34^ LÉPIDOPTÉROLOGIE COMPARÉE 



laid in thick layers, very many would never reach the food plant. 

 Once started feeding, they feed up fairly rapidly and, except in 

 Northern and Alpine localities, are ail buried for pupation before 

 August. 



The food plants of the various species are many and of varions 

 natural orders; pomonarïa and hutaria will feed on most forest 

 trees, the former preferring oak and hawthorn and the latter (in 

 my expérience) birch. Lapponaria in Scotland delights in Erica 

 and Calluna although generally fed in captivity on birch and 

 hawthorn ; abroad it has been found on birch and larch. Ursaria 

 seems attached to poplar, but rachelœ has a similar weakness for 

 dwarf willows on the prairies. AU the other species, grœcaria, 

 alpina, zonaria and italica live on various low plants, of which 

 yarrow {Achillœa Millefolium) is the spécial favourite, closely 

 followed by trefoils {Lotus, etc.) in the case of zonaria and broom 

 {Cytisus scoparius) in the case of italica. The variety : istrianiis 

 of grœcaria, is said to feed also in various species of Salix — a 

 food plant that the other species will eat. 



After pupation, the pupas remain unchanged for about two 

 months, when the imago develops in the majority of cases; it, 

 however, remains in the pupal shell throughout the winter. 



Exceptionally, in zonaria, there may be an autumnal émergence. 

 A certain proportion of imagines, varying with the species, and 

 with the brood, fail to develop and lie over for two, three, four 

 and even five winters. Lapponaria, grœcaria and alpina are worst 

 offenders in this respect, but none are free from it. Even pomo- 

 narïa. and hirtaria pupse to the extent of two or three per cent, lie 

 over two winters but never longer. It is noteworthy that the imago 

 in P. pedaria, A. betidaria and B. strataria does not develop 

 eatly. 



It would be profitless to repeat ail the structural characters of 

 the group, for the various points hâve been emphasised in descri- 

 bing the genus Pœciiopsis; the gênerai appearance of ail stages 

 must be given. 



