MOTIONS OF INSECTS. 297 
fore consider pupae as of two kinds—active pupz and 
quiescent pupe. | 
The motions of most insects whose pupz are active, 
are so similar in all their states, except where the wings 
are concerned, as not to need any separate account. I 
shall therefore request you to wait for what I have to say 
upon them, till I enter upon those of the imago. One 
insect, however, of this kind, moving differently in its 
preparatory states, is entitled to notice under the present 
head.—In a late letter, I mentioned to you a bug (Redu- 
vius personatus, F.) which usually covers itself with a 
mask of dust, and fragments of various kinds, cutting a 
very grotesque figure*. | Its awkward motions add not a 
little to the effect of its appearance. When so disposed, 
it can move as well and as fast as its congeners; yet this 
does not usually answer its purpose, which is to assume 
the appearance of an inanimate substance. It therefore 
hitches along in the most leisurely manner possible, as 
if it was counting its steps. Having set one foot for- 
ward (for it moves only one leg at a time), it stops a lit- 
tle before it brings up its fellow, and so on with the se- 
cond and third legs. It moves its antenna in a similar 
way, striking, as it were, first with one, and then, after an 
interval of repose, with the other®.—The pupz of gnats 
also, as well as those of many other aquatic Diptera, re- 
tain their locomotive powers, not however the free mo- 
tion of their limbs, "When not engaged in action, they 
ascend to the surface by the natural levity of their bodies, 
and are there suspended by two auriform respiratory or- 
gans in the anterior part of the trunk, their abdomen 
being then folded under the breast; when disposed to de- 
a See above, p. 208. » De Geer, i. 284. 
