February, ’24] clausen & king: Japanese beetle parasites 
77 
author to that field, and he was joined by Mr. King at the end of that 
year. Investigations have been in progress continuously since that time, 
being confined for the first two years to Japan and extended in 1922 to 
Korea. 
Popillia japonica is found on all of the main islands of Japan, but does 
not extend to the Asiatic mainland, and is most abundant in the northern 
half of Japan in a habitat corresponding somewhat to that of the north 
central states. Nowhere is it an economic pest. Its life cycle differs 
somewhat from that in America, and may be summarized as follows for 
the three main localities in which studies were made. At Yokohama 
one complete generation occurs each year, with adult beetles present 
from late in May to the end of July only. At Koiwai, about 300 miles 
north of Tokyo, the cycle corresponds quite closely to that in New 
Jersey, except that possibly 25-30 per cent have a two year cycle. At 
Sapporo in Hokkaido, the most northern island, and about 900 miles 
north of Tokyo, the cycle is largely two years, and in the years of 
beetle abundance they may be found from early July to September, 
whereas during the alternate years they disappear either before or 
shortly after August first, thus covering a period of less than one 
month. These points are mentioned because they have an important 
bearing upon the development of certain of the parasite species. 
Several other species of Popillia occur in Japan, but they are extremely 
rare. In Korea three species are found, Popillia atrocaerulea , bogdanowi , 
and indigonacea , these being given in the order of their appearance 
during the season. None of these are of any importance economically. 
Of the parasites of Popillia japonica those of the adult beetles may 
first be mentioned. These are: Centeter cinerea, a new genus and species 
recently described by Dr. Aldrich, Ochromeigenia ormioides Towns, and 
Eutrixa sp., all Tachinids. The first is found only in the northern 
sections of Japan under climatic conditions corresponding closely to 
those of New Jersey. In the areas mentioned this Tachinid is always 
found, and usually in considerable abundance. One generation is pro¬ 
duced each year, the adults appearing somewhat prior to those of the 
host. The parasitism of female beetles at Sapporo in 1920 and 1922 
exceeded 99 per cent, and this within two weeks after the emergence of 
the beetles. As many as fourteen eggs were found on a single beetle in 
the field, and of all eggs laid from 70 to 99 per cent were upon female 
beetles. During the alternate years, 1921 and 1923, the parasitism 
was slightly less than 50 per cent, with between 98 and 100 per cent of 
the eggs on female beetles. This biennial rise and fall is closely 
