DANGER OF SPBEAD OF GIPSY AND BROWN-TAIL MOTHS. 



17 



Seasonal History. 



The moths emerge from the pupee from the middle of July to the middle of Augiist, 

 the date varying considerably according to the season. After mating they live but a 

 short time, and the female dies after depositing her eggs. 



The eggs are laid therefore in July and August. They are deposited by the moths 

 on the trunks of the trees upon which the caterpillars have lived, and in fact usually 

 in the vicinity of the place where the female has transformed. The caterpillars before 

 transforming frequently crawl for some distance from the trees upon which they have 

 been feeding, and it therefore happens that the egg masses will be found on fences and 

 in aU sorts of protected situations in which the caterpillars hide during the day. The 

 crevices in stone fences often contain very many of these egg masses, and knot holes 

 in old trees will also contain many which would not at first be 

 discovered. The egg masses are found also in hollow trees, in 

 crevices under rough bark, on shrubbery, on buildings, in wood- 

 piles, in barrels, in boxes, and among rubbish in dooryards; 

 The moths seem to choose the inner or lower surface of an object 

 upon which to lay their eggs, and therefore egg masses are placed 

 out of sight perhaps as often as in sight. 



The eggs hatch about May 1, and the young caterpillars begin 

 immediately to feed, usually upon the lower surfaces of the 

 leaves. As they grow they cast their skins several times, and 

 as they become larger they feed only at night, hiding during the 

 daytime, usually in clusters on the shady side of tree trunks, 

 beneath laige limbs, in holes in trees, under loose bark, and in 

 fact under any near-by shelter. It is the habit of most of them 

 to descend before daybreak upon the trunks of the trees and to 

 seek for such shelters as those just indicated, returning after 

 nightfall to resume their nocturnal feeding. 



The larvae usually become full grown about the 1st of July, 

 and then transform to pupae. The pupae are found in the same 

 situations as those we described for the egg clusters, but are 

 found also in the foliage of trees and shrubs. 



Hew the Insect Spreads. 



Fig. 2.— Full-grown 

 caterpillar of the 

 gipsy mott. Nat- 

 iiral size. (From 

 Insect Life.) 



As indicated above, the bodies of the females are so heavy 

 as to prevent flight. Therefore the insect must be principally 

 distributed while in the caterpillar or larval condition. The cat- 

 erpillars are active crawlers, but as a rule do not migrate from the 

 localities where they were bom except when food is scarce. When young, and when 

 there is hardly enough food, the larvae spin down from trees by means of silken threads 

 and often alight upon vehicles of one kind or another, and are thus carried often for 

 great distances from the place of birth. Trolley cars, carriages, automobiles, and bicy- 

 cles are thus means of transportation almost unlimited in their possibilities. The 

 caterpillars often crawl upon vehicles which happen to stand for any length of time in 

 an infested locality, and thus may be carried great distances. Sometimes even pe- 

 destrians aid unwittingly in this distribution, since the caterpillars may drop by their 

 threads upon the garments of a person passing xmder an infested tree. 



The species may be transported, too, in the egg stage on nursery or ornamental 

 stock, as already noted, and it has been shown that the egg clusters are laid upon many 

 different kinds of objects. Cord wood stacked and piled may be carried away in the 

 autumn bearing many egg masses, and, if not burned before summer, larvK may issue 

 in a new locality. The same may be said for lumber piles near infested trees. Freight 



453 



