40 REMEDY FOR CANKER WORMS. 



must crawl up the tree to deposit its eggs, tar or printers' ink is 

 applied to the trees after December 1, and kept fresh by renewal 

 during warm days, when the females can run; thus the ascending 

 insects are caught and destroyed. This is an effectual remedy, 

 but requires constant attention from December to May, whenever 

 the weather is warm and there is 110 frost in the ground. 



Another effectual remedy is to encircle the tree with a metallic 

 trough in which is placed cheap oil, like crude petroleum. The 

 first cost of this remedy is more than the expense of tar, but it 

 does not require as constant attention. 



Within the past two or three years the attempt to prevent the 

 ascent of the female has been abandoned, in many sections, and 

 the larvae are destroyed as soon as they are hatched out, by the 

 mse of paris green. This is applied in water, at the rate of one 

 hundred gallons to one pound of paris green, with the common 

 hand or garden pump. This remedy is effectual, and is cheaply 

 applied by placing barrels of the mixture upon a low wagon and 

 driving among the trees. If the trees are thoroughly sprayed 

 and no rain follows for several days, one application is generally 

 effectual, but sometimes a second or third syringing is required. 

 The principal objection to this remedy is in the danger, to both 

 man and animals, in the use of so dangerous a poison. 



A safe and equally as effectual a remedy is found in the Pyrethrum 

 or Persian insect powder. If used in the same w:iy as the paris 

 green, it will destroy the larva? while young, and will paralyze the 

 larger ones so that they will fall at once to the ground. As the 

 more mature larva? will attempt to crawl back to the tree, a single. 

 application only of the band of ink is necessary to catch and 

 destroy them. This powder is />"/;/>r//// harmless to man or ani- 

 mals, is as effectual as the paris green, and should be used in 

 preference to that deadly arsenical preparation. 



THE APPLE APHIS OR PLANT-LOUSE (Aphis mali). This i-s a 

 small, green tly (Fig. ,'>9) (very similar to the common plant- 



Fig. 39. 



louse which attacks House plants), that often appears in large 

 numbers upon the young shoots, injuring them by sucking out 

 their juices. It is destroyed by the application of a strong 

 solution of whale-oil soap and tobacco water, or by the application 

 of the pyrethrum powder just at night. 



