204 KATHARINE FOOT AND E. C. STROBELL. 



DESCRIPTION OF PLATES. 



In all cases only the ventral surface of the bugs is shown. The specimens in 

 photos 2 to 6 are preserved in glycerine. The genital segment of each bug has 

 been pulled out and cotton inserted behind the segment to hold it in position to 

 show the entire ventral surface. The bugs are magnified about ij>2 diameters. 



The photographs are reproduced by the half-tone method which, unfortunately, 

 is not entirely satisfactory for showing the delicate shades of difference in the in- 

 tensity of the spot. 



Photo i. Euschistus variolarius male, showing the ventral surface and the clearly 

 defined black spot always present on the genital segment of the males of this species. 



Euschistus servus male, showing ventral surface and the genital segment without 

 any trace of the black spot characteristic of E. variolarius males. 



Photos 2 and 3. 8 of 46 males of the F generation raised from a pair of Fi 

 hybrids, which were bred from an E. variolarius female raised in our laboratory, 

 from a pair collected in Connecticut, and an E. servus male collected in North 

 Carolina. Four of these F2 individuals have no black spot on the genital segment, 

 and four show the spot in a greater or less degree. 



Photo 4. 7 of 54 males of the F generation raised from a pair of Fi hybrids, 

 which were bred from an E. variolarius female collected in Connecticut and an 

 E. servus male collected in North Carolina. 



These Fo individuals show the variations, from no spot on the genital segment, 

 to one almost as pronounced as that of a pure variolarius. 



Photo 5. Euschistus variolarius males, showing the typical black spot on the 

 genital segment. 



Photo 6. Euschistus servus males, showing the genital segments without the 

 spot characteristic of E. variolarius. 



