984 I. M Hawtey 
LIFE HISTORY AND HABITS 
The egg 
Under New York conditions, some of the eggs of Agriolimax agrestis 
are deposited in the fall, from August until December, and many of the 
mature slugs die soon afterward from the cold. If full-grown slugs live 
thru the winter, they may deposit eggs during May and June of the follow- 
ing spring. Slugs developing from these overwintering and spring eggs 
will mature and in turn deposit eggs in the fall of that year or in the follow- 
ing spring. 
In the summer of 1917, which was very wet, eggs were deposited more or 
less continuously from May to December, being especially numerous in 
September and October. Theobald (1905) reports this to be the normal 
condition in England. Lovett and Black (1920) state that in Oregon 
egg-laying occurs at all seasons of the year, and that the greatest number of 
eggs are deposited in the spring and early summer. 
In 1918, which was a drier and more nearly normal season for New York 
than the preceding years had been, eggs were deposited by the slugs in 
cages during May and June, and not again until September 23. In that 
year, as well as in 1919, most of the eggs were deposited late in October 
and during November. Moisture is a factor of great influence. A few 
of the eggs deposited in July and August of 1917 hatched that fall, but 
wether these young slugs survived the cold winter that followed is not 
<nown. 
The dates of hatching for eggs deposited on May 4, 1918, by an over- 
wintering slug were as follows: May 27, three; May 29, two; June 1, four; 
and June 2, five. The average length of the egg stage was 26.5 days. 
liggs that had been deposited late in the previous fall hatched between 
May 10 and June 6, the length of the egg stage in this case being between 
six and seven months. Early in the summer all the slugs in the fields are 
about the same size, and it is therefore probable that the fact that some 
eggs are deposited in the spring and others in the fall has little influence 
on the hatch ng date 
During the winter of 1917-18, there was in the greenhouse, where the 
temperature ranged from 55° to 75° F., a wide variation in the length of 
the egg stage, which ranged from 26 to 57 days, the average for 189 eggs 
being 37.3 days. Ina greenhouse which was kept at a constant temperature 
of 80° F., 24 eggs hatched in an average of 24.3 days. Theobald (1905) 
gives from three to four weeks as the normal egg stage in England. 
The eggs of A. agrestis are tucked into crevices of the soil, not far below 
the surface of the ground, and are also hidden under rubbish and pro- 
jecting stones, around the walls of buildings, and among the roots of grass. 
In bean fields that have been badly infested, the slugs collect under the 
bean piles in the fall and deposit many eggs. In the fall of 1917 more than 
five hundred slugs were taken under a pile of this kind, and the eggs were 
