Guide to the study of insects, and a treatise on those injurious and beneficial to crops: for the use of colleges, farm-schools, and agriculturists online

Lincecum avers that the ants even sow this grain. They also
store up the "grain from several other species of grass, as
w r ell as seeds from many kinds of herbaceous plants."

Plieidole is distinguished by having workers with enormous
heads. P. notabilis Smith, from the Island of Bachian, Indian
Archipelago, is noted for the enormously enlarged, cubical
head of the worker major, w r hich is at least six times the size
of the abdomen, while in the worker minor, the head is of
the ordinary size. An Indian species, P. providens Westwood,
according to Col. Sykes, "collects so large a store of grass
seeds as to last from January and February, the time of
their ripening, till October."

The genus Atta is also well-armed, while the workers have
a very large, deeply incised and heurt->luii>ed head, without



186



HYMENOPTEEA,




ocelli, and the second abdominal knot-like ring is very trans-
verse. A. clypeata Smith is a Mexican species.

In Eciton the man-
dibles nearly equal
the length of the in-
sect itself. This ge-
nus is the most
ferocious of all the
ants, entering the nest
of species of Formica
and tearing them,
limb from limb, and
then carrying off the
remains to their own
houses.

Eciton Mexicana
Roger (Fig. 114,
worker major, a, front
view of head, show-
Fig- 11*- ing the immense
sickle-like mandibles, and only the two basal joints of the
antennae; Fig. 115, worker minor, with a front view of the
head, showing the mandi-
bles of the usual size).
This species, with Eciton
Sumiclirasti Norton, (Fig.
116, worker minor) has
been found by Professor
Sumichrast at Cordova and
Orizaba, Mexico.

The males of Eciton are
not yet known. Smith
supposes that Labidus (a
genus allied to Dorylus) is
the male form, and Sumi-
chrast thinks this conjec-
ture is "sustained by the rig. 115.
fact that it is in the season when the sorties of the Eciton
are the more frequent that the Labidus also show themselves."




FORMICARIES.



187




An allied genus is Pseudomyrma. P. bicolor Guerin (Fig.
117) is found in Central America. P.flacidtda Smith, found in
Central and South America, in Mexico lives, according to
Sumichrast, within the spines which arm the
stems of certain species of Mimosa. These
spines, fixed in pairs upon the branches, are
pierced near the end by a hole (Fig. 118 a),
which serves for the entrance and exit of the
ants.

The genus (Ecodoma differs from Atta in
having the thorax armed with spines. (E. Fig. HG.

Jh'.i'ii-'.nnt, Smith (Figs. 119, female ;' 120, worker major) is
abundant on the Gulf Coast of Mexico. In many places, ac-
cording to Sumichrast, the natives eat the females after hav-
ing detached the thorax. The intelligence of these
ants is wonderful. They are seen in immense num-
bers transporting leaves. Sumichrast states that
"the ground at the foot of the tree, where a troop of
these 'am'eras,' or workers,. is assembled for despoil-
ing it of its leaves, is ordinarily strewn with frag-
ments cut off with the greatest precision. And if the
Fig. 117. tree is not too lofty, one can satisfy himcelf that a
party of foragers, which have climbed the tree, occupies itself
wholly in the labor of cutting them off, while at the foot of
the tree are the carrier^ which make the journeys between the
tree and the nest. This manage-
ment, which indicates among these a
insects a rare degree of intelligence,
is, perhaps, not a constant and in-
variable practice, but it is an incon-
testabie fact, and one which can be
constantly proved."

