CONTROL OF THE GRAPE-BERRY MOTH. 7 
and infested berries in the different experimental plats and in the 
adjacent untreated check plats. Counts of infested berries in each 
of the different plats were made the first season from four 40-pound 
crates of harvested fruit. In all plats in a single vineyard, the crates 
were taken from the same relative positions. During the following 
seasons a count was made from all of the fruit from 12 to 25 vines. 
These vines were taken at intervals throughout the length of each 
plat so as to include all conditions, and in the same relative positions 
in all plats in the same vineyard. 
eliminating vineyard conditions favorable to the grape-berry moth. 
Winter Exposure. 
Protected situations in vineyards, along hedgerows, fences, or 
woodlots, and low-lying spots, are invariably more heavily infested by 
the berry moth than are the less protected portions of the same vine- 
yard. On the other hand, exposed knolls seldom are infested heavily. 
This variability in infestation, according to Johnson and Hammar, 
is due to protection afforded to hibernating insects and the conse- 
quent reduction of winter mortality. Goodwin attributed the heavier 
infestation in low-lying spots to washing of cocoons in winter. 
Observations by the writer confirmed both these conclusions and 
also indicated that wind at the time of flight of moths is a factor, 
as moths drift with the wind into these low-lying spots. 
Of these factors causing heavy infestation, one at least, winter 
protection in a vineyard, can be regulated more or less by artificial 
means. The importance of this factor was tested during the winter 
of 1915-16. 
Different lots of cocoons, collected in the fall of 1915, were placed 
in cylindrical baskets of 20-inch wire mesh and wintered in vine- 
yards in protected and in exposed situations, and also in the insectary 
yard under a covering of leaves held in place by wire screen. To 
forestall accidents each lot was divided into two baskets. In May, 
1916, the cocoons were removed and placed hi rearing jars. Table 
1 shows the effect of the different conditions upon mortality: 
Table 1. — Percentage of emergence of the grape-berry moth hibernating in exposed and 
in protected situations. 
Lot No. 
Situation. 
Number 
of 
cocoons. 
Number 
of moths 
emerged. 
Emer- 
gence. 
I. 
II. 
III. 
In vineyard, naturally exposed; crest of windswept knoll. . . . 
In vineyard, naturally protected by brush and drifted snow. . 
In vineyard, artificially protected by covering with 2 inches 
350 
350 
150 
350 
20 
86 
45 
Per cent. 
5.71 
24.05 
30.00 
IV. 
In insectary yard, artificially protected under "leaf blanket". 
154 
44.00 
