65 
24 hours the shell is split its entire length and the body of the parasitic 
larva is exposed (Fig. 4). The larva remains affixed to the grub by the 
original egg-attachment (PI. II], Fig. 5, 6), and the host is more or less 
active until a day or two before the larva matures, growth up to this 
point being quite slow. At’this critical time the grub succumbs to the 
loss of its body fluids, the larva molts, and apparently having developed 
stronger mouth-parts proceeds to devour the entire grub, leaving only 
the chitinous head and portions of the shriveled hard skin (Fig. 6 and 
Pl. III, Fig. 1, 2). It was at first supposed that the Tiphia larva molted 
but once prior to spinning its cocoon and only a day or so before 
maturing, when it leaves the dorsal position on the host. However, an 
examination of the supposed skins arranged as leaflets beneath the larva 
and above the old egg-shell indicates that the !arva molts five or six 
times before pupation. The length of the larval stage, that is the time 
until the cocoon is begun, averages about two weeks, being shortest in the 
warmer months and longest in the cooler ones. There is also an indica- 
tion that the condition and activity of the grub has an influence on the 
growth of the larva. : 
After the larva has devoured its host it begins to spin the cocoon, 
first attaching loose threads of silk to all sides of the old grub-cell, 
fastening them more firmly at the small end of the cocoon with a 
“button” of silk (Pl. III, Fig. 3), and later spinning the inner layer, 
requiring from one to three days to complete the cocoon, judging from 
all external appearances. Unless the larva has a fairly uniform cell 
and one not too large it is unable to complete its cocoon, and will spin 
masses of silk at different places until it is exhausted and dies. Our 
observations indicate that most species remain in the cocoon over winter 
as larvae, although it is possible that other species, especially those 
issuing early in the spring, do pass the winter within cocoons as pupae 
or adults. The adults issue the following spring or summer, and in the 
latitude of Lafayette, Ind., all species of Tiphia have normally one annual 
generation. Several exceptions have been observed in the case of T. 
punctata and T. transversa in which the adults did not issue until the 
second season after spinning the cocoon. 
TIPHIA PUNCTATA Rob. 
This is the commonest Tiphia observed by us, and according to the 
material contained in the National Museum and our own records, it 
occurs in Ontario, Canada, and in the states of New Hampshire, Massa- 
chusetts, Connecticut, Maryland, Virginia, Ohio, Indiana, Tennessee, 
Kentucky, Illinois, Wisconsin, South Dakota, Mississippi, Kansas, 
Texas, Louisiana, and New Mexico. Detailed studies of the habits and 
life history of this wasp were made at the Lafayette Laboratory in 1915, 
and the results are given herewith. Cocoons from which adults were 
obtained and used in these studies were collected in the following locali- 
ties: Paxton, Ill., collected by G. N. Wolcott; Wellington, Kan., by E. 
