260 BRITISH LEPIDOPTERA. 



notes that in early March, 1883, a $ and $ emerged, but hung 

 almost lifeless for three weeks, during which the weather was cold, until 

 March 31st, pairing at once with a change to milder weather. The $ s 

 assemble readily in suitable weather to a newly-emerged 2 . Thus Draper 

 notes [Zoo!., p. 6066) 118 specimens being attracted by a single bred $ 

 on April 8th, 1858, at Tilgate Forest, whilst some 600 others were 

 taken or seen simultaneously with the above ; one suspects that 

 herein lies an explanation of the decadence of the species'm Sussex. 

 The males fly swiftly in the morning sunshine in search of 

 the $ s, and continue on the wing till 3.20 p.m., and will do so 

 without sun if the temperature be suitable, later in the day they 

 may be kicked up from the heather, although one has been found 

 clinging to the needles of a Scotch fir. During the day the females 

 usually hang suspended from birch twigs and are then somewhat 

 conspicuous, but sometimes they are to be found clinging to a 

 sprig of heather, low down, and are then difficult to see. The 

 female flies at dusk for the purpose of oviposition (Clarke). 

 The males fly chiefly in the morning and at midday, 

 when the sun is warmest, i.e., from about 10.30 a.m. to 2 p.m. ; 

 after this time they are to be found at rest (Holland). The 

 males appear to commence flying about 10 a.m., the females 

 are sluggish and sit exposed on the twigs of birch, heather, etc. 

 (Image). The males fly best on bright, sunny, and not too windy, 

 days at the beginning of April (Jeffrey). The female sits quietly 

 on the heather in the sunshine whilst the males are on the wing, 

 but one male was found sitting low down in the heather, and 

 another on the bole of a birch tree in Tilgate ; the females are 

 rarely found before the males have been out in the same localities 

 for a week or more (Andrews). Home records a female 

 resting on a juniper bush in the Blackall Wood, Kincardineshire ; 

 and Norman the males in great abundance in the Aityre woods 

 in 1868, whilst a 5 was taken sitting quietly on the bare birch 

 twigs in April. Riihl observes that, in the Zurich district, the male 

 flies wildly by day, the female sits at the foot of beech trunks or 

 on bushes ; whilst Nolcken says that the males fly in the afternoon, 

 the ?s at night, the latter about dwarf birches for the purpose of 

 oviposition. The insect appears to be much more abundant in some 

 years than in others. Peyerimhoff observes it as usually rare in 

 Vendenheim Forest, but abundant in 1865, and Snellen records it 

 as very common in 1888 at Apeldoorn, whilst Hofmann notes 

 the uncertainty of its appearance at Stuttgart — for jo years, he 

 says, it was sought in vain, and then, in i860, Hahn found a brood 

 of recently hatched larvae on a young birch. Bankes says that the 

 species can be inbred for a few years, but that, without the 

 introduction of fresh blood, the moths gradually dwindle in size 

 and become less fertile. 



Habitat. — Open woods, plantations, moors, hillsides and sea- 

 side sandhills, among small trees of birch and alder in the various 

 Scotch localities (Reid) ; in Rothiemurchus Forest, on the little 

 birches, the defoliated twigs betraying the presence of the larvae 

 (Morton) ; common in the Aityre wood and among the stunted 

 birches on the Culbin sands (Home); among the alders at Rannoch, 

 but among the young birches at Forres and on the Culbin sandhills 



