276 Mr. J. W. Dunning on the 



a pupa wliicli will produce a female with rudimentary 

 wings only a small part of the wing-case is occupied, as 

 may be clearly seen shortly before the moth emerges, 

 when the wings are easily distinguishable by their darker 

 colour. The diu-ation of the pupa state of existence is 

 about three weeks. 



The greater part of the larvae, however, hibernate ; this 

 they do in various stages of growth, and about the end of 

 March they become active and spread themselves over the 

 food-plant : by the end of April some spin , up, and about 

 the middle of May the first brood of the imago begins to 

 appear. A second brood appears in July, and a third in 

 August and September. The spring brood are all from 

 hibernated larva3, which may be the offspring of any of 

 the three broods of the preceding year. The summer 

 brood, also, are all from hibernated larvae, and Ritsema 

 conceives that it is to this brood, and this alone, that the 

 normally-winged female belongs, and that the larvae which 

 are their offspring all hibernate; whilst the autumn brood 

 is from larva3 the offspring of the spring brood of the 

 same year, some of which thus rapidly mature, whilst 

 others of them hibernate (cf. Ent. Mo. Mag. xii. 257). 

 Hence it follows that amongst the larvfe hibernating in 

 any winter there are or may be offspring of all the three 

 broods of the previous year. 



I do not quite gather whether the author supposes the 

 females of the summer brood to be always amply winged, 

 or whether both forms of female occur in this brood. 

 But, however this may be, the theory that the female 

 with rudimentary wings belongs to the spring and autumn 

 broods, and that the amply-winged female belongs exclu- 

 sively to the summer brood, requires further examination. 

 If this be the true view, it Avould seem that rapidity of 

 larval growth is unfavourable to the alar development of 

 the female imago : it is the larvre which hibernate earlier 

 in life, and take the longest time to feed up in the spring, 

 which produce the brood of females with fully-developed 

 wings. 



Eitsema did not meet with an absolutely apterous 

 female, but the partially-winged and the amply-winged 

 forms were equally fertile and productive. 



The imago is described at length (pp. 100 — 105) by 

 Snellen. Of males he had before him fifty-eight speci- 

 mens captured and bred by Ritsema, varying in expanse 

 of wing from 11 — 16 mm., the majority ranging about 



