-25- 
INSECT PEST SU'ETEY BULLETIN 
Voi, 19., 
supplement' to No* 1 
March 15, 1939 
COLONIZATION OP JAPAJiaSE BISTLE PARASITES IN THE 
EASTERN STATES IN 193S 
By J, L. King, l/senior entomologist. 
Division of Emit Inisect Investigations, 
United States Department of Agriculture 
In 1937 3- summary report entitled, ”Li Derat ions of Japanese Beetle Para- 
sites in the Eastern States, in 1937» ’* published in the Insect Pest Survey 
Bulletin . (Vol. 17, Supp. to No. 9* PP* '^73--^22)^ In that report the early 
colonization of the mope important established parasites, from the first 
colonization to the close of 1937t "'a'S given in tabular form. The purpose of the 
present report is to continue the colonization record of the established para- 
sites to date and to give additional notes on species receiving little or no 
attention in the former report. 
There are at present considered as established three dipterous species and 
two species and two racial forms of hymenopteroxis parasites. The status of the 
species and strains is as follows t 
Pexia ventral is Aid .— Since the initial colonization of this parasite in 
1926 , through the year 193 S, a total of 15 , 25 ^ individual parasites have been re- 
leased in varying numbers in l4 colonies, distributed in 5 States as follows: 
New Jersey, 3; Pennsylvania, 5; Illinois, Maryland, 1: and Long Island, N, Y«, 
1« ■^11 of the colonies, liberated prior to. 193 ^, been scouted for recovery 
from time to time, but only 1, at Haddonf iel^, N.,J., has been recovered. This 
colony has served as a source of matepial^ fpr several' years . One colony was 
released in Chester Gouinty, Pa., in.. 193^51 ,TN.is,porasite has 3 broods annuially, 
but it is hindered in its development^ and. increase because of the scarcity of 
Japanese beetle host larvae during the flight' period of the second brood of Dexia 
females. The general scarcity of native scarabaeid. larvae, which ndght serve as 
alternate hosts during this period, also is a' factor affecting the buil(L-up of 
this parasite in the area where it is now established. The onlv way of augment- 
ing the us e of this parasite would seem to be placing it in new areas whore 
^PPlllf ‘1 occur in conjunction- with Phyllophaga . the latter serving as an alternate 
host during the time the second brood of Dexia females are larvipositing. In its 
natural spread to the southward the Japanese beetle seems to be entering an area 
where several species of Phyllophaga are more abumdant, thus in vi^-iw of a possi- 
bility of finding new and satisfactory areas .for future liberations of Dexia 
--■ ^^ralis , a nucleus of reared material is now being hold for future experimental 
colonization of this species. At present D. ventral is is of little economic 
importance, - 
1 / 
The_writer_.->ok„0',l^p. tha as.ist.-moe ef Ms asr, L. S. Pnrkor. I. M. 
as 8 6 c 
