82 THE CANADIAN ENTOMOLOGIST. 



In turn, the third generation was allowed to parasitize numerous 

 hosts from moths in confinement during the isl of October. As formerly, 

 the dark and light specimens were intermating. The resulting fourth 

 generation emerged on Oct. 14th, consisting of 25 specimens, including 

 5 males and 7 females of the black variety. 



Eight males and 16 females of the fourth generation parasitized on 

 Oct. 14th hosts from the field. The resulting fifth successive generation 

 began to appear on Nov. 2nd, when a single specimen emerged. Others 

 emerged at intervals up to Nov. 15th. There were 4 females, 3 males, 

 plus 7, all the dark variety. Three females and two of the males were 

 totally black, one male dark, and the remaining specimens were dusky. 



A supplementary fifth generation was obtained from a single black 

 female of the fourth generation, which parasitized five hosts on Oct. 14th. 



The 9 descendants of this black variety were all black; there were 

 5 males and 4 females. They appeared on Nov. 7, and later. 



Because of the lateness of the season, the parasites began to hiber- 

 nate, and the work was discontinued. As it became colder the proportion 

 of black individuals increased. 



During October and early November pretiosa reared from hosts 

 collected from the leaves of corn, included many dark specimens. In 

 fact, the majority were moderately dark, a few entirely black, while many 

 were gradations, having the abdomen only black. Three specimens 

 issuing on Nov. 4th from a single host egg from the field, were similar in 

 colour, the head and thorax yellow, the abdomen black. Thus the varia- 

 tion was not confined to the individuals kept in confinement. It appeared 

 to be quite general. The variety may be named as follows : 



Trichogramma pretiosa, Riley, var. nigra, n. var. 



Like the type. The whole body uniformly black, excepting the 

 antennae, eyes, legs and wings. Gradating specimens of all degrees 

 present. 



From many males and females reared from the eggs of Heliothis 

 obsoleta, Fabricius, at Paris, Texas, during September, October, and early 

 November, 1904, in connection with the Cotton BoUworm Investigations, 

 Bureau of Entomology, U. S. Department of Agriculture. Preserved 

 specimens in balsam, therefore no type. 



