HYBERNATION OF EGGS. 87 



an intimate connection with heat in aninnated bodies. 

 The hving principle, to which we shall by and bye 

 advert, must also be taken into account- 

 In consequence of the minuteness of insect eggs, 

 notwithstanding the researches of enthusiastic ento- 

 mologists, we are still unacquainted with by far the 

 greater number. The hybernation of eggs is, there- 

 fore, a subject upon which little is known. In the 

 egg state insect life is, perhaps, less liable to ac-cidents, 

 than in a more advanced stage of existence ; and it is 

 most probable that the greater number remain un- 

 hatched during the cold season. Different modes of 

 depositing eggs are resorted to by different species of 

 the same genus, as may be exemplified in the plant- 

 lice {Aphides). It was observed by De Geer, that 

 those of the birch and the blackthorn {Aphu Alni, and 

 A. Pruni) covered each egg individually with a white 

 cottony down, detached from their bodies by means 

 of their hind legs, and placed by the same means over 

 the eggs*. But the greater number of this family lay 

 their eggs in an exposed situation, upon the plants 

 where the young, when hatched, may find food. Thus 

 Kirby found the small black eggs of a large species 

 on the buds of birch-trees; and we have just disco- 

 vered (Jan. 1830) a numerous deposit of the eggs of 

 the magpie plant-louse {Aphis Samhuci) on an elder 

 tree, where the insect was abundant the preceding 

 summer f. These eggs are exceedingly minute, but 

 easily observed on account of their shining black 

 colour. They are placed in an irregular patch upon 

 a part of the trunk from which the bark has been 

 stripped off, and are entirely unprotected. 



The cochenille insects (Coccidce, Leach), so called 

 from one of the species furnishing the well-known 

 valuable dye-stuff, protect their eggs in a still more 



* De Gecr, Mem. sur les Insecles, iii. 48, 51. t J. H. 



