Knowing and Loving your Backyard Spiders

Knowing and Loving your Backyard Spiders

spider with egg sac

A female striped lynx spider protects her egg sac. Photo credit: Carrie Stevenson, UF IFAS Extension

With Halloween just behind us, some of us may still have fake spiders in our yards and cotton webbing all over the shrubbery. Spiders (along with bats) are among those creatures feared and demonized in folklore this time of year. It is important to remember, however, that both organisms are important predators and managers of our insect population.

Last week during a walk on the Extension property, I came across a large brown spider hovering protectively near her egg sac. Perched in a newly planted pine tree, I saw no obvious web. Instead, the spider loosely wrapped the pine’s needles with silk, forming a support structure for the relatively large egg sac.

Newly hatched striped lynx spiderlings on silk scaffolding covering a plant. Photograph by Laurel Lietzenmayer, University of Florida.

On further research, I learned that this female striped lynx spider (Oxyopes salticus) would have mated just once, after responding to a male’s courtship display (involving drumming and elaborate leg touches). She would have produced the egg sac 1-4 weeks after mating, attaching it to the pine needles, and will tend to it until her young emerge 20 days later. Up to five days after hatching, lynx spiderlings disperse by “ballooning” from the plant—they release a silk thread into the air, allowing the wind to carry them off like a tiny skydiver. Those spiderlings will mature into adults by 9 months, living their entire lifespan in just one year.

During that year, though, lynx spiders are important predators of pest insects. Instead of catching bugs in a web, they stalk their prey like a big cat—hence the name, “lynx.” They prey on many fly species, but also on bollworms and green stinkbugs that are major pests of cotton and soybean crops. These spiders are beneficial and highly vulnerable to insecticides.

 

Be Aware of Brown Widow Spiders

Be Aware of Brown Widow Spiders

Recently, Okaloosa County Commissioner Carolyn Ketchel mentioned to me that she had seen brown widow spiders in parts of Okaloosa County on multiple occasions. Concerned about this and to provide better awareness of this spider, she asked if I could write an article about this spider.

Most people seem to be aware of the black widow spider but many people have never heard of the brown widow spider.

Brown widow spider (female)

Brown Widow spider. UF/IFAS Photo: Thomas Wright

There are four widow spiders found in Florida. They include the southern black widow, northern black widow, red widow and brown widow. All are highly venomous but they are also timid. Bites usually occur when the spider can’t easily get away and becomes unintentionally caught between a person’s skin and clothes or when a person is reaching for something where a widow spider is hiding. A UF/IFAS Extension publication on brown widow spiders states, “According to Dr. G.B. Edwards, an arachnologist with the Florida State Collection of Arthropods in Gainesville, the brown widow venom is twice as potent as black widow venom. However, they do not inject as much venom as a black widow, are very timid, and do not defend their web.”

Widow spiders are about 1½ inches long with legs extended. All have rounded, relatively large abdomens. Both of the black widows are shiny black in color. The southern black widow possesses the classic red hourglass marking on the underside of its abdomen. While the northern black widow has two reddish triangles that resemble an hourglass on the underside of its abdomen and red spots in a row along the middle of its back. The red widow’s head, thorax and legs are reddish orange. Its abdomen is black and lacks a complete hourglass but there may be one or two red spots on the abdomen. The brown widow may be gray, light brown or black in color with an orange or yellowish-red hourglass marking on the underside of its abdomen.

Brown widow egg sac

Brown widow egg sac. Photo credits: Carolyn Ketchel

The brown widow egg sac looks different as compared to the other widow spiders. They are less than ½ inch in diameter with pointed white silk spikes on the surface which are not present on egg sacs of the other widow spiders. The egg sacs of the other widow spiders have smooth surfaces.

The brown widow likes to build its web in secluded, protected areas such as empty plant containers, mail boxes, building entry way corners, under eaves and inside of old tires.

More information on widow spiders is available from the UF/IFAS Extension Office in your County or from the below links.

http://edis.ifas.ufl.edu/mg206
http://entnemdept.ufl.edu/creatures/URBAN/SPIDERS/brown_widow_spider.htm

You’d be wise to learn to identify these spiders.

Spiders as Biocontrol – Video

Spiders can act as a great bio-control for Florida Gardens. Watch this video by UF/IFAS Entomologist and spider expert Lisa Taylor to learn why having spiders around is a great way to keep pests in check.