STATES OF INSECTS. (Larva.) 189 
and others (Cerura Vinula, Deilephila Euphorbia, Cu- 
cullia Verbasci), though their usual food is of a vegeta- 
ble nature, eat with great apparent satisfaction the skins 
which they cast from time to time, not leaving even the 
horny legs. This strange repast seems even a stimula- 
ting dainty, which speedily restores them to vigour, after 
the painful operation by which they are supplied with it. 
Under this head it will not be out of place to mention, 
that some larvee of insects, which feed only on the juices 
of animals, or the nectar and ambrosia of flowers, have 
no anal passage, and of course no feces. ‘This is said to 
be the case with the grubs of bees, wasps, the larvae of 
Myrmeleon, &c.* 
vii. You will require no stimulus to induce you to at- 
tend to the subject I am next going to enter upon,—the 
Moulting, namely, of Larvee; or their changes of skin. 
This, indeed, is a subject so replete with interest, and 
which so fully displays the power, wisdom, and goodness 
of the Creator, affording at the same time such large oc- 
casion for nice investigation, that a pious and inquisitive 
mind like yours cannot but be taken with it. In the 
higher orders of animals, though the hairs of quadru- 
peds and the feathers of birds are in many cases annu- 
ally renewed, the change, or scaling and increment of 
the skin, is gradual and imperceptible; no simultaneous 
rejection of it, in which it is stripped off by the animal 
itself like a worn shirt, being observable, till you descend 
them, which they seemed to relish highly. I am inclined to believe, 
however, that this unnatural procedure was to be attributed to the 
circumstance of the female not having had it in her power to place 
her eggs in the midst of Aphides, their proper food. 
* N. Dict. d Hist. Nat. xx. 359. 
