April, '10] DAVIS: ILLINOIS INSECTS 185 



infests the lower parts of the branches, but in some cases, especially 

 in large branches, they may be found three or four feet above the 

 ground. They burrow in the sapwood, often completely girdling the 

 branch. The same species has been bred by us the past year, from 

 Cornus and Yihurnum. 



A leaf-roller (Exartema pennunclamim Clem.) did much damage 

 to Physocarpus opulifolius in some of the parks. It hibernates as a 

 larva in folded leaves, and is found in destructive numbers only in 

 those places where the leaves are not raked up and destroyed. 



A second leaf -roller {Olethrcntes hemidesma Zell.^) was found 

 quite abundant in some of the nurseries attacking Spircea vanhutteL 

 The first brood did the most damage, a large per cent of the second 

 brood being parasitized. 



Another insect which was conspicuous as an enemy to Spircea van- 

 huttei is the spirse sawfly (Prisfiphora hivittata Nort.^) It w^as 

 common in several nurseries, and in one of them a large acreage of 

 Spircea was kept completely defoliated throughout the year by its 

 ravages. Only in one park was it found, and here only in one clump 

 of shrubbery, thus indicating that it has just been introduced there. 

 I have been unable to find any record of the life history or food habits 

 of this species. The eggs are deposited along the edge of the leaf 

 within the tissue, the insertion of the ovipositor being made at the 

 edge of the leaf between the tissues. The larvae like other closely 

 related species are voracious feeders. The adult larvae make their 

 cocoons in the soil just beneath the surface. 



The second brood of the white-marked tussock-moth {Hemerocampa 

 leucostigma, S. & A.) was nearly as destructive as last year, when 

 large numbers of trees in the parks and boulevards of Chicago were 

 defoliated. The tussock-moth is by far the most common and de- 

 structive leaf-eating insect in Illinois. 



The zebra-caterpillar {Mamestra pida Harr.) was found defoliat- 

 ing the cut-leaf elders in one park. It also damaged Tamarix and 

 Hydrangea. 



In the parks, and especially along the boulevards, the large webs 

 of the fall web-worm {Hyphantria cunea Dru.) were found. They 

 were not abundant enough to be noticeably injurious, but the webs 

 gave the trees a most unsightly appearance. 



I have never found the spring canker-worm {Paleacrita vernatc^ 

 Peck) common in Chicago, but in the vicinity of Big Rock, fifty miles. 



^ Determined by C. A. Hart. 



