The spiders are a large, distinct and widespread group of Arachnids occurring in many types of habitats. Many people think that all spiders are very poisonous; however, although all spiders have venom glands, they very seldom bite people. Most spiders are beneficial because they feed on insects.
A spider’s body is divided into two sections: the cephalothorax, which bears the eyes, mouthparts, and legs; and the abdomen, which bears the genital structures, spiracles and anus. Unlike insects, spiders have eight legs and no antennae.
Commonly encountered spiders
Garden spiders often build webs in areas adjacent to open sunny fields where they stay concealed and protected from the wind. The spider can also be found along the eaves of houses and outbuildings or in any tall vegetation where they can securely stretch a web. The circular part of the female's web may reach two feet in diameter. Webs are built at elevations from two to eight feet off the ground.
Female Argiope aurantia spiders tend to be somewhat local, often staying in one place throughout much of their lifetime.
The web of the yellow garden spider is distinctive: a circular shape up to 2 feet (60 cm) in diameter, with a dense zigzag of silk, known as a stabilimentum, in the center. The purpose of the stabilimentum is disputed. It is possible that it acts as camouflage for the spider lurking in the web's center, but it may also attract insect prey, or even warn birds of the presence of the otherwise difficult-to-see web. Only those spiders that are active during the day construct stabilimenta in their webs.( From Wikipedia, the free encyclopedia)
As their name suggests, these medium sized spiders are crab-like in appearance, and walk sideways or backwards. These spiders spin no webs, but forage for their prey or wait in ambush for it. One species can change color depending upon the color of the flower it is resting on.
Small to medium in size, with short legs and stout bodies. The body is hairy and may be brightly colored or iridescent. They are found primarily under stones and in debris.
These may be quite large, some having a leg spread of three inches. Many of them live near water, walking over the surface and diving beneath it. They feed on aquatic insects and even small fish. These spiders are rovers, and the female spins a web only for the young. The female carries the egg sac underneath her until the young spiders are ready to hatch, at which time she ties it to a plant and wraps leaves around it.
Included in this group is the common garden spider. Many are brightly colored, being black and yellow, or black and red. These spiders are usually found resting head downward near the center of their large orb web.
Ground spiders and Wolf spiders
Most of these common spiders are quite large, and dark brown in color. They may be found running along the ground chasing their prey. The females carry the egg sac, and when the young hatch, they are carried on the female's back for a few days.
Harvestman or Daddy-Longlegs Although these animals are not true spiders, but rather a separate order of Arachnids, the Harvestmen and Daddy-Longlegs deserve mention here because they are found in our gardens.
These Arachnids have a small oval body, and 8 extremely long legs. They feed on plant juices and dead insects.
Some spiders considered to be dangerous
Black Widow spider
(Latrodectus spp.; L. mactans is now thought to be 3 species) The black widow is timid by nature; however, when accidentally squeezed, it will bite in self-defense. The venom is highly toxic. The bite causes extreme pain, which usually extends to the abdominal muscles. The danger exists because the black widow seeks out dark places in which to construct a retreat, often living in close proximity to people. Female black widow spiders are about a half inch long, with 1 1/2 inch leg spread; males are half that size.
Photo by Sturgis McKeever,
Georgia Southern University, from Bugwood.org
Brown Recluse spider
(Loxosceles reclusa) This spider has a dark violin-shaped marking on its back. Its bite can cause sores that are slow to heal. These range from western Georgia northward into Kentucky and westward to Kansas and Texas. They are not found in the Northeast, but since these spiders are easily transported, it is wise to check vacation gear when returning from a southern and western vacation. The spiders hide in dark corners and are generally shy. They vary in size, with a body length around 3/8 inch, and leg spread about an inch. Recluse spiders have 6 eyes (not 8 like many other spiders).
Photo by Lisa Ames,
University of Georgia, from Bugwood.org
(Cheiracanthium spp.; Family Clubionidae) Several species of sac spiders can be found indoors. They are small, with a body length generally 3/8 inch, and leg span about 1 inch. These spiders can cause painful bites. In the past they were also implicated in causing necrotic lesions, but recent information indicates that they do not cause these.
Further information on venomous spiders and spider bite symptoms is available from the Centers for Disease Control and Prevention: http://www.cdc.gov/niosh/topics/spiders/
Photo by Nate Milford
INSECT DIAGNOSTIC LABORATORY
Cornell University, Dept. of Entomology, 2144 Comstock Hall, Ithaca NY 14853-2601