JOURNAL 



pptD ]9oFh Clnl^oraologiral HoripH^g. 



Vol. XV. JUNE, 1907. No. 2 



Class I, HEXAPODA. 



Order I, HYMENOPTERA. 



NOTES ON TRICHOGRAMMA PRETIOSA RILEY. 



By a. Arsene Girault, 

 Washington, D. C. 



I. CopulatioJi. — Daring the early morning of June 14 (8 A. M.), 

 many adults of this little parasite issued from host eggs and were at 

 once confined under a suitable glass jar. At 10 A. M., observation 

 showed that the males were running very actively among the females, 

 fertilizing them. Both sexes were freely mixed and active. During 

 the act of copulation, the female is almost a passive agent ; she often 

 struggles, however, to rid herself of the male. The latter is very per- 

 sistent in his advances, and is also polygamous, — one has been ob- 

 served to unite with three females in succession. Sometimes a female 

 is besieged by several males, at which time there is a fierce struggle 

 for possession. Again, a male may unite with the same female twice 

 in succession, with an interval of but two or three seconds between. 

 The copulation is normal for the Hymenoptera, but the position as- 

 sumed by the male is peculiar. After seizing the female, he takes an 

 inclined position, leaning far back at an angle of about sixty degrees, 

 the tip of the abdomen well under the venter of the female and curved 

 up between her posterior legs. The act lasts for about three and a 

 half seconds. The pair may be motionless or running about. Copula- 

 tion generally follows soon after emergence, but may be delayed. On 

 the part of the females, it is almost immediately followed by oviposi- 

 tion. 



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