INSECTS AND OTHER ANIMAL Pests [NsuRIOUS TO FIELD BEANS 989 
RELATION OF AGRIOLIMAX AGRESTIS TO MOISTURE 
Agriolimax agrestis is a moisture-loving animal. It is found above 
ground in large numbers only after rains or on cloudy days when the 
relative humidity is high. In 1916 and 1917, wh ch were damp years at 
Perry, the slugs of this species were unusually active in the bean fields. 
During the past three years there have been no extensive, general outbreaks. 
From an examination of the relation of the rainfall of the past four years 
to the abundance of the slugs, it would seem that rainy weather in May 
and June, when the eggs are hatching and the young slugs are beg nning 
their growth, makes conditions most favorable for their development. 
Especially is this true if two or more such years come in succession. In 
1916, and again in 1917, these months were rainy. In June of 1916 the 
rainfall at Rochester, New York, was 5.72 inches, and for the same month 
in 1917 it was 6.40 inches; while in 1918, 1919, and 1920, it was below the 
monthly average of 3.13 inches. 
It sometimes happens, after a rainy period, that the ground dries and 
bakes so hard that the slugs cannot break the hard crust and are thus 
forced to feed below the surface. On heavy, undrained soils the damage 
is always greater than on lighter ground. Since the growth of the slugs 
is dependent on the amount of food eaten, and since their feeding is heavier 
in moist surroundings, it is easy to see why they mature much more quickly 
in moist than in dry seasons. During dry periods the slugs are found 
deep in the soil, in contracted positions. They work their way far below 
the surface of the soil in search of moisture. Reh (1913) says that a slug 
supplied with plenty of moisture after having been under dry conditions, 
may become three times as large as it was before. 
RELATION OF AGRIOLIMAX -AGRESTIS TO EXTREMES OF TEMPERATURE 
The field gray slug can survive cold weather if it is in a protected posi- 
tion; but a temperature of —14° F. proved fatal to specimens in flower-pot 
cages in the insectary at Ithaca when there was no fire in the building for 
several days. Few slugs survived the unusually cold winter of 1917-18, 
as was shown by the fact that in the spring of 1918 the writer could find 
but a small number in the fields near Perry where there had been thousands 
in the fall preceding. The slugs that had escaped the cold had done so 
by crawling under the sod and the rubbish in fence corners or other pro- 
tected places. Very few of the millions of eggs deposited under the bean 
piles in the fall of 1917 survived. These occasional severe winters are 
believed to have an important fnfluence in keeping down the numbers of 
this pest in New York. January of 1918 was the coldest January, as well 
as the coldest month, within the scope of the official weather records. 
The mean monthly temperature for that month at Ithaca was 9.7 degrees 
