176 PARASITES OF GIPSY AND BROWN -TAIL MOTHS. 
present has not been sufficiently large to make the rearing of the 
parasite economically worth while. It is interesting and possibly 
significant that there was no Schedius in the one locality where Anas- 
tatus was sufficiently common to be considered as a parasite of con- 
sequence, while in the other localities, where Anastatus was rare, 
Schedius abounded. More than one instance has been observed in 
which parasites having similar habits alternate but rarely or never 
occur simultaneously in anything like equal abundance in one locality. 
Two fairly consistent examples of this sort will receive further men- 
tion later on, in which the tachinids Dexodes nigripes and Compsilura 
concinnata, and Tachina larvarum and Tricholyga grandis are respec- 
tively involved. 
Schedius kuvan.e How. 
Only one species of gipsy-moth egg parasite has been received at 
the laboratory from Europe, but in Japan there are two, and, so far 
Fig. 17.— Schedius kuvanx: Adult female. Greatly enlarged. (From Howard.) 
as may be determined from their comparative abundance in the 
material from that country which has been studied, Schedius Jcuvanae 
(fig. 1 7) is the more common and important as a factor in the control 
of its host. It resembles Anastatus in its choice of host, and in the 
fact that it is similarly limited through physical inability from attack- 
ing more than a limited percentage oft he eggs in each mass. In every 
other respect the two species are widely different. 
Anastatus is a true egg parasite, and rarely attacks successfully 
tlie eggs in which the young caterpillars have begun to form. She- 
dius, on the contrary, is strictly speaking an internal parasite of the 
unhatehed caterpillar. Anastatus pas.-es through but one genera- 
