GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 



THE EGGS 



The female gypsy moth lays from 100 to 800 eggs in a cluster, 

 depending on her size. The average number per cluster is approx- 

 imately 400. In light infestations where the food supply is plentiful 

 clusters are larger than the average, and in heavy infestations where 

 the food supply becomes limited during the late larval stages they 

 are smaller. Each cluster is covered with buff-colored hairs from 

 the body of the female, which no doubt serve as a protection for the 

 eggs during the long interval between oviposition and hatching. 



Most of the egg clusters are laid in July and hatch the following 

 spring. The hatching date varies from about May 1 in southern 

 New England to May 25 in the extreme northern part. The date 

 of oviposition bears no relation to the date of hatching, as eggs laid 

 in mid-August may hatch at the same time as those laid early in July 

 under the same envi- 

 ronmental conditions. 

 Eggs deposited in warm 

 locations, as on the 

 southern exposure of 

 buildings, may hatch 

 several days earlier than 

 others laid in cool and 

 moist locations. 



The gypsy moth egg 

 must be exposed to a 

 chilling temperature 

 before it will hatch. 

 Just what this temper- 

 ature is is unknown. 

 Eggs that have under- 

 gone this conditioning 

 process will hatch in 

 midwinter in a warm 

 building. 



The female moth de- 

 posits her egg clusters 

 on the trunks of trees, 

 on the underside of limbs, under loose bark, in cavities in the trunks 

 or branches, and sometimes on leaves, on ground debris, under stones, 

 and in stone walls. When infested trees are found along stone walls, 

 a large proportion of the eggs are often laid in the wall; but where 

 the ground is free of stones or debris, a large proportion of clusters 

 will be found on the tree trunks. 



Figure 3. 



Times of the year when the different stages of the 

 gypsy moth are present in the field. 



THE LARVAE 



The newly hatched larvae begin immediately to search for palatable 

 food. In pure stands of favored food this is a simple matter, but as 

 the proportion of favored food in the stand decreases the problem 

 becomes more acute. There is no evidence that such larvae can pick 

 out a favored tree from an unfavored one without examining the 

 foliage. They find the food through random movement. The 

 normal mortality of first-stage larvae is very high. Newly hatched 

 larvae can ordinarily live only about a week without feeding. The 



