hammock spider

not listed

NNR - Unranked

not listed

There are sixteen recognized species of hammock spiders (Pityohyphantes spp.), fourteen of which occur in the United States. Hammock spider (Pityohyphantes costatus) is the most common of these in the east. Unimaginatively, it bears the same common name as the genus. There are two subspecies of Pityohyphantes costatus. Only one, P. c. annulipes, occurs in North America. It is found on low tree limbs in wooded areas, in shrubby areas and fields, and on fences and the eaves of buildings.

Hammock spider is a small, common, easily recognized, sheetweb spider. The female is 3⁄16″ to ¼″ (5 to 7 mm) in length not including the legs. The male is a little smaller, 3⁄16″ to ¼″ (4.5 to 6 mm) in length. The legspan is 9⁄16″ to 11⁄16″ (14 to 18 mm).

The front part of the body (cephalothorax) is egg-shaped when viewed from above and flat when viewed from the side. On the male the head is higher and has a crest of stiff hairs on top. There are eight eyes arranged in two parallel rows of four eyes each. All of the eyes are well developed, fully pigmented, and about the same size. The back (posterior) row is distinctly curved, the front (anterior) row is nearly straight. The eyes in the posterior row are all well spaced and almost equally distant from each other. The median ocular area (MOA), the area defined by the middle four eyes, is narrower in front than behind. The anterior median eyes (AME) are only slightly smaller than the posterior median eyes (PME). The exoskeletal plate (carapace) covering the cephalothorax is light yellow with a thin black line on the margins. There is a dark stripe behind each PME. The stripes are parallel then abruptly converge and continue to the end of the carapace, creating a distinctive tuning fork shape. The plate on the underside of the carapace (sternum) is longer than wide.

The abdomen is oval, longer than wide, and highest in front. It is yellowish with a dark brown to reddish herringbone stripe in the middle. The herringbone pattern has light spots enclosed within it. The sides of the abdomen are pale or white.

The legs have seven segments and are long, thin, and spiny. They are light yellow with dark rings and small dark spots, especially on the third segment (femur). On the front legs the seventh segment (tarsus) is only half as long as the sixth segment (metatarsus). There are two minute claws at the end of the tarsus but these are not visible without magnification.

Female Body Length: 3⁄16″ to (5 to 7 mm)

Male Body Length: 3⁄16″ to ¼″ (4.5 to 6 mm)

Legspan: 9⁄16″ to 11⁄16″ (14 to 18 mm)

Webs are constructed on fences, buildings, lower branches of trees, or on herbaceous plants. The web is an intricate, seemingly random mesh, in the form of a large, flat sheet that somewhat resembles a hammock. This is the feature that gives the spider and the genus their common names. Above the sheet is a small maze of strands forming a barrier section.

Woods, shrubby areas, fields, fences, and buildings

April to late autumn

Hammock spider is a sedentary hunter. There is often a leaf that has fallen on the web and is curled over, forming a retreat for the spider. In its absence the spider may construct a tent of silk for a retreat. Lacking any retreat, the spider will hang upside down under one corner of the web.

Spiderlings disperse in the fall by “ballooning”. They climb a branch, blade of grass, or fencepost, and release a long thread of silk. The silk thread catches the wind or even a light breeze and the spiderling floats to a new site.

Adults and final stage (instar) spiderlings hibernate over winter under loose bark and stones. They mate in mid-April to mid-May. In July the female deposits a globular egg sac on her web or on a branch or twig near her web.

Sources

24, 29, 30, 82.

Common

The common name of this species is the same as the common name of the genus.

Location: Albany, NY

Location: Albany, NY

Location: Woodbury, Minnesota

Location: Slinger, Wisconsin