IMPERFECT SOCIETIES OF INSECTS. 293 



Loose to the wind their airy garments flew, 



Thin glittering textures of the filmy dew, 



Dipt in the richest tincture of the skies, 



Where light disports in ever mingling dyes, 



While every beam new transient colours flings, 



Colours that change whene'er they wave their wings." 



I wish you may have the good fortune next year to be a spectator of 

 this all but celestial dance. In the meantime, in May and June, their 

 season of love, you may often receive much gratification from observing 

 the motions of a countless host of little black flies of the genus Hilara 

 (H. maura), which at this period of the year assemble to wheel in aery 

 circles over stagnant waters, with a rush resembling that of a hasty shower 

 driven by the wind. 



Here, also, must be noticed the bombardier beetles (Brachinus 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 (Scoto- 

 pkila Tragopoginu), 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 com- 

 panions, 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 together. De Geer has given 

 an account of the larvae of certain gnats (TipulaiitB) which assemble in con- 

 siderable 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 antennas 

 in his figure, which is very indifferent, it should seem a species of agaric- 

 gnat (Mycetophila), 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) keerwurm, 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 ( Xylophasia ? ) 

 Eiuingii Westw., a native of Van Diemen's Land, exhibited a singular 

 migrating propensity as described by Thomas I. Ewing, Esq., who has 

 given them the name of the " migrating caterpillars." Passing, about 

 December 20th, from a barley field which had been ploughed up, and 



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

 a De Geer, vi. 338. 

 * A'aturforsch. xvii. 226. 

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