apparently increased the lateral stability of a mating pair.
This can be adduced in the following observations. A mating pair
had greater stability during copulation than when a male had
backed fully beneath a female but before their genitalia had inter-
locked. Also, it was difficult for a mating pair to fall over to one side
when problems in stability occurred during copulation, although
once they fell regaining a normal mating position was impossible.
The stability supplied by the contact between the epiproctal shelf-
subgenital plate and posterior abdominal sterna, the positioning of
a female’s legs, and the interlocking genitalia probably also expe-
dited the lifting of a female by a male, although the reason for the
necessity of lifting a female is unknown.

Acknowledgements

I thank Dr. E. L. Mockford of Illinois State University, whose
beneficial discussions about Psocoptera and review of the manu-
script were greatly appreciated. 1. N. Holod and D. D. Pierce assisted
in the production and the typing of the manuscript, respectively.

Summary

Pre- through postcopulatory behavior in Trichadenotecnum alex-
anderae Sommerman is here quantified and discussed. Mating
behavior follows a pattern described for many other species of Pso-
coptera, in which a male approaches a female, fans his wings over
his head, and backs underneath her without running over her dor-
sum. Additional behavioral actions, including possible stridulation
and antennal contact of a female by a male and a female assuming a
receptive posture prior to mounting by a male, are believed to
promote copulation. Evidence is presented for a sex-attractant
pheromone produced by receptive females.

1983]

Betz — Biology of Trichacienotecnum

117

Literature Cited

Badonnel, a. 1951. Ordre des Psocopteres. Pages 1301-1340 in Grasse, P. P.,
ed., Traite de Zoologie, Vol. 10, Fasc. 2. Masson et Cie., Paris.

Betz, B. W. 1983a. Systematics of the Trichadenoiecnum alexanJerae species
complex (Psocoptera: Psocidae) based on an investigation of reproductive
modes and morphology. Can. Entomol. (in press).

1983b. The biology of Trichadenoiecnum alexanderae Sommerman (Pso-
coptera: Psocidae). 1. Habitat, life stages and events. Entomological News
(in press).

1983c. The biology of Trichadenoiecnum alexanderae Sommerman (Pso-
coptera: Psocidae). II. Duration of biparental and thelytokous reproductive abili-
ties. J. Kansas Entomol. Soc. (in press).

1983d. The biology of Trichadenoiecnum alexanderae Sommerman ( Pso-
coptera: Psocidae). IV. Mechanism of genitalic coupling. J. Kansas Entomol.
Soc. (in press).

Broadhead, E. 1961. The biology of Psoquilla marginepunciaia (Hagen) (Corro-
dentia, Trogiidae). Trans. Soc. Brit. Ent. 14: 223-236.

Eertmoed, G. E. 1966. The life history of Peripsocus quadrif asciai us (Psocopiexa:
Peripsocidae). J. Kansas Entomol. Soc. 39: 54-65.

Klier, E. 1956. Zur Konstruktionsmorphologie des mannlichen Geschlechtsap-
parates der Psocopteren. Zool. Jb. (Anatomic) 75: 207-286.

Mockford, E. L. 1957. Life history studies on some Florida insects of the genus
Archipsocus (Psocoptera). Bull. Fla. State Mus., Biol. Sci. 1: 253-274.

1977. Asiopsocus sonorensis (Psocoptera: Asiopsocidae): A new record,

augmented description, and notes on reproductive biology. Southwestern Nat.
22:21-29.

Pearman, j. V. 1928. Biological observations on British Psocoptera. HI. Sex
behavior. IV. Miscellaneous. Entomologist’s Mon. Mag. 64: 263-268.

Schneider, H. 1955. Vergleichende Untersuchungen uber Parthenogenese und
Entwicklungsrhythmen bei einheimischen Psocopteren. Biol. Zentr. 74: 273-310.

Sommerman, K. M. 1943a. Bionomics of Eciopsocus pumilis (Banks) (Corroden-
tia, Caeciliidae). Psyche 50: 53-64.

1943b. Bionomics of «/v6/7/.v (Aaron) (Corrodentia, Caeciliidae).

Can. Entomol. 75:99-105.

1944. Bionomics of (Walsh) (Corrodentia, Psocidae).

Ann. Entomol. Soc. Amer. 37: 359-364.

1956. Two new species of Rhyopsocus (Psocoptera) from the U.S.A.,

with notes on the bionomics of one household species. J. Wash. Acad. Sci. 46:
145-149.

Thornton, I. W. B., and E. Broadhead. 1954. The British species of Elipsocus
Hagen (Corrodentia, Mesopsocidae). J. Soc. Br. Ent. 5: 47-64.

PREDATORY CAPTURE OF BOMBARDIER BEETLES
BY A TABANID FLY LARVA*

By Stephen Nowicki and Thomas Eisner
Section of Neurobiology and Behavior
Cornell University, Ithaca, NY 14853

While collecting bombardier beetles {Brachinus spp.) on the eve-
ning of August 27, 1982, by a pond near Portal, Cochise County,
Arizona, a group of us, including Rodger Jackman of the British
Broadcasting Corporation and Maria Eisner, came upon an unusual
phenomenon. Thousands of young adults of the spadefoot toad,
Scaphiopus multiplicatus, were active beside the pond on that
night, having just emerged from the water after metamorphosis. On
close observation we noted a number of these toads that were dead
or dying and in various stages of partial submergence in the mud.
Each had been grasped from beneath by a larva of the horsefly
Tabanus punctifer, a mud-dwelling predator, which had seized it with
its hooked mouthparts, had pulled it partly into the substrate, and
was embibing its body fluids. Details of this first known occurrence
of predation by a fly larva on an adult amphibian will be published
elsewhere. Our purpose here is to call attention to another extraor-
dinary ability of this larva: the capture of bombardier beetles.

We transported several of the larvae to our Cornell laboratories
and established them individually in mud-filled enclosures, where
they quickly buried themselves, leaving only their mouthparts
exposed at the surface (Fig. lA). We maintained the larvae on
young spadefoot toads, which they captured as they had in the field,
and also on insects, which judging from published accounts on
tabanid larvae (Webb and Wells, 1924; Oldroyd, 1964; Burger,
1977), must be a principal staple of their diet. They proved capable
even of capturing large crickets ( Teleogryllus oceanicus), which they
hooked by a leg, drew partly into the mud, and then held for hours
while sucking out their body contents.

*Paper No. 73 of the series Defense Mechanisms of Arthropods. Paper No. 72 is
T. Eisner and J. Meinwald, Psyche 89, 357-367, 1983.

Manuscript received by the editor January 6, 1983

119

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Psyche

[Vol. 90

Figure 1. (A) Mouthparts (arrow) of a buried T. punciifer larva, projecting just
above the surface of the mud, as the animal lies in wait of prey. (B) Bombardier
beetle, caught by a submerged larva and partly drawn into the mud, in the process of
being eaten (the larvae can also pull beetles into drier mud than here shown). (C) Full
grown T. punctifer larva beside an average-sized bombardier beetle. Reference bars =
5 mm.

Bombardier beetles are doubtless among the most invulnerable of
insects. The quinone-containing spray that they eject from their
abdominal defensive glands when attacked is hot (100°C) and is
aimed accurately toward the predator by rotation of the abdominal
tip (Eisner, 1958; Aneshansley et al., 1969). A number of broadly
insectivorous predators have been shown to be repelled by the
spray, including ants, spiders, preying mantids, and toads (Eisner,
1958; Eisner and Dean, 1976; Dean, 1980).

We staged encounters between bombardier beetles and T. punc-
tifer larvae by releasing the beetles singly onto the mud in the larval

1983]

Nuw'icki & Eisner — Bombardier beetles

121

enclosures. The beetles all stemmed from the larval collecting site,
where they were taken at the very places on the edge of the pond
where the larvae were also abundant. In three encounters we were
fortunate to witness the beginnings of the attack. The events pro-
ceeded quickly and were the same in each case. No sooner had a
beetle brought one of its tarsi to rest upon the mouthparts of the
larva, than it was grasped by that tarsus and caused to spray. There
were sometimes several discharges, audible at times and visible as
misty puffs, but the larva, which had withdrawn below the surface
the moment it hooked on to the beetle’s leg, was already out of
reach. The beetle struggled as it was gradually pulled into the mud,
but the larva never released its hold. Partly submerged, the beetle
eventually died (Fig. 1 B), and when retrieved next day was found to
be largely eaten out. Five additional encounters that were not wit-
nessed from the outset were equally fatal to the beetles. We assume
that the death of the beetles was hastened by the salivary toxins that
tabanid larvae are said to inject into their insect prey (Schmidt,
1982).

Given the ecological co-occurrence of T. punetifer larvae and
bombardier beetles, we feel that encounters between the two must
inevitably occur also in nature, with the same outcome as in the
laboratory. Moreover, the larvae must have access also to diverse
other insects that discharge noxious secretions, includings ants, tiger
beetles, and additional Carabidae. Species of Chlaenius, for exam-
ple, whose odor was unmistakably suggestive of the phenolic output
that characterizes other beetles of the genus (Eisner et ai, 1963),
scurried about together with Braehinus at our collecting site at
night. Against such chemically protected insects, the predatory tac-
tic of lurking just beneath the surface, and of withdrawing into the
mud for total cover the moment a victim is seized and caused to
activate its defenses, doubtless serves the larvae well. Other mud-
dwelling tabanid larvae of similar opportunistic feeding habits might
equally profit from the tactic.

Acknowledgements

Study supported by Grant AI02908 from NIH; we thank Drs.
John F. Burger and Rodolfo Ruibal for helpful information and for
identifying the larva and toad respectively, and Maria Eisner for
technical help.

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[Vol. 90

References Cited

Aneshansley, D. J., T. Eisner, J. M. Widom, and B. Widom

1969. Biochemistry at 100° C: Explosive secretory discharge of bombardier
beetles (firflfc/7/>7w.s). Science 165:61-63.

Burger, J. F.

1977. The biosystematics of immature Arizona Tabanidae (Diptera). Trans.
Amer. Ent. Soc. 103:145-258.

Dean, J.

