Nehel—The Amount of Food Eaten by the Spider 525 
The spiders used in the present experiments were placed 
separately in eight inch test-tubes which were closed with cot¬ 
ton plugs that were saturated with water daily in order to fur¬ 
nish moisture. A certain number of fruit flies were put into 
the tubes wdth each spider every twenty-four hours. The num¬ 
ber varied according to the food capacity of the particular 
spiders. The following day the dried-up skins of the flies 
eaten and any dead flies, were removed from the tubes, together 
with any web the spider might have woven. 
From January 5 to January 12 no flies were given to the 
spiders, but the cotton plug in the test tube was moistened 
daily with water. Although spiders are able to go for a per¬ 
iod without food, water is necessary. Once when a spider 
seemed to be in a very torpid condition, it was revived and 
became very active when given an abundance of moisture. It 
will be seen that there was not a very marked increase in the 
amount of food eaten after this period. 
The temperature was varied from time to time and the num¬ 
ber of flies eaten was correlated somewhat with such variations. 
At a temperature of 19 °C the spiders showed an increase in 
the amount of food eaten on the second day. The same result 
was again obtained when the same individuals were subjected 
to a like temperature for one or more days in the following 
month. 
From constant feeding spiders 1, 2, 3, 6, and 7 increased in 
weight while 5 remained the same and 4 increased for a time 
and then decreased. 
CONCLUSIONS 
The fact that spiders are poisonous has led people to be¬ 
lieve that they are generally dangerous. Spiders do secrete 
a poison in the tips of their mouth parts but they usually use 
this as a means of killing their prey and, if undisturbed, they 
retain it. The spider, as far as is possible, obscures itself and 
very seldom goes where it is unwelcome; consequently it can 
hardly be said to be a pest. 
The common house spider is most useful for the destruction 
of flies and other pests; but most people are ignorant of its 
