THE INHERITANCE OF WING-COLOUR IN 

 LEPIDOPTERA. 



VI. DIAPHORA MEN BIG A CL. AND VAR. RUSTIC A HB. 



By H. ONSLOW, 



Trinity College, Cambridge. 



(With Ten Text-figures and Plate XXVII.) 



The inheritance of several melanic varieties has been dealt with in 

 some recent papers, the melanic character being found as a rule dominant 

 to the type form. In the case of Odontopera bidentata and of Abraxas 

 grossulariata (var. varleyata), the black variety behaves as a recessive. 

 The first insect has no doubt a true melanic form, but in the case of 

 varleyata the existence of the white collar at the base of the wings 

 suggests a pattern factor rather than melanism. Melanism as a rule 

 takes the form of a general suffusion with black or very dark scales, 

 the pattern being sometimes so completely obscured that the insect 

 appears uniformly black. 



The subject of this paper, D. mendica (The Muslin Moth), cannot 

 be included strictly among melanics. In England this insect is sexually 

 dimorphic, the male being dark brown or black, with a number of dis- 

 tinct black spots of very variable size, the female pure white with similar 

 spots (see Nos. 1, 2 and 11, 12, PI. XXVII). In Ireland, however, there 

 is a race, the males of which are nearly as pale as the females, but of 

 a creamy shade rather than dead white (see Nos. 9 and 10, PI. XXVII). 

 This race, var. rustica Hb., is also found in the Caucasus, Hungary, 

 Roumania, Silesia and Armenia. Experiments have already been carried 

 out in crossing the variety with the type form, by Caradja\ Standfuss^ 

 Tutt^ Adkin^ and recently by Cockayne^ Tutt found, as did Caradja, 



1 Societasentomologica, Zurich, Vol. ix. No. 7, p. 49, 1894—5, and Vol. x. No. 7. p. 49, 

 1895—6. 



- Standfuss, Handbuch palnarkt. Gross-SchmetterUnge, 189(5, p. 223. 



^ Tutt, J. W., British Lepidoptera, Vol. v, p. 45. 



* Adkin, R., Entomologist, Vol. xxx. p. 206, 1897. 



5 Cockayne, E. A., Ent. Record, Vol. xxxi. No. 6, p. 101, June 15, 1919. 



