June, 1907.] GiRAULT : TrICHOGRAMMA PRETIOSA RiLEY. 



59 



sented (lots No. 5, 6, 10, 11, 12, 14, 16, 18 and 33); the sexes vary in 

 relative numbers, but are about equal on an average. In four cases 

 not given in the table, however, hosts collected from the field Sep- 

 tember 27, three parasities issued from each, the proportion being one 

 male to two females, a total of four males and eight females. From 

 eight eggs of Alabama argillacea Hiibner, collected in late October 

 from cotton plants, the females generally exceeded the males in num- 

 ber, thus : 



As to the relative time of issuing of the sexes, it appears that there 

 is little or no difference. For example, from a lot of • host eggs par- 

 asitized on June 22, there issued between i and 2 P. M., June 30, 2 

 males and 3 females; at 3 P. M., 3 more females had emerged, and 

 from that hour on both sexes appeared at intervals for some hours. 

 Between the hours of 2 and 3 P. M., June 27, 2 males and 2 females 

 issued from a single host ; from 6 to 8 A. M., October 4, 2 males and 

 6 females appeared from 3 hosts parasitized at the same time, and 

 again from a single host, there issued simultaneously at 3 P. M., June 

 27, 2 males and 2 females. In the genus Anaphes of a closely re- 

 lated family of egg-parasites, it is indicated that the relative issuance 

 of adults is about the same as in Trichogramma, whereas in Te/enomus, 

 more remote, relative issuance of the sexes is more regular, the males 

 preponderating for the first day or so, then the females becoming the 

 more numerous. 



3. Size not Indicative of Sex. — As a rule the females are larger than 

 the other sex, but this cannot be relied upon to distinguish them, as 

 sometimes the reverse is the case. From a large series of measure- 

 ments, the following table is adduced, showing the range in size and 

 general average for each sex. 



