A. S. (Alpheus Spring) Packard.

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

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usual, and clavate. There are two or three
subcpstal cells, the second very small. Mi-
crogaster nephoptericis (Plate 3, figs. 3, 3 a) is
parasitic on Nephopteryx Edmandsii, found in
the cells of the Humble-bee.

Aphidius, the parasite of the Plant-lice, is
a most valuable ally of man. It is known by
its small size, and by having the second and
third segments of the abdomen moving free on
Fig. 132. each other. There are three cubital cells, though

the wings are sometimes wanting. Aphidius (Praon) avena-
pliis of Fitch, the Oat-louse Aphidius, is black with honey-
yellow legs, and is one-tenth of an inch long. Aphidius
(Toxares) triticaphis Fitch, the Wheat-louse Aphidius, is black,
shining, with thread-like antennae composed of twenty-five
joints. Its length is .08 inch. Frequently the large size of
the parasite causes the body of the dead Aphis to swell out
into a globular form.

PROCTOTRYPID^E (Proctotrupii) Latreille. Egg-parasites.
In this family are placed very minute species of parasitic Ich-
neumon-like Hymenopters which have rather long and slender
bodies, with straight or elbowed antennae of various lengths,
often haired on the joints, usually ten to fifteen, sometimes only
eight in number, while the wings are covered with minute hairs
and most of the nervures are absent. The maxillary palpi are
three to six, the labial palpi usually three-jointed. The abdo-
men has from five to seven joints, and the tarsi are mostly five-
jointed, rarely four -jointed. These insects are often so minute
that they can scarcely be distinguished by the naked eye unless
it is specially trained ; they are black or brown, and very
active in their habits. They may be swept off grass and
herbage, from aquatic plants, or from hot sand-banks. They


prey on the wheat-flies by inserting their eggs in their larvae,
on gall-midges, and gall-flies, and on fungus-eating flies. In
Europe, species of Teleas lay their eggs in those of other
insects, especially butterflies and moths and licrnipters, where
they feed on the juices of the larvae growing within the egg,
coming out as perfect Ichneumons. We probably have many
species of these insects in this country. They usually occur in
great numbers where they are found at all. They are almost
too small to pin, and if transfixed would be unfit for stud}-,
and should, therefore, be gummed on mica, or put into small
vials with alcohol.

In Proctotrupes the antennae are long, feathered, twelve-
jointed. The fore-wings have the beginning of a cubital cell,
and two longitudinal veins on the posterior half. The abdo-
men is spindle-shaped and very acutely pointed, the terminal
joints being tubular in their arrangement,
and thus, as West wood states, approaching
the CJirysididce. An unknown species
(Fig. 133) we have taken at the Glen, in
the White Mountains.

The head of Diapria is horizontal and Fig. 133.

longer than broad ; the ocelli are moved forward on to the
front edge ; the long, filiform antennae have a projection on
the under side, with the basal joint much elongated ; in the
male they are thirteen or fourteen-jointed, with one joint less
in the female. The wings are without stigma or veins. The
abdomen is long, oval, pedicelled. In Europe, D. cecidomyi-
arum Bouche is parasitic on the larvae of Cecidomyia arte-
misiju. Esenbeck considers that this genus is also parasitic on
the earth-inhabiting Tipulidce.

Gonatopus is a wingless genus, with the head very broad,
transverse, and the front deeply hollowed out, while the ten-
jointed antennae are long, slightly clavate, and the thorax is
much elongated, deeply incised, forming two knot-like portions.
Gonatitjxix h niatus Esenbeck, found in Europe, is one and a
half lines long.

Ceraphron has the antennae inserted near the mouth ; they
are elbowed, and eleven-jointed in the male, and ten-jointed in
the female. The abdomen has a very short pedicel. The fore-


wings have a very short, bent costal (radial) vein. C. arma-
turn Say was described from Indiana.

The egg-parasite, Teleas, has the elbowed twelve-jointed an-
tennae inserted very near the front of the head, and slightly
hairy and simple in the male, but in the female terminated in a
six-jointed club. The thorax is short, the legs thickened and
adapted for leaping, and the abdomen is pedicelled. Many
species have been found in Europe. According to Westwood,
"the type of this genus is the Ichneumon ovulorum of Linnaeus
(Teleas Linnwi Esenbeck), which Linnaeus and
De G-eer obtained from the eggs of moths." It
has been raised from the eggs of several Bom-
b yd dee. "Bouche observed the female deposit
rig. 134. an e gg i n each O f ^ ne e gg s of a b roo( i o f Bom-

byx neustria. He describes the larva as elliptical, white,
shining, rugose, subincurved, and one-third of an inch long."

