February, ’24] clausen & king: Japanese beetle parasites 
79 
forwarded, but apparently were unable to survive under the changed 
conditions. 
In Korea during the past two seasons 5 species of parasites on re¬ 
lated Popillia have been found, and these have been shown experi¬ 
mentally to develop equally well upon P. japonic a. Three of these are 
Tiphia , one being fairly common in restricted localities in late May and 
early June, while the first of the fall species is abundant in late July and 
early August. The normal host of the latter species is Anomala. 
The third species of Tiphia is very rare and occurs during late September. 
The past season one species of Campsomeris has been found in Korea, 
this developing equally well on grubs of either Anomala or Popillia. 
One generation is produced each six weeks, and consequently the value 
of this Scoliid against P. japonica in America is dependent upon the 
presence of some alternate host on which the midsummer generation 
may develop. 
One Dexiid ( Dexia sp.) was found parasitic upon Popillia and other 
grubs in Korea and, unlike the Japanese species, has three full genera¬ 
tions each year. From our observations on this as well as other species 
of Dexiidae it appears probably that most, if not all, members of this 
group which parasitize Scarabaeids are able to pass through the latter 
larval stages, and pupate, only in grubs which are themselves under¬ 
going histolytic action preparatory to pupation. It is for this reason 
that the Korean Dexiid has a different host for each generation. The 
value of this parasite under New Jersey and Pennsylvania conditions is 
therefore dependent upon the presence of additional hosts which pupate 
at the required time. The rate of increase of this species will conse¬ 
quently be controlled largely by the numerical abundance of these 
alternate hosts, if such are available. 
In summarizing the work in Japan and Korea during the past four 
years it may be stated that eleven species of parasites have thus far 
been found which normally do or can develop on P. japonica , three of 
these being upon adult beetles and the remaining eight upon or in grubs. 
With the exception of one Tiphia , all of these have been or will be intro¬ 
duced in numbers sufficient to establish them if such is possible. In 
general the outlook is very encouraging, and if an effectiveness equal to 
that in the native home of P. japonica is secured it should go far towards 
reducing the ravages of the beetle. A period of years will be required 
however, before full developments will actually reveal to what extent 
this hope is justified. The progress achieved in the colonizing of these 
various species will be reported on from time to time by the staff of the 
Bureau laboratory at Riverton, New Jersey. 
