A number of interesting questions are associated with the seasonal cycle
of an insect's life-history. In a previous chapter (IV. pp. 30, 34)
reference has been made to the contrast between the long aquatic life of
the larval dragon-fly or may-fly, extending over several years, and the
short aerial existence of the winged adult restricted in the case of the
may-flies to a few hours. Here we see that the feeding activities of the
insect are carried on during the larval stage only; the may-fly in its
winged condition takes no food, pairing and egg-laying form the whole of
its appointed task. A similar though less extreme shortening of the
imaginal life may be noticed in many endopterygote insects. For example,
the bot- and warble-flies have the jaws so far reduced that they are
unable to feed, and the parasitic life of the maggot (see p. 74)
extending over eight or nine months in the body of the horse or ox,
prepares for a winged existence of probably but a few days. Again in
many moths the jaws are reduced or vestigial so that no food can be
taken in the winged state, as for example in the 'Eggars'
(Lasiocampidae) and the 'Tussocks' (Lymantriidae). It is noteworthy
that in these short-lived insects the male is often provided with
elaborate sense-organs which, we may believe, assist him to find a mate
with as little delay as possible; the male may-fly has especially
complex eyes, while the feelers of the male silk-moth or eggar are
comb-like or feathery, the branches bearing thousands of sensory hairs.
A box with a captive living female of one of these moths, if taken into
a wood haunted by the species becomes rapidly surrounded by a swarm of
would-be suitors, attracted by the odour emitted from the prisoner's
scent-glands.

Very exceptionally the imaginal stage may be omitted from the life-story
altogether. Nearly fifty years ago N. Wagner (1865) made the remarkable
discovery that in the larvae of certain gall-midges (Cecidomyidae) the