986 I. M. Hawury 
earth. The same writer declares that agrestis is able to descend at the rate 
of five inches a minute on a thread of this kind, and that one specimen was 
found hanging on a thread seven feet from the point of attachment. At 
times they reascend by this same thread. 
The full-grown slug 
The adults of Agriolimax agrestis, as well as the young, are nocturnal. 
They are seen during the day only in cloudy or rainy weather, or in shady 
and concealed places. In an infestation under observation on July 13, 
1918, the slugs were on the plants from seven o’clock in the evening until 
eight in the morning. As it becomes light, the slug crawls into a crevice 
of the soil or under some protective covering such as grass, straw, or 
boards. This aversion to light is said to continue even after the eye- 
bearing tentacles have been removed. Ina bean field the slugs frequently 
burrow down near a bean plant and feed on the parts below ground. The 
writer has found them buried from four to eight inches deep in the soil, 
with their tentacles drawn in. They were contracted and inactive, and 
were covered with a coating of slime to which particles of dirt adhered. 
In the cold weather of winter they hibernate in this resting position. 
The field gray slug moves by an almost imperceptible shortening and 
lengthening of the muscles of the foot, or under side of the body. Taylor 
(1907) declares that two inches a minute is a good speed for this species, 
and has estimated that at this rate it would take twenty-two days and 
ten hours of steady movement to cover a mile. Since the slugs have 
been in this country they have apparently absorbed some of the Ameri- 
can spirit, for they have been observed to go much faster than this. Some 
slugs are reported to return to the same hiding place night after night, 
but agrestis apparently does not have this habit. 
The nocturnal travels of the slug are recorded each morning by the 
trail of slime which the animal leaves wherever it goes. After a rain 
these slime trails are often found on sidewalks, and in heavily infested 
fields the writer has seen the ground and the plants so coated with this 
glistening secretion that they have an iridescent appearance. More 
slime is secreted on a dry surface than on one that is moist, and on the 
dry surface the slime appears more milky, due, it is believed, to the pres- 
ence of particles of carbonate of ime. This mucous secretion is supposed 
by some writers to aid in locomotion, while other writers declare that it 
regulates the evaporation, thus controlling the body temperature. It 
is thought also to serve as a protection against enemies. When irritated 
by a finely pulverized substance, such as lime, agrestis will give off large 
amounts of slime from the pores of its body, and when this mixes with the 
powder it usually forms a: coat around the animal. The slug is sometimes 
able to escape by leaving this coat behind, but it may become so weakened 
by its struggles that it dies within the covering. 
