INSECTS, FUNGI, PLANT DISEASES, ETC. 



115 



the presence of the insect is detected the grain must be 

 fumigated with carbon bisulphide. This is highly in- 

 flammable, and fire must not be brought near it while 

 fumigation is going on. 



Woolly Aphis, or Apple-tree Blight (Schizonetira 

 lanigera), is found upon the 

 apple tree. The female is a 

 small, egg-shaped, dull red- 

 dish-brown insect, with a 

 black head, dusted with 

 white powder, and with a 

 tuft of white down grow- 

 ing from the hind part of 

 the back, which makes a 

 colony of these insects look 

 like a small patch of white 

 down. Each tuft contains 

 a female and her young, 

 which last are of a pale 

 color. In Europe, trees are 

 often white with these in- 

 sects. Here they are gen- 

 erally found at the base of 

 twigs and suckers from the 

 trunk, or where a wound in 

 the bark is healing. Scrape 

 the bark of the tree, if 

 rough, and wash the tree, 

 filling every crevice with 

 kerosene or a solution of 

 two pounds potash to seven 

 quarts of water, or Harris' Composition — two parts soft 

 soap and eight of water, with lime enough to make a thick 

 whitewash. Sulphuric acid, mixed with ten times its bulk 

 of water, is also recommended. 



Fig. 16 — Schizoneura lanigera. a, Root 

 of young tree, illustrating deforma- 

 tion, b, Section of root with 

 aphides clustered over it. c, Root 

 louse; female, a and b, Natural 

 size ; c, much enlarged. Marlatt. 

 Div. Ent. U. S. Dept. Agri. Cir. 20. 



