RESULTS OF CEOSSING EUSCHISTUS VARIOLARIUS AND E. SERVUS. 



337 



Results of Crossing Euschistus variolarius and Euscliistus servus with 

 reference to the Inheritance of an Exclusively Male C-haracter. By 

 Katharine Foot and E. C. Strobell. (Communicated by Prof. 

 E. B. PouLTON, F.E.S., Pres.L.S.) 



(Plates 28-34, aud 2 Text-fig-ures.) 



[Bead 5th March, 1914.] 



EuscMisTus vAEiOLABius bas an exclusively male character which is not 

 present in Euschistus servus, and it was the hope of being able to study 

 the transmission of this character, and its bearing on modern chromosome 

 theories, that led us to attempt to cross these two species *. 



This specific character is a distinct black spot on the male genital segment 

 of E. variolarius, and as there is no spot on the genital segment of the female 

 (text-fig. 1), this spot in E. variolarius is an exclusively male character. 



Fiff. 1. 



"ST 



Euschistus variolarius 5 • A compsirison of this sketch with the male variolarius of 

 photo 1 (PI. 28,), will show the marked difference in the form of the j^enital segment 

 of the two sexes, and will demonstrate that the genital spot characteristic of the male 

 could not appear in the female without a moditication of the entire genital segment. 



The two species {variolarius and servus^ are shown in photo 1 (PI. 28). 

 On the left is a male variolarius, and on the right a male servus. The spot 

 on the male genital segment of variolarius is clearly demonstrated, and the 

 complete absence of such a spot on the male genital segment of servus is 

 clearly shown. This spot in variolarius is a constant character : it appears as 

 distinctly in all the males of this species as in the seven specimens shown in 

 photo 2. Five male specimens of E. servus are shown in photo 3 (PI. 30). 



The difficulties involved in raising Hemiptera in captivity are serious. 

 For five consecutive summers we have experimented raising several species 



* The E. variolarius 5 used for the cross-breeding experiments was raised in our 

 laboratory from material we collected at Ridgefield, Connecticut, and the E. servus were 

 collected at Southern Pines, North Carolina, by Rev. A. H. Manee. 



