178 TRANSACTIONS OF THE ILLINOIS 



Trioxys salicaphis. Fitch. Willow-louse Aphidius. 



Black and shining, with a long, elliptical abdomon of honey-yellow 

 color at the base, but gradually passing to black posteriorly ; legs, yellow ; 

 feet, dusky; antennae two-thirds as long as the body, 13-jointed. Length, 

 0,06 to 0.07 inch. 



Trioxys populaphis, Fitch. Poplar-louse Aphidius. 



Black and shining, the abdomen long, elliptical, and much narrower 

 than the thorax, the basal sutures yellow ; legs yellow, except the pos- 

 terior thighs, which are black ; antennae nearly as long as the body, 15- 

 jointed ; outer margin of the fore wings, blackish ; stigma, dusky. Length, 

 0.07 inch. Parasitic on an Aphis found on the leaves of the Balm of Gilead. 



Trioxys cerasaphis, Fitch. The Cherry-louse Aphidius. 



Black, with the palpi and legs pale yellowish-brown ; antennge almost 

 as long as the body, i8-jointed; abdomen elliptical, rather narrower and 

 shorter than the thorax, with scarcely any pedical at its base, shining and 

 tinged with brownish ; wings, pellucid ; stigma, cloudy white. Length, 

 0.07 inch. 



These, as a matter of course, form but a small portion of the large 

 number of species of this group of parasitic insects. Whether any species 

 are limited in their operations to a particular aphis has not been yet 

 satisfactorily ascertained ; that some are parasitic on more than one species 

 of aphis is true, but at the same time it may be true that certain plant-lice 

 may have their special parasites. 



Another group of plant-lice destroyers is found in the order Neu- 

 roptera, which consists of the Dragon-flies, Ant-lions, Lace-winged flies, 

 etc. These are the Lace-winged flies which have rather long, slender 

 bodies, and four broad, spreading, thin, membraneous wings, with numer- 

 ous transverse veinlets. They are usually pale green, and when handled 

 leave on the hands an unpleasant odor. The female suspends her little 

 eggs on delicate threads, in clusters, on the under side of the leaves where 

 the plant-lice abound. The larvae which hatch from these are somewhat 

 spindle shaped, narrowed in front, rounded behind, and broadest rather 

 behind the middle, and furnished with large curved, sharp jaws, with which 

 they seize and devour their helpless victims. 



A description of two or three species known to inhabit Illinois will 

 be sufficient to give the reader an idea of these important aids. 



They belong chiefly to the genus Chrysopa. 



Chrysopa oculata, Say. The Eye-marked Golden-eye. 



Greenish-yellow ; antennae yellowish, apex obscure, second joint an- 

 nulated with black, first joint with a red dorsal spot at ring ; head yellow, 

 bases of the antennae surrounded with black rings, a black point each side 

 behind the eye, and four black points on the occiput ; front thorax with 



