No. 4.] INJURIOUS INSECTS. 151 



with prepared printer's ink, repainting as often as it became 

 dry or hardened enough to permit the females to cross the 

 band. The method of protecting the trees with oil troughs 

 of zinc or tin around the trunks was also mentioned. It 

 was finally stated that probably the most effectual method 

 was to spray the trees with Paris green in water as soon 

 as the eggs hatched in the spring. A further account of 

 canker worms was given in Bulletin No. 28, published in 

 April, 1895. 



A careful study of the different methods used to destroy 

 these insects, which are so prevalent in many parts of this 

 Commonwealth, has been made on thirteen apple trees on 

 my own premises in Amherst. Three years ago these trees 

 were carefully banded with heavy paper and painted with 

 Morrill's tree ink early in the spring, when the first females 

 began to ascend the trees, and the painting was repeated as 

 often as necessary. It was found that the ink would often 

 harden on the trees, even during the night following the ap- 

 plication, and remain hard on the shady side long enough in 

 the morning for some of the females to ascend the tree on 

 that side, so that this method did not prove to be a perfect 

 protection. The cost of the materials and of their ajjplica- 

 tion averaged about fifty cents to each tree. 



The oil troughs are also quite expensive, and often leak 

 so that the rain displaces the oil and then evaporates, allow- 

 ing the females to ascend the trees ; or spiders spin their 

 webs across beneath the overhanging protection, forming a 

 bridge over which the moths may easily pass, so that this 

 device does not form a perfect protection. 



Two years ago these trees were sprayed with Paris green 

 in water in the proportion of one pound of Paris green to 

 one hundred and fifty gallons, at a cost of five cents a tree, 

 allowing fifteen cents an hour for labor. There was a strong 

 wind blowing, and more time was required to do the work 

 than would otherwise have been the case. Last year the 

 same trees were sprayed with Paris green in tlie same pro- 

 portion as before. At this time it was nearly calm, and the 

 cost of spraying was three cents a tree. The contrast be- 

 tween these trees and those on adjacent lots was very 

 marked, for the sprayed trees retained their foliage and 



