Wild Guide: Trashline Orbweavers

Trashline Orbweavers

Cyclosa conica and Cyclosa turbinata

Status

Common

Size

Length (not counting legs): females 1/8–¼ inch; males about 1/8 inch

Distribution

Statewide

The webs of trashline orbweavers are more conspicuous than the spiders themselves. The webs are small, circular orbs that the spider “decorates” with a line of debris — the dried husks of insects it has eaten plus other bits of debris, wrapped loosely with silk into a straight line. The tiny, well-camouflaged spider typically rests in the center of her “trash line,” almost always at the hub of the web. Two species of trashline orbweavers occur in Missouri — conical trashline orbweaver (Cyclosa conica) and humped trashline orbweaver (Cyclosa turbinata). The conical is the larger of the two, while the humped trashline orbweaver has two humps on the top of the abdomen that resemble shoulders.

Life Cycle

Females hide their egg cases amongst the debris-filled trashline. During the first freeze, adult trashline orbweavers die, leaving young spiderlings to fend for themselves when they emerge from their egg sacs in the spring. To disperse, the young spiders climb to the top of an object, wait for a breeze, let out a loop of silk, and jump, letting the breeze carry them away. This is called “ballooning.”

Ecosystem Connections

Trashline orbweavers serve a dual role in the ecosystem. As predators, they eat a variety of small flying insects, including mosquitoes, midges, moths, small beetles and bugs, and houseflies. As prey, they employ an unusual camouflage to fend off potential predators. Their trashlines look like bird droppings that have run down the web and dried, making it look derelict and old. This would put these spiders into the same category as several types of butterflies and moths, whose caterpillars also resemble bird droppings. In each case, this camouflage sends a message to would-be predators — “Move along. Nothing to see here.”