43 



When this insect does not occur in extraordinary numbers, it is 

 probably rather beneficial than otherwise on large trees, by operating 

 as a summer priming and thereby checking the exuberant growth of 

 wood and throwing the tree to fruit. But in 1859 I found them 

 so abundant on one of my apple-trees, that if I had not destroyed 

 them, I believe they would have greatly injured it; and in June, 1867, 

 I received specimens of it from "J. M. K.," of Clarence, Iowa, with 

 the statement that "it had destroyed his apple-crop for the last three 

 years." When the trees are bare in the dead of the year it is a very 

 easy thing to find the little bunches of dry leaves — tied to the twig by 

 silken bands — in which the larva has hidden its case, to protect itself 

 from the cold blasts of winter; and it may then be readily picked off 

 the tree, and destroyed by forcibly crumpling up the whole establish- 

 ment, leaves and all, between the fingers. Comparatively a very 

 slight pressure will effect this ; for we are dealing here not with a hard 

 shelly beetle, but with a soft delicate caterpillar. Although this insect 

 is so common in Northern Illinois, and I have noticed plenty of them 

 annually for the last ten years near Eock Island, and they are equally 

 abundant, as I am assured by Mr. C. V. Eiley, near Chicago, yet, on 

 the most careful search, I could not discover a single specimen, even 

 in the dead of the year, in the apple orchards near Cobden in South 

 Illinois; and Mr. Eiley tells me that he also has failed to find it 

 there. Neither, so far as I can ascertain, does it occur in the Eastern 

 States; and most certainly it is not mentioned either by Dr. Harris 

 or by Dr. Fitch. We may set it down, therefore, for the present, as 

 and exclusively north-western species. 



INSECTS INFESTING THE APPLE.— On the Bark. 



CHAPTER Win. — The OysTER-SUEix Bakk-louse. (Aspidiotiis conchiformis, 



Gmclin.) 



There is no noxious insect existing througliout the length and 

 breadth of the United States, about which more nonsense has been 

 written and talked — concerning the Natural History of which more 

 erroneous ideas prevail — and against which a greater number of ridic- 

 ulous and useless panaceas have been recommended — than the Oyster- 

 shell Bark-louse. The reasons are many. In the first place, except 

 for a very brief period of the year, all we can see of it is a small, 

 motionless and apparently lifeless scale, closely appressed to the bark, 

 of precisely the same color as the bark itself, and so totally unlike the 

 popular idea of a "bug,'' or even the scientific idea of an animal, that 

 it is sure not to be noticed by the unpractised eye, except when it has 



