THE FALL WEB -WORM AND THE SWALLOWTAILS 



BY DR. R. W. SHUFELDT, R. A. O. U. 



(Photographs by the author) 



INVESTIGATING the life histories of the larvae or 

 caterpillars of our moths and butterflies, the fact is 

 soon discovered that the majority of them feed upon 

 the leaves of a great variety of plants, shrubs, and trees. 

 Where such defoliation does not affect man's interests, 

 but little heed is given to 

 it, except by the entomolo- 

 gists. Where the larvae are 

 small, more or less rare, 

 and non-communal by 

 habit, the effects on leaf- 

 age is comparatively very 

 slight. It may be slight, 

 too, where the caterpillars 

 are of the largest sort, not 

 abundant, and a compara- 

 tively small number attack 

 the foliage of any particu- 

 lar tree or plant. On the 

 other hand, where the 

 larvae of any special moth 

 mass in broods in certain 

 trees, feed upon the foli- 

 age, or weave their com- 

 mon web so as to envelope 

 leaves, and consume them, 

 we have in such larvae spe- 

 cies that constitute a pest. 

 The destruction that they 

 do is not lost sight of 

 until the following season, 

 should the trees rally from 

 the injury done and leaf 

 out once more. 



A good example of the 

 first species referred to is 

 seen in the caterpillars 

 known as the forest tent 

 caterpillars, the Clisiocampa 

 sylvatica of Harris, which 

 feeds on the leaves of dif- 

 ferent trees and shrubs, 

 and is especially destructive 

 in the case of the wild 

 cherry trees. This species 

 of larvae construct a web in 

 the fork of the tree where 

 they were hatched out, and very soon commence to prey 

 upon the leaves. The writer, in order to study their 

 development, reared several hundred of these larvae, 

 feeding them on the leaves of the common wild cherry. 

 It was amazing to note their rapid growth, the enlarge- 

 ment of their web, and above all the enormous number 

 of leaves required to keep them fed. A limb with 

 Mi 



PART OF A BROOD OF FALL WEB-WORMS 



Fig. 



This brood was collected by the writer on a Red Mulberry 

 tree (Morus rubra) in the rear of No. 1745 Park Road. N. W., Wash- 

 ington, D. C, early in June. These larvae are in the earty stages of 

 thei> growth, and of varying sizes. Natural size; from li 



upwards of an hundred large cherry leaves upon it 

 would be entirely consumed in the course of a couple 

 of hours. These caterpillars grew rapidly, and spun a 

 great number of small, white cocoons. From these 

 presently emerged many beautiful little brown moths, 



with broad, dark, oblique 

 bands on their upper wings. 

 The pupae from which 

 these came were strong 

 and of a deep mahogany 

 brown color. 



Such experiments are ex- 

 tremely interesting, and one 

 of the most recent ones of 

 this nature undertaken by 

 the writer was a brood of 

 the larvae known as the 

 Fall Web- worm, which 

 formerly passed under the 

 scientific name of Hyphan- 

 tria cunea of Drury, but 

 now called H. tcxtor of 

 Harris ; its moth is also 

 known as the Fall Web- 

 moth. 



Early in June, when 

 passing through an alley 

 in Washington, D. C, the 

 writer noted, in some 

 seven or eight places 

 in a mulberry tree, that 

 broods of a certain cater- 

 pillar had spun their webs 

 about masses of leaves at 

 the extremities of twigs, 

 and were devouring them. 

 These broods averaged 

 several hundred up to a 

 thousand in each com- 

 munity (Fig. i). The 

 owner of the tree inquired 

 what ought to be done ; she 

 was advised to cut off the 

 twigs bearing the webs and 

 their occupants, and to dip 

 each in a pail of boiling 

 water. The expedient saved 

 this splendid tree from complete defoliation during the 

 next few weeks. 



A large box with a tightly fitting cover of fine gauze 

 wire made an admirable "breeding-cage" in which to 

 place the reserve brood taken from the tree. Therein 

 they were fed with the leaves of the mulberry tree and 

 grape-vine until the early part of July, and it was 



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