July 29, 1918 
Parasites of the Brown-Tail Moth 
205 
the field during July. The adults of this generation, together with those 
of the other generations that have lived over, oviposit in the small brown- 
tail-moth caterpillars during the early autumn. The adults of M. 
versicolor , particularly the females, are much more rugged than those of 
A. lacteicolor , and often live many weeks, even two or three months, so 
that occasionally females of the first generation may attack the small 
brown-tail-moth caterpillars in the fall. 
ECONOMIC IMPORTANCE OF METEORUS VERSICOEOR 
As a parasite of the hibernating brown-tail-moth caterpillars M. 
versicolor is much inferior to A. lacteicolor , destroying, on the whole, only 
a small percentage of them. On some occasions cocoons of M. versicolor 
have been found in enormous numbers in heavy brown-tail-moth infesta¬ 
tions, but these cases are not common. Moreover, the parasitism upon 
the nearly full-grown brown-tail-moth larvae is slight, and that upon na¬ 
tive caterpillars appears to be almost insignificant. The reasons for the 
lesser importance of this parasite are probably in large part the depend¬ 
ency of the species upon the brown-tail moth for hibernation and the 
extremely heavy parasitism by secondaries. Fully 50 to 75 per cent 
of the cocoons of M. versicolor are parasitized by various chalcidoids and 
ichneumonids, which recalls Riley's note (4, p . 552) following his descrip¬ 
tion of Meteorus hyphantriae } where he states that— 
... of 450 cocoons collected 84 per cent were hyperparasitized. 
Among the secondary parasites reared from M. versicolor were representa¬ 
tives of the following chalcidoid genera: Eupelmus, Spilochalcis, Dibra- 
chys, Hypopteromalus; and of the ichneumonid genera Pezomachus and 
Hemiteles. Still another factor contributing to lessen the importance 
of the Meteorus is the failure of many larvae to transform to pupae after 
they have spun cocoons; the percentage of Meteorus cocoons which give 
forth neither primaries nor hyperparasites is very high. Furthermore, 
the larva of A. lacteicolor , whenever it occurs in the same hibernating 
brown-tail-moth caterpillar with M. versicolor , causes the death of the 
latter. All these checks upon its development and increase combine to 
make M. versicolor a parasite of lesser importance. 
• 
LITERATURE CITED 
(1) Howard, L. O., and Fiske, W. F. 
1911. THE IMPORTATION INTO THE UNITED STATES OF THE PARASITES OF THE 
GIPSY MOTH AND THE BROWN-TAID MOTH ... U. S. Dept. Agr. Bur. 
Ent. Bui. 91, 344 p. } 74 fig., 8 pi. 
(2) - 
1913. [report on parasite work, 1912.] In 9th Ann. Rpt. State Forester 
Mass., 1912, p. 70-73. 
(3) 
1914. parasite work. In 10th Ann. Rpt. State Forester Mass., 1913, p. 83-85. 