1980. Encounters between bombardier beetles and two species of toads (Bufo
americanus, B. nmrinus)\ Speed of prey-capture does not determine
prey-capture success. J. Comp. Physiol. 735:41-50.

Eisner, T.

1958. The protective role of the spray mechanism of the bombardier beetle,
Brachynus hallistarius Lee. J. Insect Physiol. 2: 215-220.

Eisner, T. and J. Dean

1976. Ploy and counterploy in predator-prey interactions: orb-weaving spiders
versus bombardier beetles. Proc. Nat. Acad. Sci. USA 73:1365-1367.

Eisner, T., J. J. Hurst, and J. Meinwald

1963. Defense mechanisms of arthropods. XI. The structure, function, and
phenolic secretions of the glands of a chordeumoid millipede and a
carabid beetle. Psyche 70:94-1 16.

Oldroyd, H.

1964. The Natural History of Flies. Norton: New York.

Schmidt, J. O.

1982. Biochemistry of insect venoms. Ann. Rev. Entom. 27:339-368.

Webb, J. L. and R. W. Wells

1924. Horse-flies: Biologies and relation to western agriculture. U. S. Dept.
Agr. Bull. 1218.

PREY SELECTION BY THE NEOTROPICAL SPIDER
ALPAIDA TV ON A BO
WITH NOTES ON WEB-SITE TENACITY'

By Todd E. Shelly
Department of Biology
University of California
Los Angeles, CA 90024

Introduction

Prey selection by web-building spiders includes 2 principle com-
ponents. First, webs may catch a nonrandom sample of the avail-
able prey (passive selection). Among items caught in the web, the
spider may then feed on preferred prey but reject unsuitable prey
(active selection). As evident from a recent review (Riechert and
Luczak 1982), quantitative field measurements of either component
are relatively rare and particularly so for tropical species.

Here I compare the web contents of Alpaida tuonabo (Chamber-
lin and Ivie) with sticky trap samples of available prey. Field work
was conducted at one site over a relatively short period of time thus
reducing potential complications arising from habitat and seasonal
differences in prey availability. As Olive (1980) and Uetz et al.
(1978) found, however, prey availability may vary over short verti-
cal distances, and to examine this possibility potential prey were
sampled at several different heights.

In addition, a second comparison was made between captured
items being eaten and those left unattacked and uneaten. Since prey
ignored during the day may have been consumed at night with the
web, uneaten prey did not necessarily represent rejected prey. This
comparison, however, does quantify the probability of immediate
attack upon different types and sizes of captured prey.

'While Araneus is the accepted generic designation, this species is not closely related
to other members of this genus and should perhaps be placed in the genus Aplaida
(H. Levi pers. comm.).

Manuscript received by the editor December 20, 1982.

123

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Materials and Methods

The study was conducted between July 23 and August 25, 1980,
on Barro Colorado Island (BCI), Panama. This time period falls
near the middle of a rainy season which annually extends from late
April to mid-December (Croat 1978). The island is covered by a
lowland tropical moist forest (Holdridge et al. 1971). Alpaida tuo-
nabo was most abundant on the island’s central plateau, and all
work was conducted there.

Very little is known about the biology of A. tuonabo. A descrip-
tion of the female has been published (Chamberlin and Ivie 1936),
but males have not yet been described (H. Levi, pers. comm.).
Females are relatively small; the mean wet weight and body length
of 8 adult females were 0.023 g (SD 0.005) and 5.6 mm (SD 0.94),
respectively. Females appeared to construct and tend webs during
the day and consume them at night. In 4 nights of searching, I never
saw a female or an intact web. On BCI A. tuonabo is abundant only
in the mid to late wet season (July to December) and is rarely found
during the rest of the year (Lubin 1978).

Flying insects were sampled at 10 different sites. At each site I
implanted a 2.7 m PVC pole (diameter 25 mm) by driving 0.30 m —
0.45 m of its length into the ground. Wooden rods (length 30 mm;
diameter 5 mm) were then fastened to the pole at 0.3 m intervals
(from 0.3 m to 2.1 m above ground). Fastened at one end, each rod
projected perpendicularly from the vertical pole and hence was
parallel to the ground’s surface. Insects were collected on tanglefoot
covered traps suspended from the wooden rods. Each trap was
a 15 cm by 23 cm rectangle of 3 mm thick transparent plastic coated
on both sides with tanglefoot. Insects were sampled during the day
only on August 7-9. Each day the traps were set between 0800
hrs-0900 hrs, taken down between 1600 hrs-1700 hrs, and stored
overnight in closed boxes. Aside from Diptera and Hymenoptera,
all trapped insects were identified to order. Flies were categorized as
either nematocerous or non-nematocerous, and hymenopterans
were subdivided into bees and wasps, parasitoids, and winged ants.
All trapped insects were measured to the nearest 0.1 mm using a
dissecting microscope equipped with a disc micrometer.

Each day of the study 1 walked through different areas of the
forest (between 0900-1630 hrs) and examined every web encoun-
tered. All caught items were collected and labelled as either eaten or

1983]

Shelly — Alpaicia tuutiaho

125

Diptera

nematocerous

non-nematocerous

Hymenoptera

ants

parasitoids

Coleoptera

Frequency

Figure I. Vertical distributions of the major prey categories. Each value repres-
ents the total number of individuals captured on 10 sticky traps suspended at a
particular height. See text for details of sampling method.

uneaten. Uneaten prey were also examined for evidence of wrap-
ping. For each web thus sampled, the height of the spider was also
recorded. Collected prey were later assigned to the appropriate prey
category and measured to the nearest 0.1 mm.

Prey selectivity was quantified using Ivlev’s (1961) index of elec-
tivity. Electivity (E) is calculated as follows: E = (ri — pi)/(ri + pi)
where rj is the proportion of the predator’s diet represented by prey
type (or size class) i, and pi is the proportion of the available prey
represented by prey type (or size class) i. Values of E range from
— 1.0 (complete avoidance) to +1.0 (complete preference). In this
study electivity values with absolute values less than 0.40 were not
considered to differ significantly from zero. In addition, two sets of
electivity values were calculated. For web selectivity (Ew) ri is the
proportion of the web contents (both eaten and uneaten items)
represented by prey type i, and pi is the proportion of available prey
(as measured by the sticky traps) represented by prey type i. For
spider selectivity (Eg) ri is the proportion of the spider’s observed
diet (the eaten prey) represented by prey type i, and pi is the propor-
tion of the web contents (both eaten and uneaten items) represented
by prey type i.

Results

Alpaicia tuonabo females generally constructed webs in relatively
open sections of the forest or at the edges of tree-fall gaps. Most web

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[Vol. 90

sites were shaded, and only rarely was a web placed in an area that
received direct sunlight. Various web support structures were util-
ized, including leaf tips, herbaceous stems, woody vines and
branches, and palm fronds. The circular webs averaged 21.6 cm in
diameter and 350 cm^ in catching area (n = 8).

Individuals do not appear to remain at a particular web-site for
more than 1-2 days. On August 3 I marked the location of 20
occupied webs. These sites were then revisited daily for 7 days, and
the presence or absence of the spider and the web was recorded. In
terms of the number of spiders remaining at their initial site, the
results obtained were as follows: Day 1 — 12; Day 2 — 3; Days 3 and
4 — 2; Days 5 and 6 — 1 ; Day 7 — 0. In no instance was a spider absent
but the web present; spider and web were always both present or
both absent. In addition, in examining a 2 m-3 m radius about each
vacated web-site, I never observed the presence of a newly con-
structed web.

Five prey categories comprised 89.0% of the total sample, and
vertical abundance patterns were examined for these groups only.
Beetles, parasitoid Hymenoptera, nematocerous and non-
nematocerous Diptera all exhibited a similar trend in vertical abun-
dance (Figure 1). That is, the greatest numbers of individuals were
collected at the two lowest sampling heights (0.3 m and 0.6 m).
While similar numbers of parasitoid Hymenoptera were captured at
the two lowest sampling heights, nearly twice as many beetles, nema-
tocerous and non-nematocerous Diptera were captured at 0.3 m
than 0.6 m. Ants were captured in relatively constant numbers over
all sampling heights.

Although the numbers of trapped individuals varied greatly with
height for 4 prey categories, each major category comprised a rela-
tively constant proportion of the total sample at each height (Figure
2). Similarly, within each category size frequency distributions did
not vary with height in any obvious manner (Figure 3). Thus, while
the abundance of flying insects varied with height, the taxonomic
and size composition of this fauna did not.

The vertical distribution of A. tuonabo did not closely match that
observed for available prey (Figure 4). Alpaida tuonabo preferred
web-sites between 0.6 m-1.2 m, and approximately 60% of the spi-
ders measured were within this range. Thus, while traps nearest the
ground caught the greatest numbers of flying insects, only 18% of A.
tuonabo were found below 0.6 m.

1983]

Shelly — Alpaicia tuonaho

127

Diptera

• nematocerous
o non-nematocerous

2.1r

0.9-

0.5-

40 ' 80 ' 120

Hymenoptera
• ants

o parasitoids

Coleoptera

80 120

Number

Figure 2. Relative abundances of major prey categories over all heights sampled.
Each value represents a proportion of the total number of individuals captured on 10
sticky traps suspended at a particular height. See text for details of sampling method.

Frequency

Figure 3. Size frequency distributions for the major prey categories over the 7
heights sampled. Within a category each value represents the proportion of individu-
als captured at a particular height that fell within a particular 1 mm interval. The
symbols used for the various size classes are: 0 — 1 mm (•), 1 — 2 mm (O), 2 —
3 mm (X), and >3 mm (A).

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A total of 446 insects representing 6 orders were taken from 320
webs of A. tuonabo. Approximately 95% of these insects belonged
to those 5 prey categories which were most abundant in the sticky
trap samples. Consequently, analysis of both web and spider selec-
tivities will focus only upon these groups. In addition, since the
composition of the flying insect fauna did not much vary with
height, both the data regarding prey availability and diet were com-
bined over all heights.

