of Animals to secure Warmth. 517 



as accidental rather than according to the usual order of things; 

 but there are several insects whose regular time of appearance 

 is fixed by nature in the first months of the year, pro- 

 bably for the purpose of supplying a scanty meal, to such of 

 the soft-billed birds as are permanent residents, the berries on 

 which they have in part subsisted being now useless or exhausted. 

 Amongst these we may reckon the small egger-moth (Eriogas- 

 terlanestris), which is disclosed towards the end of February, 

 having lain from the preceding July in a pupa case similar to 

 plaster of Paris in consistence and appearance. The moth 

 itself is but of middle size, and is pretty closely covered, particu- 

 larly on the body, with hair. Its inconspicuous chocolate-brown 

 colour might furnish the advocates for concealment in respect 

 of colour with a very good illustration. 



The little gnat ( Trichocera hiemalis, MEIGEN), which may be 

 seen in troops during winter weaving eccentric dances in the 

 air even when the ground is covered with snow, flies for shelter, 

 as I have frequently found, to the hollow stems of umbelliferous 

 plants and similar places near its usual haunts. A much 

 smaller and more delicate fly, which has not a little puzzled 

 systematic naturalists to class (^leyrodes Chelidonii, LA.- 

 TREILLE), preserves itself from the cold in a similar manner. 

 This species is so small, that it would not cover the area of a 

 pin's head, and its snow white wings, as well as its elegant form, 

 might entitle it to the appellation of the mite-butterfly; yet so 

 well does this tiny creature know how to avoid cold, that, after 

 the severe winter of 1829-30, I found three of them sporting 

 about in March in Shooter's-hill Wood, as lively as if no frost 

 had occurred. 



During the previous frost in that season, I opened two nests 

 of the yellow ant (Formica flava), in which the inhabitants 

 were by no means torpid or inactive, although not so lively as 

 in summer ; but these nests had been carefully constructed in a 

 peculiarly warm situation, being both in the trunks of old 

 willows, rendered quite spongy by dry-rot, and facing the souih- 

 west, where they had the benefit of every glimpse of sunshine. 

 Ants, indeed, exhibit the most extraordinary tact in attending 

 to variations of temperature, so much so, that they might, in a 

 glazed formicary, constructed upon Huber's plan, be made to 



VOL. I. MAY, 1831. 2 M 



