May, '05] ENTOMOLOGICAL NEWS. 145 



Parasitic Hymenoptera of Algonquin, Illinois. I. 

 BY WM. A. NASON, M. D. 



The subjoined list of the Ichneumonidse is the first of a 

 series, in which I record as far as is now possible, my captures 

 of the Parasitic Hymenoptera of Algonquin, Illinois. It has 

 proved a very prolific collecting ground for these insect forms 

 as my lists will show. 



A short account of the locality will be of value in elucidat- 

 ing the character of this collecting field for exploration. In 

 my notes on a collection, made here, of Micro-L/epidoptera, 

 recently published in the ENTOMOLOGICAL NEWS,* I stated that 

 the locality has some peculiar faunal relations. But it has 

 local features equally interesting and important biologically. 

 The village is situated in a triangular valley where a small 

 stream enters the Fox River. It is a valley of erosion, 

 bordered by high bluffs which come close to the river banks 

 except in the triangular delta mentioned above. The bluffs 

 are about one hundred and thirty feet above the level of the 

 Fox River, and in many places are wooded with black, red, 

 white and burr oaks, with an occasional bass-wood and maple 

 trees interspersed with hickory and black walnut. Back of 

 the bluffs the country is a typical rolling Illinois prairie. 



Algonquin is in the centre of the northern Illinois dairy 

 region, and for this reason the original prairie vegetation and 

 the undergrowth of the woods have been largely destroyed by 

 the numerous herds of grazing co\vs which exist in this neigh- 

 borhood. This fact is a prime factor in making this insect 

 fauna peculiar. The food-plants of the species having been 

 largely destroyed by causes stated above, the surviving insects 

 are necessarily those which can adapt themselves to the exist- 

 ing vegetation and physical conditions. And this makes the 

 present lists especially valuable, as during the next ten or 

 twenty years there must result a great modification of the 

 surviving forms of the present fauna and also result in the 

 creation of new forms and a possible new fauna more adupu-d 

 to the future modified conditions. 



* For January, 1905, page i. 



