THE PESTS OF THE FARM. 99 



In the chrysalis form they remain until they appear above the 

 surface of the earth as moths, when, ascending the trees they 

 deposit their eggs and die, their progeny replacing them in their 

 numbers and devastations. Dr. Harris farther continues: — 



" As the females are destitute of wings, they are not able to 

 wander far from the trees upon which they have lived in the 

 caterpillar state. Canker-worms are therefore naturally confined 

 to a very limited space, from which they spread year after year. 

 Accident, however, will often carry them far from their native 

 haunts, and in this way, probably, they have extended to places 

 remote from each other. Where they have become established, 

 and have been neglected, their ravages are often very great. In 

 the early part of the season the canker-worms do not attract 

 much attention ; but it is in June, when they become extremely 

 voracious, that the mischief they have done is rendered appar- 

 ent, when we have before us the melancholy sight of the foliage 

 of our fruit-trees and of our noble elms reduced to withered 

 and lifeless shreds, and whole orchards looking as if they had 

 been suddenly scorched with fire." 



As the eggs are deposited on the trees only after the female 

 has ascended, the manifest remedy and protection is to prevent 

 the female from crawling up the trunk. For this purpose 

 almost numberless things have been invented, some of which 

 have been in a measure successful, none more so than the strip 

 of tar painted on the trunk of the tree while the females are 

 active. 



There have been various methods tried of applying this tar, 

 the most efficacious of which being simply to tack arovmd the 

 tree a strip of thick brown paper about fifteen inches in width, 

 and over this to paint a thick coating of a mixture of tar and 

 grease two or three times in twenty-four hours, or at least once 

 during the day and once in the evening, during which latter 

 time the females swarm up the trees in the greatest numbers. 

 It is essential that the tar be applied in a liquid form and suffi- 

 cient grease should be mixed with it to give it the requisite 

 thinness. The female moths on endeavoring to pass over the 

 tar are arrested, and hundreds, sometimes thousands, are 

 caught on one tree in a single night. I am acquainted with 

 a gentleman, owner of a large orchard in Middlesex County, 

 who keeps one or two men employed through every night 



