RURALIS BETUL.E. 



305 



and almost obsolete. The fissure on the 8th succeeded by the trans- 

 verse anal flap on terminal segment (Tutt, June 13th, 1893). 



Time of appearance. — This is no doubt the latest in its time of appear- 

 ance of all our British "hairstreaks," not that late examples of Bithys 

 quercus do not often keep it company, or even occasionally outstay the 

 first-emerging examples of the early autumn ; but its average time of 

 emergence is later than that of B. quercus, and its usual time of appear- 

 ance over a series of years distinctly so. One rarely sees it, except in very 

 early seasons, in nature until early August, and usually in our Kent woods 

 not before mid- or even late-August. In late seasons it is to be found 

 throughout September and on into early October, but the average time 

 is from mid- August to mid- September, and the average individual life 

 extends probably to about three weeks. In the valleys of the Alps, in 

 the Yal d'Herens (about 3500 ft. -4000 ft. elevation) we found it in 

 mid-August ; in the Visp-Thal (also at about 4000 ft.) it was in fine 

 condition at about the same period ; whilst in the Digne district it was 

 out throughout the first three weeks of August, 1906 ; and in the 

 Verdon Valley, at some 5000 ft. elevation, mid-August again found 

 it just emerging. At the foot of the Grand Saleve it was commencing 

 to appear at the end of July, 1904, so that from 2000ft. -5000ft. 

 there would appear to be little difference in the time of its appearance 

 in the Alps of Central Europe. Doubleday observes (Ent., iii., p. 35) 

 that " Lewin, after describing the larva and pupa of Ruralis betulae, 

 says : ' The $ butterfly appears on the wing about the middle of 

 August, the 2 is nearly fourteen days later before it comes from the 

 chrysalis,' " and adds that he has " repeatedly proved the accuracy of 

 this statement." Glaser also says that, in Germany, the $ s are the 

 first to emerge, and during the later part of its emergence-period $ s 

 are much more frequently observed. Our experience in Britain is 

 somewhat similar, and the records of examples bred in confinement 

 bear out the general statement, although appearing (as is usual under 

 artificial conditions) rather earlier than in the woods. The following 

 tabulated records by Adkin (1893) and Wood (1896-1905), bear out 

 this observation : — 



1893 









S 



S 



July 16 



2 





„ 18 



4 





„ 20 



3 





„ 21 





1 



„ 23 



1 





,, 26 



1 





„ 28 





3 



„ 29 





1 



,, 30 





1 



Aug. 2 





2 



,, 3 





2 



„ 4 





1 



- ,, 9 





1 





11 



12 

 : 



1896 



July 26 

 ,, 28 

 ,, 29 

 „ 30 

 ,, 31 



Aug. 1 

 „ 3 

 „ 4 

 „ 5 

 ,, 7 



<? I ? 



1618 



1901 



July 



Aug, 



28 



30 



31 



1 



2 



3 



4 



5 



6 



7 



11 



14 



rf ? 



18 



39 



1902 



Aug. 8 



„ 9 



„ 10 



,, 12 



,, 15 



„ 21 



,, 25 



1905 



23 





J 



2 1 



July 23 





2 



„ 24 



1 





,, 25 



1 





„ 26 



4 





„ 29 



1 



1 



,, 30 





2 



., 31 





1 



Aug. 1 



1 





)5 - J 



1 





„ 3 





1 



„ 4 





4 



,. 5 





1 





9 



12 



