276 BRITISH BUTTERFLIES. 



the Chilterns and the Cotswolds, even in such seasons as postpone 

 the emergence of the second brood till well into September. Jeffreys, 

 for instance, observes that in the latter locality the second brood did 

 not appear till September 12th in 1888, while in 1887 it appeared 

 early in August. In Essex it is undoubtedly double- brooded, and this is 

 no doubt the case in the neighbourhood of Worcester, as the dates we 

 possess from that locality extend from July 30th to August 30th, 

 which, considering the dates of appearance in the north of England 

 and in Scotland, must certainly imply an earlier brood, as must also 

 the record for September, 1893, for the neighbourhood of Birmingham. 

 Bath, indeed, who supplies this record, suggests the possibility of a 

 third brood, but although one of the the earliest records we possess 

 is for the same year, the suggestion of a third brood almost on the 

 borders of the single- brooded area must be regarded as untenable. 

 From the borders of Norfolk and Suffolk, at approximately the same 

 latitude, Norgate's records show that the species is double-brooded, 

 for not only has he taken it in May and throughout August in 

 different years, but he records it, in 1884, both for May 27th and 

 August 20th, though the species is scarce in these counties. Further 

 north even than this, the dates of September 3rd from Allington, in 

 Lincolnshire, and the many dates in late August from the north coast 

 of Wales, leave little doubt of an earlier emergence at this latitude 

 also, and under these circumstances it may be regarded as probable 

 that the appearance of the species in Dovedale in the last week in May 

 implies a second brood here also; but beyond this line all the evidence 

 points to a single brood only. Even in such early seasons as 1893 

 and 1896, when medon appeared at Witherslack in the last week in 

 May, there is no record which hints at the possibility of a later brood. 

 In the double-brooded area the average time of emergence is about 

 the last few days in May and the first few in June for the first brood, 

 and the first week in August for the second ; though the first brood 

 often appears earlier in May, and we have even records for April 30th 

 (Prideaux) at Beigate, and the last week in April from so far north as 

 Swansea (Bobertson). Similarly, the second brood often appears by the 

 end of July, and, exceptionally, as late as the second week in September. 

 In most seasons, however, the second brood is worn out by the middle 

 of this month, though records of its continuance well into October are 

 not wanting. In the single-brood area in Britain the date of emergence 

 varies somewhat as we advance north, and to a greater extent with the 

 season. In its north Lancashire and Westmoreland haunts, Wither- 

 slack, Grange, Arnside, etc., this species seems generally to appear in 

 June, earlier or later according to the season, and to last till the middle 

 or end of July ; we have found no record of August for these localities, 

 but, on the other hand, in 1893 and 1896 it was taken on the 26th 

 and 28th of May respectively. Harrison states that in Durham it 

 emerges the first week in July and continues on the wing for a month, 

 and that in Scotland the second week in July is the usual time and 

 that it continues flying for eight weeks. This however is subject to 

 considerable variation, since he states that the species was out ten days 

 earlier in 1906 than in 1904, and we have a record from Bannoch of 

 June 27th. This variation in the time of emergence in Durham is 

 connected with one or two remarkable circumstances, related by 



