The Carlisle Mosquito Online

Friday, June 18, 2004

Features


Jumping Spider

photo by Tom Brownrigg
Several weeks ago, as I entered our shower stall, I noticed a black spider on the floor of the stall. Being concerned about a possible black widow spider, I decided to remove the spider before showering. I coaxed it into a transparent plastic container for closer observation. After consulting some of our identification guides (1,2), I concluded that it was the so-called Daring (or Bold) Jumping Spider, Phidippus audax.

There are two features of this spider that caught my attention: a white pattern on the black abdomen, and two bright green appendages under the head. The pattern on the abdomen resembles a "happy face" when the spider is viewed upside down. The green appendages — iridescent in bright light — are the "chelicerae," or jaws. The jaws are tipped with fangs, and the fang has a duct leading to a gland with venom. When the spider captures prey, its bite injects venom into the victim, which both paralyzes the victim and begins the digestion process. My specimen was a male, identified as such because it had enlarged "pedipalps," two small leg-like appendages located near the jaws that are used in mating. A male P. audax is 0.5 inches, and a female slightly larger, 0.6 inches. I photographed another Jumping Spider on our house last year; a photo of the current subject shows the chelicerae. Better photographs can be found on the web sites cited below.

This spider feeds mainly on small insects, but other species are also known to eat other spiders. Jumping Spiders can jump four to six inches, or about ten times their body length. These spiders have excellent vision, due mainly to their eight eyes. There are two large forward-looking eyes and six smaller eyes. Two of the smaller eyes are located aside the largest eyes; another four small eyes are located near the top and side of the head. You are most likely to notice only the two largest eyes and the two adjacent smaller eyes.

photo by Tom Brownrigg
Jumping Spiders are active during the day and like sunshine. Outdoors, they are found on trees and shrubs in woods, fields, and in ground litter. They are also fond of gardens and frequently enter houses, where they can be found on windowsills, sashes, and houseplants. They are able to recognize other spiders and prey up to eight inches away, and will leap to capture prey. Before jumping, the spider secures a thread from its abdomen that serves as a "life-line" in case it misses its target.

Are these spiders hazardous to people? I found one reference to this spider on a web site for dermatologists (3). Quoting Arthur Huntley, M.D.: "Saltids [family Salticidae, Jumping Spiders] are the most common biting spider in the US. Persons gardening appear to be at risk for disturbing the habitat of this spider which may react by inflicting a bite. The bite is asymptomatic to slightly painful and subsequently results in a local reaction such as an erythematous [red] papule or urticarial wheal [a swelling that stings or itches]." All spiders bite, and the venom of some can be dangerous, so never handle one with skin exposed, and wear gloves when working in the garden. Indoor spiders feed on flies, mosquitoes, and many other small insects that we often consider pests. Spiders are generally beneficial — don't smash them!

For those fond of spiders, Jumping Spiders seem to do well in captivity; the author of one web site (4) keeps this spider in a large glass jar, and feeds it crickets. Captive Jumping Spiders are also known to eat fruit flies.

More information including excellent photographs of colorful Florida species can be found on David Hill's web site (5). Wayne Maddison's web site (6) is a great resource also, and includes photographs and information on P. audax and many other living things. Blake Newton's web site (7) is a good source of information on this spider and others.

What happened to our Jumping Spider? My wife D'Ann relocated him to a houseplant, where we hope he will find plenty to eat.

References

1. Lorus and Margery Milne, National Audubon Society Field Guide to North American Insects and Spiders, Alfred Knopf, New York, 2000.

2. Herbert and Lorna Levi, Spiders and Their Kin, Golden Press, New York, 1968.

4. Tom Schumm (aka "Phong"): http://www.bighairyspiders.com/neutrino.shtml

Ed note:Tom Brownrigg is a member of the Carlisle Conservation Commission. His interests include birding and nature observation. To the best of his knowledge, a spider has never bitten him.


2004 The Carlisle Mosquito