PERIODS OF HATCHING. 127 



mark, however, that, the periods of hatching corre- 

 sjDond ill a striking- manner with the leafing of trees, 

 and the appearance of other materials fitted for the food 

 of the young-. We observed a good example of this 

 in the spring of 1829. A lackey-moth had deposited 

 during autumn a spiral ring of her eggs on the branch 

 of a sweet-briar planted in a garden-pot out of doors. 

 We removed this into our study during- the winter. 

 Here the warmth caused the tree to bud, and at the 

 same time hatched the lackeys about a month sooner 

 than those out of doors. Owing to the same cause, se- 

 veral colonies of the caterpillars of the brown-tail moth 

 revived from their torpidity, and came forth from their 

 winter nests before the hawthorns were in leaf, a cir- 

 cumstance which would not have happened to them 

 out of doors*. Kirby and Spence give an instance 

 precisely similar, of the eggs of an aphis found on 

 the birch, and hatched in-doors a full month before 

 those in the open airf. 



It is a remarkable circumstance, long observed by 

 collectors, that the male broods of insects appear 

 earlier than the female broods ; and it would appear 

 from the following fact, that there is a similar retarda- 

 tion in the hatching of female eggs. "Upon the leaf 

 of a poplar tree were found three eggs of the puss- 

 moth {Centra rinula), two of which were hatched 

 about two weeks before the other. The first were 

 males, the last a female. As they were on the 

 same leaf, and presumed, therefore, to have been 

 laid by the same parent, at the same time, the differ- 

 ence of hatching could not have arisen from difference 

 of weather, exposure, &c. I" In the case of the 

 lackeys on the sweet-briar above mentioned, some 

 were hatched several days before others, but whether 

 these were of ditferent sexes we did not ascertain. 

 * J. R. f Kirby and Spence, bitr. ii. 434. 



X J. Rcnnie,in Mag. of Nat, Hist. vol. i. p. 373. 



