LIFE HISTORY AND CONTROL OF HOP FLEA-BEETLE. 
39 
were brought into the laboratory died within a week. Another lot, 
brought in May 11 and placed in a lamp chimney, lived well into 
July, the last individual surviving until August 22. This was an 
exceptional case, the average length of life being between three and 
six weeks. 
HABITS. 
THE LARVA. 
Where found. — Most of the. larvae were observed to be within 18 
inches of the base of the vine, the number increasing as the vine was 
approached. A few, 
however, were taken 
between the rows, 
among the roots of 
chickweed and lambs- 
quarters, and even in 
well cultivated parts 
where no weeds were 
growing. The surface 
soil of the hopyarcls is 
filled with delicate 
rootlets (fig. 12) and 
the larvae find sufficient 
food almost anywhere. 
Depth in soil.— In 
order to determine the 
average depth at which 
the younger stages may 
be found, the earth 
was taken up around 
the base of a vine in FlG - 
3-inch layers, and the 
larvae in each layer counted. The results are as follows: 
No. of larvae 
Depth ot soil. found. 
1-3 inches 6 
3-6 inches 21 
6-9 inches 7 
9-12 inches 1 
Although some few may be found above and some below, from 2 
to 7 inches is the depth at which one may expect to find the majority 
of the larvae. 
Conditions favorable. — The soil in which the larvae were found 
varied from a light sandy loam to a very heavy, almost adobe condi- 
tion. 
66513°— Bull. 82—12 4 
12. — Filamentous roots of hop vine on which the 
hop flea-beetle larva? feed. (Original.) 
