GRAPEVINE FLEA-BEETLES. 
9 
The period covered by records of larvae in the soil extended from 
June 19, when the first larvae entered the ground, to July 27, when 
the latest adults emerged. The variation in duration of this period 
is shown in Table II. 
EMERGENCE FROM HIBERNATION AND OVIPOSITION IN 1917. 
The earliest record of adult emergence is May 11, at which time 
grape buds were swelling. Eggs were first found May 18. Adult 
beetles were found on grapevines until 
the latter part of June, when they disap- '^'^l^^chalyhea^'Nm^^ 
peared altogether. 
1916. 
INCUB ATION PERIOD IN 1917. 
The duration of the incubation period 
in 1917 (see Table III) varied from 13 to 
21 days, with an average of 15.18 days, 
as shown in Table III. The period cov- 
ered by records on the incubation period 
extended from May 26 to June 28. 
LARVAL FEEDING PERIOD. 
Number of 
Duration 
individuals. 
of period. 
Days. 
2 
15 
1 
16 
4 
17 
7 
18 
10 
19 
16 
20 
8 
21 
20 
22 
12 
23 
7 
24 
187 
2 20.71 
1 Total. 
Weighted average. 
The duration of the larval feeding period 
of 46 individuals of Altica chalybea reared 
to adults varied from 19 to 33 days with an average of 24.26 days. 
The period covered by records of feeding larvae extended from June 
4, the earliest date of hatching, to July 20, the latest date, when 
larvae entered the ground. Complete data on the larval feeding 
period are given in Table IV. 
Table III. — Incubation 'period of A. chalybea, North East, Pa., 1917. 
Date of 
Date of 
Number 
Duration 
Date of 
Date of 
Number 
Duration 
oviposition. 
hatching. 
of eggs. 
of period. 
oviposition. 
hatching. 
of eggs. 
of period. 
Days. 
Days. 
May 26 
June 14 
6 
19 
June 2 
June 15 
10 
13 
26 
16 
6 
21 
2 
16 
4 
14 
29 
12 
1 
14 
2 
17 
5 
15 
31 
13 
4 
13 
2 
IS 
2 
16 
31 
14 
4 
14 
2 
19 
2 
17 
31 
15 
2 
15 
4 
19 
25 
15 
31 
16 
2 
16 
4 
20 
17 
16 
June 1 
14 
12 
13 
13 
28 
1 
15 
1 
15 
4 
14 
1 
16 
1 
15 
1108 
2 15. 18 
1 Total. 2 Weighted average. 
DURATION OP FIRST LARVAL STAGE. 
The duration of the first stage, of 68 larvae reared, varied from 
4 to 14 days with an average of 8.74 days, as is shown in Table V. 
The total period covered by records on larvae in this stage extended 
from June 4 to July 2. 
1833°— 20 2 
