INHERITANCE OF COLOUR IN DIAPHOKA MIONOICA. 



101 



Inheritance of Colour in Diaphora mendica, CI., and 

 var. rustica, Hb. 



By E. A. COCKAYNE, D.M., F.K.C.P., F.E.S. 



In 1913 I started breeding experiments with Dia/ihora itiendica type 

 and var. rustica, with a view to proving the presence or absence of 

 segregation of colour in the males in subsequent generations. 



Unfortunately the war prevented me from carrying them out 

 fully, bat I think the results obtained were sufficiently interesting to 

 be worth publishing. The well-known cream coloured form of the 

 male, v&v.j-iistira, appears to be the only one found in Ireland. In 

 Great Britain the dark brown type form is aliuodt universal, but pale 

 coloured males have been recorded from the east coast of Scotland and 

 I have seen one from Kent. 



• My original stock of var. rnatica was obtained from Captain E. S. 

 Gwatkin-Wdliams, K.N., who sent me three dozen larvte bred from 

 eggs laid by a female taken near Queenstown in 1911. These did 

 well and I obtained a number of pupas from a pairing inter se. 



In the autumn of 1912 I received a number of pup® from Durham, 

 Suffolk and Somerset. The males of the first two broods were 

 poorly spotted and not very dark, but the Somerset males were very 

 dark brown and both sexes were heavily spotted. 



The pupae were forced and imagines began to emerge on February 

 21st, 1918. At first I had great difficulty in obtaining a cross pairing, 

 but later on I experienced no difticulty and obtained seven cross pairings, 

 four var. rustica S X type J (2 Durham, 2 Taunton) and three type 

 3 xvar. rustica J . I also obtained five pairings of var. rustica. All 

 the ova proved fertile, and the larvte throve until they were nearly 

 full grown. Disease then appeared and the majority died. At the end 

 of the season I had 35 pupte of Brood I. and 117 of Brood II. , both 

 var. rustica 3 X type $ (Durham), 20 pup^e of Brood III. type 3 

 (Durham) x var. rustica 5 , and only 17 pure bred var. rustica, two 

 broods giving only one pupa apiece. 



This shortage of pure var. rustica prevented me from obtaining 

 pairings with the cross-bred insects in 1914. The pure bred rustica, 

 in spite of the close inbreeding for three generations remained very 

 pale cream coloured in the male sex, and showed no increase in brown 

 colour such as has been stated to occur. A single specimen showed 

 very pretty clouding of the outer and lower part of the forewing and 

 of the posterior half of the hind wing with greyish- brown scales. 



In 1915 emergence of the cross-bred var. standfusd (F.l) began on 

 March 5th, and 1 obtained pairings without difficulty. I had eggs 

 from SIX pairings, two S var. staudfussi (Brood II.) x ? var. standfnssi 

 (Brood II.), one 3 var. staudfussi (Brood III.) x ? var. standfussi 

 (Brood 111.), one 3 var. standfussi (Brood 11.) x 2 var. standfussi 

 (Brood I.), and one pure var. rustica. All the ova were fertile. To 

 avoid risk of loss I sent a number away to friends, but all contracted 

 disease and died. Those I kept myself did well until June, when 

 many were nearly full grown, but eventually I obtained only ten pupae 

 (F.2) of Brood IV., 3 var. stMuifusd (Brood 11.) x ? var. standfussi 

 (Brood II.). 



The appearance of the males of the first generation of var. 

 standfussi is stated to be intermediate in colour between the males 

 June 15th, 1919. 



