792 REPORT UNITED STATES GEOLOGICAL SURVEY. 



an injurious insect, to Eastern Massachusetts and Connecticut, it is now 

 injurious in Illinois and Missouri. It must originally, at least A. vernata, 

 have occurred all over the United States east of the Mississippi, as I 

 have received it from Texas. It may possibly be introduced into the 

 Territories, and therefore I refer to it simply in this connection. 



Let us now examine the life-history of a canker-worm. And here we 

 will confine ourselves to a single species, the Anisopteryx vernata of 

 Peck, which appears in the spring, not touching at present on the 

 autumnal species. About the 1st of May, at the time when the leaves 

 of the apple are unfolding, the young canker-worms break through the 

 eggs, which have been laid earlier in the season, in March and April, in 

 patches on the bark of the trunk and limbs. They 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. 



How they grow and devour every green thing on the tree is too well 

 known to the fruit-raisers in the eastern part of Massachusetts. Fortu- 

 nately, owing to the want of wings, the female is exceedingly sedentary, 

 and year after year the trees of particular orchards and towns are defo- 

 liated and turned brown, while adjoining orchards and towns scarcely 

 sufifei*. By the 20th of June, in Essex County, Massachusetts, the orch- 

 ard looks as if a fire had run through it. 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 about 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 

 ascend the trees, and the winged males may be seen iiuttering 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 

 6 to 7 inches in thickness, besides three elms. They were more abund- 

 ant on the apple-trees than the elms. But on those seventeen trees 

 there were counted, adhering mostly to the tarred paper, 1,000 males 

 and 200 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 proportions between the sexes, 

 which seems to approximate five males to one female. 



The species I have referred to is the spring moth, the Anisopteryx 

 vernata of Peck, but not of Harris. The other species 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 addi- 

 tional 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 557 caterpillars from the apple-trees in my garden. 

 Of these 520 were vernata, and 27 were the young of the autumn species. 

 Peck, in his account i^ublished in 1795, states that vernata does the 

 principal damage. 



As for remedies, the use of printer's ink laid on tarred paper is the 

 cheapest, 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 bot- 

 tom of the trunk is almost equally efficacious. Care and attention, and, 