Web selectivity values did not differ greatly from zero for beetles,
nematocerous Diptera, or parasitoid Hymenoptera (Table 1). Non-
nematocerous Diptera, however, comprised a small proportion of
the web contents relative to their proportion on the traps. Con-
versely, ants represented a large proportion of the web contents
relative to their proportion on the traps.

Aside from nematocerous Diptera, A. tuonabo were observed to
consume prey types in proportions roughly equal to their propor-
tion in the web (Table 2). Spider selectivity values for beetles, ants,
non-nematocerous Diptera, and parasitoid Hymenoptera were all
less than 0.20 (absolute value). In contrast, the Es value for nema-
tocerous Diptera was large and negative.

Figure 4. Vertical distribution of A. tuonaho and available prey. Heights of
hub-resting spiders were measured to the nearest cm and then placed into 0.3 m
intervals. Values for prey represent the total number of insects captured on 10 sticky
traps suspended at a particular height. See text for details of sampling method.

1983]

Shelly — Alpaicia tuonaho

129

Table I. Web selectivity (Ew) values for prey types collected from webs of A.
tuonaho.

Prey type

Collected from webs
(eaten and uneaten)
no. rj

Captured on traps
no. Pi

Beetles

12.5

320

19.2

-0.21

Nematocerous Diptera

164

36.8

337

20.2

+0.29

Non-nematocerous Diptera

7.6

453

27.1

-0.56

Ants

128

28.7

1 19

7.1

+0.60

Parasitoid Hymenoptera

9.4

264

15.8

-0.25

Others

22^

4.8

175^^

10.4

♦Others include: butterflies (6), bees and wasps (10), leafhoppers (4), thrips (2)
♦♦Others include: butterflies (2), bees and wasps (2), leafhoppers (80), thrips (27),
Hemiptera (8), Orthoptera (5), Collembola (3), Zoraptera (4), Plecoptera (3),
Isoptera (21), Psocoptera (20)

As the Es values imply, the majority (87%) of uneaten prey were
nematocerous Diptera. Most of these, in turn, did not appear to
have been wrapped. Many, in fact, were observed struggling in web
while stuck by a single wing. Similarly, most uneaten non-
nematocerous Diptera and parasitoid Hymenoptera were appar-
ently unwrapped. In contrast, 9 of the 12 uneaten ants had clearly
been attacked and wrapped.

Only 2 groups, nematocerous Diptera and ants, were found in
webs in sufficient numbers to allow meaningful calculation of web
selectivity values for different size classes. Nematocerans less than 1
mm were relatively more abundant in webs than on the traps, while
the opposite was true for those between 1 mm-2 mm (Table 3a).
Web selectivity values, however, did not differ greatly from zero for
either size class. Ants in webs were rather uniformly distributed
among 8 size classes (Table 3b). The majority (76.0%) of ants on the
sticky traps, however, were less than 3 mm long. Consequently, web
selectivity values for the 1 mm-2 mm and 2 mm-3 mm size classes
were large and negative, while those for larger classes were all large
and positive.

Only ants were eaten in sufficient numbers to allow meaningful
calculation of spider selectivity values for different size classes. Yet,
since nearly all (90.6%) of the ants taken from webs were being
eaten, these selectivity values provide little new information. Among
the remaining groups, only nematocerous Diptera had large enough

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Table 2. Spider selectivity (E^) values for prey types collected from webs of A.
tuonaho.

Prey type

Collected from webs
(eaten only)
no. rj

Collected from webs
(eaten and uneaten)
no. Pi

Beetles

18.8

12.5

+0.20

Nematocerous Diptera

1 1.6

164

36.8

-0.52

Non-nematocerous Diptera

10.1

7.6

+0.14

Ants

116

42.0

128

28.7

+0.19

Parasitoid Hymenoptera

11.6

9.4

+0.10

Others

16^

5.8

22**

4.8

♦Others include: butterflies (6), bees and wasps (10)

♦♦Others include: butterflies (6), bees and wasps (10, leafhoppers (4), thrips (2)

numbers of eaten (32) and uneaten (132) individuals to permit com-
parison. Mean body lengths for eaten (x = 1.6 mm; SD = 1.8) and
uneaten (x = 0.8 mm; SD = 0.29) nematocerans were significantly
different (t = 4.86; p <.00 1).

Discussion

The present findings highlight 2 features of the predatory behav-
ior of A. tuonabo. First, the webs captured and the spiders con-
sumed nonrandom samples of the available prey. Nonrandom web
captures have been recorded for other spiders (e.g. Uetz and Biere
1980; Brown 1981; Turnbull 1960) and most likely reflect differing
abilities for web avoidance or escape among different prey. While
no avoidance was observed, 1 did see several large flies (Asilidae and
Tabanidae) strike webs but then successfully escape. Among insects
successfully restrained by the web, the spider may attack, ignore, or
reject different types and/or sizes of prey. Numerous studies (e.g.
Robinson and Robinson 1970, 1973; Riechert and Tracy 1975;
Turnbull 1960) note rejected prey, but few studies (Uetz and Biere
1980) quantify attack vs. ignore probabilities for different prey.
Here, the tendency of A. tuonabo to ignore nematocerans probably
does not reflect avoidance but rather the inability of these small,
weak-flying insects to escape or damage the web. Thus, A. tuonabo
may have ignored these weak prey only to consume them with their
web in the evening. Interestingly, the mean body length of nema-
tocerans being consumed was nearly twice that of nematocerans

1983]

Shelly — Alpaicia tuonaho

131

Table 3. Web selectivity ( values for size classes of nematocerous Diptera and
ants collected from webs of A. tuonaho.

a. Nematocerous Diptera

Size (mm)

Collected from webs
(eaten and uneaten)
no. rj

Captured on traps
no. Pi

O-I

1 18

71.9

138

40.7

+0.28

1-2

24.4

163

48.1

-0.33

2-3

2.4

9.1

-0.58

1.2

2.1

-0.27

b. Ants

Collected from webs

Captured on traps

Size (mm)

(eaten and uneaten)

no.

0-1

0.0

1-2

13.3

36.7

-0.47

2-3

8.6

39.3

-0.64

3-4

16.4

6.0

+0.46

4-5

12.5

2.6

+0.65

5-6

7.8

2.6

+0.50

6-7

18.7

6.0

+0.51

7-8

10.2

1.7

+0.71

12.5

5.1

+0.42

caught in the web but ignored. Spider selectivity for larger prey has
also recently been demonstrated for Micrathena gracilis (Uetz and
Biere 1980).

Second, A. tuonabo did not construct their webs at heights where
total prey abundance was greatest. Since the taxonomic and size
composition of the flying insect fauna varied only slightly with
height, A. tuonabo was apparently not responding to the vertical
distribution of a particular type or size of prey. Several factors
potentially affect web height in A. tuonabo. First, although females
use various support structures, the number of suitable “web spaces”
may be limited (Lubin pers. comm.). Also, other species of similar
size (e.g. Pronous tuberculifer, Edricus crassicaudus, and Leucauge
sp.) construct webs closer to the ground (Lubin 1978; Shelly pers.
obs.). Thus, the higher webs of A. tuonabo may reflect a behavioral
means to lessen interspecific competition for food. In addition.

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[Vol. 90

increased web height may reduce risks of predation from ground- or
litter-dwelling predators.

Acknowledgements

I thank H. Levi, M. Robinson, Y. Lubin, and particularly C.
Olive for helpful comments on an earlier draft. H. Levi identified
the species. D. Weinberger kindly helped process the sticky trap
samples. The Smithsonian Tropical Research Institute provided
logistic support.

IjTI RAH RI ClTHD

Brown, K.

1981. Foraging ecology and niche partitioning in orb-weaving spiders. Oeco-
logia 50: 380-385.

ChAmhkri.in, R. V. .and W. Ivn .

1936. New spiders from Mexico and Panama. Bull. Univ. Utah 27: 1-103.

Croat, T. B.

1978. Flora of Barro Colorado Island. Stanford Univ. Press, Stanford.

Holdridgh, L. R., W. C. Gri NKh, W. H. Hathhwav, T. Liang, and J. A. Tost, Jr.

1971. Forest environments in tropical life zones: a pilot study. Pergamon Press,
San Francisco.

IVLHV, V. S.

1961. Experimental ecology of the feeding of fishes. Yale Univ. Press, New
Haven.

Ft BIN, Y. D.

1978. Seasonal abundance and diversity of web-building spiders in relation to
habitat structure on Barro Colorado Island, Panama. J. Arachnol. 6:
31-51.

Olivh, C. W.

1980. Foraging specializations in orb-weaving spiders. Ecology 61: 1 133-1 144.

RiK( HHRT, S. E. AND C. R. TrA(A .

1975. Thermal balance and prey availability: bases for a model relating web-
site characteristics to spider reproductive success. Ecology 56: 265-284.

RiTGIII RT, S. E. AND J. Lu( ZAK.

1982. Spider foraging: behavioral responses to prey. In Spider communica-
tion. eds. P. N. Witt and J. S. Rovner. Princeton Univ. Press, Princeton,
NJ.

Rohinson, M. H. and B. Robinson.

1970. Prey caught by a sample population of the spider Argiope argentata
(Araneae: Araneidae) in Panama: a year’s census data. Zool. J. Linn.
Soc. 49: 345-357.

Robinson, M. H. and B. Robinson.

1973. Ecology and behavior of the giant wood spider Nephila maculata
(Fabricius) in New Guinea. Smithsonian Contrib. Zool. No. 149.

1983]

Shelly — Alpaicia monaho

133

Turnbi'll, a. L.

I960. The prey of the spider Linyphia triangularis (Clerck) (Araneae,
Unyphiidae). Can. J. Zool. 38: 859-873.

Uktz, G. W., a. D. Johnson, and D. W. Schhmskk.

1978. Web placement, web structure, and prey capture in orb-weaving spiders.
Bull. Br. Arachnol. Soc. 4: 141-148.

Uktz, G. W. and J. M. Bihrk.

1980. Prey of Micrathena gracilis (Walckenaer) (Araneae: Araneidae) in com-
parison with artificial webs and other trapping devices. Bull. Br. Arach-
nol. Soc. 5: 101-107.

