Metepeira spinipes

F. O. Pickard-Cambridge, 1903

Metepeira spinipes is a colonial -weaving in the Araneidae, ranging from southern Oregon through Mexico. Unlike typical solitary orb weavers, this exhibits flexible social , forming colonies that vary from solitary individuals to of several hundred spiders with interconnected webs. Mature females measure 5.5–7.2 mm in body length, while males are smaller at 3–4.5 mm. The species shows pronounced seasonal colony dynamics, with foundation in spring, peak size in late summer, and decline in fall.

Pronunciation

How to pronounce Metepeira spinipes: //ˌmɛtəˈpaɪrə ˈspɪnɪˌpiːz//

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Identification

Difficult to distinguish from other Metepeira without associated web structure; color pattern is highly variable and overlaps with other weavers. The combination of a small orb web with an extensive tangled cobweb-like snare and a thimble-like retreat decorated with debris is characteristic of the . Mature males may be found wandering on vegetation without webs. Definitive species identification requires examination of or geographic context (southern Oregon to Mexico range for M. spinipes).

Habitat

Occupies varied including desert scrub, tropical deciduous forest, and agricultural areas. Shows strong preference for vegetation with rigid, durable support structures such as shrubs, cacti, and fences that can sustain multiple interconnected webs. Colony size correlates with habitat and availability, with larger found in more stable, productive environments.

Distribution

United States (southern Oregon southward) and Mexico. Most diverse occur in western and southwestern regions.

Seasonality

Colonies founded in spring by overwintered females; growth and expansion through summer; peak colony size in late summer; decline in fall with of and death of . Adults reach maturity in late summer or early autumn in more northerly latitudes.

Diet

Flying captured in webs; diet composition varies with and season.

Life Cycle

Seasonal cycle with colony foundation in spring, growth through summer, and decline in fall. Females produce multiple sacs during the breeding season; egg sacs are roughly cone-shaped and covered in , papery , stacked above the retreat. Reproductive success increases with colony size due to enhanced capture and reduced individual web maintenance costs; solitary females reproduce with lower . Some females may overwinter.

Behavior

Exhibits flexible social organization ranging from solitary living to large colonial of several hundred individuals. Colonial construct interconnected webs with shared frame threads and complex communal web structures. Shows cooperative web maintenance and defense, with reduced aggression between colony members compared to non-colony . Displays site fidelity, with spiders returning to established colony locations. When impacts the web, the spider dashes down a signal thread from its retreat to secure the meal. Social tendencies are associated with higher-than-normal prey availability and certain , particularly during El Niño years.

Ecological Role

of flying ; colonial may significantly impact local insect . Provides structure for other within complex communal webs.

Similar Taxa

Metepeira labyrintheaSimilar web architecture and appearance, but M. labyrinthea occurs in the eastern half of the U.S. and north to southern Ontario, Canada, whereas M. spinipes ranges from southern Oregon to Mexico; M. labyrinthea is not known to exhibit the pronounced colonial of M. spinipes
Metepeira incrassataAlso forms large colonies in Mexico, but M. spinipes has been specifically documented to show flexible social from solitary to large ; M. incrassata colonies are more consistently social and are specifically noted for infiltration
Other Metepeira speciesAll share the characteristic combination of small web with tangled snare and retreat; -level identification requires geographic range and/or detailed morphological examination

More Details

Social Behavior and Predator Avoidance

Colonial living in M. spinipes reduces individual risk from (: Poecilopompilus mixtus) and of sacs by . However, colonies may be infiltrated by kleptoparasitic that steal or kill labyrinth spiders outright.

Research History

The was described by F. O. Pickard-Cambridge in 1903. studies by Uetz and colleagues in the late 1970s and 1990s established the relationship between structure, availability, and colonial in this species.