The Erigones are all very small spiders, and for this reason few of them will be described. They live, for the most part, near the ground in grass, moss, and dead leaves, with small webs like those of Linyphia, and are seldom seen unless carefully searched for. There is one season of the year, however, when the Erigones appear in immense numbers. This is during the fine weather that comes after the first frosts in October and November, when they, in company with the young of many larger kinds of spiders, come to the tops of posts and fences and, turning their spinnerets upward, allow threads to be drawn out by ascending currents of air, until sometimes the spiders are lifted off their feet and carried long distances. Though not so easily seen, the same performance is going on at the tops of grass and bushes, and at times the whole country is covered with threads of silk, and the threads in the air tangle together into flakes, which at length fall, sometimes from great heights. This appearance is called in England "gossamer" and in Germany the "flying summer" and the "old woman's summer." Why the spiders spin the thread and what use it is to them to be blown about are unknown. At the time of the autumn flights great numbers of these spiders may be seen on fences and doorsteps in city streets wherever there is a neighboring park or grass plat, and the spiders probably live the rest of the year among this grass near the ground. [Illustration: FIG. 360. Erigone dentigera trying to fly. Enlarged eight times. From a photograph on Boston Common.] [Illustration: FIGS. 361, 362, 363, 364, 365. Erigone dentigera.--361, side of male. 362, back of cephalothorax of male enlarged sixteen times. 363, female. 364, mandible of male. 365, maxilla of male.]