THE SPRING CANKER-WORM. 231 



been laid earlier in the season, in March and April, in patches on the 

 bark of the trunk and limbs. Thej may be soon found clustering on 

 the terminal buds and partly unfolded leaves, and are then about a line 

 in length, and not much thicker than a bit of thick thread. Fortunately, 

 3wing to the want of wings, the female is exceedingly sedentary, and 

 year after year the apple and elm trees of particular orchards and towns 

 are defoliated and turned brown, while adjoining orchards and towns 

 scarcely suffer. By the 20th of June, in Essex County, Mass., the 

 orchards or shade elms infested by them look as if a fire had run 

 through them. At that date the worms are fully fed, and they then 

 descend to the ground, letting themselves down by a silken thread. At 

 this time I have destroyed thousands by jarring the tree and collecting 

 those which fall down. I have watched old and young robins busily 

 engaged in eating them, and from the number of toads in my garden, 

 gathered under the trees, I feel confident that they eat multitudes of 

 them. 



The worms at once enter the ground, change to chrysalids several 

 inches below the surface, near the trunk of the tree, and there remain 

 until the early days of March and April, when the wingless females as- 

 cend the trees, and the winged males may be seen fluttering about. 



I took pains one spring, in the middle of April, to count the number 

 of these moths on my apple trees, fourteen in number, averaging from 

 six to seven inches in thickness, besides three elms. They were more 

 abundant on the apple trees than on the elms. But on those seventeen 

 trees there were counted, adhering mostly to the tarred paper, one thou- 

 sand males and two hundred females. The spring of 1875 was cold and 

 backward and few moths were seen before this date. From these data 

 we can ascertain approximately the relative numerical i^roportions be- 

 tween the sexes, which seems to approximate five males to one female. 



The species I have referred to is the spring moth, the Paleacrita ver- 

 nata of Peck, but not of Harris, A. pometaria is much less abundant 

 in the adult condition, and only appears in the autumn. The wings are 

 thicker than those of vernata, and the caterpillar has an additional pair 

 of prop-legs, though so short as to be useless. I find that most of the 

 damage is done by the caterpillars of vernata. On June 15, 1875, I 

 collected five hundred and fifty-seven caterpillars from the apple trees 

 in my garden. Of these, five hundred and twenty were vernata, and 

 twenty-seven were the young of the autumn species. Peck, in his ac- 

 count published in 1795, states that vernata does the principal damage.* 



Remedies. — The use of printer's ink laid on tarred paper is the cheap- 

 est, though the ink should be applied every day or two. The use of tin 

 troughs of oil surrounding the tree is almost sure to stop the ascent of 

 the females, while wooden troughs of oil built around the bottom of the 



*It is probably this species which I have found feeding on the leaves May 30 and 

 June 1, at Providence. It is a reddish-green obscurely striped larva, much like the 

 canker-worm in form and size, but a little stoutiBr. 



