Pest Preventives

20 Jul 2013

Prevention is your best bet against pests inside and outside the home. Here are eco-friendly methods for controlling common pests.

By Ruthanne Johnson

What homeowner isn’t totally bugged to discover insect pockmarks in the once-pristine petals of favorite flowers? Or yellow jackets buzzing your head while you’re trying to soak up a little R&R in the yard? Times like these make it all too easy to reach for a can of toxic Raid. But that knee-jerk reaction can actually do more harm than good, according to Rella Abernathy, integrated pest management (IPM) coordinator for the city of Boulder. 

pests_leadPesticide exposure has been linked to serious diseases, decreased cognitive function and behavioral problems. Following all product-label instructions can help minimize exposure, but these toxins also threaten backyard wildlife and beneficial soil microorganisms and insects. And think about pets, with their noses buried in chemical-laced lawns or licking their paws after a romp across newly treated grass. The good news is there are plenty of eco- and animal-friendly pest options.

Integrated pest management starts with learning about pests that live in your backyard and understanding their life cycle. “The more you understand what makes them tick, the better equipped you’ll be to prevent problems from happening in the first place,” Abernathy says.

The whole idea behind IPM is prevention, she says. “If you don’t try to prevent a problem, you’re constantly treating the issue.” Simple strategies, such as using native vegetation, watering precisely and attracting natural predators, can help decrease serious infestations, along with growing the right plants in the right places, because stressed plants are more vulnerable to pest attacks.

Abernathy suggests watering deeply, about 1 inch per week, and less often “to encourage deep root growth and healthy grass.” Keeping lawn height at about 3 inches can help prevent fungus, weeds and insect pests. Hand-pulling weeds is effective and eco-friendly. “Just keep a little grass seed while pulling dandelions and sprinkle it over the soil to push out the competing weed,” she says. But don’t pull every dandelion because their flowers provide nectar for early-season native bees. 

Other preventive measures include gradually placing starter plants outside on warm (but not hot), windless days to acclimate them, and making sure they’re big and healthy before transplanting outdoors. Place protective barriers over vulnerable plants and augment soil with organic compost and fertilizer. For home invaders, caulk cracks and crevices that lead to the inside. 

Here are more IPM tips to help local gardeners and homeowners with eco-friendly pest prevention. For more information, contact the CSU Extension ( or the city of Boulder’s IPM program ( Type “integrated pest management” into the search bars.


pests_2antsAnts inside the home are likely looking for food or water—or they’ve already found it. To discourage them, secure all food in airtight containers, fix leaky faucets, clean up grease and oil spills, and seal any possible entry.

Clean ant trails with vinegar and water to erase pheromone tracks, and lay down cedar mulch near entry points. Form a line of lemon juice, coffee grounds, cayenne pepper or cinnamon and ants won’t cross it. Trim tree branches and shrubs away from structures to prevent access, and plant ant-resistant vegetation such as catnip, peppermint, sage and mint near the home.

Ants feed on termites, fleas, aphids, caterpillars, whiteflies and other garden pests, so don’t entirely eradicate outdoor ants.


pests_1These small, soft-bodied insects use long slender mouthparts to suck fluids from stems, leaves and other tender plant structures, causing curling and yellowing. Regularly check the underside of leaves to catch infestations early.

Spray infested plants with a strong water jet to knock off aphids. Prune off populations on severely infested plants. Avoid high-nitrogen fertilizers, which favor aphid reproduction. Grow seedlings under protective floating row covers and use reflective foil to repel them before they gain a foothold (see “Reflection in the Garden” on opposite page).

If the infestation is severe, eco-friendly products like insecticidal soap and neem oil can help. Parasitic wasps, lady beetles, ants and lacewings feed on aphids. 


thumb_pestsNotorious disease transmitters, mosquitoes lay eggs anywhere there is standing water, including clogged gutters and drains, waterlogged potted plants, stagnant birdbaths, old tires, wheelbarrows, tree knotholes and even flowerpot saucers.

