SIX-SPOT BURNET. 341 



probably not exceeding half a dozen altogether, have been 

 recorded as taken in England. In typical Jilipe?idid(B the 

 dark blue border of the hind wings is narrow, but in ab. hippo- 

 crepidis, Stephens {tidii, Rebel), the borders are rather broad. 

 Another character of this form is that the nervule upon which 

 the sixth spot is placed is here of the ground colour, and 

 therefore divides the spot. (Plate 147, Fig. 3.) At Northwood, 

 Middlesex, I have found this form in May and June, and also 

 in the Weybridge district, Surrey, in late July ; and, it may be 

 added, there was a flourishing colony of Z. trifolii hard by in 

 each locality. For this reason, plus the fact that trifolii ^ is 

 known to pair with filipendulce ^ > I hold the opinion that 

 hippocrepidis is a hybrid. It may be noted here that hybrids 

 have been raised from the crossing oi Jilipe7tdulcB and lonicercB ; 

 the sexes of lonice)-ce and trifolii pair somewhat readily, and 

 the hybrid offspring of such pairings are fertile. 



It seems, then, that trifolii^ lonicercB^ dSidi fill pen didce have 

 not, so far, lost the power of fertile cross-pairing. Wherever 

 colonies of two of the kind exist within visiting distance of each 

 other, there, it appears, we may reasonably expect to find hybrids. 



From a number of cocoons collected in a Yorkshire locality 

 for lonicercB, I reared, in 1907, a good many examples of that 

 species, and also about a dozen six-spot specimens, which agree 

 in colour with filipetidulce^ but they have the vein-interrupted 

 sixth spot and broad border to hind wings, as in hippocrepidis. 



The caterpillar (Plate 145, Fig. 4) is greenish, with black 

 markings and some yellow spots, the latter chiefly on the hind 

 edges of the rings. It feeds in the autumn and after hiberna- 

 tion, on trefoils, clover, bird's-foot {Or?tithopi(s), and kidney- 

 vetch {A 71 thy I I is), completing growth in the spring. 



The moth flies on sunny days in July and August, on chalk 

 downs, etc., inland, and on cliffs and sand hills on the coast, 

 also in marshes ; but, as previously stated, it also occurs locally 

 in meadows in May and June. 



