Spiders are among a garden’s best friends. Spiders are superb predators and consume an immense number of insects. A piece in Science Daily says “Spiders feed on an estimated 400 to 800 million tons of insects and other pests annually; in comparison, all humans consume about 400 million tons in meat and fish.” However, spiders are indiscriminate hunters and are happy to eat honeybees. All spiders are carnivorous. Our use of pesticides caps their population since they depend on the insects for food, which we target. They are a part of nature’s Integrated Pest Management effort (IPM), but in our gardens they should merely be left alone to live their lives. The more spiders you have in your garden, the fewer the number of insects that will plague it. See Virginia Cooperative Extension’s Spiders: An Undeserved Bad Reputation.
True spiders comprise more than 90% of spider species and appeared about 300 million years ago. True spiders have fangs that face one another and five fused abdominal segments. Tarantulas are spiders, but not true spiders. There are over 52,000 species of spiders identified in the World Spider Catalog. Scientists speculate there are many more to be discovered. And while some may think of spiders as insects — and certainly that is the world they live in — they are not. In fact, they are an insect’s worst enemy. They prey on such insects as aphids, armyworms, clothes moths, earwigs, fleahoppers, flies, leaf miners, mosquitoes and roaches. In addition, spiders prey on other spiders and some spiders are more likely than others to eat spiders of the same species. Spiders are arachnids. Arachnids differ from insects. They have eight legs instead of an insect’s six, and instead of a body divided into three sections, an arachnid’s body is divided into two. All spiders display ingenuity, patience, and a level of cognition. Originally, spiders did not build webs, and some do not today, but when their prey took to the skies, they adapted. Spiders that do not build webs have either an excellent sense of touch or sight. All spiders are predators. Some quickly kill with venom and others wrap prey in immobilizing silk, waiting for its death from injection or immobility. Some spiders do not have venom, but nearly all do.
Spiders (the term is derived from Proto-Germanic terms meaning “to spin” — spinne is German for spider) belong to a subgroup within the phylum Arthropoda. Arthropods are invertebrates (animals lacking a backbone) with an exoskeleton (a hard external body covering), jointed appendages, and a segmented body. Spiders are arthropods, as are insects. Also included in the arachnid group are scorpions, mites, and ticks. And if insects look bizarre, spiders look like one of the stars of science fiction horror. The motion pictures Sting and Arachnophobia are scary; for other examples, visit Screen Rant’s 10 Scariest Spiders in Horror Movies, Ranked.
It’s easy to see why so many find spiders instinctively scary. They capture their prey through stealth and the technology of the web – “’Will you walk into my parlor?’ said the spider to the fly” — and some shrink-wrap their victims for consumption when needed. They generally have terrible eyesight and are propelled into action by the vibration caused by prey trapped on the web.
Generally spiders are not aggressive toward humans, but most of us have been raised to fear them. Knowing that the overwhelming majority are venomous does not help. Arachnophobia is the fear of arachnids. There is a medical literature for treating it; for instance, see: “Spider Phobia: Neural Networks Informing Diagnosis and (Virtual/Augmented Reality-Based) Cognitive Behavioral Psychotherapy – A Narrative Review published in Frontiers in Psychiatry (2021). For some practical advice, see WebMD’s What To Know About Fear of Spiders.
