DANGER OF SPREAD OF GIPSY AND BROWN-TAIL MOTHS. 



21 



that the moths have alighted upon their ships in great numbers in the vicinity of 

 Boston along toward midnight on several occasions, and the introduction of the species 

 at more than one seaport in Maine has been by means of vessels coming from the 

 infested district rather than by direct flight. Of course, the brown-tail moth is carried 

 in the caterpillar stage, just as is the gipsy moth, upon vehicles of different kinds 

 passing through the infested r^ion and upon the persons of pedestrians as well. In 

 late May, 1906, the writer, in company with three other persons, walked through the 

 woods in a region not far from Boston, and although the most careful efforts were made 

 by each of us to pick the caterpillars from the clothes of the others, an hour or two 

 afterwards, and many miles away by automobile, still others were found under the 

 upturned trousers and lapels of coats and in other hidden places about garments. 



The eggs are laid by the moths soon after the flight begins, say in the latter part of 

 July. They hatch during August and the young larvae feed in clusters on the upper 

 surface of leaves, skeletonizing them and causing 

 the foliage to turn brown as if blighted . At first 

 they feed upon the leaf which bears the egg 

 mass, but soon wander to others, returning at 

 night to the original leaf. When first hatched 

 they are about one-twelfth of an inch long, and 

 in five to six days shed their skin, increasing in 

 length to one-fifth of an inch. 



Later the second molt occurs, although this 

 sometimes does not take place until autumn 

 within the winter web. Along in September 

 they begin to spin their winter webs by drawing 

 together a number of leaves with silk, and in 

 each of these nests a large number of caterpillars 

 stow themselves away for the winter. These 

 webs or nests, composed of leaves and silk, will 

 average from 5 to 6 inches in length, and each 

 will contain 200 or more caterpillars. The 

 caterpillars feed until cold weather, and then 

 all enter the web and close the exit holes . They 

 are then about one-fourth grown. 



These winter webs (fig. 7) of the brown-tail 

 moth are very characteristic, and there are 

 practically no other insect structures common 

 upon trees which may be mistaken for them. 

 There are certain old webs of native species 

 which might possibly, by the untrained eye, 

 be considered to be those of the brown-tail 

 moth, but these are empty in the wintertime. 

 Any web of this character and general size found 

 during the winter which contains young caterpillars in any number is the web of the 

 brown-tail moth. 



The following spring, as soon as the buds begin to appear upon fruit trees, these 

 young, one-fourth-grown caterpillars issue from the overwintering nests and attack 

 first the buds and blossoms and later the foliage. Apparently half starved by their 

 long hibernation, they come out with voracious appetites, and the amount of damage 

 done by them at this time is extraordinary. Old trees may lose all their buds, or, if 

 the leaf buds and blossom buds burst, the foliage itself may be entirely destroyed at 

 a later date. The growth of the larva is rapid, and it reaches full size and begins to 

 spin its cocoon during the last half of June, transforming to pupa and remaining in 

 tiiis condition for approximately 20 days. 



453 



Fig. 7.— Winter nest of the brown-tail moth, 

 containing 300 or 400 young caterpillars. 

 (Original.) 



