120 NEBRASKA STATE HORTICULTURAL SOCIETY 



enemy of the willow, but ordinarily is not injurious to that plant, or 

 but slightly so. For Cottonwood, however, it has accquired an exceeding 

 fondness, and frequently occurs in excessive abundance upon this tree, 

 where it works great destruction. As early as 1878 the tremendous 

 destructive ability of this beetle upon the Cottonwood was brought 

 forcibly to notice in Kansas and Nebraska, and again in 1884 it was ex- 

 ceddingly injurious in Nebraska and South Dakota. As noted on a 

 preceding page the last two years have been marked by much defoliation 

 by this insect, and its close relative the. spotted willow leaf-beetle, 

 (Lina lapponica). These insects spend the winter as adult beetles. In 

 early spring as the cottonwoods and poplars commence putting out their 

 leaves the female beetles deposit their eggs on the under side of the 

 leaves in masses of a few to a hundred eggs. The larvae which soon 

 hatch from these eggs are black in color, and first skeletonize the leaf 

 upon which the eggs were laid and then gradually diffuse over the 

 tree as they grow older. "With each successive molt they grow lighter 

 in color, so that when full grown they are about three-eights of an inch 

 long, yellowish white with black legs and rows of tubercles upon the 

 back and sides, some of which emit an exceedinly pungent milky liquid. 

 They attach themselves to the leaf and go into the pupa stage, soon 

 thereafter giving forth the adult beetles. As only two weeks are re- 

 quired during midsummer for the entire development from egg to adult, 

 this species is enabled to complete four or five broods annually, in- 

 creasing in abundance and destructiveness as the season advances. 



The adult beetle of scripta is exceedingly variable with its markings, 

 but usually the thorax is black bordered on each side with yellow, and the 

 wing covers yellowish marked with broken lines of black. The beetle of 

 lapponica is of a reddish brown color usually lieavily sppotted with 

 T)lack. The larvae of the two species are so similar as to be practically 

 indistinguishable. The willow leaf-beetle, however, as its name indicates, 

 IS somewhat more partial to the foliage of the willow. The life-history 

 of scripta above given is essentially true with lapponica also. 



The most effective means of combating both these important shade 

 tree pests is a thorough spraying with arsenical poisons. But the results 

 are not always entirely satisfactory. The smooth leaf surface especially 

 of the willow causes the spray to tend to collect in drops and roll from 

 the foliage, also the habit of the beetles and grubs of feeding on the 

 under surface of the leaves to a considerable extent makes it difiicult to 

 lodge the poison effectively. The best results are to be obtained by a 

 heavy application of arsenate of lead at the rate of two pounds to 

 fifty gallons of water, early in the season before the beetles get much of 

 a start. This application must be renewed as necessary from time to 

 time during the summer, but the adhesiveness of the lead arsenate makes 

 very frequent reapplications unnecessary. In some places the shaking 

 off and collecting in kerosene troughs of the beetles and larvae has been 

 successfully practiced, somewhat after the manner used in jarring for 

 the plum curculio. This is, however, too laborious and expensive to 

 admit of very general practice. 



