LETTER XXX.

_STATES OF INSECTS._

LARVA STATE.

The _Larva_ state is that in which insects exist immediately after their exclusion from the egg (or from the mother in ovo-viviparous species), in which they usually eat voraciously, change their skin several times, and have the power of locomotion, but do not propagate.

Almost all larvæ, at their birth, are for a time in a very feeble and languid state, the duration of which differs in different species. In most it continues for a very short time, a few minutes or perhaps hours, after which they revive and betake themselves to their appropriate food. In others, as in the generality of spiders, this debility lasts for seven or eight days, and in some species even a month, during which the young ones remain inactive in the egg-pouch[206], and it is not till they have cast their first skin that their active state of existence commences.

All larvæ may be divided into two great divisions:--

I. Those which in general form more or less resemble the perfect insect.

II. Those which are wholly unlike the perfect insect.

I shall begin by calling your attention to the characters of the _first_ of these divisions: the second, which is by far the most numerous, will be afterwards considered.

I. The _first_ division includes the larvæ of _Scorpions_, _Spiders_, _Cockroaches_, _Grasshoppers_, _Lanthorn-flies_, _Bugs_, &c.; or generally, with the exception of the _Flea_ and _Crustacea_, the whole of the _Linnean_ Orders _Aptera_ and _Hemiptera_. All these larvæ, however remotely allied in other respects, agree in the general similarity which they bear to the perfect insects which proceed from them. The most acute entomologist, untaught by experience, could not even guess what would be the form of the perfect insects to be produced from larvæ of the _second_ division, while they can recognise the form of the spider, the cricket, the cockroach, the bug, and the frog-hopper, in that of the larvæ. There are, however, differences in the degrees of this resemblance, according to which we may, perhaps, divide this tribe in their second state as follows:--