"It is specially in the argillaceous
countries that the CEcodomas build
their enormous formicaries, so that
one perceives them from afar by the Fig. us.

projection which they form above the level of the soil, as
well as by the absence of vegetation in th: ir immediate
neighborhood. These nests occupy a surface of many square






188 HYMENOPTERA.

metres,* and their depth varies from one to two metres.
Very many openings, of a diameter of about one to three in-
ches, are contrived from the exterior, and conduct to the inner
cavities which serve as storehouses for the eggs and larvae.
The central part of the nest forms a sort of funnel, designed
for the drainage of water, from which, in a country where
the periodical rains are often abundant, they could hardly es-
cape without be-
ing entirely sub-
merged, if they
did not provide
for it some out-
let.

"The system
which reigns in
Fig. 119. the interior of

these formicaries is extreme. The collection of vegetable
debris brought in by the workers is at times considerable ;
but it is deposited there in such a manner as not to cause any
inconvenience to the inhabitants, nor impede their circulation.
It is mostly leaves which are brought in from without, and it
is the almost exclusive choice of this kind of vegetation which
makes the (Ecodoma a veritable scourge to agriculture. At
each step, and in almost every place in the
elevated woods, as on the plains ; in desert
places as well as in the neighborhood of
habitations, one meets numerous columns
of these insects, occupied with an admirable
zeal in the transportation of leaves. It
seems even that the great law of the divi-
120. sion of labor is not ignored by these- little

creatures, judging from the observations which I have often
had occasion to make." (Sumichrast.)

"The (E. ccpJialotcs" says II. W. Bates, "from its immense
numbers, eternal industry, and its plundering propensities, be-
comes one of the most important animals of Brazil. Its immense
hosts are unceasingly occupied in defoliating trees, and those
most relished by them are precisely the useful kinds. They

* A metre is about thirty -nine (39.37) inches.




FORMICARY. 189

have regular divisions of laborers, numbers mounting the trees
and cutting oil' the leaves in irregularly rounded pieces the size
of a shilling, another relay carrying them off as they fall."
"The heavily laden fellows, as they came trooping in, all de-
posited their load in a heap close to the mound. About the
mound itself were a vast number of workers of a smaller size.
The very large-headed ones were not engaged in leaf-cutting,
nor seen in the processions, but were only to be seen on dis-
turbing the nest." Bate j also says, "I found, after removing
a little of the surface, three burrows, each about an inch in
diameter ; half a foot downward, all three united in one tubular
burrow about four inches in diameter. To the bottom of this I
could not reach when 1 probed with a stick to the depth of four
or five feet. This tube was perfectly smooth and covered with
a vast number of workers of much smaller size than those oc-
cupied in conve} T ing the leaves ; they were unmixed with any
of a larger size. Afterwards, on probing lower into the bur-
row, up came, one by one, several gigantic fellows, out of all
proportion, larger than the largest of those outside, and which
I could not have supposed to belong to the same Species. Be-
sides the greatly enlarged size of the head, etc., they have an
ocellus in the middle of tfye forehead ; this latter feature, added
to their startling appearance from the cavernous depths of the
formicarium, gave them quite a Cyclopean character."

Of another species, the (Ec. sexdentata, Mr. Smith quotes
from Rev. Hamlet Clark, that at Constancia, Brazil, the pro-
prietor of a plantation used every means to exterminate it and
failed. " Sometimes in a single night it will strip an orange or
lemon tree of its leaves ; a ditch of water around his garden,
which quite keeps out all other ants, is of no use. This spe-
cies carries a mine under its bed without any difficulty. In-
deed, I have been assured again and again, by sensible men,
that it has undermined, in its progress through the country, the
great river Paraiba. At any rate, without anything like a nat-
ural or artificial bridge, it appears on the other side and con-
tinues its course." This testimony is confirmed by Mr.
Lincccum (Proceedings of Academy of Xatural Sciences,
Philadelphia, 1867, p. 24) in an interesting account of the (Ec.
Texana, which he has observed for eighteen years. He states



