38 



bubbles beneath the ice, or accumulates from the aquatic plants. 

 For those creatures that breathe the air dissolved in the water, e.g., 

 larvae of (hhmata and of many Diptera, breathing presents scarcely 

 more difficulty than obtains when the ^yater is open. As regards 

 the food supply, too, aquatic insects are well situated ; the larger 

 ones are mostly predatory upon the smaller, while the latter feed 

 mostly upon minute forms of vegetable growth, or upon decomposing 

 vegetable tissues. 



But even amongst the aquatic insects there are a few that 

 appear to have a true period of hibernation either as larvae in the 

 mud at the bottom, or as the perfect insect which may hibernate 

 away from the water. To the former class seem to belong some of 

 the mosquitoes, e.f/., Anopheles bifurcatiis and A. pluinheiis, while of 

 other mosquitoes such as Anopheles viacidipennis, Culex pipiens, 

 Theobaldia annulata, etc., the adult $ hibernates. 



It might be expected that Lepidoptera whose larvse feed on ever- 

 greens, would show a proportionately large number of over- 

 wintering caterpillars, but a little consideration seems to show that 

 this is not so. If we take the case of our pine-feeding larvae, for 

 instance, the only ones that hibernate in the larval state are Ellopia 

 fasciaria, and the different spp. of Thera, which hibernate as young 

 larvae. The majority. Sphinx pinastri. Trachea piniperda, Macaria 

 Uturata, Fidonia piniaria, and the pine-feeding Eupitheciae pass the 

 winter in the pupal stage (I do not include numerous other species, 

 such as Lyinantria monacha that sometimes feed upon pine, but more 

 usually upon deciduous trees). 



Of ivy feeders the proportion of hibernating larvae is greater ; 

 thus we have Vrapteryx saiiibncaria, Boar»iia re}iandata, and B. 

 rhovibnidaria, Triplucna spp., Mania spp. (but all of these also feed 

 on deciduous plants and for the most part have a period of true 

 hibernation). Celastrina aryioltis, (hlontopera bidentata, etc., pass the 

 winter as pupae. 



Other lepidopterous larvfe whose food is obtainable throughout 

 the winter, and which probably feed more or less daring mild 

 spells may be grouped in the following classes : — 



i. Stem-borers ; e.ij., Cossns, Zenzera, the Sesiidae, etc., all 

 of which grow but slowly and spend more than one 

 winter in the larval state. 

 (N.B. — Not borers in the stalks of annuals, such as 

 Gortyna flavayo, etc.) 