Of the extensive genus Platygaster over a hundred European
species are already known. The body, especially the abdomen,
is generally flattened, the antennae are ten-jointed, and in the
female clavate. The wing veins are absent ; the rather slender
legs are not adapted for leaping, and the tarsi are five-jointed.
A species of Platygaster (Fig. 134) not yet named, oviposits
in the eggs of the Canker-worm moth, Anisopteryx vernata,
and by its numbers does much to check the increase of this
caterpillar. We have seen several of these minute insects
engaged in inserting their eggs into those of the Canker-

Dr. Harris, in speaking of the enemies of the Hessian-fly,
states, that "two more parasites, which Mr. Herrick has not
yet described, also destroy the Hessian-fly, while the latter is
in the flax-seed or pupa state. Mr. Herrick says, that the egg-
parasite of the Hessian-fly is a species of Platygaster, that it is
very abundant in the autumn, when it lays its own eggs, four
or five together, in a single egg of the Hessian-fly. This, it
appears, does not prevent the latter from hatching, but the
maggot of the Hessian-fly is unable to go through its trans-
formations, and dies after taking on the flax-seed form. Mean-
while its intestine foes are hatched, come to their growth, spin


themselves little brown cocoons within the skin of their victim,
and in due time, are changed to winged insects, and cat their
way out." P. error Fitch (Fig. 135) is closely allied to P.
tijHtht'. Kirby, which, in Europe, destroys great numbers of the
Y\ 'heat-midge. Whether this is a parasite of the midge, or
not, Dr. Fitch has not yet determined.

The habits of the genus Betliylus remind us of the fossorial
wasps, lictlujlus fusticornis, according to Haliday, "buries
the larvae .of some species of Tinea, which feed upon the low
tufts of Rosa spinosissima, dragging them to a considerable
distance with great labor and solicitude, and employing, in the
instance recorded by Mr. Haliday, the bore of a reed stuck in
the ground instead of an arti-
ficial funnel, for the cells which
should contain the progeny of
the Betliylus, with its store of
provision." (AVestwood.)

The genus Inostemma is re-
markable for having the basal
segment of the abdomen of the
females furnished with a thick Fig. 135.

curved horn, which extends over the back of the thorax and
head. Dr. Fitch states that /. inserens is supposed by Kirby to
insert its eggs into those of the Wheat-midge. In the genus
(I'lilcaus of Curtis, the mandibles are so enlarged and length-
ened as to form a long beak, and Westwood farther states that
iu some specimens the anterior wings have a notch at the ex-
ti'i'iiiity. Say's genus Coptera has similar wings. C. polita
Say was discovered in Indiana.

In the very minute species of My mar and its allies, the head
is transverse, with the antennae inserted above the middle of
the face ; they are long and slender and elbowed in the male,
but clavate in the female. There are no palpi, while the very
narrow wings have a very short subcostal vein and on the
cilices arc provided with long dense ciliae. The antennae of
Mymar are thirteen-jointed in the male, and nine-jointed in the
female; the club is not jointed. The tarsi are four-jointed,
and the abdomen is pedunculated. J//////"/- /^/A7^V///.s Curtis
is a quarter of a line long. It is found in Europe. An allied


form Polynema ovulorum Linn, lays numerous eggs in a single
butterfly's egg.

In Anaphes the male antennae are twelve-jointed, those of
the female nine-jointed, and the abdomen is subsessile and
ovoid. In Anagrus the male antennae are thirteen-jointed,
those of the female nine-jointed, while the tarsi are four-jointed,
and the acutely conical abdomen is sessile. No native species
are known.

The smallest Hymenopterous insect known, if not the most
minute of all insects, is the Pteratomus Putnamii Pack. (Plate
3, figs. 8, 8 a, hind wing), which we first discovered on the
body of an Anthophorabia in the minute eggs of which it is
undoubtedly parasitic. It differs from Anagrus in the obtusely
conical abdomen, and the narrower, very linear wings, which
are edged with a fringe of long, curved hairs, giving them a
graceful, feathery appearance. The fore-wings are fissured,
a very interesting fact, since it shows the tendenc} 7 of the
wings of a low Hymenopterous insect to be fissured like
those of Pterophorus and Alucita, the two lowest Lepidop-
terous genera. It is one-ninetieth of an inch in length.

