Arboreal Orb Weavers

Marbled Orb Weaver

Neoscona spp. and Araneus spp.
Family: 
Araneidae (typical orb-weavers) in the order Araneae (spiders)
Description: 

There are several species of Neoscona and Araneus orb weavers in Missouri, and some are quite difficult to distinguish, even by specialists. Often, one must note small details of their anatomy in order to "key them out" to determine the species.

Neoscona species have a slightly triangular-ovate abdomen with a pattern resembling an upside-down spruce tree. On each side of this midline may be black, brown, and greenish-brown markings. The legs usually are gray with brown rings. The carapace may be gray with brown markings. Araneus species may be similarly marked and colored, though some are quite showy and less hairy.

Size: 
Length: usually about 1/4 inch (not including the legs); males are smaller than females.
Habitat and conservation: 
These rather large and often hairy spiders are common in open woods, brushy fields, in tall grassy areas, and around fenceposts and buildings. They are common on the eaves of houses and barns. They may build their webs wherever structures are present for support and where flying insects commonly pass through.
Foods: 
Flying insects such as moths and crane flies are the principal prey. Once caught in sticky strands of the web, they are bitten and trussed by the spider, which later eats them. Many orb weavers are nocturnal and have the peculiar habit of eating and rebuilding their webs each day. Webs are built at dusk and used for snaring prey during the night. At dawn, the spider reingests the strands (along with moisture that has collected on it as dew) and recycles the nutrients in making the next web.
Distribution in Missouri: 
Statewide.
Life cycle: 
Eggs hatch in spring and the young spiderlings disperse and begin building webs, hunting, and growing. Males do not spin webs. Once mature, the males wander in search of a mate, and the females hang in webs eating and awaiting a mate. Once mated, the female keeps eating and creates egg cases. The first freezes usually kill all the adult spiders, with only the eggs overwintering.
Human connections: 
The amazing web patterns have fascinated humans for millennia. E. B. White wrote his classic "Charlotte's Web" about an Araneus spider. Orb weavers control populations of flying insects, many of which are pestiferous. Orb weavers don't bite unless molested, and their bites are not dangerous, anyway.
Ecosystem connections: 
These spiders control populations of flying insects. Although they may seem ferocious, outside their webs and hiding places these delicate creatures are quite vulnerable to predation themselves. Also, their egg sacs are relished by many species and, for example, provide winter food for many birds.
Shortened URL
http://mdc.mo.gov/node/6456