The insects of this order, including Bees, Wasps, Ants, Ichneumon-flies,
Gall-flies, Saw-flies, and allied insects have always been of unusual
interest both to entomologists and non-entomologists on account of their
diversified and peculiar habits. In abundance of species they exceed
perhaps even the Coleoptera. In general they are day fliers and always
to be found in abundance on bright days about flowers. The best season
for collecting is in early spring, on the bloom of the Willow, Alder,
and other trees. They may also be found at any season of the year, but
the males of many species are only to be taken in fall. In this order,
species of many groups can be most easily obtained by breeding. This
includes the gall-making family, Cynipidae, and the parasitic families
Chalcididae, Proctotrypidae, Ichneumonidae and Braconidae. The Chrysididae
and certain other less important families are also parasitic, but are
more easily obtained by general collecting. The implements necessary for
collecting Hymenoptera are the sweeping-net and the beating-net. Many
rare forms of the smaller parasitic families may be obtained by sweeping
the grass and foliage of all sorts. The Proctotrypidae may be collected
in quantity by sifting leaves and rubbish collected in the woods. Mr.
William H. Ashmead, who has made an especial study of this group, finds
winter sifting profitable. Dried leaves and rubbish are sifted, the
finer portion being retained and transferred to a bag. When a sufficient
quantity is collected it is removed to a warm room. Many hibernating
species are taken in this way, and, revived by the warmth, are easily
noticed when the material is spread on white paper.
[Illustration: FIG. 60.--A Saw-fly (Nematus ventralis). _a_, _a_, _a_,
young larvae; _b_, full-grown larva; _c_, cocoon; _d_, adult; all
slightly enlarged.]
On account of the interest attaching to a knowledge of the various hosts
of parasitic insects the collector should always aim to obtain the
latter by breeding as much as possible. This can easily be done by
keeping a lookout for larvae of all sorts which give evidence of being
parasitized. The larvae of Lepidoptera found late in the fall are very
apt to be parasitized, and should be collected and kept over the winter.
The parasites will emerge throughout the winter season and in the early
spring. Such larvae will be found on the trunks of trees, in the crevices
of the bark, and the cocoons of parasites will also be found in similar
situations.
The Tenthredinidae (Saw-flies) are not so often found about flowers but
usually remain in the vicinity of the food-plant of the larva, and may
many of them be collected by sweeping. The larvae of this family are in
many cases difficult to breed, as most of them are single-brooded, and
it becomes necessary to carry the larvae over the winter.
The Gall-flies, Cynipidae, are the easiest of the families to collect,
because of their abundance and because of the ease with which they may
be reared. Their galls occur in enormous variety on oaks of various
species and also upon brambles and certain common weeds. These should be
collected when mature and be kept in glass jars. The Gall-flies and
inquilinous and parasitic species may thus be easily obtained, the
former appearing at particular seasons and the latter emerging from the
galls at all seasons of the year, and sometimes continuing to escape for
a period exceeding two years.
One of the most interesting families in this order is the Formicidae,
which comprises the true ants. In the case of these insects isolated
specimens should not ordinarily be collected, and it is especially
desirable to collect the species from colonies so that the three forms
(males, females, and workers) may be obtained together. This holds also
in the case of the social wasps and bees, but the different sexes of the
latter may be collected in a season's collecting about flowers, the
females and workers in early spring and the males in the fall.
[Illustration: FIG. 61.--An Ichneumon (_Ophion_).]
The Uroceridae or woodborers are to be found only about trees in which
the larvae breed. They may frequently be taken about tree trunks, or
burrowing with their long gimlet-like ovipositors into the trunks of
trees to oviposit. Breeding is also a satisfactory method of obtaining
these insects.
Some special methods of collecting Hymenoptera may be briefly outlined.
In the case of the social bees, particularly bumble-bees, and also the
smaller wasps and yellow-jackets, a very satisfactory method of
collecting consists in first stupefying the insects in the nest by
introducing a small amount of chloroform, benzine, or bisulphide of
carbon. This should preferably be done in the late evening, after all
the insects have come in for the night. The nest may then be opened and
examined without any danger of being stung, and the different forms may
thus easily be obtained, together with any rare parasitic or inquilinous
insects. In the case of the nests of Bombi this is the best method of
obtaining the inquilinous Apathus species.
On account of the danger of being stung, and also on account of the
extremely quick flight of these insects, the removing of Hymenoptera
from the net is not always an easy task, and in many cases rare
specimens escape. One method of avoiding the danger of being stung is to
have the collecting net constructed with an opening at the bottom which,
during the sweeping, is tied with a string. When a sufficient quantity
of insects is obtained they are, by a few quick motions, driven to the
bottom of the net, and the net is then seized just above the insects
with the hand, the folds of cloth preventing the insects from getting
to the hand, so that there is little danger of being stung. The lower
end is then carefully untied and inserted into a wide-mouthed bottle,
and the contents of the net shaken out into the bottle. After the catch
is stupefied the vial may be turned out and the undesirable material
discarded. A second method consists in the use of an ordinary
sweeping-net of light material. A quantity of Hymenoptera are collected
from flowers and driven to the bottom of the net, and secured as in the
preceding method. The portion of the net containing the insects is then,
by means of a pair of forceps, thrust bodily into a large collecting
bottle. After a few minutes the insects are stupefied and may be readily
examined.
[Illustration: FIG. 62.--The Little Red Ant (_Monomorium pharaonis_).
_a_, female; _b_, worker enlarged.]