172 



INSECTS. 



the pieces of tin are shaped, and fitted to the trees, some- 

 what like the boards above-mentioned, and perhaps, if the 

 outer rims of the collars were curved, or bent downwards, 

 they might present obstacles, which the worms could not 

 pass, even if no tar was applied. We fear that this 

 method would prove too expensive for general adoption, 

 but would solicit further information on this subject from 

 those who have a practical knowledge of its application 

 and results, 



4. Another method, proposed by Dr. Jeremiah Spof- 

 ford, of Bradford. Mass., is, to spread mercurial ointment 

 ( Unguentum hydrargyri) upon strips of woollen cloth, or 

 narrow lists, such as are cut from the edges of broadcloth, 

 and apply them closely round the trees, having first made 

 the bark smooth where it is not so, that none of the grubs, 

 or females that deposit the eggs, from which the worm? 

 are produced, may pass under the band or strip, which 

 contains the ointment. Dr. Spofford observes that " the 

 advantages, of using the unguentum over any mode in 

 common use are obvious. While tar requires to be renew- 

 ed every night, that it may catch and hold the grub, merely 

 by its tenacity, tius mode requires preparing but once a 

 year, and will be growing stronger for a long time, by an 

 increased oxidation of the mercury, when exposed to the 

 air." — See N. E, Farmer^ vol. iv. p. 377. 



The Mass. Agr, Repos. vol. iii. No. 4, contains some re- 

 marks on the canker-worm, by the Hon. Johr; 1.* well, 

 president of the Mass. Agr. Soc. from which the following 

 is extracted : — 



^' I had the turf dug in around sixty apple-trees, and the 

 earth laid smooth. I then took three hogsheads of effete, 

 or air-slaked lime, and strewed it an inch thick round my 

 trees, to the extent of two or three feet from the roots, so 

 that the whole diameter of the opening was from four to 

 six feet. 



^' I tarred these trees as well as the others, and, although 

 I had worms or grubs on most that were not limed, I did 

 not catch a single grub where the trees w^ere limed. 



" I do not speak with confidence. I am, however, 

 strongly encouraged to believe the remedy perfect. It was 

 ascertained by Professor Peck, that the insect seldom de- 

 scended into th^ ground at a greater distance than three or 

 four feet from the trunk, and to the depth of four inches, 

 or that the greater part come within that distance. The 

 lime is known to be destructive of all animal substances, 



