The marbled orbweaver is a colorful spider with a wide range across North America. The pattern is variable ranging from marbled swirls, furrows or fir-tree shapes, zigzags, or a big black spot. The overall color can be white, yellow, orange, tan, grayish, or even white, with mottling and spotting of black, brown, or purple. Mature females, full of eggs, have a nearly spherical abdomen. After creating an egg case, the abdomen shrivels until the next batch of eggs are ready.
Similar species: Missouri has 14 species of orb-weaving spiders in genus Araneus, which as a group are sometimes called the "angulate and roundshouldered orbweavers." Another common Missouri member of this genus is the openfield orbweaver (Araneus pratensis), which is smaller and is easy to distinguish by comparing pictures and habitat. Our other 12 Araneus species are less commonly encountered. Some species in this group are quite difficult to distinguish, even by specialists. For the less common species, you often must observe small details of the anatomy in order to determine the ID.
Spiders in genus Neoscona are similar, as well; common Missouri representatives include the spotted orbweaver and arabesque orbweaver.
Spiders in genus Larinioides, called furrow orbweavers, are also camouflage-patterned orbweavers commonly encountered.
Length: usually ½–¾ inch (not including the legs); males are smaller than females, only about ¼–½ inch.
Statewide.
Habitat and Conservation
The marbled orbweaver is most often encountered in late summer through fall in rich bottomland forest and thickets. Females build their vertical, wheel-shaped webs among trees and tall weeds in moist woods, often near streams.
This species has a Holarctic distribution (it occurs all around the Northern Hemisphere, including North America, Eurasia, and Japan).
Food
Flying insects such as moths and 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.
From the center of the web, a strand of silk called a signal line extends outward to the place where the female is hiding, often in a folded-over leaf tacked shut by the spider's silk. When a fly, moth, or other insect is trapped by the web and struggles, the female feels the vibrations via the signal line and knows to dash out and subdue the prey.
Life Cycle
In spring, the young spiderlings emerge from their egg case, 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 build webs, eat, and wait for a mate. Once mated, the female keeps eating and creates egg cases. The first freezes usually kill all the adult spiders, with only the egg cases overwintering.
Human Connections
Do you think spiders are pretty? This species is eye-catchingly colorful, often with contrasting patterns. Considering they are often bright orange and black, balloon-shaped, and usually seen in fall, calling them "pumpkin spiders" is pretty appropriate.
The amazing web patterns of orbweavers have fascinated humans for millennia.
E. B. White wrote his classic book Charlotte's Web about a spider in genus Araneus.
Orbweavers control populations of flying insects, many of which are pests.
Orbweavers don't bite unless molested, and their bites are not dangerous, anyway.
These are some of the spiders that commonly build their webs right across trails. An oldtime Ozark folk belief held that if you encounter a big orbweaver right in the middle of your path, you'll be getting a letter within a few days.
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. Orbweaving spiders usually have poor vision and are awkward when not in their webs. Also, their egg sacs are relished by many species and provide winter food for many birds.
