480 MOTIONS OF INSECTS. 



surprising agility. Its mode of springing seemed t(^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 had received this history, I happened to have occasion to look at 

 Reaumur's Memoir upon the enemies 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 transpa- 

 rent, of a coffee-brown color, 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 con- 

 vex 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 probably sometimes place it in a different and unsuita- 

 ble position, 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^, for different cocoons gave 

 different flies : whence it was evident that these ichneumons were infested 

 by their own parasite.^ 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 belong- 

 ing to the present head. 



You may probably here feel some curiosity to be informed how the nu- 

 merous larvae that are buried in their pupa state, either in the heart of trees, 

 under the earth, or in the waters, effect their escape from their various 

 prisons and become denizens of the air, especially as you are aware that each 

 is shrouded in a winding-sheet and cased in a cofiin. In most, however, if 

 you examine the coffin closely, you will see resurgam written upon it. 

 What I mean is this. The pitpariam, or case of the animal, is furnished 

 with certain acute points (ad minicula) , generally single, but in some in- 

 stances forked, looking towards the anus, and usually placed upon trans- 

 verse ridges on the back of the abdomen, but sometimes arming the side5 

 or the margins of the segments. By this simple contrivance, aided by 

 new-born vi^or, when the time for its great change is arrived, the included 

 prisoner of hope, if under ground, pushes itself gradually upwards, till 

 reaching the surface its head and trunk emerge, when an opening in the 



' Mr. Wesiwood states that it belongs to the genus PeriHius, belonging to the Ichneu- 

 moni'lrc. See Mod. Class. Ins. ii. p. 14y. for further notices upon it. 

 * Reaum. ii. 450. 



