52 
THE GRAPE ROOT-WORM. 
LIFE HISTORY OF FIDIOBIA FLAVIPES ASHM. 
During the summer of 1909 the junior author had opportunity to 
rear Fidiobia Jiavipes Ashm. (fig. 24) and to make some observations 
relative to its habits and occurrence in the Lake Erie grape belt. 
The parasitized root-worm eggs can be readily recognized in that 
they assume a brownish-yellow cast and become gradually darker 
with the development of the parasite. The grape root-worm eggs 
when first deposited are whitish, but soon take on a yellowish cast. 
In view of the semitransparent eggshell it is possible to observe the 
development of the different stages. 
Parasitized eggs were obtained in the vineyards July 13, from 
which adults issued on August 3. These adults were then placed in a 
vial August 4, with fresh eggs which had been laid in breeding cages 
the previous day. On August 7 an 
irregular area could be distinguished 
in the center of each egg, indicating 
a breaking up of the yolk tissue. 
On August 11 the parasitized eggs 
were already of a dark yellowish- 
brown cast. In one extremity of 
the egg there began to appear an 
Fig. 24.— Fidiobia Jiavipes, an egg-parasite of ii.11 1 1 
the grape root-worm: Adult and enlarged empty Space and the larva COllld 
antenna. Very greatly enlarged. (Orig- be distinguished feeding toward the 
mal ) opposite end. On August 14 most 
of the parasite larvae pupated. Two or three days after pupation 
the eyes could be distinguished in the form of black spots, and a few 
days previous to the time of the emergence of the adults the entire 
pupa assumed a dark color. The minute hymenopterous flies emerged 
August 28, 29, and 30. 
In summarizing these data, we get 10 days for the egg and larval 
stages, 14 to 15 days for the pupal stage, or a total of 24 to 26 days 
for the whole life cycle. It is possible to recognize parasitized eggs 
3 or 4 days after they become infested. Adult insects lived from 5 
to 7 days in a test tube without food. 
To determine the development of parasites from root-worm eggs of 
different ages and also to test in a general way the resistance of eggs 
of different ages to parasitism, the following experiments were carried 
out as summed up in Tables XXI and XXII: 
