474 Bulletin No. 116. lAugust, 



ment of the pupa is rather narrowly truncate, with a small slender 

 spine on each side of the truncation, and a shorter one beneath each 

 of these. 



Considerable numbers of another species of parasitic larva were 

 taken by Mr. Kelly at Elliott, 111., August 29 and September 20, 



1906. These were evidently white-grub parasites, as the remains of 

 the grubs were still clinging to several of them. This species is still 

 in the larval stage at this writing. 



Three yellow coarcate meloid larvae were also found by the same 

 assistant in an infested oats field with the remnants of white-grubs 

 attached to them, and another was taken in a similar condition Oc- 

 tober ID. These specimens have not yet matured. 



Pyrgota undata Wied. — One of the most interesting parasitic 

 enemies of the white-grubs is a large, rather unusual-looking fly of 

 the family Ortalida, noticed by Mr. J. A. West, an assistant of my 

 office, as abundant among the beetles at night. Now and then May- 

 beetles were seen to drop to the earth, trying to rid themselves of the 

 adult flies which were clinging to their backs, each with the last 

 segment of the abdomen thrust in between the wings and wing- 

 covers of the beetle and firmly held in place over the middle of the 

 abdomen. The flies were apparently thus thrusting their eggs into 

 the backs of the beetles through the thin dorsal skin beneath the 

 wing-covers. The tip of the abdomen of the female fly is admirably 

 adapted to this object, being hard and subconical, and directed down- 

 wards at a right angle to the axis of the body. 



The relations of these insects were experimentally determined 

 by confining, June 9, 1906, adult May-beetles in a breeding-cage 

 with several of the flies. These would light on the backs of the 

 feeding beetles, which would at once drop to the ground with the 

 flies clinging to them. Whenever a beetle spread its wings for flight 

 the insect on its back inserted the tip of its abdomen between the 

 May-beetle's wings, evidently depositing an &gg in its back. Beetles 

 so treated lived for some days, and then began to die. On the 27th 

 of June, five of the beetles were dead, and in the bodies of two of 

 these, dipterous maggots were found. July 10, three of the beetles 

 contained each a dipterous puparium, which remained unchanged 

 until May of this year, when all produced adults of P. undata. Au- 

 gust 29 and September 20, 1906, several puparia were found in the 

 bodies of dead May-beetles, and these, kept in breeding-cages 

 through the winter, produced adults of P. undata May 14 and 17, 



1907. Like experiments begun during the present year have pro- 

 gressed similarly to the time of writing. Adult flies of this species 



