532 
Journal of Agricultural Research 
Vol. XXVII, No. $ 
reached without her leaving the delicate, naked young or exposing them 
to the cold. Approaching maternity may often be noted by this habit. 
IN CAPTIVITY 
In captivity mice will eat a great variety of green vegetation, but 
they show an especial fondness for all of the clovers and other legumes. 
Grass is extensively eaten, but does not satisfy them so well as clover, 
and is always left if abundance of both are fed together. Mice are especi¬ 
ally fond of cantaloupes, completely devouring the rinds left from the 
table. Green corn is one of their favorite foods, and even the cobs are 
picked bare to the core. Most vegetables are eaten with more or less 
relish, as well as all grains and seeds, bread, fruit, fresh meat, fat, or 
bacon. Rolled oats seems to be a favorite food with both young and 
old. 
Like all their vital processes, feeding and the elimination of waste 
are very rapid. The animals apparently eat every few hours all day 
and dll night, and the accumulations of pellets in the corners of the 
cages grow rapidly. 
QUANTITY OF FOOD REQUIRED 
The quantity of food eaten is astonishing. In one cage, 30 days’ feed¬ 
ing of 10 mice with all the clover, cantaloupe, grain, and seeds they would 
eat showed, after deducting 10 per cent for waste which could not be 
otherwise accounted for, that an average of 55 per cent of the weight 
of each animal was eaten every 24 hours. This was on the richest kind 
of food. Such as they rarely obtain in the wild state. 
In another cage during the same period nine that were fed grass, 
clover, and cantaloupe rinds, with no grain or seeds, ate, after deducting 
10 per cent for waste, an average of 107 per cent of their weight every 
24 hours. This would seem more nearly their normal ration in a wild 
state and the best basis for computing food consumption. Some days 
they ate nearly twice their weight in green food, but only after they had 
become unusually ravenous. In both cages they had revolving wheels 
on which they exercised vigorously and were living fairly normal, con¬ 
tented lives. 
In one cage the average weight of the animals was 30 and in another 
33 gm. a part of the animals being immature. The adults average 
about 50 gm. but 30 gm. would be a fair average for the general run 
of young and old meadow mice in the field. 
AGGREGATE DESTRUCTIVENESS 
At 30 gm. a day one meadow mouse would consume 10,950 gm. (23 
pounds) of green food in a year, and 100 mice 2,300 pounds, or a 
little over a ton of green grass or clover, which would make about half 
a ton of dry hay. 
A hundred mice to an acre is not an unusual number in meadows 
favorable to theirhabits, while in “mouse years” or during mouse plagues, 
the number has been estimated at thousands to the acre. Even with 
1,000 to the acre it is easily shown that mice consume more vegetation 
(11^2 tons) than would ordinarily grow on an acre in a year. 
