THE FALL WEB-WORM AND THE SWALLOWTAILS 



365 



astounding to note the enormous amount of fodder they 

 got away with in one night. As many as fifty grape-vine 

 leaves were placed in their cage in the afternoon, in 

 layers ; the next morning only their stems and coarse 

 veins or ribs remained. 



As will be noted in Figure i, these caterpillars are 

 extremely hairy, and range in length from one to about 

 three centimeters. They are a pale, yellowish green, 

 with a darkish stripe down the middle of the back. On 

 either side of this there is a longitudinal row of some 

 ten minute dots. As these larvae mature, the dorsal 

 stripe gradually becomes almost black, and the animal 

 grows much stronger. When very small they consume 

 only the soft parts of the leaves, completely skeletonizing 

 each leaf before leaving it. As they grow bigger and 

 stronger, however, the entire leaf is consumed, and 

 only the stem and stoutest 

 ribs are left. 



Changing the kind of 

 leaf they were fed upon, 

 produced no change in the 

 color of the caterpillars, 

 and their heads are always 

 black. While the pattern 

 remains very much the 

 same in the adults, it does 

 vary somewhat in color- 

 shade, even in individuals 

 of the same brood. The 

 hairs are invariably light- 

 colored, and each springs 

 from a small, deep-yellow- 

 ish-black wart at its base. 

 Autumn specimens are 

 darker than those compos- 

 ing a spring brood. 



. When these caterpillars 

 get hungry, they swarm on 

 the outside of their web ; 

 and on one occasion the 

 writer had a small branch 

 of a mulberry tree, carry- 

 ing a large web with its 

 owners, in his study. It was screwed into a small vise, 

 which was attached to the top of a big tripod. There 

 were some 250 of the caterpillars on the outside of the 

 web. When the room was perfectly quiet, they all 

 remained motionless ; but should any one suddenly speak 

 or clap the hands together, every one of the caterpillars 

 would commence violently swinging the front half of 

 its body, while the rear half remained still. This extra- 

 ordinary procedure they performed in unison, sometimes 

 keeping up the swinging for as long as fifteen or twenty 

 seconds, depending upon the loudness and character of 

 the noise that started them. Should the cause of the 

 disturbance cease, the entire brood would stop their 

 wagging motion at the same instant, and not one of 

 them would move for several seconds. This is a 

 very remarkable habit ; the writer has never observed 

 anything like it in any other species of caterpillar. 



fc ilflT 



W 



THE MOTH OF THE FALL WEB-WORM 



Fig. 2. These are living and cabinet specimens of this moth (Hyphan- 

 tria textor), with a pupa in situ. The living specimens are the ones 

 with the wings closed, and the pupa is distinctly seen in its opened 

 cocoon to the right. The males are the smallest specimens. 



About the first week in July, the entire brood became 

 very restless in their cage, and the smaller specimens 

 readily escaped every night through the openings in 

 the wire gauze. Between the 7th and the 14th of July, 

 the full-grown individuals commenced to pupate, a few , 

 at a time, and they built their cocoons among the dead 

 leaves at the bottom of the box. On or about the night 

 of the 10th, however, there apparently arose in the full- 

 grown specimens a common impulse to make their 

 escape, and some two hundred of them, in some mysteri- 

 ous manner, squeezed themselves between the wire cover 

 of the box and the edges of the box itself, escaping into 

 the room. In the morning not a dozen of them were in 

 sight, and not over twenty of them were left in the box. 

 Neither were any of the pupae visible; but that is not 

 to be wondered at, as there were no end of places where 



the caterpillars could hide, 

 the room being filled with 

 all sorts of things usually 

 found in a naturalist's 

 workshop. There is but 

 one large window in the 

 room, facing west; so that 

 on sunny days, when the 

 shade is raised and the 

 blinds thrown back, it is 

 flooded with sunlight for 

 hours. On bright moon- 

 light nights, it may like- 

 wise be lit up in that way. 

 Beautiful little pure white 

 moths, few in number, be- 

 gan to make their appear- 

 ance on the big pane of this 

 window in the morning, 

 the imagoes having made 

 their emergence from the 

 pupae sometime during the 

 night. This became the 

 rule in fact, there was a 

 fresh crop of these moths 

 on the window-panes every 

 morning for the ensuing 

 fortnight. They ranged in number from a dozen to 

 thirty for every lot that appeared, all coming to the 

 window during the night, and not being seen in any 

 other part of the room. Over two hundred moths were 

 thus taken during the entire time of emergence, and on 

 the 28th of July only three moths came out a male and 

 two females. 



With one exception, all these moths were pure white. 

 The exception proved to be a male that had very minute 

 black spots on the middle of either upper side of the 

 front wings. The females are seen to be one-third 

 larger than the males, and the very tiny green eggs they 

 carried were distinctly visible through the thin skins of 

 their abdomens. The males out-numbered the females 

 about three to one, while their activity was no greater. 

 In fact, after finding a resting-place, they all settled down 

 as here shown in Figures 2 and 3, remaining so during 