190 HTMENOPTERA.

that they often carry their subterranean roads for several hun-
dred yards in grassy districts, where the grass would prove an
impediment to their progress. On one occasion, to secure ac-
cess to a gentleman's garden, where they were cutting the
vegetables to pieces, they tunnelled beneath a creek, which was
at that place fifteen or twenty feet deep, and from bank to bank
about thirty feet. He also observes that the smaller workers
which remain around the nest do not seem to join in cutting or
carrying the leaves, but are occupied with bringing out the
sand, and generally work in a lazy way, very differently from
the quick, active leaf-cutters. Also, that the piece's of leaves
are usually dried outside before being carried in, and that if
wet by a sudden shower are left to decay without. He also
thinks that their lives are dependent upon access to
water, and that they always choose places where it
is accessible by digging wells. In one case, a well
was dug by Mr. Pearson for his own use, and water
found at the depth of thirty feet. The ant-well
which he followed was twelve inches in diameter."
Fig. 121. (Norton, American Naturalist, vol. 2.)
The genus Cryptoccrus is remarkable for its flattened head,
with the sides expanded into flattened marginal plates, con-
cealing, or partly hiding the eyes. C. multispinosus Norton
(Fig. 121) is the most common species about Cordova, Mexico,
where they live, according to Surnichrast, within the trunks of
trees.

CHRYSIDIDJS Latreille. In this small group the thirteen-
jointed antennae are elbowed, the eyes are oval and the ocelli
distinct. The maxillary palpi are five, and the labial palpi
three-Jointed. There are about four hundred species known.

These insects are very different from the ants in their oblong
compact form, their nearly sessile, oblong abdomen, having only
three to five rings visible, the remaining ones being drawn with-
in, forming a long, large, jointed sting-like ovipositor, which
can be thrust out like a telescope. The abdomen beneath is
concave, and the insect can roll itself into a ball on being dis-
turbed. They are green or black. The sting has no poison-
bag, and in this respect, besides more fundamental characters,




CHRYSIDIDJE. 191

the Chrysis family approaches the Ichneumons. They best
merit the name of "Cuckoo-flies," as they fly and run briskly
in hot sunshine, on posts and trees, darting their ovipositor into
holes in search of the nests of other Hymenoptera, in which to
lay their eggs. Their larvae are the first to hateh and devour
the food stored up by other fossorial bees and wasps. "St.
F:i r^oau, however, who has more carefully examined the econ-
omy of these insects, states that the eggs of the Chrysis does
not hatch until the legitimate inhabitant has attained the greater
part of its growth as a larva, when the larva of the Chrysis
fastens on its back, sucks it, and in a very short time attains
its full size, destroying its victim. It does not form a cocoon,
but remains a long time in the pupa state." (Westwood.)

" In the Entomological Magazine has been noticed the dis-
covery of Hedychrum bidentulum, which appears to be parasitic
upon Psen caliginosus ; the latter insect had formed its cells in
the straws of a thatched arbor, as many as ten or twelve cells
being placed in some of the straws. Some of the straws, per-
haps about one in ten, contained one or rarely two, of the
Hedychrum, placed indiscriminately amongst the others.
"VValkenaer, in his Memoirs upon Halictus, informs us that
Hed3 r chrum lucidulum waits at the mouth of the burrows of
these bees, in order to deposit its eggs therein ; and that when
its design is perceived by the bees, they congregate together
and drive it away. St. Fargeau states that the females of
Hedychrum sometimes deposit their eggs in galls, while II.
regium oviposits in the nest of Megachile muraria ; and he
mentions an instance in which the bee, returning to its nearly
finished cell, laden with pollen paste, found the Hedychrum
in its nest, which it attacked with its jaws ; the parasite im-
mediately, however, rolled itself into a ball, so that the Mega-
chile was unable to hurt it ; it, however, bit off its four wings
which were exposed, rolled it to the ground and then deposited
its load in the cell, and flew away, whereupon the Hedychrum,
now being wingless, had the persevering instinct to crawl up
the wall to the nest, and there quietly deposit its egg, which it
placed between the pollen paste and the wall of the cell, which
prevented the Megachile from seeing it." (Westwood.)

