LIFE HISTORY AND CONTROL OF HOP FLEA-BEETLE. 35 
vine and about 1^ inches down in the soil. Although conditions 
such as the looseness and water content of the soil may cause a 
variation in the depth, and the lack of cultivation, in the distance 
that they are placed from the vine, the above is probably the average 
position for the eggs deposited in the field. 
Arrangement. — Eggs obtained under laboratory conditions were 
deposited both singly and in clusters of from 2 to 8, but with no 
regular arrangement. All the eggs which were observed in the field 
were found one in a place, but some of them are probably laid in 
clusters under natural conditions. 
Conditions favorable for incubation. — The eggs which were found 
in the field were in moist soil, and those which were kept under like 
conditions in the laboratory hatched in due time. On the other hand, 
eggs which were allowed to dry soon died and shriveled up. A 
moist, warm soil appears to be the most favorable condition for 
incubation. 
Time of incubation. — Several hundred eggs which were obtained 
on the cheese cloth were placed in black satin bags and buried in 
moist soil, both in the laboratory and in the hopyard. These eggs 
required from 19 to 22 days to incubate; those in the field hatched 
a little sooner than the ones in the laboratory. This difference in 
time may be explained by the fact that the soil in the yard was 
heated by direct sun rays, while that in the laboratory was not. 
Hatching process. — The eggs of this beetle change but little in 
general appearance during the first thirteen days of incubation. 
After this period a transparent place appears near one end, and a 
few days before hatching this spot turns dark. In emerging, the 
larva evidently breaks its way out through the side of the egg, for a 
longitudinal slit was observed in all empty eggshells. 
THE LARVA. 
Description. — When it first emerges from the egg the larva is a 
delicate, slender, white, grublike creature, about one-half millimeter 
in length. After a few hours it turns gray, the head darkens, and a 
dark patch appears on the last segment of the abdomen. The larva 
(fig. 9, a) grows slowly, passing through several molts, and when full 
grown is about 5 millimeters in length and three- fourths of a milli- 
meter in diameter. When it first emerges from the egg it is very 
active and crawls through the soil at a rapid rate, but as it grows 
this activity gradually decreases, and when the last stage is reached 
it is little able to crawl about. 
Length of larval stage. — To determine the length of the larval stage, 
many beetles were confined around hop vines, in an uninfested area, 
for three days and were then removed. When observed at a later 
