eastern long-legged cobweaver

Eastern long-legged cobweaver is a small, highly variable, cobweb spider. It occurs in the United States from Maine to North Carolina, west to Minnesota and Missouri, and there is just a handful of scattered records in the south and further west. It occurs across southern Canada from Nova Scotia to British Columbia.

Adults are active from June to August. They are found in forest understories, forest edges, and old fields, on tall grasses and on shrubs.

Females are ⅛″ (3.0 to 4.2 mm) in length. Males are smaller, ⅛″ (3.0 to 3.5 mm) in length. The legspan is ¼″ to 5⁄16″ (6 to 8 mm).

Eastern long-legged cobweavers are highly variable in appearance. The color is relatively consistent, a white, light yellow, or greenish white (pale) background, with brownish-yellow, dark brown, or black (dark) markings. The pattern is highly variable. Two authors, Emerton, The Common Spiders of the United States, 1902, and Kaston, Spiders of Connecticut, 1948, each show illustrations of six different patterns on the cephalothorax and abdomen of females. Fortunately, the drawings are consistent.

On the female, the front part of the body (cephalothorax) is flat and short, slightly longer than wide. It does not have a distinct depression in the middle. The upper side (carapace) has a distinct, dark, longitudinal stripe in the middle and a thin black line on each lateral margin. The central stripe may be narrow or broad, sometimes covering most of the carapace. When narrow, it is split on the front half, looking like a tuning fork.

There are eight eyes arranged in two parallel rows of four eyes each. The front (anterior) row is straight when viewed from the front and the rear (posterior) row is straight when viewed from above. On each side the lateral eyes are widely separated from the middle (median) eyes and are almost touching each other. All of the eyes are small. The anterior median eyes (AME) are slightly larger and are dark, while the rest of the eyes are pearly. The jaws (chelicerae) have one or two strong teeth on the front margin and no teeth on the rear margin. The chelicerae on the male are much larger than on the female.

The abdomen is rounded, almost spherical but slightly flattened in front, and pale with dark markings. The dark markings vary in intensity and fall into two general groups. Four of the patterns have a narrow or broad central stripe bordered by broad dark stripes. The dark stripes are often broken into distinct spots, varying from four large spots extending from the front to the rear of the abdomen, to two large or medium-sized spots on the rear of the abdomen. The remaining two patterns have a single broad, dark, median stripe on the carapace which continues onto the abdomen, either on just the front half or extending all the way to the rear.

The legs are long, slender, and pale or colorless. On the male, each leg has a dark spot at the end of the third, fifth, and sixth segments (femur, tibia, and metatarsus, respectively). On the female, each leg has a dark spot at the end of the tibia and metatarsus, but these spots may be faint or not readily discernible. The first pair of legs is the longest, the third pair is the shortest. On the female, the fourth pair is longer than the second pair. On the male that is reversed, the second pair is longer than the fourth pair. On the front pair the fourth segment (patella) and tibia, taken together, is at least one and a half times as long as the carapace. There is a row of 6 to 10 slightly curved bristles (“comb”) on the last segment (tarsus) of each hind leg. This is the feature that gives the family one of its common names “comb-footed spiders.” There are three claws at the end of each tarsus, but these are not visible to the naked eye.

Female Body Length: ⅛″ (3.0 to 4.2 mm)

Male Body Length: ⅛″ (3.0 to 3.5 mm)

Legspan: ¼″ to 5⁄16″ (6 to 8 mm)

A web is built on the underside of a blade of grass or a leaf on a shrub. It can be from a few inches to three feet long. It consists of a small tent-like retreat covered with dirt and pieces of plant material, and numerous loose threads radiating from the retreat in all directions.

Forest understories, forest edges, and old fields, on tall grasses and on shrubs

June to August

Sources

24, 29, 30, 82, 83.

Levi, H. W. (1957a). The spider genera Enoplognatha, Theridion, and Paidisca in America north of Mexico (Araneae, Theridiidae). Bulletin of the American Museum of Natural History 112: 1-124.

Common

COBWEB SPIDER Theridion frondeum
Rob Curtis

Location: Woodbury, MN