1889.] Entomology. 1 107 
stood. Nowhere among insects may be found better examples of this 
principle than in this group. The majority mimic bees and wasps, 
particularly the latter. We all know, and most insect-destroying ani- 
mals know, that wasps hold out strong and pointed inducements for 
being left alone ; surely the wide-spread knowledge of their armament, 
and their disposition to use it, prevents many rash attacks, and secures 
them practical immunity from a host of enemies. Now, the defence- 
less aegerians have, in some way, come to so closely resemble these 
batteries of potential energy and poison, that the practiced eye of the 
collector is often deceived ; in consequence, these delicate moths, 
incapable of offense or defense except by flight, are allowed to pass 
without the destructive attention accorded to most conspicuous Lepi- 
doptera by entomologically inclined birds and others. 
This mimicry is more than a superficial resemblance ; it is deeper 
and more substantial. Let us specify : first, the long, narrow wings, 
which are so often more or less hyaline and veined, are close imita- 
tions of those of the Hymenoptera ; again, the steel-blue wings and 
bodies recall well-known wasps ; third, the transversely markea or 
ringed bodies of many afford another mark of resemblance ; fourth, 
when captured or disturbed, their sounds and attitudes are striking 
imitations of those of wasps ; fifth, they fly about and rest on flowers 
in a manner quite similar to bees; and sixth, when captured some 
species at least give off the characteristic odor of the hornet. 
It is scarcely possible that all these particulars are mere accidental 
coincidences, or that they are due to a common ancestry. It seems 
more rational to believe that the protection thus afforded gave direc- 
tion to natural selection in the evolution of the present forms. 
It was remarked above that segerian larvae are universally borers. 
But in the choice of food-plants there is the widest diversity ; some 
bore through and devour solid woods as do the larvae of the cossids ; 
some prefer the pith of woody stems ; others are found in the super- 
ficial woody layers ; still others corrode the roots of plants, both 
woody and herbaceous, or herbaceous stems. These differences in 
taste, and the consequent variety of habits, suggest the interesting 
question of the duration of their larval period. The wood-boring 
larvae of several species of Lepidoptera are known to require several 
years to reach maturity. For example : in June, 1885, I placed eggs 
of Cossus robincB in wound^ made in the bark of an unaffected common 
locust ; the caterpillars hatching therefrom were seen to bore beneath 
the bark, and in June, 1888, at least one imago issued from the same 
place. I have strong evidence that Hepialus argenteofnacuiatus also 
