496 Journal of Agricultural Research Voi. xviii. No. 9 



upon which to oviposit because of the emergence of Calosoma sycophanta 

 from hibernation. The summer generations issuing in July and August 

 are more abundant than the first generation, but they find comparatively 

 few beetles to parasitize because the beetles begin to enter hibernation 

 about July 1 5 and decrease very rapidly in numbers above ground after 

 that date. There is an abundance of flies issuing after this period that 

 must perish for want of a host unless they attack some host other than 

 species of Calosoma or Carabus. This probably accounts for the present 

 limits to the increase of the parasite. 



Additional recorded hosts for this parasite are comparatively rare in 

 the New England section where Calosoma sycophanta abounds. It is 

 difficult to predict the future effect of the species on C. sycophanta 

 since future rarity or abundance of other related hosts may have a great 

 bearing on the subject ; but it is believed that the parasite will not become 

 much more abundant than it is at present. The average of 3.3 per cent 

 parasitism secured from the small collections of C. calidum indicates that 

 the parasite is more effective on C. calidum than on C. sycophanta, upon 

 which the highest parasitism was 3.4 percent, secured in 1916, or an 

 average of i . 1 2 per cent for a period of several years. Should C. calidum 

 by chance become very abundant in eastern Massachusetts and southern 

 New Hampshire where C. sycophanta is now very abundant, the depreda- 

 tions of the parasite might also increase, since a longer breeding season 

 for the latter would be furnished. C. calidum emerges from hiberna- 

 tion in the territory mentioned about May i to 15, and C sycophanta 

 about June i to 15. It is therefore apparent that the two species of 

 hosts which occur abundantly in the same locality might increase the 

 abundance of the parasite materially. 



SUMMARY 



Euhiomyia calosomae has two full generations per year and a partial 

 third under favorable seasonal conditions. The eggs hatch in from 3 

 to 24 hours, the larvae develop in from 9 to 12 days, and the pupae in 

 from 9 to 18 days, making it possible for a generation to develop fully 

 in from 20 to 25 days. 



The first record of the rearing of this parasite in this country was 

 from a specimen of Calosoma calidum in 1896. If one judges from 

 the literature on the species and the small representation of specimens 

 in the collections which were taken with the net, one would infer that 

 the species is rare in the East; but this may be due to the peculiar habits 

 of the adults in the field, which are not well known. The species seems 

 to have attracted little attention between 1896 and 191 2, when it was 

 first bred from C sycophanta, six years after the successful introduc- 

 tion of the latter species into New England. During the seasons from 

 1915 to 1918, over which period a study was made of its life history, 

 the highest parasitism upon C. sycophanta was 3.4 per cent in 1916, 



