CHAP. V.] DESTROYING IX>ECTS. Ill 



the tobacco, or using it alone, caterpillars, but- 

 terflies, snails, &c, may be stupified, so that 

 they will fall from the branches, and may be 

 gathered up and destroyed. There are also 

 several kinds of fumigating bellows. 



An excellent preventive remedy is to wash 

 the stems and branches of deciduous rose trees, 

 in winter, with water heated to 200°, or with a 

 mixture of strong tobacco-water and soft soap ; 

 cleaning the branches well, at the same time, 

 with a soft brush. 



The American blight shows itself in little 

 tufts, of a white woolly or cottony substance, 

 which appear on the stems and branches of 

 apple trees, general! v where thev are cankered, 

 or have been injured. This woolly substance 

 is the covering of a kind of aphis, and it is 

 not known why it is called the American blight, 

 as it appears to have been first brought into 

 England from France, about the vear 178". 

 "When the insect was first discovered, it was 

 thought to be a kind of coccus, like that on the 

 vine, and, in fact, it has very much the appear- 

 ance of insects of that kind. The coccus, how- 

 ever, only envelopes its eggs in a white woolly 

 substance ; but in the American blight, both the 

 male and female insects are covered with this 

 white substance, and in very hot weather, the 

 male, which has wings, may be seen occasion- 

 ally floating in the air, and looking like a piece 

 of cotton wool. Wherever these insects esta- 

 blish themselves, the part they attack soon 

 becomes ulcerated or cankered ; and if their 

 ravages be not stopped, the tree will die in the 

 course of a few vears. Various means have 



