Vol. XIV Washington, D. C., July 29, 1918 No. 5 
TWO IMPORTANT INTRODUCED PARASITES OF THE 
BROWN-TAIL MOTH 1 
By C. F. W. Mu^sebeck 
Scientific Assistant, Gipsy Moth and Brown-tail Moth Investigations ,, Bureau of 
Entomology, United States Department of Agriculture 
INTRODUCTION 
To make clearer the following discussions of two parasites of the brown- 
tail moth (Euproctis chrysorrhoea Linnaeus), a brief summary of the 
introduction and life cycle of the host species is given here. The brown- 
tail moth was introduced accidentally from Europe about 1890, probably 
on nursery stock, and made its first appearance in the vicinity of Boston, 
Mass. It increased rapidly and soon became widely distributed, extend¬ 
ing its ravages over very nearly all New England, and also became 
established in portions of New Brunswick and Nova Scotia. The 
destructiveness of the species has diminished very markedly during the 
past few years, however, due in large part to natural control agents. 
The brown-tail moth deposits her eggs during the latter part of July, 
in an elongate mass of several hundred on the underside of a leaf, com¬ 
monly of apple (Malus sylyestris ), pear (Pyrus communis ), oak (Quercus 
spp.), or wild cherry (Prunus spp.), and covers them with a dense layer 
of brown hair taken from the tuft at the posterior end of her body. 
These eggs hatch after from two to three weeks and the very small pale 
brown caterpillars begin feeding in a colony on the terminal leaves, which 
they tie together with a large amount of fine silk to form a firm web 
3 or 4 inches in length. For a considerable period in the early autum 
the caterpillars feed slightly, coming out of their webs for this purpose 
from time to time; their growth is very slow, however, and although they 
molt once or twice they do not attain a length of .more than 4 or 5 mm. 
before becoming dormant for the winter. In the early spring, with the 
„ opening of the buds, the caterpillars leave their webs and begin feeding, 
1 The investigations which form the basis for this article were conducted at the Gipsy Moth Laboratory, 
Melrose Highlands, Mass., under the general direction of Mr. A. F. Burgess. The writer wishes to acknowl¬ 
edge the assistance received from Mr. S. S. Crossman, of the Laboratory, and from many others of the staff 
who have helped in various phases of the work. The photographs were taken by Mr. H. A. Preston, 
Determinations of chalcidoid hyperparasites were made by Mr. D. W. Janes, of this Station, and Dr. Robert 
Matheson, of Cornell University. 
Journal of Agricultural Research, Vol. XIV, No. 5 
Washington, D. C. July 29, 1918 
Key No. K-69 
( 191 ) 
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