Why, you may wonder, should spiders be our friends? Because they destory so many insects,
and insects include some of the greatest enemies of the human race. Inserts would make it
impossible for us to live in the world; they would devour all our crops and kill our flocks
and herds, if it were not for the protection we get from insect-eating animals. We own a lot
to the bird and beasts who eat insects but all of them put together kill only afraction of
the number destroyed by spiders. Moreover, unlike some of the other insect eaters, spiders
never do the least harm to us or our belingings.
Spiders are not insects, as many people think, nor even nearly related to them. One can tell
the difference almost at a flance, for a spider always has eight legs and an insect never
more than six.
How mnay spiders are engaged in this work on our behalf? One aythority on spiders made a
census of the spiders in a grass fiekd in the south of England, and he estimated that there
were more than 2,250,000 in one acre; that is somthing like 6,000,000 spiders of different
kinds on a football pitch. Spiders are busy for at least half the year in killing insects.
It is impossible to make more than the wildest guess at how many they kill, but they are
hungry creatures, not content eith only three meals a day. It has benn estimated tha the weight
of all the insects destroyed by spiders in Britain in one year would be greater than the
total weight of all the human beings in the country.