83 Wisconsin State Horticultukal Society. 



made by Miss Emma A. Smith, of Peoria, and her results 

 were published in the paper referred to. By that time the 

 insect had spread widely over central and northern Illinois, 

 and was doing serious injury. Its ravages have continued 

 since that time with fluctuations. In some places it has dis- 

 appeared, and in some of these, as Bloomington, it has re- 

 appeared in full force. 



LIFE history. 



The Bark lice are seen in spring, fixed lengthwise to the 

 under side of branches. Each house looks like a dark- col- 

 ored scale covering what appears to be a cottony mass. 

 This is the female insect. During the latter part of May 

 the eggs are laid, and in about three and a half weeks they 

 begin to hatch and the first young lice appear. As soon as 

 they are hatched, they move about actively and crawl to 

 the leaves and most of them attach themselves to the under 

 surface near the midrib and principal veins. Some are 

 found on the upper surface, but the under surface is more 

 favorable to their growth, because the epidermis is thinner 

 there, more easily penetrated by their delicate beaks, and 

 they are also better protected. By the beginning of July 

 (in Central Illinois) nearly all the old lice on the branches 

 are found to be dead, and most of the new brood have' at- 

 tached themselves to the leaves. During the summer they 

 increase in size and become gradually darker in color. If 

 undisturbed they remain inactive, but if the leaf is picked 

 from the tree, they withdraw their beaks and move about 

 in search of a new place to feed. 



When young, the males and females can not be distin- 

 guished, but after a few weeks the males stop growing, go 

 into the pupa state, and then come out with wings. The 

 first males were observed by Miss Smith about the middle 

 of August, and continued to appear for over two weeks. 

 Each individual probably lives only a few days and they 

 are comparatively few in number. During this time fecun- 

 dation takes place and the development of eggs begins; but 

 they are not matured and deposited till the next spring. 

 There is some reason to believe that as in ordinary plant 