CHALCIDID^E Westwood. This is a group of great extent ;
the species are of small size ; they are often of shiny colors, as
the name of the principal genus implies, being either bronzen
or metallic. They have also elbowed antennae with from six
to fourteen joints, and the wings are often deficient in veins.
In some genera, including Chalcis, the hind thighs are thickened
for leaping. The differences between the sexes, generally very
marked in Hymenoptera, are here especially so. The abdo-
men is usually seven-jointed in the male and six-jointed in the
female, the other rings being aborted. The male of several
species has the joints of the antennae swelled and furnished with
long hairs above. Some of the species of Pteromalus are wing-
less, and closely resemble ants. They infest eggs and larvae.
Some species prey upon the Aphides, others lay their eggs in
the nests of wasps and bees. One species is known in Europe
to be a parasite of the common house-fly. Others consume
the larvae of the Hessian-fly, and those Cecidomyiae that pro-
duce galls, and also the true gall-flies (Cynips). Some are



parasites on other Ichneumon parasites, as there are species
proving on the genus Aphidius, which is a parasite on the
Aphis. Mr. Walsh has bred a species of Hockeria and of
(ilyphc. which are parasitic on a Microgaster, which in turn
preys upon the Army-worm, Leucania unipuncta ; and Chalcis
albifrons Walsh, was bred from the cocoons of Pezomachus, an
Ichneumon parasite of the same caterpillar.

The pupae of some species are said to hare the limbs and
wings soldered together as in Lepidoptera, and the larvae sel-
dom spin a silken compact cocoon. We have
probably in this country at least a thousand
species of these small parasites, nearly twelve
hundred having been named and described in
Europe alone. They are generally large enough
to be pinned or stuck upon cards or mica ; some
individuals should be preserved in this way,
others, as wet specimens. Fig. 136.

Chalcis is known by the abdomen having a long pedicel, its
much thickened, oval thighs, and curved tibia?. Clialds bra-
cata (Fig. 136), so named by Mr. Sanborn "in allusion to the
ornamental and trousered appearance of the posterior feet"
is about .32 inch in length. "Reaumur has described and
figured a species of Chalcis, which is parasitic in the nest of
the American wasp Epipone nitidulans and which he regarded
as the female of that wasp." (Westwood.)

The genus Leucospis is of large size. It is known by having
the largo ovipositor laid upon the upper surface of the abdo-
men, and being spotted and banded with
yellow, resembling wasps. One of our more
common species is the L. affinis (Fig. 137) of
Say. The Cuban L. Poeyi Guerin is para-
sitic on the Megachile Poeyi of Guerin.

The well-known . Joint-worm, Eurytoma,
is thought by many to produce galls on
The antenna? are, in the male, slender and pro-
vided with verticils of hairs. The acutely oval abdomen has
a short pedicel. The hind legs are scarcely thicker than the
fore limbs. E. hordei Harris (Fig. 138) is found in gall-like
swellings of wheat-stalks. It is still a matter of discussion,

Fig. 137.



whether it directly produces the galls, or is parasitic, like
many of the family, on other gall-insects. Dr. Harris, who has
studied the habits of the Joint-worm, states that the body of
the adult fly is jet black, and that the thighs, shanks (tibiae),
and claw-joints, are blackish, while the knees and other joints
of the feet, are pale^ellow. The females are .13 inch long,
while the males are smaller, have a club-shaped abdomen, and
the joints of the antennae surrounded with a verticil of hairs.
The larva is described by Harris from specimens received from
Virginia, as varying from one-tenth to nearly three-twentieths
of an inch in length. It is of a pale yellowish white color,
with an internal dusky streak, and is destitute of hairs. The
head is round and partially retractile, with a distinct pair of
jaws, and can be distinguished from the larvae of the dipterous
gall-flies by not having the v-shaped organs on the segment
succeeding the head. During the sum-
mer, according to Mr. Gourgas's observa-
tions reported by Dr. Harris, and when
the barley or wheat is about eight or ten
inches high, the presence of the young
Joint-worms is detected "by a sudden
rig. 138. check in the growth of the plants, and

the yellow color of their leaves," and several irregular gall-
like swellings between the second and third joints, or, accord-
ing to Dr. Fitch, " immediately above the lower joint in the
sheathing base of the leaf;" or, as Harris states, in the joint
itself. The ravages of this insect have been noticed in wheat
and barley. During November, in New England, the worms
transform into the pupa state, according to the observations of
Dr. A. Nichols, and "live through the winter unchanged in
the straw, many of them in the stubble in the field, while others
are carried away when the grain is harvested." In Virginia,
however, the larva does not transform until late in February,
or early in March, according to Mr. Glover. From early in
May, until the first week in July, the four-winged flies issue
from the galls in the dry stubble, and are supposed to im-
mediately lay their eggs in the stalks of the young wheat or
barley .plants. The losses by this insect has amounted, in
Virginia, to over a third of the whole crop. The best remedy


against the attacks of this insidious foe, is to burn the stubble
in the autumn or spring for several successive years. Plough-
ing in the stubble does not injure the insects, as they can
work their way out of the earth.

