18 



call them "willow-bugs", as the full-grown nymph crawls up on the 

 trunks of the willo^\ s of the flooded bottoms to cast off the pupa skin 

 and emerge as adult. The tree trunks are often covered with these 

 exuviae. The adults fly actively about at night, and their numbers 

 are so great that the heaps of dead willow-bugs accumulated under 

 the arc lights have had to be hauled away in wagon-loads. Several 

 species of Bphcmcrida are very numerous in early summer at the 

 Devil's Hole ; they probably form an appreciable element in the food 

 supply of predaceous insects. 



Hexagenia variabilis Say. June 25. 



A rather large May.-fly with yellow wings. Very common through- 

 out the sand region in the breeding season. The larvse are very nu- 

 merous in the river. The adults are found as far as three miles from 

 the river. 



Order neuroptera 



Chrysopa ocidata Say. August. 



The "lace-winged fly", a common and widely distributed species. 

 The larvse are known as "aphis-lions", and roam about on plants in 

 search of plant-lice, from which the juices are extracted by means of 

 the mandibles. The eggs are laid on long stalks. No specimens 

 were taken, though several were seen. Hart took it at the Devil's 

 Hole. 



Cryptoleon signatmn Hag. June to August. 



This species was seen, but no specimens were captured. Hart 

 found it very common in different parts of the sand regions. No 

 other Illinois records. 



The larvse of the Mynneleonidae dig pits in loose soil and lie in 

 wait at the bottom for insects to fall into the trap. These pits are 

 common in sand, wherever there is protection from wind. 



Two other myrmeleonids taken by Hart were not formerly re- 

 corded from Illinois. These are Brachyneuinnis irregularis Currie 

 and Myrmeleon immacidatiis occidentalis Currie. The family reaches 

 its highest development in the southwest. 



Order odonata 



IscJiiiura verticalis Say. July 8. 



One specimen, taken at the Devil's Neck in bunch-grass. Dragon- 

 flies are very abundant in the bunch-grass areas, even as far as sev- 

 eral miles from the river, which, with its lowlands, is their principal 

 breeding-place. They form a derived element in the bunch-grass. 



