14 BULLETIN 1429, U. S. DEPARTMENT OF AGRICULTURE 
At first it might be supposed that the males, having a smaller 
quantity of food material in the body, would succumb to the attack 
of the parasite more quickly than the females, but this is not the case. 
The vital organs of the female are attacked sooner than those of the 
male and consequently death takes place earlier. A series of females 
under observation averaged 5.2 days from the time of deposition of 
the egg until death, whereas the males averaged 5.8 days, with a 
maximum of 6 days for the former and 8 days for the latter. 
The time elapsing between oviposition and the pupation of the 
parasite was 9.1 days for the females and 9.2 days for the males. It 
is thus seen that the early stages of this parasite are of extremely 
brief duration. Shortly prior to its death the beetle host buries 
itself in the soil and thus the parasite, being within the body, is pro- 
vided with an air-filled chamber within which to pass the dormant 
period. 
The number of eggs deposited upon single beetles led to observa- 
tions to determine if it were possible for more than a single individual 
to reach maturity in each host. In the case of excessive duplication 
of oviposition — that is, with five or more eggs upon the body — it was 
found by dissection that the surplus larvae were killed in the second 
stage, whereas with less than that number the mortality occurred 
largely in the third stage. Two mature larvae have been found in a 
single beetle, but the weaker of these is usually killed and the other 
pupates normally. In the laboratory, occasional instances have been 
noted of two puparia being produced in a single host. 
Pufdl stage. — Of a quantity of .beetles collected bearing only one 
parasite egg each, 88 per cent eventually produced puparia, the re- 
maining 12 per cent having died in the egg or first larval stage, and 
before any effect was produced upon the host. This loss resulting 
from mortality in the early stages is largely offset in the field by 
duplicate oviposition. 
The mature fly. — The duration of the pupal stage averages about 
10.5 months, and emergence is effected during the latter part of 
June at Sapporo. The cap of the puparium is broken off, the dorsal 
portion of the two caudal segments of the beetle abdomen pushed 
away, and the fly then works its way up through the soil into the 
open air. Emergence occurs largely during the early morning hours. 
Mating has not been observed. 
Feeding occurs principally in the afternoon upon aphis honeydew 
and at the nectar glands of various plants, particularly itadori {Poly- 
gonum reynoutria). At Sapporo large numbers of males and some 
females were collected on aphis-infested elm foliage. In the breeding 
cages honey or sugar water served very satisfactorily as food materials. 
In the field the flies were found most commonly along roadsides, 
pasture borders, and streams, where more or less wild vegetation 
was present and where cultivation did not interfere with the puparia 
in the soil. In general it may be said that conditions suitable for 
the development of the host are also nearly ideal for the parasite. 
The degree of parasitism in the field was unusually uniform through- 
out all the types of habitat favored by the beetle. 
Oviposition does not occur extensively during the cool days fre- 
quently prevailing in mid- July in Hokkaido, or upon the days of 
unusually high temperatures. The optimum condition for oviposi- 
tion is a temperature of about 85° F. with a fairly high humidity 
