photo from National Parks Gallery
Latin Name: Gasteracantha cancriformis
Species: Terrestrial Invertebrate
Conservation Status: Not Evaluated
Despite the dangerous-looking spikes protruding from its abdomen, this small spider is harmless to humans and even considered beneficial given the number of insects they eat. Only reaching about 0.3 inches across, the female spiny orb-weaver is distinct looking with bright yellow, red, white, and black coloring on its abdomen and 6 sharp spikes protruding outward. The males are smaller with less distinct gray and white markings and shorter spikes.
Range & Habitat (map)
There are many species of orb-weaver spiders, but only the spiny orb-weaver is native to North America. The web of this small spider is distinct, about 12 inches in diameter with as many as 30 radii or radial threads. Webs are built in most surroundings, including trees and shrubs, building structures, and even low in the grass to catch prey.
Diet
Spiny orb-weavers construct their web to trap prey such as flies, beetles, moths, mosquitos, etc. It is mostly the female spiders that build and man the web, quickly immobilizing insects that get trapped. The spider eats the innards of its prey and discards the exoskeleton from the web.
Life History
The life cycle of the spiny orb-weaver is short; males die within 6 days of fertilizing the female’s eggs. Females build an egg case out of silky threads, in which they lay between 100-250 eggs. This egg case is attached to the underside of a leaf, then the female dies. The eggs hatch after about 12 days, but the tiny spiders stay inside the egg case for several weeks until they reach maturity. Then they leave the case and start building their own webs.
Significance
This spider’s unique appearance makes it an easy one to spot and identify, both around neighborhoods and in forested areas.
Threats & How You Can Help
Spiny orb weavers are colorful, spiky harmless spiders that eat mosquitos and other insects — there is no downside to having them in your yard. Don’t be afraid of them, and don’t kill them.