TOUCH. 211 



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 we have fre- 

 quently 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 (Aley- 

 rodes Cheledonii, LATREILLE), 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, we 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, we 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 pecu- 

 liarly warm situation, being both in the trunks of 

 old willows, rendered quite spongy by dry rot, and 

 facing the south-west, where they had the benefit of 

 every glimpse of sunshine, 



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