IMPERFECT SOCIETIES OF INSECTS. 293 
Loose to the wind their airy garments flew, 
Thin glittering textures of the filmy dew, 
Dipé 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 
(I. maura), which at this period of the year assemble to wheel in aéry 
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- 
phila 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 com- 
panions, which exhibit no marks of alarm. 
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 larva of certain gnats (Z%pularie) 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 
kind of glutinous secretion ; but when disturbed they separate without 
difficulty. Kuhn mentions another of the same tribe—from the antenne 
in his figure, which is very indifferent, it should seem a species of agaric- 
gnat (Mycetophila), — the larvee 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) heerwurm, and view them with great dread, regarding 
them as ominous of war. ‘These larve are apodes, white, sub-transparent, 
with black heads.$ The caterpillars of a moth Noctua (Xylophasia ? ) 
Ewingii Westw., a native of Van Diemen’s Land, exhibited a singular 
migrating propensity as described by Thomas I. Ewing, Esq., who has 
ae them the name of the “ migrating caterpillars.” Passing, about 
ecember 20th, from a barley field which had been ploughed up, and 
1 Ann. Soc. Ent. de France, xi. bull. xii. 
2 De Geer, vi. 888. 
5 Naturforsch, xvii. 226. 
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