12 FIELD WORK AGAINST GIPSY AND BROWN-TAIL MOTHS. 



Trevor Kincaid, who was engaged by the Bureau of Entomology, 

 in cooperation with the State of Massachusetts, for the purpose of 

 collecting parasites of this insect in Russia, found during his explo- 

 rations that thousands of acres of forests were completely denuded, 

 and in other localities trees were dying over large areas as a result 

 of previous defoliations. Dr. L. O. Howard, Chief of the Bureau 

 of Entomology, while visiting, in 1909, the corps of European agents 

 engaged in collecting parasites of the gipsy moth in Europe, found 

 a large forest area near Nantes, France, which was completely 

 stripped by this pest. In fact, the whole European history of this 

 moth is a continuous record of periodical outbreaks of greater or 

 less severity, which have caused enormous damage to trees from 

 the time of the earliest writings on entomology down to the present 

 time. The situation in Japan is not as serious as in Europe, owing 

 to the efficient work of certain parasites which tend to keep the 

 insect under control. 



LIFE HISTORY OF THE GIPSY MOTH. 



THE EGGS. 



(PL I, fig. 5.) 



The female gipsy moth deposits her eggs in clusters containing 

 normally from 400 to 500 eggs, which are covered with hair from her 

 body; this protects them from the action of the elements and ren- 

 ders their destruction, even by fire, quite difficult. The clusters 

 are fully 1 inch in length and about half as wide, and have the general 

 appearance and color of a small piece of sponge. The number of eggs 

 varies considerably and depends largely on the food supply and the 

 vigor of the caterpillar from which the female develops. In colonies 

 where the food supply has been practically exhausted by the larvae, 

 egg clusters are often found containing not more than 50 or 75 eggs, 

 while, on the other hand, a number of cases are on record where sin- 

 gle clusters contained over 1,000 eggs. The majority of the eggs 

 are deposited about the middle of July, although there is consider- 

 able seasonal and individual variation. Females have been found 

 depositing egg clusters as early as June 25 and as late as October 7. 

 Crevices in the bark, holes in trees, stone walls (PI. Ill, fig. 2), or 

 rubbish piles are favorite places for the deposition of eggs, as they 

 afford shelter for the full-grown caterpillar about to pupate and 

 protect the pupa and the newly emerged moth. Many clusters are 

 deposited under steps or porches of houses, in outbuildings near 

 infested trees, as well as on the trunks (PI. Ill, fig. 1 ) and on the under 

 side of the branches of the trees themselves. Hatching takes place 

 early in the spring, about the time the trees are coming into leaf. A 

 few cases are on record where the caterpillars hatched in the fall, but 

 this is unusual. ' 



