444 MOTIONS OF INSECTS. 



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 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 sub- 

 stance. 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 ot 

 repose, with the other. 1 The pupae of gnats also, as well as those of many 

 other aquatic JDiptera, 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 j 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. 2 



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

 that of the common glow-worm (Lampyris noctiluca) will sometimes push 

 itself along by the alternate extension and contraction of the segments of 

 its body. 3 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 turns round 

 with great quickness j but, as if fearful of breaking the thread by which it 

 is suspended by constantly twisting it in one direction, it performs its gy- 

 rations alternately from left to right and from right to left. 4 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 collected 

 and studied insects with more than common ardour 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 colour 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 pill-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 surprising 

 agility. Its mode of springing seemed to be by balancing itself upon one 

 extremity of its case. About the end of October one end of the case grew 

 black, and from that time the motion ceased; and about the middle of 

 April, in the following year, a very minute ichneumon made its appearance 

 by a hole it had made at the opposite end. Some time after I received 



i De Geer, iii. 284. 9 Ibid. vi. 308. 



3 ibid. iv. 43. 4 Dumeril, Trait. Element, ii. 49. n. G03. 



