36 
BULLETIN 1429, U. S. DEPARTMENT OF AGRICULTURE 
cured, but collecting was found to be impracticable there in 1922 
and consequently 10,000 were collected in Hokkaido during late July 
and shipped to Koiwai. The mortality among these grubs during 
the month from collection to the time of use for breeding purposes 
was about 50 per cent. A total of 3,350 cocoons have thus far been 
obtained by the method described above, these being from approxi- 
mately 10,000 ovipositions. After the formation of the cocoons they 
were removed from the soil, packed in moss in metal containers, 
and forwarded to the Riverton laboratory. 
LIFE HISTORY AND HABITS 
The account of the life history of Tiphia may be started from the 
egg upon the body of the host grub. This is normally placed ven- 
trally between the fifth and 
Tijohia ko re ana sixth abdominal segments, 
and half way between the 
median ventral line and 
the lateral margin (fig. 26). 
This position may occa- 
sionally vary to the extent 
of one segment either way. 
The anterior pole of the egg 
faces inward. It is always 
placed in the crevice be- 
tween the segments and is 
laid with the ventral sur- 
face adhering for its entire 
length to the derm of the host 
by means of a mucilagi- 
nous material provided by 
the female wasp at the time 
of oviposition. This adhe- 
sive material darkens con- 
siderably in color within one 
or two days after deposition. 
The duration of the egg stage varies considerably under different 
temperature conditions. A series of eggs secured at Yokohama 
averaged 4.5 days, the temperature during that period ranging from 
a minimum of 80° up to 97° F. At Koiwai, where the breeding work 
was conducted, the weather was much cooler and the general duration 
of the stage was prolonged to about eight days. 
Hatching is effected by a vertical split at the anterior end of the 
egg, the head of the young larva being then thrust out and the 
integument of the host pierced by the mandibles. Feeding begins 
almost immediately, and as the body becomes distended the break 
in the shell enlarges and extends down the median line almost to the 
posterior tip. The shell remains as a ventral pad beneath the larva, 
and this serves to maintain its attachment to the host. 
The first molt occurs very soon and is effected by a dorsal longi- 
tudinal split in the skin, beginning at the first thoracic segment and 
extending almost to the tip of the abdomen. The head is lifted out 
of the cast skin, moved forward slightly, and reapplied to the host. 
The cast skin remains adhering to the ventral surface of the body. 
Fig. 26. — A Popillia japonica grub, showing the position of 
the eggs of the four species of Scoliidae parasitic upon it 