Spiders are fascinating, and there are many sources to consult for detailed descriptions of their anatomy and behavior. Begin with My Wild Backyard’s excellent video Everything You Didn’t Know About Spiders. What follows is just to whet your appetite. It is condensed primarily from Britannica. Another excellent source of information is Wikipedia’s article on spiders. In fact, it is identified by Wikipedia editors as a good or especially solid article. Generally, female spiders are larger than males. With a few exceptions, all spiders are terrestrial. The overwhelming majority of spiders are nocturnal. Small or young spiders are distributed by the wind, a phenomenon known as ballooning. Only a few spider species have venom dangerous to humans. Although insects are their primary prey, there is evidence of some spiders feeding on small bats and birds. Spiders possess six pairs of appendages (4 pairs of legs and 2 pairs of mouthpart appendages). Spiders can even amputate their own legs. This ability is called autotomy. Like all arthropods, spiders molt as they grow. Different spider families have characteristic eye arrangements and can have as many as eight eyes. The hunting wolf and jumping spiders have excellent eyesight. There are hunting spiders that shoot a stream of sicky material that ensnares prey before they strike. Fangs are used to inject venom. Food is digested outside the mouth through the use of enzymes. Spiders chemically break down the tissue of prey and suck it up through a straw-like mouth part and then may manipulate what they can of the remaining body with their mouthparts. Spiders cannot chew or swallow as we do. They literally liquify their prey using a combination of venom and digestive fluids to derive nutrients. Some insects produce silk, but spider silk is especially sophisticated. Glands in the abdomen produce silk. It is extruded through spigots and regulated by abdominal pressure. Spiders have courtship rituals. You can watch spider sex at ABC (Australian Broadcasting Corporation) Science’s Why Sex Kills: Spider Mating with Dr. Ann Jones. Male spiders die after or during mating and the female of some species eat the male. After producing the last egg sac, females of some species die. Others may live for as many as two years providing care for the young. The life span of a spider is generally one to two years; most are dead in a season. Mortality varies by species. Life begins with an egg sac. Depending on the species, eggs in the sac can number from 4 to 600.
How intelligent are spiders? For an introduction to what goes on in the minds of spiders see the NPR piece What Goes On In The Minds of Spiders? Although tiny, it’s unexpected what spiders can apparently remember. There is evidence they have some numerical sense. And there is also evidence that they make decisions based on incoming data, which they seek actively. Their actions are not based solely on instinct. See also Psychology Today’s “Spider Smarts: Data Show Their Minds Extend Into Their Webs.” and “Do Spiders Think?”
E. B. White uses the spider Charlotte A. Cavatica (cavatica is Latin for belonging to, born in, or living in caves) to give wisdom in his novel Charlotte’s Web (also available as a film). Charlottle is a barn spider, Araneus cavaticus. In real life these spiders are very aggressive with one another. The spider’s patience is illustrated in the anonymously authored humble little spider of “The itsy bitsy spider climbed up the water spout,/Down came the rain and washed the spider out,/0ut came the sun and dried up all the rain,/And the itsy bitsy spider climbed up the spout again.” Today the talents of the spider are epitomized in the skills and capabilities of Spider-man.
Only two dangerous spiders are found in Virginia: widow spiders (only females bite) and recluse spiders (male brown recluse spiders have about half as much venom as females). Others are mistaken as dangerous: jumping spiders, wolf spiders, nursery web spiders, funnel weavers, and house spiders. To be well-informed on this subject, visit the fact sheets at the end of this section. Some people will have no reaction to a bite, but the severity of reaction spans all the way from none to severe. Virginia Cooperative Extension’s Spiders of Medical Concern in Virginia advises: “Even if a spider does bite someone it may not inject any, or only very little, venom into the bite. . . Most spider bites can be treated with just ice and a pain reliver.” Only two small families of spiders lack venom glands. Only about 1% of the over 50,000 species possess venom that can adversely affect a human. Nonetheless, the venom from a harmless species may cause severe symptoms for the young, old, or immunocompromised.
In the garden, spiders, including widow and recluse spiders, inhabit such places as debris piles, areas under rocks, and woodpiles. Precautions to take, to some extent, are like the steps to avoid snakebite. When in an area rich in spiders, shake out gloves, foot gear and clothing before wearing. If a bite from one of the two dangerous species (widow or recluse) occurs, “apply ice to the bite, elevate the wound, and seek prompt medical attention. Whenever possible, kill and take the spider to your physician for positive identification.” For a concise deep dive into medical concerns, visit: Virginia Cooperative Extension’s Spiders of Medical Concern in Virginia (also noted above) and VCE’s fact sheets for widow spiders and the brown recluse spider.
