BIOLOGICAL NOTES ON THE PARASITES. 35 
scrobicollis, which breeds in great abundance in the stems of the com- 
mon road weeds Ambrosia trifida and A. psilostachya, at Victoria,Tex., 
April 5, 1905 (1 female). In a personal letter dated August 30, 1906, 
Dr. Wm. H. Ashmead writes of this species: ‘“‘ Hurytoma tylodermatis 
Ashm. is another similar case [referring to his remarks on Ceramby- 
cobius, given later]. I have had several species of Eurytoma bred 
by Hopkins, Marlatt, etc., from beetles, and I can only quote their 
records. The genus seems to be primary and secondary as well as 
phytophagous, unless we can find characters to still further subdivide 
it generically.”’ 
This parasite is quite abundant throughout the season and is a con- 
tinuous breeder. The number of generations is probably little less 
than that of the weevil. There is but one individual to each host, and 
the latter may be in the larval or pupal state when attacked. The 
sexes are in the proportion of 29.1 per cent male and 70.9 per cent 
female. The females are very much larger than the males. 
Proceeding in the same manner as for the preceding species it is 
ascertained that the total developmental period is over 12 to 15 days, 
that the larval plus pupal period is over 11 to 14 days, and that the 
pupal period alone is at the minimum 6 days and maximum 13 days. 
Judging from this last period, for which the figures are definite, it 
may be safely said that the estimates for the larval and egg periods 
are very low. The increase in the length of the pupal period in 
October is noticeable. 
The data upon the biology of Eurytoma tylodermatis are compara- 
tively continuous from July 18 to October 19. In studying the length 
of the various stages the same methods were used as outlined for 
Microdontomerus. The only stage which could be definitely limited 
as to the period of development was the pupal stage, which was found 
to last from 7 to 8 days in the latter half of July, 6 to 9 days during 
August, 7 to 9 days in September, and 11 to 13 days in October. 
The larvee of Eurytoma were described in the notes as smooth, 
transversely lineolate, and with wrinklings at the sutures. The 
pup are white, pink-eyed, turning black toward maturity. They 
may be easily distinguished, by the lateral compression of the abdo- 
men and the straight venter, from the pup of Catolaccus with their 
dorso-ventral compression and obtusely angulated venter. The 
exuvium is cast in parts and is never found intact as in the case of the 
other chalcidoids studied; the remains are yellowish transparent. 
(See figure of pupa, Pl. I, fig. 1.) 
Secondary parasitism: One male was bred from material collected 
August 9 at Trinity, Tex., and two males from material collected 
September 19 at Waco, Tex., as secondary parasites in the cocoons 
of Bracon mellitor. In each case the cocoon was isolated when first 
