366 INSECTS INJURIOUS TO VEGETATION. 



after they were hatched from the eggs, and were dispersed over 

 the leaves of the trees. It is said that some persons have saved 

 their trees from these insects by freely dusting air-slacked lime 

 over them while the leaves were wet with dew. Showering 

 the trees with mixtures that are found useful to destroy other 

 insects, has been tried by a few, and, although attended with 

 a good deal of trouble and expense, it may be worth our while 

 to apply such remedies upon small and choice trees. Mr. 

 David Haggerston, of Watertown, Mass., has used, for this 

 purpose, a mixture of water and oil-soap (an article to be 

 procured from the manufactories where whale oil is purified), 

 in the proportion of one pound of the soap to seven gallons of 

 water; and he states that this liquor, when thrown on the trees 

 with a garden engine, will destroy the canker-worm and many 

 other insects, without injuring the foliage or the fruit. This 

 application may be found useful in protecting grafts; for if 

 canker-worms attack these they will very much injure if not 

 entirely destroy them. Jarring or shaking the limbs of the 

 trees will disturb the canker-worms, and cause many of them 

 to spin down, when their threads may be broken off with a 

 pole; and if the troughs around the trees are at the same time 

 replenished with oil, or the tar is again applied, the insects 

 will be caught in their attempts to creep up the trunks. In 

 the same way, also, those that are coming down the trunks to 

 go into the ground will be caught and killed. If greater pains 

 were to be taken to destroy the insects in the caterpillar state, 

 their numbers would soon greatly diminish. 



Even after they have left the trees, have gone into the 

 ground, and have changed their forms, they are not wholly 

 beyond the reach of means for destroying them. One person 

 told me that his swine, which he was in the habit of turning 

 into his orchard in the autumn, rooted up and killed great 

 numbers of the chrysalids of the canker-worms. Some per- 

 sons have recommended digging or ploughing under the trees, 

 in the autumn, with the hope of crushing some of the chrysa- 

 lids by so doing, and of exposing others to perish with the 

 cold of the following winter. If hogs are then allowed to go 

 among the trees, and a few grains of corn are scattered on the 



