6 



IMPERFECT SOCIETIES OF INSECTS. 



Here, also, must be noticed the bombadier beetles (Bra- 

 chinus crepitans), which, with several others of the same 

 family, are usually found together in considerable numbers 

 under stones, &c, and the red field-bugs Cimex (Pyrrhocoris) 

 apterus, which, in like manner, have a very social propensity, 

 though in both instances we are ignorant of any common 

 labours or other motive than the love of society, which can 

 lead them to associate. The same may be also said as to the 

 numerous assemblages of a moth (Scotophila Tragopoginis), 

 mentioned by M. de Villiers, which he finds in July under 

 the bark of willows, ranged side by side, generally touching 

 each other, and with the head always turned the same way, 

 and which if you disturb them do not attempt to fly, but run 

 upon the backs of their companions, which exhibit no marks 

 of alarm. 1 



The next description of insect associations is of those that 

 congregate for the purpose of travelling or emigrating to- 

 gether. De Geer has given an account of the larvae of 

 certain gnats ( Tipularice) which assemble in considerable 

 numbers for this purpose, so as to form a band of a finger's 

 breadth, and of from one to two yards in length. And, what 

 is remarkable, while upon their march, which is very slow, 

 they adhere to each other by a kind of glutinous secretion ; 

 but when disturbed they separate without difficulty. 2 Kuhn 

 mentions another of the same tribe — from the antennae in his 

 figure, which is very indifferent, it should seem a species of 

 agaric-gnat (MycetophilcL), — the larvae of which live in society, 

 and emigrate in files, like the caterpillar of the procession- 

 moth. First goes one, next follow two, then three, &c, so 

 as to exhibit a serpentine appearance, probably from their 

 simultaneous undulating motion, and the continuity of the 

 files, whence the common people in Germany call them (or 

 rather the file when on march) heenvurm, and view them 

 with great dread, regarding them as ominous of war. These 

 larvae are apodes, white, sub-transparent, with black heads. 3 

 The caterpillars of a moth Noctua (Xylopliasia f) Ewingii 



1 Ann. Soc. Ent. de France, xi. bull. xii. 



2 De Geer, vi. 338. 



3 Natwforsch. xvii. 226. 



