DESCRIPTION. 



37 



SECONDARY SEXUAL CHARACTERS. 



We are indebted to Dr. A. D. Hopkins, of the Bureau of Entomology 

 for indicating the most strongly marked points of difference in the sec- 

 ondary sexual characters of the boll weevil. (See fig. 3.) The dis- 

 tinctive characters are found upon the snout and upon the last two 

 abdominal segments. The differences are subject to some variation, 

 but are still sufficiently constant to enable a close observer with the 

 aid of a hand lens positively to differentiate males from females. 



Female. The snout of the female is slightly longer and more 

 slender than that of the male. When viewed from above it usually 

 appears to taper slightly from each end toward the middle. The 

 antennae are inserted slightly farther from the tip than is the case in 

 the male. The insertion is at about two-fifths of the distance from 

 the tip of the snout to t he eyes. As a rule the surface of the snout is 

 more smooth and shining than in the male. A slight depression, 



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Fig. 3. -Secondary sexual characters of Anthonomus grandis. (From Bind and Yothers, aftei Hopkins.) 



rather elongated and much larger than any of the other punctures 

 upon the snout, occurs between the bases of the antenna 1 . When the 

 wing covers and wings are unfolded the abdomen shows seven distinct 

 dorsal segments. The last segment visible in the female, called the 

 propvgidrum, can be seen only from the sides. 



Mate. — In the male the snout is slightly shorter, thicker, and more 

 coarsely punctured than in the female. The depression mentioned in 

 the female is lacking. The antenna 1 are inserted at practically one- 

 third of the distance from the tip of the snout to the eyes. The sides 

 of the snout are very nearly parallel. In the abdomen the male shows 

 eight distinct dorsal segments, the terminal segment (pygidium) not 

 bemg covered by the propygidium as is the casein the female. 



In general practice an examination of the beak is sufficient to deter- 

 mine the sex of each weevil. 



1 This discussion id modified from Hull. 77, Bureau of Entomology, pp. 91, 92. 



