Spinybacked Orb Weaver Spiders

Scientific Name

Gasteracantha cancriformis

Appearance

What does it look like?
Spiny Orb Weaver Illustration
The spineybacked orb weaver spider, also known as the crab-like orbweaver and the spiny orbweaver, get their common name from the spines that protrude from their abdomen and their body shape that generally looks like that of a crab. They are a very colorful, easily recognized spider. Their abdomen is white and contains black spots with large red spines extending from the edge of the abdomen. Their legs and cephalothorax are black. Throughout its area of distribution, there can be some specimens with a yellowish abdomen instead of white, and their spines may be black instead of red.

Females of this species are ¼ to ½ inch long. The males are smaller than females and are colored similarly to the females except they are gray with white spots and they also lack the big spines of the females.

Behavior, Diet & Habitat

Typical habitats for the spineybacked orb weaver spider are the edges of woodlands, shrubs and gardens. They also frequent plant nurseries and are commonly seen in citrus groves. They frequently spin their webs in shrubs, trees, and the corners of windows and doors and on porches and patios. This spider normally does not enter homes, but can be unintentionally brought inside with potted plants and other outside items.

The spineybacked orb weaver’s diet consists of small insects that are captured in its web. Insects such as beetles, moths, mosquitoes and whiteflies are likely prey and after biting and paralyzing their prey, they consume the liquefied insides of their “catch”, much like most other spiders. An interesting characteristic of its web is the presence of silk tufts the female spider builds into the web. Possibly, the purpose of these tufts of silk is to make the webs more conspicuous to birds, thus reducing the likelihood of them flying into and destroying the spider’s web.

Spinyback Spider Web
Spinyback Spider Web

The Spineybacked orb weavers’ typical lifespan only lasts for about one year. In most of their distribution area, females can be found at any time of the year, but mostly from October to January, while males are most often found during October and November.

Reproduction

The female produces an egg sac in the summer or fall that contains from 100-260 eggs. The female spider attaches eggs under a leaf, wraps them in webbing and dies. Eggs take about eleven to thirteen days to hatch.

Signs Of An Infestation

The appearance of the spiders, their webs and egg sacs are evidence of an infestation. Spinybacked orb weavers are considered a nuisance when they build large webs in places that are bothersome to homeowners.

These spiders can bite, but are not medically important. If touched, the spider’s spines can puncture the skin, but this is not much more than what is produced by a slight pinprick.

Distribution

Spineybacked orb weaver spiders are found across the world, with U.S distributions ranging from southern California to Florida.

More Information

Preventing a spinybacked orb weaver spider infestation begins with making sure the population its food source is kept to a minimum. Sealing holes, cracks and gaps in the home’s doors, windows and foundation may also help prevent entrance into the home’s living space. Managing lighting to minimize attracting insects is a good practice to reduce prey insects that will attract spineybacked orb weaver spiders. In addition, removing ground litter that serves as harborage for spiders is also helpful.

Do they bite?
The spineybacked orb weaver can bite, but they are not aggressive spiders. They do not bite people unless picked up or otherwise provoked and are not known to cause serious symptoms if they do bite someone.

Contact your pest management professional and request an inspection if you need assistance to control these or any other spiders. Your pest management professional can then use his or her inspection findings to prepare a comprehensive pest management plan that will effectively and efficiently deal with the specific pest problem.