38 BULLETIN 1429, U. S. DEPARTMENT OF AGRICULTURE 
Popillia grubs on which to oviposit. Oviposition occurs largely 
during the afternoon, but in the warmer periods may continue into 
the night. 
The complete process of egg laying naturally could not be observed 
in the field, since this takes place entirely underground. In the 
laboratory, however, visible oviposition was very readily obtained 
by the use of No. 00 gelatin capsules, a single Tiphia female with 
a medium-sized Popillia grub being placed in each. Under confine- 
ment in such close quarters, comparable to the grub cell in the soil, the 
attention of the wasp is centered on the grub. She quickly quiets 
down after being placed in the capsule and soon begins an examination 
of the grub. She approaches it from the rear, advances over its dor- 
sum until her own head is near that of the host, and then lowers the tip 
of the abdomen around the side of the body and up between the legs, 
after which stinging is effected in the ventral thoracic region, usually 
between the first and second segments. This may be repeated a con- 
siderable number of times before the nerve ganglion is reached, after 
which the grub becomes almost instantly quiescent. The Tiphia 
then turns to the abdomen and, beginning at the first segment, starts 
a thorough kneading of the ventral surface with her mandibles. This 
extends for the entire length of the abdomen but is more thorough on 
the median segments. From five to seven minutes are devoted to this 
operation. When it is completed the wasp coils itself transversely 
about the body in the mid-abdominal region, the mandibles being 
firmly fastened at the lateral margin, with the body curving over the 
dorsum and the abdomen extending across that of the host ventrally 
and almost reaching the point at which the mandibles are attached. 
The tip of the abdomen is applied to the crease between the fifth and 
sixth segments and worked back and forth rhythmically for from three 
to five minutes. This enlarges the crevice somewhat and the rasping 
of the roughened abdominal tip may also wear away the integument . 
of the host at this point, thus permitting its easier perforation by the 
young larva. This conjecture is borne out by the fact that, in 
parasitized grubs, if the body is straightened out between the fingers 
the point of oviposition is the first to break, and this very readily. 
The actual deposition of the egg requires only about 15 seconds. It 
will thus be seen that the entire time elapsing from stinging to the 
completion of oviposition is from 8 to 12 minutes, but the preliminary 
examination may prolong the period to half an hour. Within 15 to 20 
minutes after it has been stung the grub begins to revive, being then 
able to move the mouth parts to a certain extent, but movement of the 
legs and body is not possible within less than 30 minutes. Repeated 
stinging occasionally brings about the death of the host by mechanical 
injury. 
After oviposition it is a frequent occurrence for the Tiphia female to 
grasp one of the forelegs between her mandibles and bite it until 
a break in the derm is effected, or the leg entirely bitten off. This 
being accomplished, feeding takes place upon the body fluids exuding 
from the wound. Grubs are frequently found in the field showing 
this type of injury, and the wound is often accentuated by a blackened 
area caused by bacterial infection. 
When a grub which already bears one egg is attacked a second time, 
the first egg is almost invariably destroyed by the wasp in the course 
of kneading the abdominal surface with the mandibles, or broken 
