One of the quintessential images of Halloween just might be spiders: huge black, crouching, fanged spiders, ready to jump out from a shadowy webbed corner and bite!
But as gardeners, should we view spiders as our enemy? Spiders are counted as “natural enemies”—but not of humans! According to UCANR (University of California Agriculture and Natural Resources), beneficial insects and other organisms that kill pests are called natural enemies—and most gardens typically contain far more of these than pest insects. In any pest management program, it is important to encourage the beneficial insects or natural enemies by avoiding pesticides that kill them. You also can encourage beneficial insects by choosing plants that provide them with pollen, nectar and shelter.
The benefit of spiders: The biggest benefit of garden spiders is that they help maintain a healthy balance in your landscape by trapping and eating pest insects that you don’t want in your flower beds, like aphids, wasps, beetles, mosquitoes and flies. Spiders have voracious appetites, eating at least one insect per day, and this means you can decrease or stop the use of pesticides. Organic gardeners can appreciate spiders for this very reason. When you see spiders in your garden, it means you need to use fewer chemicals.
Another benefit of having spiders in your yard is they can reduce harmful plant pathogens by controlling the insect pests that transfer many types of fungal and bacterial diseases from plant to plant. These diseases damage plant tissues and sometimes even kill the plant. The fewer pests there are in your garden, the fewer ways there will be for certain diseases to spread.
How to attract spiders: While it may seem counterintuitive to those of us who are arachnophobes (myself included!), we should want some garden spiders in our yards. A healthy garden filled with lush bushes and perennials makes a great habitat for many garden spiders. Using grass clippings as mulch specifically attracts wolf spiders. Instead of building webs and waiting for prey to come to them, these hunters actively seek out their dinner. If you want to attract weaving spiders, try adding tall plants that can serve as spots to anchor their webs. Tomato plants, sunflowers and cornstalks are good options. Other anchoring spots could be garden arbors or trellises.
In California, spiders commonly encountered around buildings include jumping spiders, tarantulas, orb weavers, sheet web spiders, cellar spiders, wolf spiders and widow spiders. While different spiders are active all year, it’s more likely that you will see them moving and hunting during warmer months.
Do garden spiders bite?: Most spiders will bite if provoked, but very few spider bites are dangerous to humans. If you happen to brush up against a garden spider’s web and it bites you, the bite area may swell slightly and itch. But in most cases, these spiders are happy to hide away when you’re around.
Widow spiders: The only potentially dangerous spiders in California are widow spiders. These are smooth bodied, shiny spiders, with long slender legs and a bulbous abdomen in the females. They appear to be hairless. Females have a bright hourglass shaped mark on the underside of the abdomen. Widow spiders are shy, reclusive spiders and prefer quiet dark places. They generally go into hiding when confronted by any animal larger than they are.
A black widow bite can cause reactions ranging from mild to painful and serious, but death is very unlikely. The bite can cause fever, muscle and joint aches and muscle cramping. Anyone bitten by this spider should remain calm and promptly seek medical advice. One of our local Master Gardeners was bitten by a black widow in the garden last summer and did experience a reaction, but it was relatively mild.
Recluse spiders: The brown recluse spider is not found in California. While the brown recluse has occasionally been brought into California in household furnishings, firewood and motor vehicles, there are no breeding populations in the state.
Spiders in the garden: Hopefully, we’ve learned that spiders in our gardens should not be feared. When you discover a spider and its web in an inconvenient spot for you, (like sprawled across a walkway or over your door), it’s fine to remove it but not necessary to kill the spider, too. Once its web is destroyed, it’ll most likely realize its mistake and build a new home in a more secluded spot.
As the gardening season here in the Central Valley winds down, it’s wise to resist the urge to remove all the old plant debris and leaves. Leave a spot for our beneficial insects and pollinators to overwinter. An out-of-the way corner of the backyard is perfect to leave a little messy as a winter home for spiders and other helpful insects and pollinators.
In spite of our natural fear of creepy-crawlies, spiders are actually quite beneficial to our gardens. Let them do their job and eat all those pesky critters that are harmful to our plants!
And finally, in case the facts of this article haven’t convinced you, how about a bit of enticing and fun folklore. Even though there are many negative superstitions and fears regarding spiders, some believe spiders to be omens of good luck. One superstitious belief is that seeing a spider in your home or garden can mean that good fortune is heading your way, and in particular money. The bigger the spider, the bigger the reward! Who can resist a bit of magical thinking, especially at this time of year?
For more info on the types of spiders found in California, visit: ipm.ucanr.edu/PMG/PESTNOTES/pn7442.html.
This column is not a news article but the advice of the writer and does not reflect the views of Mid Valley Times newspaper.