Theridium murarium.—Length about one-eighth of an inch, with the abdomen nearly spherical. The general color is gray. The legs are pale, with dark bands at the end and middle of each joint. The cephalothorax is pale, with a dark line in the middle and one on each side, the middle line sometimes divided into two near the eyes [(fig. 267)]. On the abdomen there is an undulated middle stripe, white at the edges and the front end, and reddish in the middle. On both sides of this stripe the abdomen is nearly black and becomes gradually lighter toward the sides. The sternum is pale, with a black edge and black stripe in the middle. The under side of the abdomen is gray, with a long black spot in the middle and a smaller one over the epigynum. There is little difference in size or color between the sexes. The epigynum [(fig. 269)] has two round holes, wide apart, near the thickened edge. The palpal organ [(fig. 268)] is shorter and simpler than it is in differens.

Theridium spirale.—This is a round-bodied spider of the same size as differens and murarium. The cephalothorax is orange brown above and below, with an indistinct dark stripe as wide in front as the eyes and narrowed behind. The abdomen has a middle stripe like differens, nearly as wide in front as it is in the middle [(fig. 271)]. The rest of the abdomen is gray, darkest toward the stripe. The legs are pale, sometimes with faint gray rings at the ends and middle of each joint. The middle stripe of the abdomen is sometimes reddish as in murarium, but oftener gray, with a dark spot near the front end. The males [(fig. 270)] have the same color and markings as the female and are sometimes more distinctly marked. The male palpi [(fig. 272)] are very large, and the palpal organ has a long tube coiled on the under and outer side. The openings of the epigynum [(fig. 273)] are about their diameter apart.

Theridium frondeum.—White, light yellow, or greenish white, with black markings that are very variable [(fig. 274)]. Usually the cephalothorax has two fine black lines running back from the eyes and uniting behind the dorsal groove, and black edges. The legs are usually darkened with brown at the ends of the joints. The abdomen is large and round, and has on the back a light undulated band bordered by brownish translucent spaces, with two black spots just over the spinnerets. Sometimes there are black spots in the translucent spaces, especially toward the hinder end, and these may be united into two long black stripes. In some individuals of either sex the black on the cephalothorax forms a wide band in the middle, almost covering the back, and a black stripe of similar width extends backwards on the abdomen for half its length. These black-striped individuals have all the other variations of color and markings. The males have all the colors and spots brighter and the legs longer than the females. The mandibles of the male are longer than those of the female and have at the base, in front, a low conical point.

This species is found from the White Mountains to Alabama. In New England it matures in July and is found on bushes all summer.