REPRODUCTIVE BEHAVIOR OF
CLAEODERES BIVITTATA
(COLEOPTERA: BRENTIDAE)*

By Leslie K. Johnson
Department of Zoology
The University of Iowa
Iowa City, Iowa 52242

Promiscuous aggregations of adult brentid weevils often occur on
host trees, where females gather to oviposit (Meads 1976; Johnson
1982). In such a circumstance, in which a male can potentially
inseminate many females, intense competition by males for females
typically occurs (cf. Thornhill 1976; Alexander and Borgia 1979;
Fincke 1982). In addition, members of the family Brentidae show
considerable intraspecific variation in adult size (Sharp 1895; Soares
1970; Damoiseau 1967). From the numerous studies that show that
larger body size enhances competitive aggressive success (e.g. John-
son and Hubbell 1974; Hamilton et al. 1976; Heinrich and Bartho-
lomew 1979), it might be predicted that larger male brentids would
enjoy greater mating success in breeding aggregations, and —
provided that male size is an important competitive characteristic —
that variation in male mating success would be commensurate with
variation in male body size. I tested these predictions on an aggrega-
tion of C/aeoderes bivittata Kirsch. (Coleoptera: Brentidae) in
which the adults varied more than ten-fold in body weight.

The results of the present study support the idea that body size is
an important trait. Males of nearly equal size engaged in a ritualized
contest which appeared to permit sensitive assessment of relative
size, and larger males enjoyed greater success in fights over females.
However, small ( 1 1-22 mm) as well as large males (31-39 mm long)
were disproportionately represented in mating. Small males had
greater than expected success partly because they at times took
shelter under, rather than guarded, their females, emerging for cop-
ulation when a larger rival was not present.

* Manuscript received hy the editor December 12, 1982

135

136

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[Vol. 90

Materials and Methods

Claeocleres hivittata adults were studied on a dying tree of Qua-
rarihea asterolepis (Bombacaceae) on Barro Colorado Island (9° 09'
N, 79°51' W) in the wet season of 1980.

On June 9 all weevils from ground level to 2 m on the standing
tree were collected, placed in a bag, sexed, measured in length to the
nearest mm, and replaced. On June 13 all weevils up to a height of 2
m were collected and brought to the laboratory, where they were
sexed, measured, cleaned of most mites with masking tape, and
weighed to the nearest tenth mg on a Mettler H35AR balance. On
June 14 these weevils were replaced on the trunk. On six dates
between June 28 and July 14 the behavior of individually marked
weevils of different sizes was described into a portable tape recorder,
for a total of 13 hours. Rectangular and trapezoidal arenas about
1 / 3 m" were drawn on the sides of the trunk between buttresses. On
a given date the trunk was circled clockwise. The reproductive and
competitive behavior that was centered around all male-female pairs
in an arena was recorded, until none of the pairs originally in the
arena remained. Durations of acts were timed with a stopwatch.
Weevil density on the trunk slowly dwindled from 27-36/ m- on
June 28 to 15 or fewer/ m- on July 14. A few weevils were collected
in alcohol for identification and dissection.

Description of Weevil Activities

Oviposition

Before drilling, a female walks slowly over the smooth trunk,
touching the substrate with her antennae. When a favorable site is
found the female chews for 30-60 min until her rostrum is buried to
the depth of the antennal insertion. Periodically she withdraws her
snout, lifts her head, and expels sawdust from her jaws.

To oviposit, a female turns around and locates the drilled hole by
tapping with rear end and hind legs. She then everts her telescoped
sclerites, bringing the ovipositor to the hole, and remains still for 70
sec to 3 min. The hole drilled is the right size for one egg.

After oviposition the female rocks by bending and straightening
her forelegs 12 times per min for 3.5-12 min, repeatedly moving the
tip of her abdomen between the hole and positions further back. As
the female rocks out, a bristled tergite is everted, to which bits of

1983]

Johnson — Claeoderes hivinaia

137

sawdust and other debris adhere. As she rocks in, the material
appears to be added to the hole.

A female may drill and oviposit three times in succession (Fig. 1).
Female Aggression

Aggression is instigated by females before they drill and by
females that have just completed oviposition. The aggression is usu-
ally directed against drilling females. The encounter may involve
only an intention movement, or the instigator may push, poke, or
swat a drilling female with her snout, or pry her out of her hole by
sticking the snout under her abdomen and lifting. A fleeing female
may be pursued several cm. Reciprocated aggression may result in a
fight lasting 6 min or more in which the combatants kick, face one
another and swivel their heads and forebodies, or thrust the snout
under the other and lift suddenly; females of the same length may
also stack themselves head-to-tail and sweep their snouts over the
tip of their opponent’s abdomen. Fights end when a female leaves
or is flipped from the tree.

Guarding

A guarding male stays with a female as she antennates the trunk,
drills, or oviposits, keeping his rostrum or his body over her (Fig. 2).
He responds aggressively if a rival male draws near, and he may also
threaten a female if she approaches his female too closely, by facing
her, advancing on her, or chasing her with a yawing movement of
the head.

Mating

A male mates with the female he is guarding one to several times
during drilling, and is especially likely to do so Just before the female
pulls her beak out of the wood to oviposit (the onset of oviposition
occurs less than a minute after the termination of copulation in
about 80% of the cases (see Fig. 1)). A few seconds before mating a
male accelerates his movements, antennates the female, and then
mounts, sometimes trying the female’s head. Copulation lasts about
a minute.

Rejection

A female not ready to drill or oviposit will walk away from males
that approach. A drilling female can thwart mating attempts by
walking her hind end in a circle around the pivot point of her snout
in wood, or by withdrawing her snout entirely and walking away.

Guard

138

[Vol. 90

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1983]

Johnson — Claeoderes hivittata

139

Fig. 2. A male, with enlarged jaws for nipping rivals, guards a female Claeoderes
hivittata as she prepares to drill an oviposition hole. A guarding male typically
places all or part of his body (particularly the rostrum) over the female. A small male
in the presence of a large male, however, may insert himself partly under the drilling
female.

Male Aggression

Males fight for access to females. Initially they may intermingle,
jerk, or lash their antennae. Attacks involve nipping, kicking, pok-
ing with the snout, or putting the snout under the rival’s body and
Jerking upwards 3 times/ sec. A male may also interfere \yith copula-
tion by thrusting his snout between a mating pair and pushing. An
attacked male may flee, or reciprocate in kind.

Two males of approximately the same length may engage in a
more stylized contest in which they align themselves, side by side,
1-10 mm apart, facing opposite directions. On the side of the rival a
male taps his antenna and hind leg 4-5 times/ sec, and when the
opponent does likewise, the males fence leg against antenna at either
end. The “appendage-fencing” contests observed in this study lasted
3 sec to 9 min.

Results

Size Variation

Male weevils in the June 13 sample (n = 67) ranged from 12-38
mm in length and from 19-334 mg wet weight, i.e., the biggest male
was 3 times as long and 17 times as heavy as the smallest. Males 1 1

140

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[Vol. 90

and 39 mm long were found subsequently. The females (n = 81)
ranged from 12-29 mm and 19-247 mg with the biggest female 2Vi
times as long and 13 times as heavy as the smallest. At all lengths
females were heavier than males, and they increased in weight faster
with length than did the males (Fig. 3).

A frequency histogram of the lengths of males (n = 101) and
females (n = 128) measured June 9 is shown in Fig. 4. Mean male
length ±S.D. was 25.91 ±7.21; mean female length ±S.D. was 20.97
±4.35.

Five females were dissected. Each had two ovarioles and 3 or 4
large, yolked eggs. The length of the largest yolked egg increased
monotonically with female length, from a 1.3 mm egg m a 13 mm
female to a 2. 1 mm egg in a 29 mm female.

Size ami Aggressive Success

In aggressive encounters between females the female that fled was
deemed the loser. The winners by this criterion were larger in 14 of
14 contests involving weevils of unequal length (p = .0001, sign test).
Even if four additional encounters involving females of equal length
were conservatively counted as victories for the smaller weevil, the
winners were still significantly more likely to be the larger (p =
.0154).

In male encounters the winner was considered to be the male that
remained by the female. Here again the larger weevil was signifi-
cantly more likely to win (p < .005, sign test). Defending males (the
ones originally with the female) were not significantly more likely to
win encounters than intruding males (p .18).

The relative size of the rivals was also a factor in the occurrence of
the appendage-fencing contest. An analysis of the differences in
length between the rivals in five encounters in which the contest
occurred and sixteen encounters in which it did not, showed that
rivals using the contest were significantly more similar in length (p =
.002, Mann-Whitney U test). The mean ±S.D. difference in length
for rivals using the contest was 1.8 ±2.0 mm; for rivals not using it,
8. 1 ±7.4 mm.

One effect an intruding male may have, whether or not he wins
the female, is to shorten the duration of the defending male’s copu-
lation. Uninterrupted copulations lasted a mean ±S.D. of 82.4
±48.7 sec, with 2/3 of the copulations lasting between 40 and 90 sec.
Copulations interrupted by rivals, however, lasted 31.0 ±15.1 sec
(p = .026, Mann-Whitney U test).

I9K3] Johnson — Claeoderes hivittata 141

Fig. 3. Log,o length (mm) vs. log,o wet weight (mg) of male (•) and female (O)
ClaeuJeres hivinaia. For males, log, q( weight, mg) = -1.53 + 2.54 log, q (length, mm).
For females, log,^ (weight, mg) = -1 .78 + 2.83 log,o (length, mm).

142

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[Vol. 90

Size and Mating

Individual weevils were compatible with mating partners of many
sizes. In 52 different pairings, females mated with males as much as
10 mm shorter than themselves, and males with females as much as
16 mm shorter. Despite this, mating was size-assortative overall.
The Pearson product moment correlation for male and female
length was r = .323 (p = .021) for the 52 different pairings, and r =
.398 (p = .002) if multiple matings of a pair were included.