It has been objected by Westwood, Ratzburg, and more
recently by Mr. Walsh, in the Practical Entomologist, vol. i,
that as all the species of this family, so far as known, are para-
si tic. the Eurytoma cannot be a gall-producer, and that the
galls are made by a dipterous insect (Cecidomyia) on which
the Euiytoma is a parasite ; but, as they offer no new facts to
support this opinion, we are inclined to believe from the
statements of Harris, Fitch, Cabell, T. Glover (Patent Office
Report for 1854), and others, that the larva of the Eurytoma
produces the gall. We must remember that the habits of
comparatively few species of this immense family have been
studied ; that the genus Eurytoma is not remotely allied to
the Cynipidse, or true gall-flies (which also comprise animal
parasites) , in which group it has actually been placed by Esen-
beck, for the reason that in Europe "several species of
Euiytoma have been observed to be attached to different
kinds of galls." (Westwood.) Dr. Fitch also describes the
Yellow-legged Barley-fly, Eurytoma flcwipes, which produces
similar galls in barley, and differs from the Wheat Joint- worm
in having yellow legs, while the antennae of the male are not
surrounded with whorls of hair. The Eurytoma secalis Fitch
infests rye. It differs from E. hordei in ' ' having the hind pair
of shanks dull pale-yellow, as well as the forward ones." We
shall also see beyond that several species of Saw-flies produce
true galls, while other species of the same genus are external
feeders, which reconciles us more easily to the theory that the
Euiytoma hordei, and the other species described by Dr. Fitch,
differ in their habits from others of the family, and are not ani-
mal parasites. Indeed the Joint-worm is preyed upon by two
Chalcid parasites, for Harris records finding the larvae, proba-
bly of Torymus, feeding on the Eurytoma larvse, and that a
species of Torymus (named T. Harrisii, by Dr. Fitch, and per-
haps the adult of the first-named Torymus) and a species of
Pteromalus are parasites on Eurytoma.

In Monodontomerus (Torymus) the third joint of the an-



tennae is minute, and the hind femora are thick, but not ser-
rated, and beneath armed with a tooth near the tip.

The wings are rudimentary so that it does not quit the cell.
Newport states that the larva is flat, very hairy, and spins a
silken cocoon when about to pupate. It is an "external feed-
ing parasite" consuming the pupa as well as the larva of An-
thophorabia. The imago appears about the last of June,
perforating the cell of the bee. It also lives in the nests of
Osmia, Anthophora, and Odynerus.

The genus Antlwpliorabia is so-called from being a parasite on
Anthophora. The males differ remarkably from the females,
especially in having simple instead of compound eyes, besides
the usual three ocelli. A. megachilis Pack. (Plate 4 ; fig. 7,
larva ; 7 a, pupa) is a parasite on a species of Megachile.
The larva is white, short and thick, cylindrical, with both
extremities much alike ; the segments are slightly convex, and
the terminal ring is orbicular and rather large. Length, .04
inch, being one-third as broad as long. On opening the cells
of Megachile, we found nearly a dozen containing these para-
sites, of which 150 larvae were counted clustering on the out-
side of a dead and dry Megachile larva. In England they
occur, according to Newport's observations, in much less num-
bers, as he found from thirty to fifty in a cell of Anthophora.
A few females hatched out in the middle of October, and there
were a few pupae left, but the majority wintered over in the
larva state, and a new and larger brood appeared in the spring.

Perilampus is a beautiful genus, with its shining, metallic
tints. The eleven-jointed antennae are short, lying when at
rest in a deep frontal furrow. The head is large, while the
abdomen is slightly pedicelled, being short, contracted, with
the ovipositor concealed. P. platygaster Say and P. triangu -
laris Say were described from Indiana.

