PARASITES OF GIPSY-MOTH PUPJE. 
237 
If it is, in truth, single-brooded, like its host, it ought to multiply 
mijch more rapidly than it has done, in view of the superlative 
opportunities which the past 10 years have afforded. 
THE GENUS PIMPLA. 
The several forms of the genus Pimpla which have been reared 
from gipsy-moth pupae received from Europe and Japan are not, 
like the forms of Theronia, confusing and indefinitely separable, but 
good and distinct species. There are 3 European, and a like number 
of Japanese, making together, with the 2 American, a total of 8 of 
the genus known to attack this host. Notwithstanding their variety, 
all the species acting together in any one locality have never effected 
the degree of parasitism resulting from the attack by Theronia in 
the same locality. Being collectively of so little importance it is 
unnecessary to say more concerning their relative importance indi- 
vidually. 
Quite a little lias been learned at first hand concerning the two 
European >|>e<ie> most frequently encountered, Pimpla instigator Fab. 
and Pimpla i fa initiator Fab. Both have been received inconsiderable 
numbers in shipments of brown-tail moth pupa\ and have been 
liberated to the number of several hundred each in 1!)()(>, 1907, and 
1909. Neither has since been recovered from the field. 
Both have been carried through all of their transformations in the 
laboratory upon the gipsy moth, the brown-tail moth, or the white- 
marked tussock moth, and in the case of P. i nsti gator upon all three 
above-mentioned hosts. The early stages of the Larvae have not 
been seen. In nearly every respect, so far as observed, they resemble 
each other in habit and biology and also P. (I/ophctis) conquisitor 
Say. and /\ ptdalis Cress., their American congenors. The one* point 
of difference between them i> the tendency of Pimjtfa instigator to 
hibernate within the pupa of the brown-tail moth. A very few have 
been reared each spring since 1!)()S from cocoon masses received the 
summer before. The proportion thus hibernated is very small. 
Pimpla instigator, like the American P. (Hoplectis) amquisitor, may 
become hv perparasit ic on occasion. On August 7, 1907, five female 
specimens of P. instigator were confined with several tussock-moth 
cocoons which contained the cocoons of Pimpla (Ppiurus) inquisi- 
toriella Dalla Torre, from some of which adults were emerging, and 
all of which had been spun for several days. Oviposition was imme- 
diately attempted. It was certainly successful, for on August 29, 
at least two weeks after the Epiurus had ceased to issue, a greatly 
dwarfed male P. instigator appeared and it was followed by another 
similarly small male on September 3. There is not the slightest 
doubt that the European parasite attacked the native and that its 
larvae fed to maturity. At the same time it is not likely that it would 
