THE LIFE HISTORY OF INSECTS 199 
is about the limit of an insect’s span of life. There are, of 
course, many exceptions. For example, honey-bee queens 
live about three years, though the workers live only from five 
to seven weeks. The seventeen-year cicadas or “ locusts ” 
live in the larva state the greater part of seventeen years, 
and as adults only about a month. Mayflies live two or 
three years in the larva state, but as adults only a few hours 
or, at most, a few days; upon arriving at the adult state 
they immediately lay eggs and die. 
How Insects Pass the Winter. — In cold countries it is 
of greatest importance to small animals that they should 
have some method by which they can successfully live through 
the winter. Besides escaping the enemies that are liable to 
attack them at all seasons, it is now necessary that they should 
be able to endure a freezing temperature for a long period 
of time. The different species of insects pass the winter 
in different stages of their life, —some of them (as the flies 
and potato beetles) in the adult state; others (as most moths 
and butterflies) in the pupa state; and still others, in the 
larva state. But the greater number of insects die in the 
fall, leaving eggs to perpetuate the species. These eggs are 
laid in the ground, as in case of grasshoppers, under the bark 
of trees in case of those that live upon the foliage, or in the 
water if the larve are to live there. Usually a given species 
follows either one or another of these methods, but in some 
instances the same species may hibernate in two or more of these 
conditions. A large proportion of every kind of insects per- 
ish during the winter, no matter in which stage of their life 
they attempt to live through this season. 
If a search be made for insects toward the end of autumn, 
it will be found that they have become scarce. This is what 
has happened : 
