Spiders form good subjects for a rainy-day study, and two hours spent in a neglected garret watching these clever little beings will often arouse such interest that we shall be glad to devote many days of sunshine to observing those species which hunt and build, and live their lives in the open fields. There is no insect in the world with more than six legs, and as a spider has eight he is therefore thrown out of the company of butterflies, beetles, and wasps and finds himself in a strange assemblage. Even to his nearest relatives he bears little resemblance, for when we realise that scorpions and horseshoe crabs must call him cousin, we perceive that his is indeed an aberrant bough on the tree of creation.
Leaving behind the old-fashioned horseshoe crabs to feel their way slowly over the bottom of the sea, the spiders have won for themselves on land a place high above the mites, ticks, and daddy-long-legs, and in their high development and intricate powers of resource they yield not even to the ants and bees.
Nature has provided spiders with an organ filled always with liquid which, on being exposed to the air, hardens, and can be drawn out into the slender threads we know as cobweb. The silkworm encases its body with a mile or more of gleaming silk, but there its usefulness is ended as far as the silkworm is concerned. But spiders have found a hundred uses for their cordage, some of which are startlingly similar to human inventions.
Those spiders which burrow in the earth hang their tunnels with silken tapestries impervious to wet, which at the same time act as lining to the tube. Then the entrance may be a trap-door of soil and silk, hinged with strong silken threads; or in the turret spiders which are found in our fields there is reared a tiny tower of leaves or twigs bound together with silk. Who of us has not teased the inmate by pushing a bent straw into his stronghold and awaiting his furious onslaught upon the innocent stalk!
A list of all the uses of cobwebs would take more space than we can spare; but of these the most familiar is the snare set for unwary flies,—the wonderfully ingenious webs which sparkle with dew among the grasses or stretch from bush to bush. The framework is of strong webbing and upon this is closely woven the sticky spiral which is so elastic, so ethereal, and yet strong enough to entangle a good-sized insect. How knowing seems the little worker, as when, the web and his den of concealment being completed, he spins a strong cable from the centre of the web to the entrance of his watch-tower. Then, when a trembling of his aerial spans warns him of a capture, how eagerly he seizes his master cable and jerks away on it, thus vibrating the whole structure and making more certain the confusion of his victim.
What is more interesting than to see a great yellow garden-spider hanging head downward in the centre of his web, when we approach too closely, instead of deserting his snare, set it vibrating back and forth so rapidly that he becomes a mere blur; a more certain method of escaping the onslaught of a bird than if he ran to the shelter of a leaf.
Those spiders which leap upon their prey instead of setting snares for it have still a use for their threads of life, throwing out a cable as they leap, to break their fall if they miss their foothold. What a strange use of the cobweb is that of the little flying spiders! Up they run to the top of a post, elevate their abdomens and run out several threads which lengthen and lengthen until the breeze catches them and away go the wingless aeronauts for yards or for miles as fortune and wind and weather may dictate! We wonder if they can cut loose or pull in their balloon cables at will.
Many species of spiders spin a case for holding their eggs, and some carry this about with them until the young are hatched.
A most fascinating tale would unfold could we discover all the uses of cobweb when the spiders themselves are through with it. Certain it is that our ruby-throated hummingbird robs many webs to fasten together the plant down, wood pulp, and lichens which compose her dainty nest.
Search the pond and you will find another member of the spider family swimming about at ease beneath the surface, thoroughly aquatic in habits, but breathing a bubble of air which he carries about with him. When his supply is low he swims to a submarine castle of silk, so air-tight that he can keep it filled with a large bubble of air, upon which he draws from time to time.