Females, however, tended to reject males smaller than themselves
when such males attempted to mate. In 57% of the cases of rejection
(4 out of 7) the female was larger, whereas in only 37% of the cases
of mating (22 out of 60), was the female larger. When lengths of
males rejected and accepted for mating were examined, it was found
that rejected males were shorter (p < .05, 1 -tailed, Mann-Whitney U
test).

Given the more frequent rejection of small males, and the greater
success of larger males in aggressive encounters over females, it was
expected that males found mating would tend to be larger than
males simply present in the aggregation. Whereas females that
mated were larger than unattended drilling females (p < .02, 2-
tailed, Mann-Whitney U test), males that mated were not signifi-
cantly larger than guarding males, males in a random sample, or
males that were alone (Table 1). Instead, a frequency histogram of
mating males showed a bimodality in the size of males that mated
compared to an unimodal distribution of males in the breeding
aggregation (Fig. 4). There appeared to be a dearth of medium-sized
mating males. Indeed, a chi-square test on the 52 different pairings
found that mating males were significantly more likely to be large
(^ 31 mm) or small (^ 22 mm) than would be expected if they
mated in proportion to their abundance in the random sample (x^ =
4.87, 1 df, p = .027).

Extra opportunities for small males to mate could arise if guard-
ing males drove away small rivals less frequently than they did rivals
more their size. With this in mind, I compared the 7 cases in which
two males co-occurred at a drilling female for 3 min or more with
the 19 cases in which one male drove off the other within the first
minute. In 6 of the 7 cases of co-occurrence, one male was small
(^ 22 mm) and the other large (^ 31 mm). In the remaining case
both males were medium-sized. In the 7 cases of co-occurrence the

1983]

Johnson — Claeocleres hivittata

143

Table I. Lengths (mm) of ClaeoJerc.s hivinata individuals in different categories.
The two means marked with an asterisk are the only two compared within a sex that
are significantly different.

Females

Males

S.D.

99 drilling alone

1 1

19.73*

2.45

(5(5 without partners

25.21

7.30

Guarded, drilling

20.08

3.67

Guarding 55

24.55

6.76

Random sample of

128

20.97

4.35

Random sample of

(5(5

101

25.91

7.21

99 that mated

22.21*

4.20

55 that mated

24.77

8.09

mean ±S.D. size difference between the males was 13.6 ±8. 5mm. In
the 19 cases of intolerance, the mean S.D. size difference was only
5.8 ±5.7 mm. The males in the cases of co-occurrence were, in fact,
significantly more disparate in size (p < .02, 2-tailed, Mann-
Whitney U test).

The joint attendance of a drilling female by the two medium-sized
males was short-lived (4 min). The small and large male combina-
tions, on the other hand, were more persistent (x = 19.8 ±10.5 min).
Stability was achieved in part because the small male kept a “low
profile.” The small males were unaggressive, even if poked, and 5/6
of them spent most of their time partway under the drilling female.
Usually it was the rostrum that was tucked under the female, but
two individuals crawled under the female at right angles to her long
axis and centered themselves beneath her. Postures in which a male
placed part of himself under the female were exhibited only by small
males in the presence of a large male guard.

Opportunities to mate did arise for 5 of the 6 small males, despite
the existence of the larger guards. Three of the small males mated
while the large male was fighting off a large intruder. One small
male mated while the large male stood with his snout resting on the
female’s head. Another small male waited until the onset of oviposi-
tion, when the large male left. He then interrupted the post-
oviposition rocking behavior of the female in order to copulate. The
small male that did not mate was driven off by the large male guard,
who was aroused from quiescence by a 38 mm intruder who nipped
him and mated with his female.

144

Psyche

[Vol. 90

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1983]

Johnson — Claeoderes hivinata

145

Despite their mating successes, the small males were not the equal
of the large ones. The copulations of the small males appeared to
require the absence or inattention of the larger attendant. In con-
trast, the large males mated when they chose. All 6 large males, for
instance, were the last to mate before the female oviposited, after
which they left.

Discussion

In Claeoderes hivittata, there is a great deal of variation in adult
size, presumably due in part to variable growth conditions expe-
rienced by the larvae (Kleine 1933; Haedo Rossi 1961 ; Galford 1974;
Peters and Barbosa 1977). As with another brentid, Brentus ancho-
rago (Johnson 1982), the larger individuals have several reproduc-
tive advantages. In both species, larger females can clear from the
region in which they just oviposited, more of their drilling rivals
(thus possibly reducing later crowding of their larvae), and are less
likely to be ousted from their chosen drilling site. Larger females
also lay larger eggs, an initial advantage which in other beetles has
been shown to significantly affect final adult size (Palmer 1983).
Larger males do more mating than average, and assortatively mate
with larger females who have the reproductive advantage of larger
eggs and greater competitive success at oviposition sites.

There is, however, a principal difference between B. anchorago
and C hivittata. In B. anchorago, the bigger the male, the more he
mates (Johnson 1982). In C. hivittata, the middle-sized males mate
the least. In B. anehorago, males are highly intolerant of other males
at a drilling female. In C. hivittata, a female can sometimes have
two attendants if one is large and one is small.

The circumstances that permit the co-occurrence of a large and
small male at one female need further investigation. In a proximal
sense, small males may be less easily perceived than larger ones.
Certainly, the small males appeared to assist this process by making
themselves less conspicuous. They frequently tucked their snout
under the female, along with the antennae which in other encounters
permit male-male recognition. The small males were not seen to
advertise their presence by initiating acts of aggression. Similar
unprovocative tactics were noted in the smallest males of the wood-
boring weevil, Rhinostomus harhirostris, at females guarded by
large males (Eberhard 1980). Then too in the ultimate sense, it may

146

Psyche

[Vol. 90

not be worth the energy expenditure for a large male to keep small,
persistent males from the vicinity of the female. Despite matings by
small males, large males may enjoy most of the paternity.

A true answer to the question of the relative reproductive success
of large and small males awaits determination of the mode of sperm
competition in C hivittata. Whatever the mode, the relative repro-
ductive success of a small male is probably less than the relative
number of matings he achieves. If there is sperm mixing, the small
males (which in the six cases observed here averaged 200 mg lighter
than the males with which they co-occurred), probably transfer less
sperm per copulation than the large ones. In two species of helico-
niine butterflies, for example, smaller males transfer smaller sper-
matophores (Boggs 1981). If there is sperm precedence, we would
expect large males, with the advantage of weight and strength in
aggressive encounters, to copulate at will when the probability of
fertilizing the egg is the highest. Small males, mating when they
could, might or might not transfer sperm at the opportune time.

The mode of sperm competition is unknown in C. hivittata;
however, sperm displacement has been found thus far to be the rule
in Coleoptera (Walker 1980). If sperm displacement does occur in
C. hivittata, the last male to mate before oviposition would have
the advantage in paternity. That last male advantage occurs in C.
hivittata is suggested by the fact that copulation immediately pre-
cedes oviposition, and that when the female ceases to explore the
trunk and drill, the male ceases to guard her.

I would argue, then, that small males of C. hivittata do not enjoy
nearly as much reproductive success as their proportion of the copu-
lations would suggest, and that there has not been intense- selection
for large males to assiduously expend energy excluding them from
drilling females they are guarding. For small males, however, there
must at times be an advantage to lingering near a female guarded by
a larger rival, for otherwise one would predict that small males
would avoid such females. If there is complete or partial sperm
mixing in C. hivittata, there exists a possibility, however small, that
a given copulation by any male at any time will result in fertiliza-
tion. Even if sperm displacement is complete, there remains the
possibility that the larger rival, distracted by competitors or a more
attractive female, will not return before oviposition begins, leaving
the way open for the small male to copulate last. Similarly, a small
male that mates just after oviposition might still fertilize the next

I9S3]

Johnson — Claeoderes hivinaia

147

egg to ripen if by chance the female went unmated during her next
drilling.

The above arguments do not provide an ultimate explanation for
why small males of C. /?/v/7/^7/^7 enjoy greater mating success than
small males of B. anchorago. Comparative studies are planned for
these two species, which have similar breeding ecologies. Sperm
competition and methods of detecting rivals will be explored, and
the behavior and reproductive input of small, medium, and large
males of both species will be compared. Possibly the system in C.
bivittata represents an early stage of the development of dual male
strategies, and may be a step on the evolutionary road to male
dimorphism (Eberhard 1980). If so, elucidation of the differences
between C. bivittata and B. achorago could help our understanding
of the selective environments favoring dimorphic male behavior and
structure.

Summary

Adults of Claeoderes bivittata aggregated on a Quararibea tree
in Panama. Males ranging in length from 1 1-39 mm guarded and
mated with females 12-29 mm long as they bored holes in the wood
for their eggs. Fights often ensued as females tried to pry other
females from their drilling sites; larger females more often won.
Males fought males for access to females; larger males won signifi-
cantly more often. Disputes involving males of similar size could be
settled by a contest in which the two males stood closely parallel
head-to-tail, while an antenna lashed a hind leg at either end. Such
an appendage-lashing contest may permit rivals to assess one
another’s relative size.

Although individuals differing by at least 16 mm in length could
couple, significant size-assortative mating was observed (r = .4).
Due to the greater aggressive success of larger males and the fact
that males rejected by females were smaller than males they
accepted for mating, it was expected that mating males would be
above average in size. Instead, mating males were significantly more
likely to be large 31 mm) or small 22 mm). The dispropor-
tionate mating of small males may be explained in part by the
tendency of smaller males to wait partly sheltered under a drilling
female, emerging for copulation when larger males are not guarding
the female.

148

Psyche

[Vol. 90

Acknowledgments

I am grateful to Lenny Freed, Jim Palmer, Bob Silberglied, and
Barbara Stay for statistical and biological input, and to Charles
O’Brien for identifying C. hivittata. I also thank Hank Howe, who
found the tree with weevils, and Steve Hubbell, who lent a hand
weighing them. The Smithsonian Tropical Research Institute pro-
vided laboratory space and facilities.

Ijil RATl Rh Cm-;D

Au xandi R. R. D. AND G. Borgia.

1979. On the origin and basis of the male-female phenomenon. In: M. Blum
and N. Blum (eds.). Sexual Selection ami Repruduetive Competition in
Insects. Aeademic Press, N.Y.

