THE PARASITES OE POPILLIA JAPONICA 
35 
In using the above method it was possible to carry about 500 
females through the entire period of oviposition, and this was nearly 
the maximum number available in the field. In general, it was 
found that cocoons could be procured to the extent of about 42 per 
cent of the original number of ovipositions. The loss of more than 
Fig. 25.— Rearing Tiphia, Koiwai, Japan: A, tins in which female Tiphia were kept for oviposition 
and method of transferring each day to tins containing unparasitized larva?; B, oviposition tins 
and cross-section trays in which the parasitized Popillia were kept until the Tiphia had killed 
them and spun their cocoons 
half during the egg and larval periods may be attributed to several 
factors, among these being mechanical injury to the grubs, fungous 
and bacterial attack, and finally, but most important, the rubbing off 
of the first-stage parasite larvae by the movements of the host grub 
in the soil. 
In 1920 and 1921 all grubs used for rearing purposes were collected 
in the immediate vicinity of the place where the Tiphia were pro- 
