4 Yearbook of the Department of Agriculture. 



tends to bring about a general spread of the insect toward 

 the seacoast instead of inland. 



The female moths deposit egg masses on the underside of 

 the leaves of apple, pear, oak, cherry, rose, and numerous 

 other trees and plants. The caterpillars hatch about the 

 middle of August and feed for about a month. The eggs 

 are usually laid on the leaves on the terminal twigs and the 

 small caterpillars draw a number of these together to form a 

 web, in which they remain during the winter. In the spring, 

 as soon as the buds begin to expand, the caterpillars emerge 

 from the webs and feed on the buds and developing leaves. 

 They become full grown about the middle of June and spin 

 cocoons either singly or in masses, from which the moths 

 emerge during the first part of July. 



The large caterpillars, which are provided with many 

 long hairs, are particularly poisonous. 



The male and female gipsy moths differ in color, the 

 former being chocolate brown, while the latter is light cream 

 color, having wings marked with black. This insect is in 

 the moth stage during early July, but, fortunately, the 

 female moths are unable to fly on account of the size and 

 weight of their bodies, so that their natural spread is not 

 as rapid as is that of the brown-tail moth. Clusters con- 

 taining 400 or more eggs are deposited by the females on 

 trees or, in fact, on any material which furnishes a some- 

 what sheltered location. These clusters are about an inch 

 long, oval in form, and are covered with yellowish hair 

 from the body of the female. As the eggs do not hatch 

 until the following spring, there is ample opportunity 

 for the insect to be spread in the egg stage during the fall 

 and winter if lumber, plant products, or other material 

 upon which they are deposited is shipped to outside points. 

 The caterpillars hatch late in April or early in May, de- 

 pending on the season, and feed on the leaves which are be- 

 ginning to expand. They continue to feed and develop until 

 about the first of July, when pupation takes place, the moths 

 emerging a week or more later. 



During the first work which was done for the purpose 

 of controlling the gipsy moth, a study was made of the man- 

 ner in which this insect was spread. It was determined that 

 while the female did not cause spread, since it was impos- 

 sible for her to fly, egg clusters were frequently transported 



