138 HjftMBLES OF A VOMINIS 



ground beyond the reach of frost, others sleeping in the 

 mud at the bottom of ponds and ditches. The few 

 species of butterflies that live into a second season, the 

 wasps that survive the general destruction, the few 

 moths and flies that stand the winter, hide in old trees, 

 or roofs, or walls, or even in loose heaps of stone. 



Insects which thus hibernate appear dead. Their 

 animal functions are probably suspended. Their stiffened 

 limbs display no sign of life. Some, again, seem entirely 

 unaffected by the cold ; and in the bitterest season will 

 even frolic on the snow. 



It is often said that a hard frost must do great 

 service to the farmer by destroying grubs and hiberna- 

 ting insects ; but it may be considered more than doubt- 

 ful whether the frost does not tell rather the other way, 

 and by hindering rooks and starlings from digging in the 

 ground, prove to lower forms of lif e a defence instead of 

 a destruction. For on insects, in any stage before the 

 perfect form is reached, cold seems to have but slight 

 effect. Some of those which pass the winter in the 

 chrysalis condition do indeed defend themselves with 

 thick wrappings of silk ; but others are not so protected, 

 and it has been shown that as a rule immature insects 

 at least are unharmed by very low temperatures indeed. 

 Eggs of the silkworm moth have survived a prolonged 

 exposure to a cold of 38 deg. below zero Fahrenheit. 

 " Caterpillars, so frozen that when dropped into a glass 

 they chinked like stones, nevertheless revived." Chrys- 

 alids, converted by a cold of zero Fahrenheit into lumps 

 of ice, have still produced butterflies. The larva of the 