What would a spider be without a web? A spider’s life literally hangs on a thread of silk. How strong is spider silk? See NOVA’s “Making Stuff” Explores Spinning of Steel-Strength Spider Silk. Actually, spiders create different kinds of silk for different construction uses. Half of spiders create webs not for entrapping prey, but as hiding places. Different spiders create different webs, from irregular to defined and immediately recognizable. Orb webs (wheel-shaped) are designed to capture flying insects (insects began to fly more than 100 million years ago), and are the most well-known. Often, they are rebuilt daily. Sheet-webs are designed like a deadly hammock hung between leaves or grass and can even cover a shrub. Cobwebs are designed to capture crawling insects. The tangled mess is intentional. They are built by the common house spider and the feared black widow. Woolly webs are distinguished by adhesive silk that snags prey with electrostatically-charged silk nanofibers. Funnel webs have a sheet that spans the exterior of the tunnel in which the spider hides and waits. Funnel-weaver spiders are harmless but Australia’s funnel-web spiders are dangerous. Trap-door spiders burrow into the ground and build a silk-hinged door at the entrance. For a deep dive into the above, along with instructive illustrations, see: “Learn How to Recognize a Spider By Its Web.” For easily understood illustrations of web design, visit Your Guide to Spidering.
Images of spiders are numerous and some of the best images on the Wikipedia family of sites are found at the Wikimedia Commons’ Featured Pictures of Spiders. Spiders in Virginia and Spider ID’s Spiders in Virginia are excellent resources with which to learn about the diversity of spiders in Virginia. Photographs and descriptions are provided. For a quick orientation to identification, you can begin by consulting wikiHow’s How to Identify Spiders. There are outstanding manuals and field guides, see especially Common Spiders of North America by Richard A. Bradley and Steve Buchanan (University of California Press, 2019) and Spiders of North America: An Identification Manual, 2nd edition by Darrell Ubick, Pierre Paquin, Paula Cushing, and Nadine Dupérré (American Arachnological Society, 2017). Both are available as Kindle ebooks. There are also apps for your phone. To fully appreciate the beauty of spiders — gorgeously other worldly – a magnifying glass or photograph is essential. Fifty percent of spiders are 1mm – 5mm in length. A hand lens will increase your enjoyment of your garden’s tiny citizens. When is a spider, not a spider? The daddy-long-legs or harvestmen – which has neither venom nor the ability to create silk — is of the related class Opiliondae. A distinguishing feature of Opiliones is a pair of eyes in the middle of their cephalothorax.
If you would like to welcome a spider into your garden, you need to make them feel at home; first, of course, don’t spray to kill them, and second, provide places where they can find refuge: small piles of leaves, mulch, twigs, and rocks can be delightful refuges for spiders. Sunflowers provide great places for web suspension, native plants attract insects they feed on, and loose layers of mulch between plants are attractive. Have these environmental features in place when spiders disperse in spring. See Maryland Cooperative Extension’s Let Spiders Help in Your Vegetable Garden for guidance on respecting the spider’s reproductive efforts to survive the seasons. If spiders become a hazard or a nuisance, consult Virginia Cooperative Extension’s 2024 Pest Management Guide — Home Grounds & Animals, see the section “Nuisance Insects of the Home and Yard.”
There are many resources with which to pursue a knowledge of spiders. Special attention can be given to the resources available from the European Society of Arachnology, the American Arachnological Society, the British Arachnological Society, the Asian Society of Arachnology, and Arachnofila – Associazione Italiana Di Aracnologia (use Google Translate to translate the Italian). For bibliographic information on the vast array of spiders. the truly dedicated and super-scholarly-inclined can visit the Natural History Museum of Bern’s (Switzerland) World Spider Catalog. Registration is required for free access to a wealth of full-text scientific material.
