[Illustration: FIG. 253. Webs of Theridium in a fog, on the tops of
burnt bushes. Half the real size. These webs are too fine to be noticed
in dry weather.]
[Illustration: FIG. 254. Webs of Theridium in a fog, on the tops of
golden-rod. One-third the real size.]
The Therididæ are the builders of the loose and apparently irregular
webs in the upper corners of rooms, in fences and among rocks, and
between the leaves and branches of low trees and bushes. They are
generally small, soft, and light-colored spiders, with the abdomen large
and round and the legs slender and usually without spines. The eyes are
all about the same size and in two rows across the front of the head,
with the lateral eyes of the two rows near together and often touching
each other. The mandibles are weak and without teeth at the end. The
maxillæ are pointed at the end and turned inward toward each other. Most
of the Therididæ live always in their webs, hanging by their feet, back
downward. The webs have in some part a more closely woven place under
which the spider stands, sometimes in the middle of the web, sometimes
in a corner out of sight. Where the spider's usual standing place is
without other shelter, it is often concealed by pieces of leaves or sand
carried into the web by the spider, and sometimes made into a tent. The
outer part of the web is usually loosely made in large meshes, but is
sometimes in a distinct sheet spreading from the nest and held out by
threads in all directions. The cocoons are round and soft and hang in
the web, several being made in the same season by one spider.
[Illustration: FIG. 255. Web of Theridium tepidariorum in a dark corner.
Half the real size.]
Several of this family, like Spintharus and Euryopis, have the abdomen
smaller and flatter than usual and the fourth legs longer, so that they
are better fitted for walking. They are found on plants, and little is
known about their webs.