CHARLES W. HOOKER. 35 



In describing this species I have compared numerous speci- 

 mens with the descriptions. 



Type. — 9 d^. Location unknown to me. 



This species is readily recognized by the small eyes, broad 

 face, abdomen not strongly compressed and discocubital vein 

 generally not appendiculate ; there is the usual variation to- 

 wards the light and dark forms. Brull6's type was evidently 

 one of the lighter forms in which the head, thorax, and some- 

 times the legs and first abdominal segment are light fulvous, 

 the rest ferruginous ; the dark forms are entirely ferrugin- 

 ous, and between these are all sorts of gradations. The 

 thorax is sometimes marked with black, and O. bifoveolatus 

 nigrovarhis is evidently an extreme case of this. 



Distribution. — This species is generally distributed through- 

 out the United States, ranging from southern Canada to 

 northern Mexico. 



Specimens have been taken in Ottawa, Canada ; Mt. Wash- 

 ington, N. H. ; Pennsylvania ; California ; Illinois ; Montana, 

 and many intervening localities. 



Life history. — This species is one of the most common of 

 the genus and well represented in collections ; this is partly 

 due perhaps to the fact that it seems to be diurnal, and not 

 crepuscular or nocturnal as is the case with some closely 

 related forms ; in the Cornell trap-lantern experiments very 

 few specimens, compared with the newly related O. bilineatus 

 Say, were taken. The adults usually appear about the mid- 

 dle or last of May and early in June, but specimens have 

 been taken in Massachusetts as early as May 4 ; at Ottawa, 

 Canada, May 30; at Palo Alto. Cal., March 25; and in Illi- 

 nois, March 11 and April 27 to September 1. They are prob- 

 ably most abundant in June and July, but Prof. Forbes states 

 that in Illinois they emerge in breeding cages from March 

 31 to April 27. Little is known of its life history, but it is 

 somewhat peculiar in being parasitic upon white grubs — the 

 larvae of Lachnosterna hisca and probably of other species. 

 In one case the head and skin of a grub were woven into the 

 wall of the cocoon of the parasite. A specimen in the Massa- 



TRANS. AM. ENT. SOC, XXXVIII. 



