NOXIOUS INSECTS. 



THE BARK-LICE OF THE APPLE-TREE. 



(Homoptera, Coccidae.) 

 [Fig. 1.] 



There are two species of Bark-lice that attack the 

 Apple-tree in the United States, which I will briefly 

 describe. 



The first, which ie a native North American insect, 

 is now known as Harris's Bark-louse (Aspidiotus liar- 

 risii, Walsh.) The color of the scale is dirty white, 

 and its form is irregular, being usually egg-shaped ; 

 but, however variable in outline, it is always quite 

 flat and causes the infested tree to wear the appear- 

 ance of Figure 1 ; while the minute eggs which are 

 found under it in winter time are invariably blood red 

 or lake-red. This species has scarcely ever been 

 known to increase sufficiently to do material damage, 

 for the reason doubtless that there have, hitherto, al- 

 ways been natural enemies and parasites enough to keep it in due 

 bounds. Though I have not witnessed it in Missouri myself, I am in- 

 formed by several persons that it occurs in the northern part of the 

 State, and a communication from R. B. Palmer, of Hartville, "Wright 

 county, published in the Rtiral World, of October 15, 1866, and stating 

 that the lice are destroying the best apple orchards in that neighbor- 

 hood, evidently refers to this species. 



The second species, which is known as the Oyster-shell Bark-louse 

 (Aspidiotus conchifovmis, Gm6lin), is by no means so harmless 

 however, for it is one of the most pernicious and destructive insects, 

 which the apple-grower in the Northern States has to contend with. 

 This species presents the appearance of Figure 2, and may always be 

 distinguished from the former by having a very uniform muscle- 

 shaped scale of an ash-gray color (the identical color of the bark), 

 and by these scales containing, in the winter time, not red, but pure 

 white colored eggs. 