Featured image: Argiope aurantia. The black and yellow garden spider. Other names include yellow garden spider, writing spider, and zigzag spider. An orb weaver. Class: Arachnida, Domain: Eukaryota, Genus: Argiope. See Clemson Cooperative Extension’s Beneficial Yellow Garden Spiders. Photo: Patrick Edwin Moran, Wikimedia Commons, CC By 2.0
Resources
Arachnophobia. IMDb.
Beneficial Yellow Garden Spiders. Clemson Cooperative Extension.
Brown Recluse Spiders. By Theresa A. Dellinger and Eric Day. ENTO-135. Virginia Cooperative Extension.
Common Spiders of North America. By Richard A. Bradley and Steve Buchanan (University of California Press, Berkeley, 2019).
“Do Spiders Think?” By Mary Bates. Psychology Today.
Everything You Didn’t Know About Spiders. By Spencer Hoffman. My Wild Backyard.
Featured Pictures of Spiders. Wikimedia Commons.
How to Identify Spiders. By Kevin Carrillo and Christopher M. Osborne. wikiHow.
“’Itsy Bitsy Spider’” The History of the Classic Nursery Rhyme.” By Jane Alexander. Mental Floss (April 10, 2024).
“Learn How to Recognize a Spider by Its Web.” By Alison Hawkes. Bay Nature. See the associated Your Guide to Spidering.
Let Spiders Help in Your Vegetable Garden. Maryland Cooperative Extension.
Myth: Sone spiders are poisonous and others are not. The Burke Museum, Seattle, Washington.
“Spider.” By Lorna R. Levi, Herbert W, Levi, and Joseph Culin. Britannica.
“Spider-Man.” Wikipedia.
“Spider Smarts: Data Show Their Minds Extend Into Their Webs.” By Marc Berkoff. Psychology Today.
Spider Webs in the Garden. By Mary Jo T. Gibson. Penn State Extension.
“The Spider and the Fly.” Wikipedia.
“Spiders eat astronomical numbers of insects.” Science Daily (March 14, 2017)
Spiders: An Undeserved Bad Reputation. By Jim Revell and Tim McCoy. ETO-393NP. Virginia Cooperative Extension.
Spiders in Virginia. Spider ID. This project: “Spider ID provides an interactive framework for community-driven spider identification, a growing informational and pictorial library providing accurate spider resources to the public, and data collection and data visualization dedicated to spiders.”
Spiders in Virginia. Spiders USA.
Spiders of Medical Concern in Virginia. By Theresa A. Dellinger and Eric Day. ENTI-346. Virginia Cooperative Extension.
Spiders of North America: An Identification Manual, 2nd edition By Darrell Ubick, Pierre Paquin, Paula Cushing, and Nadine Dupérré (American Arachnological Society, 2017).
Spinning of Steel-Strength Spider Silk. Making Stuff. NOVA.
Sting. IMDb.
2024 Pest Management Guide — Home Grounds & Animals. Publication 456-018. Virginia Cooperative Extension.
The 10 Scariest Spiders in Horror Movies, Ranked. Screen Rant.
What Goes On in the Minds of Spiders? By Barbara J. King. NPR.
What to Know About Fear of Spiders. WebMD.
Why Sex Kills: Spider Mating. By Dr. Ann Jones. ABC Science. (Australian Broadcasting Corporation)
Widow Spiders. By Charles Hannum and Dini M. Miller. 444-422. Virginia Cooperative Extension.
World Spider Catalog. Natural History Museum, Bern.
Your Guide to Spidering: Know Your Spider Webs. Illustrations by Rachel Diaz-Bastin. Bay Nature. For discussion and excellent drawings see “Learn How to Recognize a Spider By Its Web.” By Alison Hawkes. Bay Nature (September 29, 2015).