Boggs, C. L.

1981. Seleetion pressures affecting male nutrient investment at mating in heli-
coniine butterflies. Evolution 35: 931-940.

DAMOlSl At , R.

1967. Monographic des Coleopteres Brentidae du Continent Africain. Mus.
Royal de L’Afrique Cent., Tervuren, Belg. Ann. Ser. IN-8°-ser. Zool.
160: 1 507.

EhI RIIARD, W. G.

1980. Horned beetles. Scientific American 242 (3); 166-182.

Ein( Kh, O. M.

1982. Lifetime mating success in a natural population of the damselfly, Enal-
laf^nia hu^’eni (Walsh) (Odonata: Coenagrionidae). Behavioral Ecology
and Sociobiology 10: 293-302.

GaI I ORD, J. R.

1974. Some physiological effects of temperature on artificially reared oak bor-
ers. ,1. Econ. Ent. 67: 709 710.

Hai do Rossi, J. A.

1961 . Brent idos Argentinos ( Brent hidae, Coleoptera). Opera Lilloana 6: 1-317.

Hamiiton, W. j. Ill, R. E. Buskirk and W. H. Buskirk.

1976. Social organization of the Namib Desert tenebrionid beetle Onymaeris
ruyatipennis. The Canadian Entomologist 108: 305-316.

Hi nirk II, B., AND G. A. Bartiiolomkw.

1979. Roles of endothermy and size in inter- and intraspecific competition for
elephant dung in an African dung beetle, Searahaeus laevistriatus. Phys-
iological Zoology 52: 484-496.

.loiINSON, 1.. K.

1982. Sexual selection in a brentid weevil. Evolution 36: 251-262.

.loiINSON, L. K. AND S. P. HuBMELL.

1974. Aggression and competition among stingless bees: field studies. Ecology
55: 120 127.

1983]

Johnson — C/aeocIeres hivittata

149

Kl.HINh, R.

1933. Weitere biologische Mitteilungen iiber Brenthiden. Ent. Rdsch. 50:
25 28, 49 50.

Mhads, M. J.

1976. Some observations on Lasiorhynchus harhicornis (Brentidae; Coleop-
tera). New Zealand Entomologist 6: 171 176.

PaI MKR, J. O.

1983. Seasonal body size variation in the milkweed leaf beetle, Lahidomera
(7/wVo///.v (Kirby). Unpublished manuscript.

Pktkrs, T. M. and P. Barbosa.

1977. Influence of population density on size, fecundity and development rate
of insects in culture. Ann. Rev. Entom. 22: 431-450.

Sharp, D.

1895. Brenthidae. Biologia Centrali-Americana 4 (6): 1-80.

SOARKS, B. A. M.

1970. Contribui(;ao ao estudo das especies do genero Acratus Lacordaire.
(Coleoptera, Brentidae). Studia Entomologica 13: 193-252.

Tiiornhiu,, R.

1976. Reproductive behavior of the lovebug, Plecia nearciica (Diptera:
Bibionidae). Annals of the Entomological Society of America 69:
843-847.

Walkkr, W. F.

1980. Sperm utilization strategies in nonsocial insects. American Naturalist
115: 780-799.

POLYDOMY IN THE SLAVE-MAKING ANT,
HARPAGOXENVS AMERICANVS (EMERY)
(HYMENOPTERA: EORMICIDAE)*

Maria Gi adaluph Del Rio Pesado and Thomas M. Alloway
Erindale College
University of Toronto
Mississauga, Ontario L5L 1C6
Canada

Introduction

Slavery in ants is a form of social parasitism in which parasitic
“slave-making” species exploit the labor of workers derived from
host-species colonies. The slave makers raid host-species nests,
where they capture all or part of the brood. Subsequently, workers
maturing from the captured brood form a social attachment to the
slave makers and perform all the usual worker-ant functions in the
parasites’ colony (see review in Buschinger et al. 1980).

Harpagoxenus aniericanus (Emery) is an obligatory slave maker
living in eastern North America, where it forms mixed colonies with
members of certain Leptothorax species (see Alloway 1979). Two
kinds of H. aniericanus nests are found: “primary nests” containing
a single slave-maker queen and slaves with or without slave-maker
workers, and “secondary nests” consisting of slave-maker workers
and slaves without a slave-maker queen (Creighton 1927; Sturtevant
1927; Buschinger & Alloway 1977). Primary nests are apparently
established when a parasite queen successfully invades a host-
species nest (Wesson 1939), but the origin of secondary nests is
questionable. The problem is compounded by the fact that secon-
dary nests are usually more numerous than primary nests and fre-
quently produce slave-maker females (workers and / or queens) from

'This research was supported by a scholarship from CONACYT [Consejo Nacional
de Ciencia y Tecnologia, Mexico] to the first author and by a grant from the Natural
Sciences and Engineering Research Council (Canada) to the second author. The
authors would like to thank Victor Chudin for his assistance in collecting the data
and Robin Stuart for his constructive comments on the manuscript.

Manuscript received hy the editor February 19, 1983.

151

152

Psyche

[Vol. 90

their broods (Wesson 1939; Buschinger & Alloway, 1977). In the
related European slave maker, H. sublaevis, “ergatoid queens”
(individuals with fully functional ovaries and a spermatheca, but
with a more or less worker-like external morphology) are common
and function as the usual female reproductives (Buschinger, 1978).
However, Buschinger and Alloway (1977) found that, while many
H. americanus workers have functional ovaries and lay eggs that
can mature to produce males, they rarely, if ever, possess a spermat-
eca. Thus, “ergatoid queens” are absent or very rare in H. ameri-
canus. Moreover, these authors thought that thelytoky was unlikely
in this species.

Wesson (1939) observed the formation of secondary nests in the
laboratory. Slave-maker colonies which had conducted several
ordinary slave raids sometimes concluded the final raid of the sea-
son by splitting into two components. In these cases, a few slave-
maker workers and slaves remained indefinitely in the raided nest
with part of the captured brood. Wesson suggested that this might
be a sufficiently common late-season activity to account for the
frequent occurrence of secondary nests. However, even if secondary
nests are formed in this manner, there are still two possibilities for
the relationship between secondary and primary nests and for the
origin of the female slave-maker brood in secondary nests. Follow-
ing their formation, secondary nests might become autonomous
entities functionally separate from their parental primary nests. In
this case, if we exclude thelytoky, the female slave-maker brood in
secondary nests would have to be derived exclusively from brood
carried over from the primary nest when the secondary nest was
initially occupied (Buschinger & Alloway 1977). Alternatively, the
primary nest and one or more secondary nests might comprise a
single multiple-nest (polydomus) colony (Sturtevant 1927). Interac-
tions between the nests of such polydomous colonies would be pro-
tracted, and the slave-maker queen would continue to supply female
brood for all nests in her colony. The latter possibility is supported
by the fact that polydomy of this type has recently been demon-
strated in two of the host species of H. americanus, Leptothorax
ambiguus Emery and L. longispinosus Roger (Alloway et al.
1982). The objective of the present study was to examine these two
possibilities by collecting and mapping H. americanus and host-
species nests in nature, reconstructing their spatial relationships in
the laboratory, and observing the interactions among them.

1983]

Pesach & Alloway — Harpagoxenus aniericanus

153

Material and Methods

The ants were collected on the Erindale Campus of the University
of Toronto in Mississauga, Ontario, during the spring and summer
of 1980 and 1981. Since our purpose was to determine whether
colonies of H. americanus sometimes occupy more than one nest,
we looked for areas where two H. americanus nests occurred within
2 m of each other. Whenever such a place was located, we layed out
a 2 m by 2 m quadrant centering on the two nests and then collected,
numbered and mapped the location of every H. americanus nest and
every nest of its host species (L. ambiguus and L. longispinosus) in
the quadrant. In some cases, adjacent quadrants were combined to
permit the collection of a larger group of slave-maker nests.

In the laboratory, we removed the ants and their brood from their
natural nests and established them in artificial nests of the type
described by Alloway (1979). For censusing, the artificial nests were
placed in petri dishes (diameter = 14.5 cm; height = 1 .5 cm) contain-
ing a water bottle and food (Bhatkar & Whitcomb 1970). Then the
ants were transported to an unairconditioned, naturally lighted
room. On the floor of this room, quadrants were layed out with
masking tape; and the field maps were used to locate the position
occupied by each nest. A thick layer of petroleum Jelly on the mask-
ing tape formed a barrier which confined the ants to their respective
quadrants. A water bottle and food were placed near each nest. In
this way, it was possible to set up the artificial nests so that we
duplicated the spatial arrangement of the natural nests.

In addition to the quadrants collected from the field, we set up
one control quadrant to study behavioral interactions between two
H. americanus nests which had not been collected near one another
in nature. The sides of this control quadrant were 100 cm long, and
the two nests were placed 80 cm apart.

During the course of our observations, some of the ants were
marked so that they could be individually identified. Each mark
consisted of a very small dot of colored nail polish applied to the
dorsal surface of the gaster with the tip of a minuten pin embedded
in the end of a wooden stick. Ants remained marked for periods of 1
day to 1 month.

Observations were made 8 h a day, 5 days a week between 10 June
and 27 August 1980 and between 7 May and 30 August 1981. Five
quadrants were collected and observed during 1980; and 14 quad-
rants were collected and observed during 1981.

154

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Results

There was a total of 19 quadrants. However, quadrant 1 was
merged with quadrant 2 and quadrant 9 with quadrant 10 when an
additional H. americanus nest was found in close proximity to a
group of other H. americanus nests, but outside the original quad-
rant boundary. Altogether, the quadrants contained 49 H. ameri-
canus nests, 57 L. ambiguus nests, and 59 L. longispinosus nests (see
Table 1).

