EXPERIMENT STATION BULLETINS. 



287 



INSECTS INJURIOUS TO THE APPLE. 



BY. R. H. PETTIT. 



[Special Bulletin No. 24.] 



AFFECTING THE BOOTS. 



The Woolly Aphis of the Apple. (Schizoneura lanigera.) 



A plant-louse widely distributed and of very considerable importance; working 

 on the aerial branches and on the roots, producing swellings, and impairing the 

 health of the trees, beside often killing young trees outright. 



This little creature which has gained the name of the "American blight" in 

 the Eastern Continent because of its destructiveness, is a small plant-louse, either 

 winged or wingless, and having the body covered with a delicate filmy wool-like 

 coat which projects in a brush beyond, the rear end of the body. 



Fig. 1. — The Woolly Aphis of the Apple, from Riley, First Rep. State P^ntomologist of Mo. 



They love to gather in numbers on wounds or in places where the bark has 

 been cracked, or where a limb has been cut off and the healing process has com- 

 menced. Wherever they congregate there is a roughening of the bark. The 

 aerial lice are seldom very serious but they indicate the probable presence of 

 lice on the roots. The underground lice produce large, knotty swellings on the 

 roots, seriously injuring young trees and often leading to their death. Older 

 trees will stand these ravages much better, especially if well fertilized and culti- 

 vated. Trees attacked by these pests usually show that something is the matter 

 by the foliage, which is less brilliant and not so plentiful. 



BEMEDIES. 



The insect is already widely distributed in our state, but nevertheless it will 

 pay to try to evade it. In setting out new orchards dip all young stocks in hot 

 water (about 130 F.) or in tobacco water. If kerosene-emulsion is to be had, 

 that will do. Dilute to the ordinary strength for summer spraying. 



A liberal use of tobacco-dust about young trees, and old ones as well, will 

 help to restrict the lice. Use wood-ashes whenever they may be obtained. The 

 aerial lice on the limbs may be killed by a spray of kerosene-emulsion diluted 

 ten times and forcibly applied. It has been found that trees grafted on Northern 

 Spy stocks are very resistant to the woolly aphis. Abroad where this pest is 



