Fig. [192].—Snare of Epeira basilica. (After M‘Cook.)
The Irregular Snare.—The great majority of British Spiders belong to the family of the Theridiidae, or Line-weavers. Some of these are among the handsomest of our native species, and are in other respects highly interesting, but their snares lack the definiteness of structure exhibited by the orb-web, and little need be said about them.
For the most part they consist of fine irregular lines running in all directions between the twigs of bushes or among the stems of grass and herbage. One large and important genus, Linyphia, always constructs a horizontal sheet of irregular threads with a maze of silk above it. Such snares may be seen in myriads in the wayside hedges during the summer, and they are especially notable objects when heavily laden with dew. Insects impeded in their flight by the maze of threads drop into the underlying sheet, and are soon completely entangled. The spider usually runs beneath the sheet in an inverted position.
The sheet or hammock of silk is absent in the case of most of the other genera of this family, their snares being innocent of any definite method in their structure. They are frequently quite contiguous, and it is no uncommon thing to find a holly bush completely covered with a continuous network of threads, the work of a whole colony of the pretty little spider Theridion sisyphium.
As might be imagined from the simplicity or absence of design in the structure of the net, there appears to be very little complexity in the nature of the silk used. It is interesting, however, to find that viscid globules, not unlike those which stud the “spiral line” of the Epeiridae, are sometimes present in the snares of the Line-weavers,[[277]] and in these, too, aggregate glands are present. There is a large spider of this family, Theridion tepidariorum, which may be found to a certainty in almost any hothouse in this country. In its snare, which is of the ordinary irregular type, F. Pickard-Cambridge has observed little patches of flocculent silk, calculated to render more certain the entanglement of prey, and he has further described a curious comb-like structure on the hind leg of the animal which is probably used in the production of this phenomenon. It is by no means unlikely that a more careful study of these apparently simple snares will lead to the discovery of further complexity of structure.
Fig. [193].—Snare of Uloborus sp., some of the lines being thickened with threads from the cribellum. (After M‘Cook.)
Uloborus, a cribellate genus which has an Epeirid-like, orbicular snare, decorates some of the lines with the produce of the cribellate glands, but viscid globules are absent.
Sheet-Webs.—The webs which are such familiar—and, by association, unpleasant—objects in unused rooms and outhouses are usually the work of spiders belonging to the Agelenidae and the Dictynidae. To the first belongs the common House-spider, Tegenaria civilis, and its larger congener, T. parietina. These spiders are not attractive in appearance, and the last-named species especially, with the four-inch span of its outstretched legs, is a formidable object, and a terror to domestic servants. An obscure tradition connecting it with Cardinal Wolsey and Hampton Court has caused it to be known as the Cardinal Spider. An out-door example of the Agelenidae is the very abundant Agelena labyrinthica, whose sheet-web, with its tubular retreat, is to be sought on the banks of ditches, or in the hedges of our country lanes.
The snares of these spiders are exceedingly closely woven of very fine silk, and take a long time to complete. The process of their construction may be watched by keeping an Agelena labyrinthica confined in a box with a glass front, and the web, kept free from dust, is a beautiful object, as its fine texture gradually becomes visible as a delicate transparent film which develops by imperceptible stages into an opaque white sheet. The excessive fineness of the silk makes it difficult at first to see what is taking place. The animal is seen to be busily moving about, but the result of its labours only gradually becomes visible. A few delicate foundation-lines are first stretched across the compartment in which it is confined, and upon these the spider walks to and fro incessantly with a serpentine motion, and by and by a muslin-like floor of silk comes into view.