Our most common observation was “fusion” of all the H. ameri-
canus nests in a quadrant. By “fusion”, we mean that eventually all
the ants from two or more H. americanus nests peacefully moved
into a single nest after exchanging adult nest-mates and brood
among the different nests for varying lengths of time (Figure 1). This
exchange was carried out exclusively by slaves. The ability of nests
to fuse shows that there is no behavioral barrier to interactions and
exchange of nestmates among nests and thus indicates either that all
the ants are members of the same polydomous colony or that H.
americanus is a unicolonial species with no behavioral barriers
between its nests. Fusion of all the slave-maker nests was observed
in quadrants (1 + 2), 5, 6, (9 + 10), 11, 12, 13, 16, 17, and 18, in
which there was never more than one slave-maker queen.

However, we did not always observe fusion among H. americanus
nests:

a. In the control quadrant where two H. americanus nests
from different collection sites were arbitrarily set up near each
other, the ants showed no tendency to fuse; and the slave makers
from one nest successfully raided the other slave-maker nest.

b. Quadrants 3 and 8 each contained two H. americanus
queens living in different nests with slaves and a brood. In quad-
rant 3, there was little behavioral interaction between the ants in
the two nests. However, in quadrant 8, after the brood matured,
the H. americanus workers in one nest raided the other slave-
maker nest.

c. In quadrant 4, there was little contact between the ants in
the two H. americanus nests, but the small amount of contact
observed was hostile.

d. In quadrant 14, slaves and slave makers in two nests fused
and then fought with the slaves and slave makers in a third nest.

1983]

Pesach & AUoway — Harpagoxenus americanus

155

Figure 1 - Set-up date, duration of nestmate
exchange until date of fusion.

NO. OF
QUAD.

10
11
12

18
19

, ' 1

1980

1981

10 20 30 10 20 30 10 20 30 10 20 30
MAY JUNE JULY AUGUST

\ set-up date

I nestmate exchange until fusion.

156

Psyche

[Vol. 90

e. In quadrant 19, both the slaves and the slave makers from
different nests fought whenever they met; and the slave makers in
one nest mounted an incomplete raid against the other slave-
maker nest.

These observations indicate that H. americanus is not a unicolo-
nial species. Aggressive behavioral barriers preventing the exchange
of nestmates and nest fusion exist between some H. americanus
nests. This fact strengthens the conclusion that exchange of nest-
mates and brood and nest fusion, when they do occur, are indicative
of the existence of a polydomous colony.

Somewhat peculiar partial fusions were observed in quadrants 7
and 15. In both quadrants, the slaves peacefully moved into a single
nest. In quadrant 7, the slave makers from the two nests fought. In
quadrant 15 where there were 5 H. americanus nests, some of the
slaves attacked slave makers which had been living in other nests
prior to the fusion. These partial fusions may represent situations in
which lack of contact between nests had begun to produce auton-
omy between nests.

Once the raiding season was over, we observed the formation of
secondary nests in quadrants 1 and 6. In both quadrants, some of
the ants which had been occupying a single nest moved into a
second nest. In both cases, exchange of nestmates and brood con-
tinued for two weeks, when observations ended.

In 7 quadrants, we were unable to find an H. americanus queen,
despite our efforts to collect each nest completely and to search
beyond quadrant boundaries for additional slave-maker nests belong-
ing to these nest groups (see Table 1). However, in each of these
cases, all the maturing H. americanus adults were males, a fact
which indicates that these particular nests had not been receiving
female brood from a primary nest and is consistent with the suppo-
sition (Buschinger & Alloway 1977) that thelytoky does not occur in
H. americanus.

The total number of adults of various species in all nests studied is
summarized in Table 1. The total number of H. americanus workers
was 1 15, with the average slave-maker nest containing about 2 H.
americanus workers. The largest number of slave makers in a single
nest at the time of the original census was 13; and the largest number
of nests in a single apparently polydomus H. americanus colony was
6 in quadrant (9 + 10). Altogether, this colony contained 19 H.

1983]

Pesacio & A I Iowa y — Harpagoxenus aniericanus

157

aniericanus workers, 54 L. longispinosus slaves and 53 L. ambiguus
slaves. The average distance between H. aniericanus nests in nest
groups apparently comprising a single colony was 43.5 cm, with a
range of 1 1 to 159 cm. The average distance between H. aniericanus
nests among which there were aggressive interactions was 61.36 cm,
with a range of 19 to 180 cm.

In the H. aniericanus nests, L. longispinosus slaves outnumbered
L. ambiguus slaves by a ratio of almost 4:1, the total number of
slaves being 803 (79.5%) for L. longispinosus and 207 (20.5%) for L.
ambiguus. All the H. americanus colonies contained L. longispino-
sus slaves, and 9 colonies contained slaves of both species. However,
none of the H. americanus colonies used in this study had only L.
ambiguus slaves, although such colonies are occasionally found in
the Toronto region (Alloway unpublished data). Nevertheless, 7 of
the quadrants studied contained no nests of free-living L. longispino-
sus, and one of the quadrants in which there were L. ambiguus
slaves contained no nests of free-living L. ambiguus (see Table 1).
Unenslaved nests of L. longispinosus were on average somewhat
more populous than the unenslaved nests of L. ambiguus, the mean
number of workers per nest being 25.6 for L. longispinosus and 16.8
for L. ambiguus.

Discussion

Our observations indicate that many Harpagoxenus americanus
colonies are polydomus. This conclusion is based primarily on
observations of peaceful interactions and of nest fusion among nests
collected close together in nature, contrasted with observations that
ants from different H. americanus nests do not always interact
peacefully. The fighting and raiding observed indicate that H. ameri-
canus does not possess a unicolonial population structure. Thus,
peaceful exchange of nestmates and nest fusions, when they occur,
signify the existence of polydomous colonies. However, polydomy
in H. americanus is not obligatory. New colonies are monodomous,
becoming polydomous as they grow. Finally, our observations of
partial fusions suggest that nests in polydomus colonies may gradu-
ally become autonomous, perhaps due to cessation of regular con-
tact between nests. Under these circumstances, new queenless
“secondary colonies,” similar to those envisaged by Wesson (1939),
could be formed.

Table 1. Total number of nests and individuals by species in each quadrant.

158

Psyche

[Vol. 90

sisau lie
*0 16)01

free living

s)sau

.'1

L a

D+

107

261

s)sa

L 1

D+

112

116

166

291

125

sisau
B H

slaves

Tin

131

H a

Quad

1983]

PesacU) & AUoway — Harpagoxenus americanus

159

164

r*-

136

100

958

204

222

1509

C>J

«=

207

803

115

TOT

arpagoxenus americanus. L 1 = Leptothorax longispinosus.

L a = Leptothorax ambiguus. $ = queen. $ = worker.

160

Psyche

[Vol. 90

Nevertheless, the fact that ants which had been living in several
different nests in nature so frequently moved into a single artificial
nest in the laboratory is somewhat problematic. Under our labora-
tory conditions, polydomy seldom persisted, possibly because our
artificial nests were somewhat more spacious than the acorn nests
which these ants inhabit in nature. If the ants live in more than one
acorn because no single acorn is large enough for the whole colony,
then giving the colony a larger artificial nest might produce nest
fusion. However, many factors other than space may be involved in
producing and maintaining polydomy in these ants (see discussion
in Del Rio Pesado, 1983).

Our observations of nest divisions in two quadrants further sup-
ports the polydomy hypothesis. However, the nest fusions which we
saw did not closely resemble those described by Wesson (1939). In
only one of our colonies did raiding parties tend to remain in target
nests; and even these raiders returned home after 1 to 3 days. What
we observed was that ants which had been occupying one nest came
to occupy two nests after the “raiding season” was over.

Several previous investigators have noted that many H. ameri-
canus nests are queenless (Buschinger & Alloway 1977; Creighton
1927; Sturtevant 1927; Wesson 1939). The usual conjecture has been
that most of these queenless nests are “branches” located near
queenright nests. Our data confirm this supposition by showing that
many queenless nests are parts of queenright polydomus colonies.
However, there were 7 quadrants in which we could not find a nest
containing an H. atnehcanus queen. Since these queenless nests
produced only male slave-maker brood, it is unlikely that they
represent components of a queen-right polydomous colony; and the
males produced in these nests are probably the offspring of H.
aniehcanus workers (Buschinger and Alloway 1977). Some of these
isolated nests may be remnants of colonies whose queen has died,
while others may be products of long-distance raids from which the
raiders failed to return. The presence in some H. americanus nests of
slaves belonging to a species for which there were no free-living
nests in the same quadrant suggests that H. americanus raids may
occur over distances of several meters; and far-ranging raiders may
sometimes fail to return to their base (Creighton 1927).

In our study area, L. longispinosus slaves outnumbered L. ambi-
guus slaves by a ratio of almost 4: 1 . This finding is typical through-
out southern Ontario and the adjacent parts of New York state,

1983]

Pesacio & Alloway — Harpagoxenus americanus

161

despite the fact that L. ambiguus colonies are generally more
abundant than L. longispinosus colonies (Alloway et al. 1982).
Two factors probably account for the prevalence of L. longispinosus
slaves in H. americanus nests. First, H. americanus seems to mani-
fest an ecological preference for rather cool, shady places, a habitat
preference which closely matches that of L. longispinosus. Second,
at our study site, we found that L. longispinosus nests were on
average ore populous than L. ambiguus nests. Thus, a raid against
a nest of L. longispinosus might net more worker pupae than a raid
against a nest of L. ambiguus.

Summary

Field maps were made while collecting nests of the slave-making
ant, Harpagoxenus americanus, and two of its host species, Lepto-
thorax ambiguus and L. longispinosus. The ants were then trans-
ferred to artificial nests arranged to reconstruct the natural spatial
relationships among nests. Ants from adjacent slave-maker nests
often exchanged nestmates and brood for a period of time before
moving into a single nest; and ants which had been living in a single
nest in the laboratory sometimes moved into two nests. However, in
other instances, ants from adjacent nests fought. These observations
were interpreted as indicating that colonies of H. americanus some-
times occupy more than one nest (facultative polydomy). Nest popu-
lation data were also presented and discussed.

References

Alloway, T. M.

1979. Raiding behaviour of two species of slave-making ants, Harpagoxenus
americanus (Emery) and Leptothorax duloticus Wesson. Animal Behav-
iour 27: 202-210.

Alloway, T. M., A. Buschinger, M. Talbot, R. Stuart, & C. Thomas.

