hammock spider

(Pityohyphantes costatus annulipes)

Conservation Status
hammock spider
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

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 316 to ¼ (5 to 7 mm) in length not including the legs. The male is a little smaller, 316 to ¼ (4.5 to 6 mm) in length. The legspan is 916 to 1116 (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 (AMEs) are only slightly smaller than the posterior median eyes (PMEs). 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 leg 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.

 
     
 

Size

 
 

Female Body Length: 316 to (5 to 7 mm)

Male Body Length: 316 to ¼ (4.5 to 6 mm)

Legspan: 916 to 1116 (14 to 18 mm)

 
     
 

Web

 
 

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.

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Woods, shrubby areas, fields, fences, and buildings

 
     
 
Biology
 
 

Season

 
 

April to late autumn

 
     
 

Behavior

 
 

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.

 
     
 

Life Cycle

 
 

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.

 
     
 

Food

 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

29, 30, 82.

 
  8/28/2021      
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
  Class Arachnida (arachnids)  
 

Order

Araneae (spiders)  
 

Suborder

Araneomorphae (typical spiders)  
  Infraorder Entelegynae (eight-eyed spiders)  
  Superfamily Araneoidea  
 

Family

Linyphiidae (sheetweb and dwarf spiders)  
 

Subfamily

Linyphiinae  
 

Genus

Pityohyphantes (hammock spiders)  
 

Species

Pityohyphantes costatus) (hammock spider)  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
  hammock spider  
     
 

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

 
       

 

 

 

 

 

 

Glossary

Carapace

The hard, upper (dorsal), shell-like covering (exoskeleton) of the body or at least the thorax of many arthropods and of turtles and tortoises.

 

Cephalothorax

The front part of a spider’s body, composed of the head region and the thoracic area fused together. Eyes, legs, and antennae are attached to this part.

 

Femur

On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.

 

Instar

The developmental stage of arthropods between each molt; in insects, the developmental stage of the larvae or nymph.

 

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot). The fifth segment of a spider leg or palp.

 

 

 
 
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Alfredo Colon

 
    hammock spider   hammock spider  
           
 
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  Alfredo Colon
Summer 2019

Location: Woodbury, Minnesota

hammock spider  
  Alfredo Colon
August 2019

Location: Slinger, Wisconsin

hammock spider  
           
 
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Created: 8/28/2021

Last Updated:

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