In Cleptes the -underside of the abdomen is not hollowed out ;



192 HYMENOPTERA.

it is acutely oval, and with five -rings in the male. Cleptes
semiaurata Latr. is found in Central Europe. We have no na-
tive species. In Chrysis and the other genera, Stilbum, Parno-
pes, and Iledychrum, the abdomen is hollowed beneath, and
the tip is broad and square. Chrysis hilaris Dahlb. (Fig. 122)
is a short, thick, bluish green species, .32 inch in length. It
is not uncommon in New England.

In Iledychrum the maxillary palpi and ligula are rather short,
the last cordate ; the mandibles are three- toothed within. The
abdomen is broad and short, almost spherical, the second seg-
ment being the largest. H. dimidiatum Say is found in the
Middle States.

The European Stilbum splendidum, Fabr. according to Du-
four, lives in the cells of Pelopaeus spirifex. It makes oblong
cocoons of a deep brown, with rounded
ends ; they are of great tenacity, being
mixed with a gummy matter.

Mr. Guenzius states that in Port
Natal "a species of Stilbum lays its
eggs on the collected caterpillars stored
Fig. 122. up by Eumenes tinctor, which con-

structs a nest of mud and attaches it to reeds, etc., not in a
single, but a large mass, in which cells are excavated, similar
to the nest of Chalicodoma micraria ? * First, it uses its ovi-
positor as a gimlet, and when its point has a little penetrated,
then as a saw or rasp ; it likewise feels with its ovipositor, and,
finding an unfinished or an empty cell it withdraws it immedi-
ately, without laying an egg."

ICHNEUMONID^E Latreille. The Ichneumon-flies are readily
recognized by the usually long and slender body, the long ex-
serted ovipositor, which is often very long, and protected by a
sheath formed of four stylets of the same length as the true
ovipositor. The head is usually rather square, with long,
slender, many-jointed antennae which are not usually elbowed.
The maxillary palpi are five to six-jointed, while the labial

* A query ( ?) after the name of a species indicates a doubt whether the insect
really belongs to that species; so with a ? after the name of a genus. A ? before
both the genus and species expresses a doubt whether that be the insect at all.




ICHNEUMONIDyE . 1 ! ) ; ;

palpi are three to four-jointed. The abdomen is inserted im-
mediately over the hind pair of trochanters, and usually consist >
of seven visible segments. The fore-wings have one to three
subcostal (cubital) cells.

The larva is a soft, fleshy, cylindrical, footless grub, the
rings of the body being moderately convex, and the head rather
smaller than in the foregoing families. The eggs are laid by
the parent either upon the outside or within the caterpillar, or
other larva, on which its young is to feed. "When hatched it
devours the fatty portions of its victim which dies gradually of
exhaustion. The ovipositor of some species is very long, and
is fitted for boring through very dense substances ; thus Mr.
liond, of Kim - l:md, observes that Rliyssa persuasoria actually
bores through solid wood to deposit its eggs in the larvae of
Si rex; the ovipositor is worked into the wood like an awl.
When about to enter the pupa' state the larva spins a cocoon,
consisting in the larger species of an inner dense case, and a
looser, thinner, outer covering, and escapes as a fly through
the skin of the caterpillar. The cocoons of the smaller genera,
such as Cryptus and Microgaster, may be found packed closely
in considerable numbers, side by side, or sometimes placed up-
right within the body of caterpillars.

The Ichneumon-flies are thus very serviceable to the agricul-
turist, as they must annually destroy immense numbers of cat-
erpillars. In Kurope over 2,000 species of this family have
been described, and it is probable that we have an equal num-
ber of species in America ; Gerstaecker estimates that there
are 4,000 to 5,000 known species.