1982. Polygyny and polydomy in three North American species of the ant
genus Leptothorax Mayer (Hymenoptera: Formicidae). Psyche, 89:
249-290.

Bhatkar, a. & W. H. Whitcomb.

1970. Artificial diet for rearing species of ants. Fla. Entomologist 53: 217-232.
Buschinger, A.

1978. Genetically induced origin of alate females in the slave-making ant, Har-
pagoxenus sublaevis (Nyl.) (Hym., form). Insectes Sociaux 25: 163-172.
Buschinger, A., & T. M. Alloway.

1977. Population structure and polymorphism in the slave-making ant Harpa-
goxenus americanus (Emery). Psyche 83: 233-242.

162

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[Vol. 90

Buschinger, a., W. Ehrhardt, and U. Winter.

1980. The organization of slave-raids in dulotic ants: A comparative study
(Hymenoptera: Formicidea). Zeitschrift fur Tierpsychologie 53: 245-264.

Creighton, W. S.

1927. The slave raids of Harpagoxenus americanus. Psyche, 36: 48-80.

Del Rio Pesado, M. G.

1983. Polydomy in the slave-making ant Harpagoxenus americanus (Emery)
(Hymenoptera: Formicidae). M.Sc. Thesis, University of Toronto.

Sturtevant, a. H.

1927. The social parasitism of the ant Harpagoxenus americanus. Psyche 34:
1-9.

Wesson, L. G., Jr.

1939. Contribution to the natural history of Harpagoxenus americanus Emery
(Hymenoptera: Formicidae). Transactions of the American Entomolog-
ical Society 65: 97-122.

Wheeler, W. M.

1910. Ants: Their Structure, Development, and Behavior. Columbia Univer-
sity Press, N.Y. & London, 663 pp.

Wilson, E. O.

1971. The Insect Societies. Belknap Press of Harvard University Press, Cam-
bridge, 548 pp.

SITUATION AND LOCATION-SPECIFIC FACTORS
IN THE COMPATIBILITY RESPONSE IN
RHYTIDOPONERA MET A LUC A
(HYMENOPTERA: FORMICIDAE: PONERINAE)*

By Caryl P. Haskins and Edna F. Haskins
Haskins Laboratories, Inc.

New Haven, Connecticut 06510

Introduction

Hangartner, Reichson, and Wilson (1970) reported some years
ago that individual communities of harvester ants of the genus Pogo-
nomyrmex are able to distinguish the scent of their own nesting
material from that of other conspecific colonies. Holldobler and
Wilson (1977) were able to show that the African weaver ants,
Oecophylla longinoda, mark and advertise individual community
territories by means of colony-specific pheromones deposited in the
rectal fluids. And Traniello (1980) has recently demonstrated that,
in the typically densely packed aggregations of colonies of Lasius
neoniger, persistent trunk trails are maintained which arise from
recruitment trails marked, again, with hindgut material. Here we
describe what we believe to be nest-area marking with hindgut
material in the primitive Ponerine ant Rhytidoponera metallica.

Experiments and results

The tests reported here were a continuation of a series carried on
for some years, and earlier reported in part (Haskins and Haskins,
1979). Material and methods were essentially as described there, and
need only be briefly reviewed. The specific population used in this
work was collected as a single, rather small colony taken at Mont-
ville, in the Blackall Range of northern Queensland, Australia, on
December 23, 1963. It was maintained as a closed inbreeding unit in
the laboratory until the fall of 1979, at which time it had greatly
increased in numbers, was active and vigorous, and contained

* Manuscript received by the editor February 24, 1983

163

164

Psyche

[Vol. 90

numerous “worker”, female and male brood.' Other things being
equal, it might have been expected to have attained considerable
genetic homogeneity, since new generations of “workers” and young
queens were fathered exclusively by males reared within the colony.

On November 4, 1979 this population was divided into two
roughly equal halves and placed in separate arenas standing side
by side on the same laboratory bench. All conditions were kept
constant for the two moieties, designated A and B, except that they
were maintained on differing diets, comprising crickets and dilute
honey water for A and mealworm larvae and dilute sugar water for
B. Two years later, on November 7, 1981, a series of compatibility
tests were run between pairs of individuals taken one each from the
two halves and allowed to encounter one another in fingerbowls, as
described earlier. These demonstrated only very limited incompati-
bility, as reported earlier (Haskins and Haskins, 1979), and sug-
gested that diet, though possibly a measurable influence, was almost
certainly not a critical factor in mediating compatibility as charac-
terized in this test procedure.

Individual pair-tests after isolation on the same diets

On November 1 1, 1981 a further separation of the population was
made by dividing Moiety B into two, designated B' and B'\ and
continuing to maintain both on the identical diets of mealworms
and sugar water, and continuing with no worker interchange or
communication between them. They were held in this manner for a
further year. Then, on November 15, 1982, fifty pair-tests were run
between Moieties B' and B". In all but two of these pairs, full
compatibility was exhibited in the fingerbowl trials. The same tests
run the next day, November 16, between members of one of the pair
of moieties maintained on the same diets {B' and B"), and the first
moiety. A, still maintained on crickets and sugar water, showed

' In /?. metallica reproduction occurs exclusively through fertilized ergatogynes which
may make up from 5% to as much as 15% of the colony population and are morpho-
logically indistinguishable from unfertilized sister workers. Thus reproduction is
continuous and self-sustaining. Colonies are thus characteristically highly polygy-
nous, and may persist nearly indefinitely under laboratory conditions. “True”
females, fully winged and otherwise morphologically typical, can also be produced
(and frequently were in the present population) but they seem to be without repro-
ductive function, soon dealating themselves, functioning briefly as workers, and
dying in a short time.

1983]

Haskins & Haskins — Rhyticloponera mefai/ica

165

results generally confirmatory of those reported earlier, though with
somewhat higher levels of aggression than the year before. Thus, of
fifty-one pairs tested, 37 showed full compatibility, 8 exhibited
“startle” reactions, in 2 cases there was momentary seizure with
immediate release, and in 4 cases there was violent attack. Thus
noncompatibility between the members of Moieties B' and B"
maintained for a year separately on the same diets, was virtually
negligible, while that of moiety A and the other pair, maintained on
different diets, was generally confirmatory of earlier findings: signif-
icantly higher but still, after two years of separation, not nearly
comparable with reactions toward the members of another, widely
separated population taken near Sutherland, N.S.W., as earlier
reported. From all these tests it might have been concluded that, as
indicated by pair compatibility encounters, genetic factors were sig-
nificant but were overlain by a measureable diet factor. In fact, the
situation now appears more complex.

Tests with whole nests

On June 27, 1982, a single nest, housing 70-100 workers of the
second moiety {B') (nests consisted of earth-filled Lubbock-type
glass “sandwiches” stacked) was transferred to the arena of the first
moiety {A). The introduced nest was placed as far away as possible
from the stacked A nests in the arena. Arenas used throughout were
fabricated from 5/8 cm. thick transparent polyster sheets glued
together to form lidless boxes of dimensions 59.5 cm. X 44.5 cm. X
18.5 cm. covered with screening set in wooden frames, and lined
with white paper.

The reaction was immediate, violent, and virtually universal.
Massed workers from A entered the introduced B' nest in force, show-
ing unequivocal hostility, seized and dragged out almost the entire B
population, ultimately killing a large fraction of them. The struggle
went on for two days, and resulted in the apparent total occupation
of the B' nest by A workers. Subsequently, this nest was fully incor-
porated into the A colony. Thus the reaction in this experiment was
in dramatic contrast to the very limited aggression shown in the
pair-tests.

It remained to determine whether similar behavior would occur
between moieties B' and B'\ which had been maintained on the
same diets and, as described, had exhibited nearly complete compat-
ibility in the pair-tests.

166

Psyche

[Vol. 90

At 2:03 p.m. on November 15, 1982 a nest of moiety B' was
transferred to the arena of moiety B" immediately following the
B'-B" pair-tests described above (workers of B' and B" which had
been used in the pair-tests were not returned to their respective
arenas until after the nest-transfer experiment was complete).
Again, in the most conspicuous contrast to the experience in B'-B"'
pair-tests, but in the same pattern as the reaction when the nest of B'
was introduced to A, immediate mass hostility was exhibited
between the two fragments. Eight minutes after introduction it had
become general, with many interlocked pairs. By 6:55 p.m. pairs
“clinched” and stinging were still present within the introduced B'
nest, and disturbed young males present in that nest were emerging
prematurely. This condition persisted until the following day, by
which time it appeared that occupation of the B' colony by
members of the B" moiety had been completed, and things settled
down, leaving many dead workers in the arena.

It therefore became clear that previous dietary history was not a
dominant factor in mediating the mass hostility so conspicuous
between A and B on the one hand and B' and F' on the other. It
remained to test whether it was in fact the presence of the “foreign”
nest with its soil that triggered the mass incompatibility or simply
the introduction of many alien workers at one time near the home
“site” — a “mass” effect of numbers on the one hand or the possible
influence of a familiar site for the test, rather than fingerbowls, on
the other. To check this, at 8:00 a.m. on November 18, 1982 ten
workers of B' were introduced together into the B" arena, being
placed close to the entrances of the B'' stack of nests. Reactions were
completely compatible until 8:25, when two of the introduced
workers were seen being dragged about. This continued for the next
five minutes, when one was released, the other being freed by 8:30.
There was then entire quiet and apparent compatibility until 3:15
p.m., with no further aggression except that a single worker (living
and uninjured) was being dragged about the arena at 12:00 noon of
the following day. The remaining nine were apparently “adopted”.

Simultaneously with this experiment, the reciprocal transfer was
carried out. (10 workers of B" introduced into the B' arena, near the
entrances to the B' nests). The experiment was begun at 8:10 a.m.
Here also there was complete compatibility, except for two workers
seen dragged out of a nest entrance at 3:15 p.m., as observations

1983]

Haskins & Haskins — Rhyticioponera nieta/lica

167

Tabu; 1

A. 10 WORKERS OF GROUP B' INTRODUCED CLOSE TO THE NEST ENTRANCE OF GROUP B"