28 MODERN CLASSIFICATION OF INSECTS. 
In some specimens which I have reared, I have invariably found that 
the casting off of this pellicle takes place during the night. In some 
species, the operation of shedding this pellicle takes place immediately 
after flight, and is so quickly performed, that the whole operation 
does not exceed three minutes; immediately after which the insect 
again takes wing. (Davis, in nt. Mag. vol. ii. p. 322.) [have observed 
in one instance, at least, that the insect remained in the pseudimago 
state upwards of twenty-four hours. In consequence of this pecu- 
liarity, these insects have been described as undergoing a quadruple 
metamorphosis.* After coupling has taken place, the females deposit 
their eggs in a mass, and which they drop into the water. This being 
the only operation which the perfect insects are able to perform, they 
die as soon as it is accomplished. 
Notwithstanding the dangers to which the eggs, larvae, and pupz 
are constantly exposed, from the attacks of fishes and predaceous 
aquatic insects, the number of specimens which arrive at the per- 
* Swammerdam asserts of the species which he observed, that the males only un- 
dergo this second moulting. I can affirm that in E. vulgata both sexes are subject to ite 
This power of flight by the insect, previous to attaining its final form, is perfectly 
anomalous; and if we were to adopt the opinion expressed by Mr. Newman ( Ent. 
Mag. vol. iii. p. 19.), that the pseudimago state of the May fly is analogous to the 
pupa of the bee, or the chrysalis of the butterfly, it would necessarily follow that the 
state in which rudimental wing-covers are developed, preceding the pseudimago state 
of the former, is analogous to the last stage of the larva of the latter insects. But 
Mr. Newman has shown that he is aware of the fact, not only that the dragon fly, 
on becoming a perfect insect, quits a double skin, the interior of which is analogous 
to the external pellicle of the pseudimago, but also that butterflies, moths, and 
gnats, “ which do not retain the skin of the previous state, on entering the quiescent 
state, retain two distinct coverings ;” the interior being a soft pellicle, which must 
have been observed by all who have paid any attention to the rearing of Lepidoptera. 
But Mr. Newman further contends that the pupa of a bee or beetle is enveloped in 
only a single skin; whilst the flesh fly, &c. (or the insects which undergo the true 
coarctate metamorphosis, that is, ‘‘ on assuming the quiescent state they retain the 
last cuticle of the previous state,”) cast off two skins on becoming perfect insects. Now, 
both those assumptions are contrary to fact as well as to analogy, since it is certain 
that the beetles, after quitting the pupa skin, are at first enveloped ina thin pellicle, like 
the May-fly, and which I doubt not is general, and to be found in the bee, as well as 
the beetle, if sufficient careful researches were made for it; whilst, at the same time, we 
are warranted in considering that the real pupa of the flesh fly is likewise inclosed in a 
similar membrane, so that the latter insect, on arriving at the perfect state, casts three, 
and not two, skins; namely, the hardened ultimate larva skin, the real pupa skin, and 
the pellicle analogous to the pseudimago skin of the May fly, which, from its 
firmer consistence is retained longer by the last-mentioned insect, If this be a cor- 
rect view of the real nature of the pseudimago state, there will be no grounds for 
rejecting the Linnzan definitions of metamorphosis. 
