67 



When working the Zygaenids, one very often finds two species 

 flying together, and pairing often takes place between distinct 

 species ; but in the majority of instances the resultant ova are 

 infertile. Still there are records of hybrids having been successfully 

 reared. The following species have been found in cop : — 

 fiUpendulae $ x achilleae J . 



do. X ephialtes. 



do. X lonicerae. 



do. X hi/ipocrc/iidis (? ticntsalpina). 



do. X 111 inns. 



do. X trifolii. 



Hybrids were most successfully obtained by W. H. B. Fletcher, 

 who obtained fertile crosses between tilipendidae x lonicerae and 

 trifolii X lonicerae ; with the former, fertile ova were produced and 

 successfully reared, but on these being paired only infertile ova were 

 produced ; as a result of the latter pairing, not only were the hybrids 

 reared, but these on being paired produced fertile ova. On several 

 occasions Fletcher obtained pairings between filii>eiidiilae x trifolii, 

 but in every case the result was infertile ; and he states that he 

 doubts whether this cross would ever give fertile results. However, 

 in 1920,1 obtained three such pairings, with the result that two of these 

 produced infertile ova, but those from the remaining pair were fertile. 

 The latter I divided with Mr. Tonge and we were both successful in 

 rearing imagines. Two pairings of these hybrids were obtained, but 

 both were sterile. The hybrids produced were curious. It is usual 

 in trifolii and in filipendiilae, that when the former produces a six- 

 spotted race it is ahvays the female that first acquires the sixth spot, 

 and it is not until this feature has become plentiful that one finds 

 any males bearing the sixth spot. Although there has not been 

 found in England a colony of trifolii showing this aberration, it has 

 been noted on the Continent. In fdipendnlae it is always the male 

 that first loses the sixth spot, and it is by no means rare, especiall)'' 

 on the North Downs, to find filipendiilae with this spot greatly reduced, 

 although I have never actually found it absent. In the hybrids the 

 result was the opposite, 50% of the males had the sixth spot 

 developed in varying degrees, the remaining 50% were five- 

 spotted ; but in the females there is no trace of the sixth spot. On 

 .three or four occasions I have found on the same ground where 

 the pairings were obtained, males with this sixth spot, which might 

 possibly be wild hybrids. It is of course impossible to dift'erentiate 

 the females, as they are not to be distinguished from the true species. 

 Cross pairings may be readily obtained between the early form of 

 filipendiilae and the late or true filipendiilae, and as the emergence 

 of these is extended it is always possible to obtain late examples of 

 the early form, and early examples of the late form. These, if put 

 together, will pair quite readily. 



In regard to the early form of filipendiilae, which Tutt considered 



