Poisonous Spiders in Hawaii

Just the sight of a spider sends some people screaming in panic and running for dear life. Although all spiders are predators, that doesn't mean they actively seek people and pounce on them. This is small consolation, however, to scores of arachnophobes, particularly since a few species may actually deliver a painful and skin-marring bite. Of the more than 200 spider species in Hawaii, only four are potentially dangerous to people.

Although poisonous and venomous are used interchangeably when referring to spiders, these terms carry different meanings. Poison refers to a substance that is harmful after being ingested or absorbed, while venom is a toxic substance injected by an animal, insect or arachnid, such as a spider.

Perhaps the most recognizable widow spider species because of the red hourglass-shaped marking on the underside of the female's abdomen, the black widow is typically hard to find because of its secretive nature. Its preferred habitat is on Australian saltbush (_Atriplex semibaccata_), a perennial shrub in U.S. Department of Agriculture plant hardiness zones 8a through 10b.

In Hawaii, you're more likely to see a relative of the black widow -- the brown widow. The top of its brown abdomen features geometric patterns of circles and stripes, and the underside of the abdomen has a brownish hourglass marking. Be careful around its preferred habitat, sites that include wood piles, crawl spaces underneath homes and storage sheds. A black widow retreats into its cone-shaped web if you disturb it, but it won't bite unless provoked.

These pale yellow spiders are typically active at night. They're classified in the group of spiders called "sac spiders" because of the way they weave silken sac-like retreats inside rolled leaves, typically in shrubbery. They're common in Hawaii, and their bites are often reported.

A characteristic violin-shaped marking can be seen on the lighter abdomen of the brown recluse spider. A recently introduced species to Hawaii, the brown recluse is considered more dangerous than the black widow. Unlike widow and leaf spiders, the venom of a brown recluse spider doesn't disperse from a bite. Instead, the venom stays concentrated near the bite wound and can cause ulceration and gangrene. The spider's preferred habitat is in rock piles and stacked logs.

If you experience spider-bite symptoms such as redness, swelling, pain, dizziness, nausea, tremors or paralysis, seek medical help immediately.

Immediate first-aid measures include:

Apply an ice pack to the affected area to reduce swelling and lessen tissue damage.

Apply hydrogen peroxide to sanitize the area around the bite.

If you're able to find the spider and capture it safely in a sealed container, take it with you to the doctor's office or hospital emergency room.