454 BRITISH LEPIDOPTERA. 



the latest on January 6th, 1901. In 1900, the forcing (60 to 70 

 pupae) was conducted at not more than 70 F., the first imago was 

 bred on October 12th, and it was followed by others regularly 

 until November 12th, when about 12 remained, and, as these 

 began to die off, the heat was raised to about 8o° F., and four 

 more appeared, the last as stated above, on January 6th, 1901 ; 

 but so much depends on individual constitution, time at which 

 forcing is begun, the fluctuation of temperature during the process, 

 that little value can be placed on any but the most detailed results. 

 Glenny records (foe. cit., pp. 156 et seq.) that, by the end of October, 

 1900, he had 184 pupae, that many were injured, but that 62 

 perfect imagines and 15 cripples resulted, the pupae being placed 

 on slightly damped moss and kept in boxes on a kitchen mantelpiece, 

 and he thinks that they would force in a temperature of from 

 6o° F. to 70 F., with this slight amount of moisture if it were 

 begun early enough, say in September or October. Bond-Smith, 

 however, points out (Ent. Rec, viii., p. 244) that he had two 

 imagines emerge on the evening of October 8th, 1896, after an 

 exceedingly cold, rough and miserable day, from two pupae that 

 had only been down 7 weeks, were in quite dry sand, without 

 any moisture, and were in a very cool outhouse. Thorpe 

 observes (Ent., v., p. 143) that the larvae that pupate by the 

 end of August have, with him, generally produced imagines during 

 October, and that a great proportion have been $ s, whilst those that 

 have remained as pupae during the winter and emerged in May have 

 generally been 2 s. He bases this generalisation largely on breeding 

 i4 2s and 3 s in May, 1870. Anderson's experience (E?it., xi., 

 p. 188) in which he bred 1 2 in the autumn of 1877 and 6 $ s and 1 2 

 in June, 1878, does not support this assertion, although, in a later 

 communication, Anderson notes (Ent., xix., p. 249) that, in the autumn 

 of 1885, he had several pupae, from which no imago emerged in the 

 autumn, but that 8 appeared between July 20th and August 3rd, 1886, 

 all 2 s. Glenny observes (Ent. Rec, xiii., pp. 157-158) that, of the 62 

 perfect examples he reared in the autumn and winter of 1 900-1, 

 10 only were $ s and 52 $ s. So-called barren 2 s : Verlofen claims 

 (Ent., hi., p. 28) to have discovered that the abdomen was empty in 

 the 2 s that emerged in autumn, whilst those that come out in the 

 spring had swollen ovaries. [See, however, Reaumur, Memoires, ii., 

 p. 296.] Newman asserts (Entom., ii., p. 283) that the imagines 

 that emerge in October and November are, with rare exceptions, 

 barren 2 s ; the abdomen, he says, is an empty cylinder, 

 containing neither eggs nor ovary, but Doubleday notes (Zoo/., 

 p. 1862) that this is not always so and instances a 2 that emerged 

 in the autumn and laid eggs, and also another 2 bred after being 

 more than 12 months in the pupal stage that was barren. Newman 

 adds that all the 2 s bred or captured in June are abundantly 

 prolific, but we do not know that this is based on actual 

 dissection, and he does not give any evidence in favour of this view 

 nor of the statement that examples that emerge in the winter may live 

 till the following midsummer. In explanation of what he means 

 by "barren ? s," Newman states (foe. cit., p. 297) that he 

 considers the autumnal imagines " are, with rare exceptions, 

 barren 2 s., i-c., neither S s nor fertile 2 s," a most marvellous 



