COBWEBS.
The simple nests and tubes that have been described are made by spiders, most of which spin no other webs. The larger and better known cobwebs for catching insects are made by comparatively few species. On damp mornings in summer the grass-fields are seen to be half covered with flat webs, from an inch or two to a foot in diameter, which are considered by the weatherwise as signs of a fair day. These webs remain on the grass all the time, but only become visible from a distance when the dew settles on them. [Fig. 24] is a diagram of one of these nests, supposed, for convenience, to be spun between pegs instead of grass. The flat part consists of strong threads from peg to peg, crossed by finer ones, which the spider spins with the long hind-spinnerets, [Fig. 20], swinging them from side to side, and laying down a band of threads at each stroke. The web is so close and tight, that one can hear the footsteps of the spider as she runs about on it. At one side of the web is a tube leading down among the grass-stems. At the top the spider usually stands, just out of sight, and waits for something to light on the web, when she runs out, and snatches it, and carries it into the tube to eat. If any thing too large walks through the web, she turns around, and retreats out of the lower end of the tube, and can seldom be found afterward. In favorable places these webs remain through the whole season, and are enlarged, as the spider grows, by additions on the outer edges, and are supported by threads running up into the neighboring plants. Similar webs are made by several house-spiders, and are enlarged, if let alone, till they are a foot or two feet wide, and remain till they collect dirt enough to tear them down by its weight.
Fig. 24.
Nearly all spiders that make cobwebs live under them, back downward; and many are so formed, that they can hardly walk right side up. The spiders of the genus Linyphia make a flat or curved sheet of web, supported by threads above and below; the spider standing, usually, underneath in some corner, out of sight. Linyphia Marmorata makes a dome-shaped web, [Fig. 25], supported by threads that extend up into the bushes two or three feet. The spider stands under the middle of the dome, where it draws in a small circle of web with its feet. The upper threads of the web interfere with the wings of small insects flying between them, and they fall down to the dome below, where they are seized, and pulled through the nearest hole. Linyphia communis makes a double web, [Fig. 26]. The spider stands under the upper sheet, which curves a little downward. What the use of the lower web is, is not easily seen. Either of these spiders, when frightened, leaps out of the web to the ground; but Linyphia communis must go to the edge before she can clear herself, and so is easily caught in her own web.
Fig. 25.
Fig. 26.
A little spider, Argyrodes, belonging to the same family, lives among the upper threads of webs of this kind, without being troubled by the owner. It resembles in size and color the scales of pine-buds that often fall in the web, and may easily be mistaken for them. It probably spins a few threads of its own among the borrowed ones, and does, at times, make a separate web of its own.
The webs of Theridion usually have at some part a tent, or at least a thicker portion, under which the spider stands; and from this run irregularly simple threads, crossing each other in all directions, and held in place by threads above and below. Such irregular webs are made often in houses by Theridion vulgare, Hentz, in corners of rooms, under furniture, and in cellar-stairways. The same spider spins occasionally out of doors on fences, but never on plants. When it has caught an insect, and tied it up, it hoists it up into the web, sometimes a considerable distance.
They do this by fastening to it threads from above, which, as they dry, contract, and pull it up a little. They keep on bringing down more and more threads, until the insect is at last hoisted to the top of the web, where they can suck it without exposing themselves.
Pholcus, the long-legged cellar-spider, makes an irregular web of this kind, and has a curious habit when alarmed. It hangs down by its long legs, [Fig. 27], and swings its body around in a circle, so fast that it can hardly be seen. [Fig. 27], a, represents the spider as seen from below; and the dotted circle shows the path in which it revolves.