22 



IMPEKFECT SOCIETIES OF INSECTS. 



files, the march is resumed, and all follow as regularly as if 

 they kept time to music. These larvae may be occasionally 

 found at mid-day out of their nests, packed close one to 

 another without making any movement; so that, although 

 they occupy a space sufficiently ample, it is not easy to dis- 

 cover them. At other times, instead of being simply laid 

 side by side, they are formed into singular masses, in which 

 they are heaped one upon another, and, as it were, interwoven 

 together. Thus, also, they are disposed in their nests. 

 Sometimes their families divide into two bands, which never 

 afterwards unite. 1 



The processionary caterpillars of the fir (those of Cnetho- 

 campa pityocampd), like the preceding, live in a common 

 silken net placed at the extremities of its branches, on which 

 they feed ; and when they leave one tree to proceed to another 

 they also move in procession, but with this striking difference, 

 that they all range themselves in a single file, the head of 

 each so exactly touching the tail of that before it as to form 

 apparently one vast caterpillar of from fifteen to twenty feet 

 long, and thus traversing by a continuous and occasionally 

 slightly jerking motion, without ever breaking their line, the 

 path they have chosen. What is singular is, that if the first 

 caterpillar of the file be touched with the hand or a stick, it 

 shrinks and is visibly agitated, as if it feared to be stung by 

 an Ichneumon, and the last of the file, even if composed of six 

 hundred, makes at the same instant, as well as every inter- 

 mediate individual, the same movements, as if struck by an 

 electric shock. 2 — The individuals of another processionary 

 caterpillar, the perfect insect of which Mr. Ewing had not 

 been able to rear, he informs us march in circles, or rather 

 ovals, and, when young, follow one another round and round 

 for hours together! 3 



I have nothing further of importance to communicate to 

 you on imperfect societies : in my next I shall begin the most 

 interesting subject that Entomology offers ; a subject, to say 

 the least, including as great a portion both of instruction and 



1 Reaumur, ii. 180. 



2 De Villiers, Ann. Soc. Ent. de France, i. 201 . 



3 West wood in Trans. Ent. Soc. Lond. ii. proc. lv. 



