THE PARASITES OF POPILLIA JAPONICA 55 
Its rate of increase will also depend upon the numerical abundance- 
of these hosts, if such are available. 
Four species of Scoliidae have been found which either normally 
attack Popillia japonica or readily accept it as a host. Campsomeris 
annulata readily accepts full-grown grubs of P. japonica, but success 
in establishing it will depend upon the abundance of other acceptable 
native grubs which will support the broods for which large Popillia 
grubs are not available. 
Of the Tiphia species, T. popilliavora at Koiwai effects a parasitism 
of 20 per cent upon grubs of P. japonica. It is a fall species, occurring 
during late August and early September. T. vernalis is a spring 
species occurring in Chosen during May and early June. It effects 
a field parasitism of 10 per cent upon native Popillia, and it readily 
accepts P. japonica. Tiphia Icoreana from Chosen is normally 
parasitic upon Anomala sp., but readily accepts P. japonica. The 
average parasitism by this species in the field is 20 per cent, but 
ranges at times as high as 76 per cent. 
Craspedonotus tibialis is the only predator which has been con- 
sidered for introduction. Large numbers were forwarded, but estab- 
lishment was not successful. 
In the Orient Popillia japonica is found only in Japan proper, and 
in that country it is of very minor importance as an enemy of eco- 
nomic crops. The most striking difference in its life history in Japan 
is the occurrence of a two-year cycle in 75 per cent of the total 
Popillia fauna on the island of Hokkaido. At Koiwai, in northern 
Honshu, only 25 to 30 per cent undergo a two-year cycle, whereas 
for Yokohama and regions southward only a one-year cycle is found. 
Three species of Popillia occur commonly in Chosen, aud the chief 
importance of these lies in the fact that their special parasites may 
be of use in combating P. japonica in America. The known parasites 
of these have been tested on the latter host, and in all cases have 
accepted it readily. 
