Victoria County Master         Gardener Association

Gardeners' Dirt:

Spiders in the garden

October 04, 2015

By Beth Ellis/Victoria County Master Gardener

Edited by Charla Borchers Leon/Victoria County Master Gardener

These large circular webs are shown on a foggy morning among trees in Goliad State Park and were spun by spiders known as orb weavers.

The wolf spider does not construct a web as it prefers to chase down its prey. It is about 1 to 2 inches in size, a camouflaging brown or tan in color, nocturnal in nature, and can live up to 2 years old. The female is known to protect its young as shown here with its newly hatched babies on its back.

This colorful, spiny orb weaver is also known as a crab spider because of its appearance. Females construct small, circular webs while males dangle from a single thread. Mating takes place in the late summer and fall, and neither sex lives long after mating.

This thin, black and yellow male Argiope (garden spider) is an orb weaver that spins a smaller web than the larger female that has a rounded abdomen. These spiders mate once a year with the male usually dying after mating.

Did you know spiders are some of the best biological controls of insects that gardeners and homeowners could ask for? Read on to find out just how these eight-legged wonders help humans in our quest to combat bugs that plague our homes and wreak havoc on our flowers, fruits and vegetables.

Spider cuisine

Simply put, spiders have voracious appetites. Most are generalists in their dining habits, with all insects on the menu.

While spiders will dine on beneficial insects, their ability to capture large numbers of pest insects - particularly those undergoing population explosions - makes up for what gardeners might view as an occasional lapse in culinary judgment.

Table manners are not a spider virtue. They practice "external digestion," which means enzymes they spit into a victim's body reduce the innards to soup. The resulting gooey deliciousness is sucked up, leaving an empty shell behind.

Spiders capture prey differently depending upon species. About 40 percent (i.e. wolf spiders) actively hunt for food. The remaining 60 percent (i.e. orb weavers) construct webs to snare victims.

Life cycle

Spiders are arachnids rather than insects. They have eight legs, six to eight eyes, and two body parts - a combined head and thorax, and an abdomen. They also outgrow their skins, so they shed periodically.

Spiders have piercing jaws and fangs that subdue prey and inject venom, but it should be noted that the fangs of most species are too weak to penetrate human skin. For those that can, the venom is not very toxic - producing only slight inflammation and itching at the bite site, though some bites can feel like a wasp or bee sting. The only two Texas spiders with venom having notable toxicity to humans are black widows and brown recluses.

Female spiders are larger than males. As a result many females become widows shortly after mating because frankly, they can't resist a quick snack. If a particularly cautious male survives the encounter, he usually expires on his own within a few days.

A few common spiders

Black and yellow Argiope (Argiope aurantia) - Females build large circular webs with central zigzag reinforcements. Wandering males build smaller webs nearby and court females by plucking web strands. Argiopes mate once a year, producing up to three egg sacs. Females have rounded abdomens and are much larger than the slender males. In warmer climates, females of this beautiful species can live a few years, but males usually die after mating.

Spiny orb weaver (Gasteracantha cancriformis) - These lovely little spiders have white, orange, yellow or black polka-dotted spiny backs that make them look like tiny crabs. Females construct circular webs, while smaller males dangle on a single thread nearby. Egg sacs are hidden under a leaf, with spiderlings hatching in spring. Spiny orbs mature and mate in late summer and fall. Neither sex lives long after mating.

Orchard orb weaver (Leucauge venusta) - "Venusta" means "beautiful" in Latin, and it certainly applies to this tiny spider. The abdomens of these delicate creatures are oblong in shape and bright with vibrant reflective colors. The young overwinter after hatching and mate in spring and early summer. They prefer shady, moist areas and females build circular webs in shrubs fairly close to the ground.

Wolf spider (Lycosidae sp.) - Nocturnal in nature, these large ground spiders (1 to 2 inches) do not build webs except as small lairs, preferring instead to chase down prey. They are found in various habitats and are camouflaged in browns, tans, and stripes. Momma spiders are protective of their young and carry newly hatched babies on their backs. Females can live as long as two years.

No fear

Contrary to popular belief, humans have nothing to fear from most spiders. So next time you find yourself face to face with one, instead of feeling a tinge of fear, stop to thank it instead for all its hard work in removing mosquitoes, flies, aphids, and other bugs we humans constantly battle when it comes to our lawns and gardens.

The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or vcmga@vicad.com, or comment on this column at VictoriaAdvocate.com.