ENTOMOLOGY. 
77 
either heat or cold, none having ever been found pro- 
ductive after remaining for a time in the vacuum of 
an air-pump. 
When the whole of the fluid in the interior of the 
egg has been assimilated, and the young larva ma- 
tured, it emerges either by rupturing the envelope, 
gnawing it asunder, or pushing open a kind of move- 
able lid at the end, constructed apparently for the 
express purpose of facilitating its exit. 
Larva. Insects as often present themselves to 
our notice in this stage of their existence as in their 
perfect state, and not unfrequently attract our atten- 
tion by their depredations on the produce of our 
fields and gardens. In consequence of being so 
familiarly known, they are distinguished by a variety 
of popular names. Grubs are the larvse of coleop- 
tera ; maggots, mawks, and gentles, those of diptera ; 
and caterpillars the larvro of butterflies, moths and 
saw-flies : the larvae of most of the other £aces not 
differing materially in appearance from the matured 
insects, do not require a distinctive appellation in or- 
dinary language. Lepidopterous larvae, or the cater- 
pillars of butterflies and moths, we have already de- 
scribed at considerable length ; * those of beetles also 
have been occasionally noticed,! and the particular 
history of the other kinds will be afterwards given 
under their respective orders and families. The pre- 
* See Naturalist’s Library — Entomology, British But- 
terflies. 
t See Naturalist’s Library — Entomology, Beetles. 
