Phil Peters
Adam's County Master Gardener Program

They’re out there! And as fall comes on we are going to see more of them right in our own back yards. All summer they have been quietly going about their business policing our gardens, Occasionally, their paths have crossed ours, sometimes with disastrous results for them.

Spiders! Despite their size and proximity to man these little creatures that do so much good at keeping our insect pest population down are among the most universally feared inhabitants of the garden. The fact that they often drop out of nowhere and run with astonishing speed startles us. Even though most of them have jaws so small that they can not pierce human skin, the fear of their bite makes them seem more of a threat than the honeybee. Indeed, bee sting reactions cause many more deaths per year than spider bites.

The 37,000 species known worldwide are perhaps one fourth of all species out there. They are native to every continent but Antarctica, and from desert valleys to mountain peaks. Scientific counts show over 11,000 spiders per acre in the U.S. Imagine how many insects they take out of a field each day!

Spiders are not insects. Whereas insects are distinguished by six legs and two antennae, spiders are arachnids who have no antennae, nor wings, and have four pairs (8) legs on two body segments. Most spiders have eight eyes that are arranged differently on the head depending on the species. Their bodies are covered with fine hairs and often have beautiful geometric patterns, sometimes with iridescent markings. With autumn coming on some of the most interesting species will be very evident in our gardens.

The most spectacular is the large, black & yellow argiope (Argiope aurantea) whose conspicuously colored body hangs head-downward in the center of a huge orb web. She’s the spider we refer to when we think of garden spider. A slightly smaller cousin, the banded argiope (A. trifasciata), has an abdomen covered by silvery bands. You might notice the heavy zigzag pattern in the center of the web before you see the spider. The spider you see is the female. In late summer look near the margins of the web. You may be fortunate enough to see the male, or even several. Only a fraction of the size of the female, they will try to get her attention by twanging on the support thread of the web. It pays to knock in this world!

Other orb webs may reveal the large barn spider, Araneus cavaticus. This spider with its mottled brown abdomen likes to build its web near buildings. Look around your porch or deck railings.

Maybe the web is an orb with a line of debris down the center. Look closely and you will see a small dark brown spider with a cone-shaped abdomen in the midst of the debris. Cyclosa conica likes to camouflage herself and her egg sac in this way.

Walking beneath trees in our garden or on woodland paths we may have met another small orb-weaver when we ran face first into an unseen web. The spider who built it has a unique abdomen covered with small spines. You can pick her up easily; she won’t bite. The whit and black ones are Micrathena mitrata. You may be luck to find a black and yellow one, Micrathena sagittata. Both are common in the fall.

Some spiders build their orbs horizontally and hang under it. Leucage spp. is one such, often called an orchard spider. She prefers trees and low bushes and shrubs. A small spider (.3") she can be recognized by her colorful oblong abdomen marked with white & yellow stripes on a black background. At the tip of the abdomen are some pinkish-orange spots.

Looking closely at your flowers or the garden fence you may see one of the many species of jumping spider (Salticidae). As the name says they run along the fence and pounce on their prey. They attach a drag line as they move about so that if they fall they can pull themselves back up. Able to see a distance of 8" or more, they have the best vision of all spiders. Many have very colorful iridescent coats.

Lurking inside the petals of your roses or zinnias may be a small crab-shaped spider lying in wait for a victim to land. These spiders are distinguished by their very long forelegs that they use to grab their prey. Thy look like small crabs which are close relatives of the spiders. The crab spider can change color to blend in with its background flower. But, unable to distinguish friend from foe, the spider will eat a bee if it buzzes too close.

In the grass or along the garden wall you will see many funnel webs made by a common grass spider, Agelenopsis sp. Vibrations on the web will bring her out. Despite her fast movements and hairy appearance she won’t bite you. Look around the edge of the web and try to find her prospective mate. He’s a very small version of the female.

The wolf spider is the one you have seen racing along the ground in your garden. Often she may be carrying an egg sac on her back, sometimes even young spiders. There are two large varieties In Pennsylvania. Lycosa carolinensis is one of the largest spiders in the state at an inch to an inch & a half long. She and her cousin, Lycosa aspera, who has a yellow line of hairs on her head and light-brown bands on her legs, may be trying to com in the house this fall.

If you would like to know more about spiders, the best and most affordable is Spiders & Their Kin by Herbert W. and Lorna R. Levi in the Golden Guide series. 

Read other articles on birds, wildlife & beneficial insects

Read other articles by Phillip Peters