THE PARASITES OF POPILLIA JAPONICA 27 
parasite could not be of value against P. japonica in America. The 
1923 investigations, however, revealed two additional generations 
each year, and this fact changed the status of the species markedly 
as regards its potential value. 
LIFE HISTORY 
In a consideration of the life history of Dexia, the young larvae pro- 
duced by the spring generation of females may be taken as the start- 
ing point. These burrow about in the soil in search of hosts in 
exactly the same manner as Prosena, and penetration is effected in 
the same way. This occurs largely on the dorsal portion of the 
anterior half of the body. Here the analogy between the two species 
ends, however, for the young larva upon penetration attaches its 
caudal end to the aperture in the derm of the host and thus sets up 
immediately respiratory connection with the outside air. (Fig. 21, B.) 
The first molt occurs within a few hours thereafter, and consequently 
the dark-colored respiratory funnel is distinctly visible externally on 
the same day that the host is entered. This is in marked contrast 
to the attachment of the respiratory funnel of Prosena in the early 
second stage to the tracheal trunk of the host, the funnel of which is 
not visible until the host is almost entirely consumed. Feeding 
during the early stages is largely upon the fluid contents of the host 
body, and in the later stages upon the fat bodies, and finally on the 
vital organs. During this period the parasite body lies with its head 
directed caudad with respect to the host. 
Growth in all of the larval stages is very rapid, the host being 
dead and the body contents entirely consumed within 10 to 15 
days after penetration. A hole is cut ventrally in the wall of the 
abdomen by the mature larva after the host is killed; it then turns 
about and feeds in the thoracic regions, and finally emerges and 
pupates exactly as does Prosena. The pupal period covers seven 
to nine days. Under field conditions only a single individual reaches 
maturity in each host, though many grubs have been collected which 
contained 20 or more first-stage larvae. 
Second generation 
The midsummer generation of adults appears during the period 
beginning about July 25 and extending to August 20, though the 
greatest numbers are present during late July. The lengths of the 
various stages correspond very closely to those of the preceding 
generation. 
Third generation 
The first of the fall brood of adults appears in the field about 
September 1, and a maximum abundance is attained by the middle 
of that month, although females may still be found commonly as 
late as the middle of October. The temperature during the latter 
part of this period is very cool, being often below freezing in the 
early mornings. The progeny produced by these females enter the 
host and pass the winter in the second larval stage. On account of 
the lower spring temperatures, the pupal stage is somewhat longer 
than in the other two generations. The first adults appear about 
May 22 and persist not later than the middle of June. 
