THE PRACTICAL ENTOMOLOGIST. 



113 



ly, of disappearing in particular seasons. Some nine or 

 ten years ago they were very destructive in this neigh- 

 borhood, some orchards being entirely stripped. Yet the 

 next summer there was scarcely one to be seen. In 1S67 

 they have swarmed here worse than they ever did be- 

 fore. 



Harris slates that the Tent-caterpillar of the Forest oc 

 curs on "oak and walnut trees," {Inj. Ins. p. 375), and Fitch 

 classifies it as one of the larvae found on Oak. ( JT. Y. Hep. 

 II, § 321.) There is considerable Oak and Walnut timber 

 in this section, but I have never seen or heard of any 

 larva;, such as those which infest our apple-trees, being 

 found on those trees. A neighbor of mine has a butter- 

 nut (Juglans cinerea) in the middle of his orchard, that 

 has not been eaten at all in 1867, while he has had great 

 difficulty in saving his apple-trees. And to-day I have 

 seen a butternut standing in full leaf on one side of an 

 orchard, where the apple-trees are stripped all around it. 

 Another neighbor has several black-waluut trees (J. ni- 

 gra) along the road by his buildings, one of which is al- 

 most, if not quite, in actual contact with his apple-trees. 

 Yet these trees are never troubled, while the caterpillars 

 are very bad in his orchard. Next to apple-trees they 

 appear to prefer black ash, white ash and basswood. I 

 have just been to the woods, and find many of these trees 

 nearly denuded of foliage, while oak and walnut in the 

 immediate vicinity are not injured. They are also found 

 on beech and dogwood, and wo meet with a good many 

 on quince bushes. 1 understand that they work on pear- 

 trees also this year. Cherry-trees are not much injured 

 by them. 



The only other locality, besides Western Nevr 

 York, where this insect has ever been noticed as 

 swarming on apple-trees, is the State of Maine, as 

 has been recorded by Harris, but exclusively in 

 the later editions of his Injurious Insects, (p. 375.) 

 I suspect that certain caterpillars seen on apple- 

 trees in Maine in 1866, by Mr. G. E. Brackett, 

 which built no tents and yet strongly resembled 

 the common Tent-caterpillar, could have been no- 

 thing but our friend from the Forest. Mr. Brac- 

 kett, however, suggests that " there may have been 

 something in the weather which caused the depar- 

 ture from their general habit of tent-building," 

 and asserts that they are "the true tent-caterpil- 

 lar." (Maine Farmer, June 28, 1866.) 



As to the question whether this same larva ever 

 feeds upon oak and walnut, as stated by authors, it 

 may probably be the case that there are distinct races 

 of this species feeding on those particular trees, and 

 indisposed or incapacitated to feed upon apple-tree 

 leaves. Thus there is a distinct race, or as I have 

 called it " Phytophagic species," of the Handmaid 

 Moth (Datana ministra), which, as I have experi- 

 mentally proved, will feed upon Walnut or Hicko- 

 ry, but will starve upon Oak or Apple-tree ; and 

 another distinct race, which feeds upon Oak and 

 Apple-tree, but will starve upon Walnut or Hicko- 

 ry. Many other such cases I have already pub- 

 lished as occurring in America, and many more 

 may be met with scattered through the works of 

 European Entomologists as occurring in the Old 

 World. For example, Curtis has recorded the 

 very remarkable fact, that in England the larva of 

 the Sawfly'of the Turnip (^Aihalia spinarurn) gene- 

 rally attacks exclusively the common Turnip, but 

 in particular localities attacks the Swedish Turnip 

 exclusively. (^Farm Insects p. 50 ; see also, on this 

 subject, a Paper by Mr. McLachlan in Trans. Ent. 

 Soc. London, 1865, p. 467.) 



In confirmation of the above theory — which, 

 however, requires further and fuller investigation 



before it can be finally adopted as certain — it may 

 be remarked that S. K. Williams, M. A., Principal 

 of the Sayre Institute in Kentucky, writes me word 

 that "he finds the Tent-caterpillar of the Forest 

 {Clisiocampa sylvaticd) only on Black Walnut 

 (Juglans nigra) ;" and Mr. Ferris has called my 

 attention to a paragraph in the Evening Journal, 

 (Albany, N. Y.,) stating that "the Army-worm is 

 now [1867] committing great ravages in the oak 

 forests of Virginia," and subsequently observing 

 that the same worm is very destructive to the or- 

 chards in Niagara Co. in Western New York. The 

 same fact, namely, that this insect "is sometimes 

 so plentiful in Virginia as to strip the oak-trees 

 bare," had previously been recorded by Abbott, 

 but on very insufficient grounds, has been discre- 

 dited by Dr. Fitch. (See Harris Inj. Ins. p. 375, 

 and Fitch JV. Y. Rep. II, § 321.) On the whole, 

 unless we adopt some such theory as the above, it 

 seems difficult to account for the circumstance that, 

 while the Tent-caterpillar of the Forest occurs, ac- 

 cording to Harris and Fitch, generally throughout 

 the Eastern States, it should only have been proved 

 to attack the Apple-tree there to any noticeable ex- 

 tent in two localities, namely, Maine and North 

 Western New York. 



All the Tent-caterpillars, instead of belonging to 

 the Owlet-moths {Hoctux), belong to the great 

 group of Spinners {Bombyces). Like the Cotton- 

 caterpillar, but unlike the true Army-worm, they 

 all make their cocoons above ground, an4 they 

 agree with the true Army-worm and differ from 

 the Cotton-caterpillar in there being but one brood 

 of them in one year. Like both these two insects, 

 they come out into the Moth state the same season. 

 As is usually the case with the Spinners, the co- 

 coon of all the Tent-caterpillars is constructed of 

 silk, spun froin the mouth of the larya. But 

 instead of spinning its cocoon in out-of-the-way 

 holes and corners, as is the habit of the com- 

 mon Tent-caterpillar, the Tent^caterpillar of the 

 Forest, as I am informed by Mr. Ferris, always 

 spins it upon trees, folding together one or more 

 leaves by way of envelop for its cocoon, and often 

 deserting the tree it had fed on for this purpose. 



Mr. Ferris having sent me seven or eight of 

 these larv£B, and selected the smallest specimens 

 he could find, for convenience of packing, they 

 were every one of them a day or two afterwards 

 destroyed by the larvae of parasitic two-winged 

 Flies, belonging to the Tackina family, which 

 dropped from their bodies on the ground, leaving 

 the shrunken skins of their victims strongly adhe- 

 ring, as is usual in such cases, to the surface upon 

 which they had rested in the agonies of death. Si- 

 milar parasitic larvas largely infest the true Army- 

 worm, as I have shown, and also the larvae of the 

 Handmaid Moth (^Datanaministra),w\n(i)i in some 

 sections of country is a great pest upon apple-trees. 

 What percentage of the whole crop of these Tent- 

 caterpillars in Western New York is destroyed in 

 this manner, it is impossible to say with any cer- 

 tainty ; but I strongly suspect that it is only the 

 dwarfed and stunted specimens which are thus in- 



