If you’re devoted to promoting beneficials in your garden to keep pest insects at bay, make room for a small army of helpers eager to do their part.
Sure, they’re leggy, spiny and sport a fang or two, but gram for gram, no predator is mightier than the spider for policing the garden and ensuring nature’s checks and balances.
“Besides being totally cool, spiders help facilitate the actions of other predators that keep pest populations down,” said Dr. Paula Cushing, curator of Invertebrate Zoology at the Denver Museum of Nature & Science. “As generalist predators, spiders keep constant pressure on all insects. They’re not picky about what they eat.”
This allows other good insects, such as lacewings and mantises, to focus on those pests that really bug us.
Despite their helpful actions, the eight-legged beasts remain little understood by many humans. Hollywood and novelists play upon arachnophobia by casting spiders as bloodthirsty villains; it’s rare that a benign spider like the title character in “Charlotte’s Web” appears in pop culture. In real life, spiders are usually timid and uninterested in harming humans.
“Spiders hunt with venom and silk, so, yes, the vast majority of them have venom,” said Cushing. “They use it to immobilize prey. It’s specific to the insect body and physiology, not to humans. If you’re bitten, it usually only causes localized pain that goes away quickly.”
Here’s how to know — and appreciate — the common spiders in your Colorado landscape.
Cat-face spider (Araneus gemma)
Looks like: a tan-and-brown, ball-shaped spider whose body (that’s not including legs, folks) can be larger than a quarter in size.
Behavior: spinning its web near lights and in quiet corners of porches and buildings, A. gemma grows into a large spider by fall. Females give the species its nicknames of cat- or monkey-face spiders with a pair of raised bumps and dark markings on their abdomens that resemble ears and eyes. Don’t let appearances fool you; though they’re big and spiny, cat-face spiders are harmless to humans.
Fun fact: Cat-face spiders play hide and seek with their webs, spinning them in the evening and eating the silk in the morning. Hiding in a nook during the day, they digest the silk, recycling the protein back into their spinnerets for use the next evening.
“So you come home in the evening to find a beautiful, big web, and when you go to show it to the kids the next day, it’s gone,” said Cushing. “She’ll do this until she’s old and senile. Older spiders don’t seem to care about going to the trouble anymore.”
Roly-poly hunter (Dysdera crocata)
Looks like: A red and satin-gray spider with huge fangs.
Behavior: Yes, those fangs make the roly-poly hunter look fierce, but relax. This garden predator has to eat, after all; those jaws are designed to crush the tough, armored exoskeleton of pill bugs and sow bugs for its supper. Hiding under planters or in mulch during the day, the half-inch-long D. crocata roams to hunt at night. Its appearance often gives gardeners the shivers because of its hairless, creamy-gray abdomen and red legs and cephalothorax.
Fun fact: If you disturb them, they’ll quickly scurry for cover.
Wolf spider (Lycosa species)
Looks like: Medium to large spiders with slim legs, large front eyes, and brown, black, gray, yellow, or burnt-orange in color.
Behavior: Hunting by stalking, ambushing, or running their prey down, they are as efficient as the wild canids they’re named after. Their niche is on the ground, where they dig burrows and line them with silk to create cozy resting spots. Some wolf spiders are a medium size of one-half inch, legs not included; others are big enough to be mistaken for tarantulas.
Fun fact: Female wolf spiders deposit their eggs in a silken sac they attach and carry around on their spinnerets. When the eggs are beginning to hatch, they can feel the spiderlings start moving in the sac. Once this happens, the wolf spider mother tears open the sac and lets the spiderlings climb onto her back. There they ride about until they’re able to fend for themselves — about a month.
Bold jumper (Phiddipus audax)
Looks like: A fuzzy, wedge-shaped spider that’s black with white (and sometimes red) markings. Their chelicera — the muscular portion of their fangs — is metallic green.
Behavior: These are little spiders with big personalities. If there were any justice in the world, they’d be as popular on YouTube as kittens. They are the fuzzy, goofy class clowns of the arachnids and highly entertaining to have in the garden. They’re curious, brave, athletic and possess some of the best eyesight of any arthropod.
The bold jumpers hunt like cheetahs, stalking their prey, then pouncing on it in a flash of feet and fangs. This doesn’t mean they’ll jump to grab your jugular, but they can cover a distance several times their body length. They’re generally docile spiders, biting only when threatened or grabbed.
Fun fact: “The spider that appears to have a striking personality is Phiddipus audax due to its keen eyesight. It watches you, tracking movement. You can get them to jump from finger to finger or move as you wave your finger in front of them,” said Cushing. They’re great musicians, too, wooing their females by drumming on the ground to put them in the mood.
Banded Garden Spider (Argiope trifasciata)
Black and yellow garden spider (Argiope aurantia)
Look like: Both species are large, brilliantly colored spiders. A. trifasciata, the banded garden spider, has a silver and black abdomen with yellow and black legs, while A. aurantia, the black and yellow garden spider, has a yellow and black abdomen and legs. Both live on the eastern part of the Front Range.
Behavior: “If you’re lucky, you’ll have these spiders,” said Cushing of these weaving giants who create the large, classic round webs. They live in gardens, orchards, shrubbery, and along forest edges. The web is designed to capture flying insects, who are then quickly and efficiently subdued by a paralyzing bite from the spider and wrapped in silk to save for a later meal. The female, typically much larger and more spectacularly colored than the male, sits in the center of the web, feet touching different hub lines to feel when prey blunders into — and is trapped by — the silken strands.
Fun fact: Argiopes accessorize their webs with a stabilimentum, a design woven into the center of the web that’s often zigzagged. Hey, it’s just their way of decorating the dining room.
Black widow (Latrodectus species)
Looks like: A glossy black, ball-shaped spider with long, delicate legs. The poster spider for Halloween fright fests, black widow females have the characteristic red hourglass marking on the underside of their abdomen (males, in contrast, are small, with a less bulbous shape, and red, white and black).
Behavior: Cushing includes the black widow in her short list of impressive spiders in the garden. Found everywhere in Colorado, the black widow is both timid and beautiful — and it spins an extraordinarily strong web. “When you push through it, it feels like you’re pulling paper,” Cushing says.
They’re also undeniably dangerous if they bite. So every gardener should be aware of where this spider lives: dark, undisturbed places like brush piles, rock walls, irrigation boxes, old rodent burrows or little-used garden sheds. Use a long-handled tool to drag debris out in the light if you’re working in potential hiding places. Gloves, hats, and long pants are also a good idea.
Spider trivia
• Spiders avoid being ensnared in their own webs by using their claws to skate along the surface of the strands. Clasping the lines in grooves on the claw, the spider’s foot keeps the silk away from their bodies so they run unimpeded along the web.
• The fact that spiders don’t fly is a comforting thought to many arachnophobes, but it isn’t entirely accurate. Spiderlings have the ability to toss a silken thread up, where it’s captured by wind, lifting the spiderling aloft to drift on the breeze. Known as ballooning, it’s a common way for spiders to move around when young.
• Spiders have different types of silk they use for different jobs. Strong, flexible silk is used for draglines or webs, while softer silk is used to line egg sacks or refuges. Some web silk is sticky to trap prey; other types of silk snares a spider’s food with a series of small loops.
Carol O’Meara is a Colorado garden writer and entomologist with an abiding interest in, and respect for, the creepier cousins of insects.
