Fig. 37.
THE TRIANGLE SPIDER.
Among those spiders that use the calamistrum is one which makes a web unlike any other. It has been described by Professor Wilder, in the “Popular Science Monthly” for April, 1875, under the name of the “triangle spider.” It lives usually among the dead branches around the lower part of pine and spruce trees, and is colored so like the bark, that when it stands, as it usually does, on the end of a branch, it is easily mistaken for a part of it. The web seems to be made in the night. Wilder saw them early in the morning; and I, in the evening, between sunset and dark. A single thread five or six inches long runs from the spider’s roost; and from its extremity radiate four branches, attached to various twigs in the neighborhood, [Fig. 38], AE, AF, AG, AH.
Fig. 38.
The spider begins to cross them with adhesive threads near the end of the upper ray at S′. After fastening the end of the thread, she walks along toward the centre, scratching away all the time with her calamistrum, till she comes to a place, 5, where she can cross to the next ray. She crosses over, and goes outward toward S″, the thread shrinking as she goes, until, when she arrives at S″, it is just long enough to reach across to S′. She fastens it by laying it along the ray for a short distance, and goes inward again till she reaches 7, where she crosses to the next ray; and so on till the thread is finished to S‴′. Here she stops spinning, and goes up the lower ray to A, and along the upper one to 4, where she starts another cross-thread. This goes on till the whole web is filled, as in [Fig. 39], nearly to the centre.
When the web is finished, the spider goes up the thread A o, to within an inch or so of the twig to which it is fastened; turns round, and takes hold of the thread with her front-feet; then pulls herself backward with her hind-feet up to the twig. She thus tightens the web, and draws up a loop of thread between her front and hind feet, [Fig. 39], lower figure.