MOTIONS OF INSECTS. 



241 



end. Some time after I had received this history, I happened 

 to have occasion to look at Reaumur's Memoir upon the ene- 

 mies of caterpillars, where I met with an account of a similar 

 jumping chrysalis, if not the same. Round the nests of the 

 caterpillar of the processionary moth, before noticed, he found 

 numerous little cocoons suspended by a thread three or four 

 inches long to a twig or a leaf, of a shortened oval form, and 

 close texture, but so as the meshes might be distinguished. 

 These cocoons were rather transparent, of a coffee-brown 

 colour, and surrounded in the middle by a whitish band. 

 When put into boxes or glasses, or laid on the hand, they sur- 

 prised him by leaping. Sometimes their leaps were not more 

 than ten lines, at others they were extended to three or four 

 inches, both in height and length. When the animal leaps, it 

 suddenly changes its ordinary posture (in which the back is 

 convex and touches the upper part of the cocoon, and the head 

 and anus rest upon the lower), and strikes the upper part with 

 the head and tail, before its belly, which then becomes the 

 convex part, touches the bottom. This occasions the cocoon 

 to rise in the air to a height proportioned to the force of the 

 blow. At first sight this faculty seems of no great use to an 

 animal that is suspended in the air ; but the winds may pro- 

 bably sometimes place it in a different and unsuitable posi- 

 tion, and lodge it upon a leaf or twig : in this case it has it 

 in its power to recover its natural station. Reaumur could 

 not ascertain the fly that should legitimately come from this 

 cocoon 1 , for different cocoons gave different flies: whence it 

 was evident that these ichneumons were infested by their own 

 parasite. 2 This might be the case with that of the lady just 

 mentioned. Perhaps, properly speaking, in this last instance 

 the motions ought rather to be regarded as belonging to a 

 larva ; but as it had ceased feeding, and had inclosed itself in 

 its cocoon, I consider it as belonging to the present head. 



You may probably here feel some curiosity to be informed 

 how the numerous larvae that are buried in their pupa state, 

 either in the heart of trees, under the earth, or in the waters, 



1 Mr. Westwood states that it belongs to the genus Perilitus, belonging to the 

 Ichneumonida?. See Mod. Class, Ins. ii. p. 149. for further notices upon it. 



2 Reaum. ii. 450. 



VOL. II. 



