INFESTED MALE CUCUMBER BEETLES 



351 



vaguely cephalated, and at their cephalated ends are a little wider than anywhere 

 else. They taper rather regularly to the blunt distal ends. There is a short, sim- 

 ple, narrow, refractive gubernaculum, about one-third as long as the spicula. No 

 definite ribs or special papillae have been seen on the tail, or in front of the anus. 

 The wings project sufficiently so that the cross section of the nema in the vicinity 

 of the anus must be thrown out of dorso-ventral symmetry considerably. The pos- 

 terior extremity of the male is more or less helical, and, oppo- 

 site the anus, the somewhat raised wing occupies nearly one- 

 fourth the corresponding width of the body. The contour of 

 the wing is almost imperceptibly and very finely crenate, the 

 corresponding annules of the cuticle here averaging about one 

 micron. 



Habitat: Garden soils near cucurbits, and especially near 

 eggs and very young larvae of D. vittata; widespread. The 

 spherical and refractive intestinal granules hinder an examina- 

 tion of other anatomical and histological features. 



Possible transfer of nemas by beetles in copula. 



Males and females of D. vittata were gathered and examined 

 for their nematization with H. benigna. Of 15 females, 7 were 

 infested; 8 not infested. Of 29 males, 17 were infested; 12 not 

 infested. Roughly speaking, therefore, there was a 50 per cent 

 nematization, of which each sex had about half its individuals 

 nematized. This seemed a suitable case to scrutinize with re- 

 gard to the transfer of larval Howardulas from the male beetle 

 to his mate. 



Of 19 infested males, 7 had nemas in the genitalia, the 

 number of nemas varying from 1 to 14. The nemas seemed to 

 tend to gather in the distal end of the genitalia, though found 

 in all parts. 



Following up this observation, beetles in copula were gath- 

 ered and the females examined. If the female was infested in malTcucumb7rl:>eetle* 

 the body cavity, she was not further examined; if not infested tst, testis; gl, glands, 

 in the body cavity, then her more external genitalia were scru- Note nemas in cavity 



,..,., , u-T-Tr j uu j j. f genitalia, genit 



tinized for larval nemas, which, if found, could be assumed to ( w hite) and ros 

 have been placed there by the males with which these females (black)'. Nemas seem 

 were known to have copulated. less abundant in male 



Examination of 13 such non-nematized females disclosed no ge 

 larvae of Howardula in the distal genitalia. This might seem to indicate that 

 such transfer of Howardula larvae from male beetle to female was improbable. 

 On the other hand, no sperms were found in these females, although they were pres- 

 ent in all the males examined. The fact that no sperms were transferred to the fe- 

 males seems to indicate that the copulation was a mere gesture, which did not 

 result in fertilization. The females were not yet at the egg-laying stage, as was 

 indicated by the condition of their ovaries. In only one female examined dur- 

 ing the whole of these examinations was an egg found lower down than the 

 ovaries. This egg was in an infested female and had two or three nemas on its 

 surface; the egg was in the oviduct. This experiment should be repeated. 



nan 



Fig. 7. Gonads of 