The numerous species of Pteromalus often oviposit in the
larvae of butterflies. In this genus the antennae are inserted
in the middle of the front. The abdomen is nearly sessile, ob-
tusely triangular, or acutely ovate in form, with the ovipositor
concealed. The femora are slender. There are about three
hundred species known to inhabit Europe. Pteromalus va-
nessce Harris is a parasite on Vanessa Antiopa. P. clisio-



Fig. 139.

campcc Harris infests Clisiocampa. "Pteromalus apum is

parasitic in the nests of the Mason-bee." (Westwood.) A spe-

cies of this or an allied genus (Fig. 139)

infests the eggs of the Clisiocampa Ameri-

cana. Its eggs are probably laid within

thpse of the Tent-caterpillar moth early

in the summer, hatching out in the autumn,

and late in the spring or early in June.
An allied genus, Siplionura, is a para-

site on galls. It resembles a beetle, Mor-

della, from its very peculiar scutum.

The antennae of Semiotellus are twelve-jointed. S. (Ceraph-

ron) destructor Say (Fig. 140), according to that author,

destroys the Hessian-fly, while lying
in the "flax-seed" state. Fitch de-
scribes it as being a tenth of an
inch long, black, with a brassy
green reflection on the head and
thorax, while the legs and base of
the abdomen are yellowish.

In Encyrtus, which comprises
over a hundred species already
known, usually rather small in
size, the body is short and rounded.

The eleven-jointed antennae are inserted near the mouth. The

thorax is square behind, and the sessile abdomen is short and

broad at the base. Encyrtus Bolus

and E. Reate are described from

North America by Mr. F. Walker.

Encyrtus varicornis is in Europe

found as a parasite in the cells of

Eumenes coarctata.

The antennae of Euloplius are nine- F5g . 141>

jointed, with a long branch attached to the third, fourth, and

fifth joints. The abdomen is flattened, sessile. E. basalts

Say was described from Indiana. We figure a Chalcid (Fig.

141, #), allied to Eulopus, which preys upon the American

Tent Caterpillar.

A species of Blastophaga (B. grossorum Grav.) is interest-

ing as it is the means of assisting in the fertilization of the Fig

14 -


blossoms, which act, as applied to this instance of the fertiliza-
tion of flowering plants by insects, has been called by Mr.
Westwood " caprification."

Westwood. (Diploleparice Latreille.) Gall-flies.
In this most interesting family we have a singular combination
of zoological and biological characters. The gall-flies are closely
allied to the parasitic Chalcids, but in their habits are plane-
parasites, as they live in a gall or tumor formed ~by the ab-
normal growth of the vegetable cells, due to the irritation first
excited when the egg is laid in the bark, or substance of the leaf,
as the case may be. The generation of the summer broods is
also anomalous, but the parthenogenesis that occurs in these
forms, by which immense numbers of females are produced, is
necessary for the work they perform in the economy of nature.
When we see a single oak hung with countless galls, the work
of a single species, and learn how numerous are its natural


Fig. 142

enemies, it becomes evident that the demand for a great nu-
merical increase must be met by extraordinary means, like the
generation of the summer broods of the Plant-lice.

The gall-flies are readily recognized by their resemblance to
certain Chalcids, but the abdomen is much compressed, and
usually very short, while the second, or the second and third seg-
ments, are greatly developed, the remaining ones being imbri-
cated or covered one by the other, leaving the hind edges
exposed. Concealed within these, is the long, partially coiled,
very slender ovipositor, which arises near the base of the abdo-
men.* Among other distinguishing characters, are the straight

* Fig. 142. I, abdomen of Cynips quercus-aciculata Osten Saoken, with the ovipos-
itor exserted ; II, the same with the ovipositor retracted; III, the abdomen of the
female of Fiyitcs (Diplolepis) b-lineatus Say; IV, the same showing the ventral
portion, in nature covered by the tergal portion of the abdomen ; V, end view of the


(not being elbowed) thirteen to sixteen- jointed antenna?, the
labial palpi being from two to four-jointed, and the maxil-
la IT palpi from four to six-jointed. The maxillary lobes are
broad and membranous, while the ligula is fleshy, and either
rounded or square at the end. There is a complete costal cell,
while* the subcostal cells are incomplete. The egg is of large
size, and increases in size as the embryo becomes more devel-
oped. The larva is a short, thick, fleshy, footless grub, with
the segments of the body rather convex. When hatched they
immediately attack the interior of the gall, which has already
formed around them. Many species transform within the gall,
while others enter the earth and there become pupse.

It is well known that of many gall-flies the males have never
been discovered. "Hartig says that he examined at least
15,000 specimens of the genus Cynips, as limited by him, with-
out ever discovering a male. To the same purpose he collected
about 28,000 galls of Cynips divisa, and reared 9,000 to 10,000
Cynips from them ; all were females. Of C. folii, likewise, he
had thousands of specimens of the female sex without a single

Online LibraryA. S. (Alpheus Spring) PackardGuide 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 text (page 19 of 29)