MOTIONS OF INSECTS. 479 



The motions of most insects whose pupae 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, how- 

 ever, 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 

 (Reduvius personatus) , which usually covers itself with a mask of dust, 

 and fragments of various kinds, cutting a very grotesque figure. Its awk- 

 ward 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 

 forwards (for it moves only one leg at a time), it stops a little before it 

 brings up its fellow, and so on with the second and third legs. It moves 

 its antennae in a similar way, striking, as it were, first with one, and then, 

 after an interval of repose, with the other.^ The pupae of gnats also, as 

 well as those of many other aquatic Diptera, retain their locomotive 

 powers, not, however, the free motion 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 organs in the anterior 

 part of the trunk, their abdomen being then folded under the breast ; 

 when disposed to descend the animal unfolds it, and by sudden strokes 

 which she gives with it and her anal swimmers to the water, she swims to 

 the right and left as well as downwards, with as much ease as the larva.^ 

 Bonnet mentions a pupa which climbs up and down in its cocoon, — 

 and that of the common glow-worm {Lampyris noctilucd) will sometimes 

 push itself along by the alternate extension and contraction of the seg- 

 ments of its body.^ Others turn round when disturbed. That of a 

 weevil (Hypera arator), which spins itself a beautiful cocoon like fine gauze, 

 and which it fixes to the stalks of the common spurrey (^Sagina arvensis), 

 upon my touching this stalk, whirled round several times with astonishing 

 rapidity. The chrysalis of a moth (Hypogymna dispar) when touched 

 truns round with great quickness ; but, as if fearful of breaking the thread 

 by which it is suspended by constantly twisting it in one direction, it per- 

 forms its gyrations alternately from left to right and from right to left.^ 

 Generally speaking, quiescent pupae when disturbed show that they have 

 life, by giving their abdomen violent contortions. 



But the most extraordinary motion of pupae is jumping. In the year 

 1810 I received an account from a very intelligent young lady, who col- 

 lected and studied insects with more than common ardor and ability, that 

 a friend had brought her a chrysalis endued with this faculty. It was 

 scarcely a quarter of an inch in length ; of an oval form ; its color was a 

 semi-transparent brown, with a white opake band round the middle. It 

 was found attached, by one end, to the leaf of a bramble. It repeatedly 

 jumped out of an open ])ill-box that was an inch in height. When put 

 into a drawer in which some other insects were impaled, it skipped from 

 side to side, passing over their backs for nearly a quarter of an hour with 



» De Geer, iii. 284 « Ibid. vi. 308. ' Ibid. iv. 43. 



♦ Dumeril, Trait. EUmtnt. ii. 49. n, 603. 



