16 



DANGER OF SPREAD OP GIPSY AND BROWN-TAIL MOTHS. 



large portion of the Old World range of the gipsy moth it is occasion- 

 ally abundant and injurious, but as a rule it is held in check by 

 parasites and natural enemies, and in no instance have there been 

 such continuous and disastrous depredations as those exhibited in 

 Massachusetts and more recently in the adjacent New England 

 States. 1 



European outbreaks usually terminate in two or three years. 

 Nevertheless in recent years in Europe and Asia exceptional out- 

 breaks have occurred in which thousands of acres of forests have 

 been completely denuded, and where such denudation has been 

 repeated for two or three years in succession enormous areas have 

 been found covered with dead and dying trees. 



The following description of the different 

 stages and habits of the insect is reproduced 

 from Farmers' Bulletin 275 (pp. 12 to 15) : 



Description of the different stages of the insect. 



The eggs. The eggs of the gipsy moth are laid in 

 masses (fig. 1) of about 500. The individual egg is mi- 

 nute, about the size of a pinhead, and is salmon-colored 

 when first laid, but turns dark in the course of a few 

 weeks. Each egg mass is yellowish in appearance and 

 seems covered with hair. It is somewhat oval, being 

 one-half of an inch long and about three-fourths of an 

 inch wide. During winter, from exposure to moisture 

 in the atmosphere, it becomes dingy white in color. 

 Egg masses have been found on bark of imported stock 

 during the last two years, and inspectors should be on 

 the lookout for them. 



The larva, or caterpillar. The young larvae or young 

 caterpillars are dark in color and well furnished with 

 dark hairs. The full-grown larva (fig. 2) is between 2 

 and 3 inches long, dark brown or sooty in color, with 

 two rows of red spots and two rows of blue spots along 

 the back, and with a yellowish but rather dim stripe between them. The body gen- 

 erally is clothed with long hairs, and sometimes reaches the length of 3 inches. 



The pupa. The pupa (fig. 3) is not inclosed within a perfect cocoon, but the full- 

 grown larva spins a few threads of silk as a sort of support and changes to the pupa, 

 which is dark reddish or chocolate in color and very thinly sprinkled with light reddish 

 hairs. 



The adult, or moth. The male moth (fig. 4) is brownish yellow in color, sometimes 

 having a greenish-brown tinge; it has a slender body, well-feathered antennae, and a 

 wing expanse of about an inch and a half. The forewings are marked with wavy zigzag 

 darker lines. It flies actively all day as well as by night. 



The female moth (fig. 5) is nearly white, with slender black antennae, each of the fore- 

 wings marked with three or four zigzag, transverse, dark lines, and the outer border of 

 both pairs of wings with a series of black dots. The body of the female is so heavy as to 

 prevent flight. 



i For a more detailed account of the gipsy moth, see Farmers' Bulletin No, 275 (1907) and Bulletin 87 

 (1910), Bureau of Entomology, U. S. Department of Agriculture. 

 453 



FIG. 1. Egg mass of the gipsy 

 moth (Porthetriadispar). (From 

 Kirkland.) 



