102 STATES OF INSECTS. 



lar views is in many circumstances impossible. When 

 the heat of the atmosphere has reached a certain point, 

 the hatching cannot be retarded by cellars ; and M. 

 Faujas has remarked, that in June the silk-worm's eggs 

 would hatch in an ice-house a . 



The period of exclusion does not, however, depend 

 solely upon temperature : the hardness or softness of the 

 shell, and possibly differences in the consistence of the 

 included fluid, intended to serve this very purpose, cause 

 some eggs to be hatched much sooner than others exposed 

 to the same degree of heat. Thus the eggs of many flesh- 

 flies are hatched in twenty-four hours b ; those of bees and 

 some other insects in three days; those of a common 

 lady-bird {Coccinella bijpunctatd) in five or six days; 

 those of spiders in about three weeks; those of the mole- 

 cricket in a month; while those of many Lepidoptera and 

 Coleoptera require a longer period for exclusion. The 

 hard eggs of Lasiocampa Neustria and castrensis, noticed 

 above, remain full nine months before being hatched , 

 as do those of another moth (Hypogymna dispar\ which, 

 though laid in the beginning of the warm month of Au- 

 gust, do not send forth the included caterpillar till the 

 April following 11 . We know no more of the cause of 



a Young's France, ii. 34. This author asserts, that no art will 

 hatch the eggs of the common silk-worms the first year, or that in 

 which they are laid ; but that there is a sort brought from Persia 

 which are hatched three times a year, and which will hatch in fifteen 

 days in the proper heat. In 1J65, it is said, the common sort hatched 

 in the first year. Ibid. 226 — . 



b In the N. Diet. d'Hist. Nat. xii. 564. the eggs of the flesh-fly 

 are said to hatch in two hours. This is true I believe in very warm 

 weather. 



c Brahm. 310. <* Rimrod Naturf. xvi. 131. 