The Ichneumons also prey on certain Coleoptern and Ilymcn-
optera, and even on larva} of Phryganida*, which live in the
water. In Europe, Piinpla Fairmairii is parasitic on a spider,
Clubione holosericea, according to Laboulbenc. Boheman
states that P. ovivora lives on a spider, and species of Pimpla
and Ilemitelcs were also found in a nest of spiders, accord iiur to
( iruvciihorst. IJouchc says that Pimpla rufata devours, during
winter and spring, the eggs of Aranea diadema, and Kat/burg
gives a list of fourteen species of Ichneumons parasitic on
spiders, belonging to the "vncni Pimpla, Pezomachus, Ptero-
malus, Cryptus. Ilemitelcs, Microgaster. and Mesochorus. Mr.
13



194



HYMENOPTERA.




Emerton informs me that he has reared a Pezomachus from
the egg-sac of Attus, whose eggs it undoubtedly devours. They
are not even free from attacks of members of their own family,
as some smaller species are well known to prey on the larger.
Being cut off from communication with the external world,
the Ichneumon larva breathes by means of the two principal

tracheae, which
terminate in the
end of the body,
and are placed,
according to Ger-
staecker, in com-
munication with a
stigma of its host.
From the com-
plete assimilation
of the liquid food,
Fig. 123. the intestine ends

in a cul de sac, as we have seen it in the larvae of Humble-bees
and of Stylops, and as probably occurs in most other larvae
of similar habits, such as young gall-flies, weevils, etc., which
live in cells and do not eat solid food.

The first subfamily, the Evaniidce, are insects of singular and'
very diverse form, in which the antenr.se are either straight or
elbowed, and thirteen to fourteen-
jointed ; the fore-wings have one to
three subcostal (cubital) cells, and the
hind wings are almost without veins.
In Evania and Foenus the abdomen
has a very slender pedicel, originating
next the base of the metanotum. The
former genus has a remarkably short
triangular compressed abdomen in the
female, but ovate in the male. The Fi s-

species are parasitic on Blatta and allies. Evania Icevigata
Olivier (Fig. 123, $ and pupa) is a black species, and is para-
sitic on the cockroach, Periplaneta, from the eggs of which we
have taken the pupa and adult. The eggs of the cockroach are
just large enough to accommodate a single Evania. This species




ICHNEUMONIIXE .



195




is widely distributed, and in Cuba, according to Cresson, it
devours the eggs of Periplaneta Americana.

Tin' genus Autocodes of Cresson, "forms a very close con-
necting-link between the minute Ichneumons and the Evaniae."
A. nigriventris Cresson (Fig. 124, a; 6, metathorax ; c, inser-
tion of the abdomen) lives in Cuba.

Foenus is quite a different genus, as the abdomen is very long
and slender. Foenus jaculator Linn, is known in Europe to
frequent the nests
of Crabronidce,
ovipositing in the
larvae.

Pelednus is a fa-
miliar insect, the im-
mensely elongated,
linear abdomen of
the female easily Fig. 125.

distinguishing it. The male is extremely rare ; its abdomen
is short and clavate. It strikingly resembles Trypoxylon,
though the abdomen is considerably larger. Pelednus poly-
cerator Drury (Fig. 125, $ and ?) is widely distributed
throughout this country.

The genuine Ichneumonidce have long, straight, multiarticu-
late antennae. The first subcostal (cubital) cell of the fore-

wings is united with the median
cell lying next to it, while the
second is very small or wholly
wanting. There are two recurrent
veins. Mr. Cresson has described
the genus Eiphosoma (Fig. 126),
Fig. 126. which he states may be known by

the long, slender, compressed abdomen, and the long posterior
legs, with their femora toothed beneath the tips. E. annu-
latum Cresson, a Cuban species, is, according to Poey, "para-
sitic upon a larva of Pyralis." (Cresson.)

