DEVELOPMENT 161 
to fasten the eggs to appropriate objects, such as food plants, 
the skin of other insects, the hairs of mammals, etc.; it may 
form a pedicel, or stalk, for the egg, as in Chrysopa (Fig. 
209); may surround the eggs as a gelatinous envelope, as in 
caddis flies, dragon flies, etc.; or may form a capsule enclosing 
the eggs, as in the cockroach. 
The number of eggs laid by one female differs greatly in 
different species and varies considerably in different individ- 
uals of the same species. Some of the fossorial wasps and 
bees lay only a dozen or so and some grasshoppers two or three 
dozen, while a queen honey bee may lay a million. Two 
females of the beetle Prionus laticollis had, respectively, 332 
and 597 eggs in the abdomen (Mann). A. A. Girault gives 
the following numbers of eggs per female, from an examina- 
tion of twenty egg-masses of each species: 
Maximum. Minimum. Average. 
Thyridopteryx ephemereformis 1076 753 O4I 
Clisiocampa americana 460 218 Biss 
Chionaspis furfura 84 ayn 60.5 
Hatching.— Many larve, caterpillars for example, simply 
eat their way out of the egg-shell. Some maggots rupture 
the shell by contortions of the body. Some larve have spe- 
cial organs for opening the shell; thus the grub of the Colo- 
rado potato beetle has three pairs of hatching spines on its 
body (Wheeler) and the larval flea has on its head a tempo- 
rary knife-like egg-opener (Packard). ‘The process of hatch- 
ing varies greatly according to the species, but has received 
very little attention. 
Larva. 
one another much less than their imagines do, they are easily 
Although larve, generally speaking, differ from 
referable to their orders and usually present specific differ- 
ences. Larve that display individual adaptive characters of 
a positive kind (Lepidoptera, for example) are easy to place, 
but larve with negative adaptive characters (many Diptera 
and Hymenoptera) are often hard to identify. 
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