CANKER-WORM. 253 



and it rolls down, carrying them down with it, is prac- 

 tised. When the sand is moistened with rain or dew, it 

 will not roll down ; hence this remedy is almost or 

 quite useless. If the sand keeps them down, they 

 might lay their eggs below, and the young worms 

 would ascend over the sand, wet or dry. 



Heaping sheaves of flax around the tree, which is 

 sometimes done, is liable to the same objections as 

 sand ; and one other is, that there is so little raised that 

 it would be hardly possible to procure sheaves. 



Putting circular tin troughs around the trees, and 

 filling them with a decoction of tobacco, was tried 

 by George Irish, of Middletown, R. I. and found to 

 be very expensive, as the liquor evaporated, and re- 

 quired to be filled very often ; and, when it rained, the 

 water collected in them, and, freezing, burst them, 

 leaving them very leaky ; and, as the trees grew, they 

 burst them, and rendered them quite useless, and they 

 were abandoned in one or two years. 



Putting a square tin trough around the trees, with a 

 roof over it, the trough to have a little cheap oil in 

 it, was found to answer better than any of the fore- 

 going remedies ; but it is very expensive, and requires 

 much care, as it is necessary to make a platform of 

 boards to support the trough, and prevent the insects 

 from ascending between the trough and the tree. As 

 the tree grows, it separates the platform, and the trough 

 is required to be made larger. In making the. trough 

 larger, it is necessary to unsolder, or cut it open, and 

 put four pieces into the trough and four into the roof : 

 and the tin, by being continually exposed to the 

 weather, soon rusts through and becomes worthless. 



I have noticed in some parts of the country a piece 

 of tin put around the trees, in the form of an inverted 

 tunnel. This apparatus must have been contrived by 

 some person who was ignorant of the entomology of 

 the canker-worm, as it has been ascertained by experi- 

 ment that the grub, when put in a glass tumbler, will 

 22* 



