1916 



ENTOMOLOGICAL SOCIETY 



141 



One may judge from these statements that the fly was not so serious as usual, 

 but, nevertheless, under such a degree of prevalence it was found that large numbers 

 of eggs were laid, as indicated in the following table : — 



Table A — Enc. DKrosrrinx Recoud. 



Another answer is that of the control by parasitic insects. On several occa- 

 sions the Cynipid parasite Cothonaspis gillettei has been bred from puparia col- 

 lected in the field. Unfortunately we cannot, from our study up to the 

 present time, consider this parasite of any practical benefit in the control of the 

 fly at Agassiz, B.C., its numbers are shown to be entirely too few. From the 

 large numbers of puparia that have been taken and studied this past summer, only 

 twelve Cynipid adults appeared. They started to emerge from puparia on i^ugust 

 16th and continued until October 18th. Further, there is little doubt that some 

 carry over the winter within the puparia of the maggot to emerge in the spring. 



Except for tliis Cynipid parasite, no other true parasite has been observed or 

 recorded in British Columbia. 



The third answer to the above question, and probably the most important, is 

 the control by predatory insects and mites. 



Red Trombidium Mite. 



A Eed Ivlite may very commonly be found on the surface of the soil in the 

 vicinity of cruciferous plants. It has been shown by laboratory experiments that 

 this mite will attack the eggs of the Cabhage Maggot fly. Several investigators 

 liave sho\ni mites of this nature of great importance in the natural control of the 

 fly, but our studies at Agassiz do not show that it is of such importance and not 

 comparable in usefulness to certain Carabid and Staphilinid beetles. 



Several Staphylinids are of importance, notably : 



Orus pu7ictaius Casey. 



XanthoUnus hamatus Say. 



Hisperobium califoiiiicuni Lee, 



* (Cabbages and Cauliflowers transplanted on May 18th and 14th) 



