March, 1893.] 53 



NOTES ON SOME EXPERIMENTS IN HYBRIDISINa BUENET MOTHS 



(ZYGMNM). 



BT W. H. B. FLETCHER, M.A., P.E.S. 



On page 115 of Yol. xxvii of this Magazine is a record of my 

 having shown at a Meeting of the Entomological Society some hybrids 

 between Zygoena lonicerce and JlUpendulce reared in 1889 and 1890. 

 These were intermediate in markings between the parents. Some of 

 the males show only a slight trace of the sixth spot when examined 

 with a strong lens, while some of the females have it as well developed 

 as it is in typical Z. JlUpendulce. They are the largest Burnets I have 

 bred, one of them having an alar expanse of 40 mm. Not having 

 learnt the best way of keeping the larvae during the winter, I only 

 bred about a dozen moths in each year, so was not plucky enough to 

 waste many in attempts to carry on the broods for another year. Two 

 pairings, however, were obtained, but none of the eggs laid hatched. 

 Still, judging by experience with other crossed and uncrossed eggs, 

 I do not feel justified as yet in assuming that the cross between these 

 two species is always sterile. 



More recently I have experimented with Z. lonicer<s and trifolii, 

 and in 1891 and 1892 succeeded in rearing a fair number of both the 

 crosses obtainable between them: lonicerts ^ — trifolii $ z^ndL trifolii 

 ^ — lonicerce $ . Unlike those mentioned above these hybrids laid 

 fertile eggs, and I had, in 1892, the satisfaction of getting specimens 

 of the following crosses : hybrid (^ — trifolii $ , lonicerce ^ — hybrid ? 

 and hybrid ^ — hybrid ? . At the present time I have hibernating 

 larvae with the following pedigree : — 



trifolii $ lonicercB 2 trifolii $ trifolii ^ 



I I I _l 



I I 



hybrid 1890 ? lonicerce $ lonicercB ? trifolii $ 



I I I I 



I I 



hybrid 1891 i hybrid 1891 ? 



hybrid 1892 (now larvae). 



These results seem to prove that the fertility of crosses between 

 Z. lonicerce and trifolii is fairly complete. These two species also 

 pair readily, thus contrasting with the unions of Z. filipendulce and 

 lonicerce, of which I could obtain but one or two pairings out of 

 several dozens of moths set aside for that purpose, while the single 

 couplings obtained between Z. filipendulce and trifolii, and between 

 the former and lonicerce-trifolii hybrids, failed to produce fertile eggs. 



Among the last-named hybrids there is a strong tendency to re- 



F 