Birdbath drippers and water agitators help eliminate standing water. Make a cheap dripper by suspending a milk jug above a birdbath, cap side up but with the cap removed. Poke a couple of small holes in the jug and then fill it with water. Healthy bird and bat populations also keep mosquito populations at bay (buy or construct a bat box for bats to nest in).

Clear decaying vegetation from pond edges and stock the water with mosquito-eating fish. Use a pond mosquito dunk made with Bacillus thuringiensis (Bt) ssp. israelensis, a bacterium that causes disease in mosquitoes and blackflies.


pests_3bedbugsBedbugs are resilient blood-sucking insects that feed on humans at night. Rusty red or brown with very flat bodies about one-fifth of an inch long, bedbugs hide in crevices inside mattress seams, box springs and bed frames, and behind loose wallpaper and picture frames.

If you spot them, vacuum up adults and eggs and dispose of the vacuum bag in a sealed plastic bag. All infested materials must be removed and hiding places like cracks and crevices treated with insecticides, which means you’ll need to enlist professional help; exterminators have access to the most effective products. Preventive measures include steam-cleaning mattresses and furniture, washing and drying bedding at high temperatures, and clearing away clutter to minimize hiding spots.

To prevent the return of bedbugs, coat bed legs with petroleum jelly, or place the legs inside glass jars. Bedbug interceptor trays are also sold online. Mattress covers specifically made to keep out bedbugs are commercially available. 

Yellow Jackets

pests_4yellowjacketsAs predators, these social wasps provide a great benefit by scavenging and killing large numbers of plant-eating insects and nuisance flies. However, their aggressive nature is often troublesome to homeowners.

In fall, yellow jackets are primarily scavengers and tend to make appearances at picnics and barbecues, around garbage cans, at dog or cat food placed outside, and wherever there’s fallen fruit. The best defense is avoidance, keeping food shielded or indoors, and tightly sealing garbage.

Hang a lure trap in early spring, when the females search for nesting sites, and knock down any nests early to encourage the female to move on. In spring and summer, use yellow jacket traps baited with meat. In late summer and fall, yellow jackets prefer sweeter baits like sugar water or flavored sodas. For larger nest removal, call a professional, but make sure they practice eco-friendly methods.

Flea Beetles

pests_5fleabeetlesFlea beetles are small shiny beetles with enlarged back legs for jumping. They feed on greenery, causing tiny pits in leaves, bleached areas and ragged holes. Damage is not usually serious beyond the early seedling stage, but does allow fungi an entry point. Protect seedlings from beetles and other predators with protective floating row covers. Reflective foil applied just after planting is also helpful. 


pests_5whitefliesWhiteflies are tiny sap-sucking insects that frequent vegetable, citrus and ornamental plantings. The sticky honeydew they excrete yellows and sickens leaves, and eventually causes the plant to die. Whiteflies have yellowish bodies and whitish wings, and usually occur in groups on the underside of leaves. 

The best strategy against them is prevention: encouraging natural enemies like lady beetles and lacewings, removing plants that repeatedly host high whitefly populations, and pruning infested leaves. You can also vacuum up or hose off adults. Reflective foil helps repel them from vegetable gardens. If insecticides are necessary, use insecticidal soap, or neem or horticultural oils.

Spider Mites

pests_spidermiteSpider mites have eight legs and two red eyespots near their head, and resemble tiny moving dots to the naked eye. They weave silky webs on leaves and stems, damaging plants by  sucking on their cells. The damage appears as a light stippling on leaves and a bronze coloration that turns yellowish or red as feeding continues.

A good defense is adequate watering, as spider mites love water-stressed plants and reproduce rapidly in dry, hot weather. Forceful water blasts, insecticidal oils and soap sprays are effective against spider mites. Create a soap spray by mixing 1 cup vegetable oil with 1 teaspoon mild liquid dishwashing soap and 1 quart water in a spray bottle.

You can also purchase predatory mites from gardening centers. A good guideline is one predator for every 10 spider mites.

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