THE CRANBERRY ROOTWORM. 
flood is drawn in the spring. Soon after the water is drawn the larvae 
commence to feed again, which may be noted by the fresh barking of 
the roots. Before commencing to pupate the larvae move closer to 
the surface of the bog, the majority being found in the first inch of 
soil. Some idea of their abundance was obtained by counting the 
larvae under plats of soil 10 inches square. Twelve larvae were obtained 
in one instance and other counts of 11 and lesser numbers were made 
where the injury to the vines was quite apparent. From the fore- 
going it will be seen that the species spends most of its life in the larval 
stage, or approximately 10 months. Possibly some of the larvae fail 
to mature at the expiration of this period and spend another year in 
the bog before reaching the adult stage. 
PUPAL STAGE. 
The time when pupation commences varies somewhat with the 
management of the bog. The earlier the flood is drawn the earlier 
will be the date of general pupation. In 1913, when the water was 
drawn April 1, pupae were in the majority June 6; while in 1914, 
when the water was drawn May 20, the larvae outnumbered the pupae 
two to one on June 15. Pupation studies were carried on in wooden 
cages having glass bottoms, which permitted one to observe those 
larvae which formed cells against the glass. The average duration 
of the pupal stage was found to be 14J days, and from 2 to 3 days were 
spent by the adult hardening in the cell and reaching the surface. 
SUMMARY OF LIFE HISTORY. 
Stage. 
1 
Period of usual occurrence, t Range in occurrence. 
1 
Usual 
duration. 
Range in 
duration. 
Adult 
June 20-Aug. 1 
June 6-0 ct. 20 
July 10-Sept. 3 
Days. 
35 
8 
10| 
14J 
Days. 
56 
Egg 
July 10-30 
6-11 
Jrly 16-June 1... 
June 1 0-30. 
May 25-July 9 
13 17 
RECOMMENDATIONS FOR CONTROL. 
Some way in which to control an insect infestation by the use of 
water usually first suggests itself to one connected with the cranberry 
industry. The particular bog, however, upon which most of the obser- 
vations were made has an insufficient water supply limited to a win- 
ter flooding with no available water for reflooding. Late holding of 
the water — that is, until May 20 — had no effect in reducing the infes- 
tation. The larvae were in as good condition after this treatment as 
when, the year previous, the water was drawn April 1. Laboratory 
experiments have shown that the larvae can live submerged in clean 
water for as long as 41 days, while pupae have not survived more than 
9 days. Examination of a bog which had been reflowed for a period 
of 4 days in the latter part of May disclosed many live larvae but no 