In Opliion the antennae are as long as the body, the abdo-
men is compressed, and the species are honey-yellow in color.
0. macrurum Linn. (Fig. 127) attacks the American Silk-
worm, Telea Polyphemus. Anomalon is a larger insect and
usually black. A. vesparum is, in Europe, parasitic on Vespa.




196



HYMENOPTEEA.




The genus Rliyssa contains our largest species, and frequents
the holes of boring insects in the trunks of trees, inserting its

remarkably long ovipositor
in the body of the larvae
deeply embedded in the
trunk of the tree. Harris
states that Rliyssa (Pimpla)
atrata and lunator (Fig. 128,
male) of Fabricius, "may
frequently be seen thrusting
their slender borers, measur-
ing from three to four in-
ches in length, into the
trunks of trees inhabited
~by the grubs of the Tre-
mex, and by other wood-
Fi s- 127 - eating insects ; and, like

the female Tremex^ they sometimes become fastened to the
trees, and die without being able to draw their borers out
again." The abdomen of the male is very slender.

Pimpla has the ovipositor half as long as the abdomen. P.
pedalis Cresson is a parasite on Clisiocampa.

The genus Trogus leads to Ichneumon. The antennae are
shorter than the body ; the abdomen is slightly petiolate, fusi-
form, and the second subcostal cell
is quadrangular. Trogus exesorius
Brulle is tawny red, and is a para-
site of Papilio Asterias.

The genus Ichneumon (Fig. 129)
is one of great extent, probably
containing over three hundred spe-
cies. The abdomen is long and
slender, lanceolate ovate, slightly
.petiolate. The second subcostal cell
is five-sided, and .the ovipositor is
either concealed or slightly exserted.
Ichneumon suturalis Say is a very common form, and has been
reared in abundance from the larva of the Army- worm, Leu-
cania unipuncta. The body is pale rust-red, with black sutures
on the thorax. Another common species, also parasitic on the




128.



lOHNEUMONnxffl.



197




Army- worm, is the Ichneumon paratus, which is black i>h,
banded and spotted with yellow.

Tlie singular genus Grotea, established by Mr. Cresson, has
along and narrow thorax (Fig. 130 a), and a very long and
petiolated abdomen (c). We have
lake u (Y. <ntynina Cresson, the only
species known, from the cells of
C'nibro in raspberry stems received
from Mr. Angus.

Cryptus is a genus of slender
form, with a long, cylindrical abdo-
men, which is petiolate. In the fe-
male it is oval with an exserted
ovipositor. Cresson figures a wing

(Fig. 131) of CJ ornatipennis, a Cuban species, which has the
wind's differently veined from the other species. Westwood
remarks that in Europe a species of this genus preys on the
larvae of the Ptinidce.

Pezomachus is usually wingless, and might at first sight read-
ily be mistaken for an ant. The body is small, the oval abdo-
men petiolate, and the wings, when pres-
ent, are very small. The species are very
numerous. Gerstascker suggests that
some may be wingless females, belong-
ing to winged males of allied genera.

The third subfamily is the Braconidce, containing those
genera having long multiarticulate antennae, and with the first
subcostal cell separate from the first median, lying just behind
it. The second subcostal cell is usually
large, and there is only one recurrent vein.

The genus Bracon is distinguished by the
deeply excavated clypeus. The first sub-
costal cell is completely formed behind,
wanting the recurrent nerve ; the second cell
is long, and four-sided. More than five
hundred species, mostly of bright, gay
colors, arc already known. The genus Rlwpalosoma of Cres-
son connects Bracon and other minute genera (Braconidae)
with the true Ichneumons. R. Poeyi Cresson (Fig. 132) is a




Fig. 131.





198 HYMENOPTEEA.

pale honey-yellow species, with a long club-shaped abdomen.
It lives in Cuba.

Rogas is a genus differing from Bracon in having the three
first abdominal rings long, forming a slender petiole.

In Microgaster, a genus containing numerous species, the
antennae are eighteen-jointed, and the abdomen is shorter than