Homeowner’s Guide To Garden Pest Control
From bugs to bunnies, here's what to know about garden pests, how to prevent them and what to do if they've moved in.
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Garden pests come in all shapes and sizes, from tiny mites to mighty elk. They can fly, burrow, crawl, climb and jump their way into your garden. How do you keep them all out?
First, keep in mind that most insects and other wildlife in your garden are not pests. A healthy garden should be full of bugs and other critters.
“A lot of times, when we see an animal or an insect, it is not a problem,” says Thomas Ward III, a training specialist and biologist at Critter Control. “We are simply sharing habitats.”
The first step in successful pest control, then, is identifying which insects and wildlife are actually problematic. Usually, these are the ones eating up all your vegetables or seriously damaging leaves and root systems. Once you know the who and the what, work to keep those specific pests from getting out of hand.
“With a little planning, you can enjoy your garden and avoid conflicts,” says Ward.
Types of Garden Pests
Insects and wildlife are the most common offenders in our vegetable and flower gardens. Where you live will determine which ones might invade your garden, but below are some of the most common:
- Beetles: Some beetles can eat a lot, and do it quickly. Main offenders include the Colorado potato, Mexican bean, flea and Japanese. Japanese beetles eat leaves of more than 300 plant species, including roses, grapes, crabapples and some maples.
- Caterpillars: Maintaining huge appetites, caterpillars munch their way toward their future selves as butterflies and moths. The larvae from spongy moths (formerly called gypsy moths) are invasive and particularly damaging to tree leaves. They can completely defoliate a tree between spring and fall.
- Aphids and thrips: These damage plant leaves, fruit and sometimes roots. “Aphids are pesky indoors and outside,” says Chris Plante, district manager of Davey’s Tree Care Service in Portland, Maine. “They’re hard to see and can attack a broad range of plants including fruits, vegetables and ornamentals.”
- Mammals: Chipmunks, deer and rabbits tend to eat their way through gardens, while skunks, opossums and raccoons might dig it up searching for insects. Smaller animals might also hang around because gardens provide cover from predators.
- Burrowing wildlife: Gophers, moles and voles damage gardens by tunneling and gnawing on root systems.
How To Keep Garden Pests Out of the Garden
The first rule of pest-free gardening is to give that up as a goal. “Every gardener, whether advanced or beginner, deals with garden pests,” says Plante. “The experienced gardener knows there is no way to completely rid your garden of them.”
So, here are some ways to minimize the likelihood of a serious pest invasion.
If you’re still in the planning stages of your garden, research common pests in your area and what they like to eat.
“Think about your garden in both the short and long term,” says Bernie Holst III, CEO of Horizon Pest Control in Midland Park, N.J. “If you know certain pests already exist in your yard, then try to make choices that those pests will find less attractive.” A university extension agent can be a great resource for this.
Planting a greater variety of species, especially emphasizing native plants, will help support the beneficial insects that eat the pesky ones. Beneficial insects can include ladybugs (which eat aphids), lacewings, soldier beetles, tachinid flies, predatory stink bugs and parasitic wasps.
Top plants to attract these “good bugs” are yarrow, laceflower, cosmos, angelica, tickseed, sunflowers, Shasta daisies, black-eyed Susans, hardy aster, dill and goldenrod. Note: Goldenrod can sometimes be an invasive weed.
“If you plant it, they will come,” says Plante. “But please do not buy insects. When you purchase bugs, you may either be buying invasive species that don’t belong here in the first place, or supporting wild harvesting of natural lands.”
Head off invasive species
Invasive species, like emerald ash borers, often don’t have natural predators so they can spread quickly. Professional treatments for emerald ash borers and related pests include soil or trunk injections, and sometimes canopy sprays.
Regularly monitor your garden so you can stop a problem before it gets out of hand. Check under leaves and on stems. Also, remember that bugs can overwinter in the soil and crawl back to the plants when the weather warms.
Maintain healthy soil
A healthier plant is more apt to withstand pressure from pests, diseases and drought, and soil is a key to health. Get a soil test, fertilize, don’t over-till and regularly water roots deeply.
Create a barrier
For flying pests, lay netting over berries and fruit trees. For crawlers or diggers, try a mesh fence buried at least six inches to prevent anyone from burrowing under it.
A fence at least eight feet tall can stop deer. Row covers keep worms and birds off cabbage plants, while raised planters shoud deter rabbits from eating your veggies.
Pheromone and rodent traps can control pests before they reach your flowers and vegetables. Place them away from the garden so they don’t attract pests right to it.
How To Get Rid of Garden Pests
When your garden is under fire, figure out what is responsible, what’s drawing them into your garden and what conditions they need to thrive. Once you know all that, you can decide on the best solution. In general, there are four pest mitigation processes: cultural, mechanical, biological and chemical.
While chemical treatments can sometimes bring immediate gratification, many experts recommend them as a last resort. That’s because they focus on the symptoms instead of preventing the problem. They can also hurt beneficial bugs, contaminate the soil with toxins, harm birds and disrupt ecosystems. Try other methods first, especially if you plan to eat from your garden.
Cultural pest removal
Cultural mitigation involves shaking things up to make your garden naturally less desirable to pests. “Using insect or disease-resistant plants is the easiest method of battling insects,” says John Bell, III, a board-certified entomologist with Florida Pest Control. “Changing the environment to be less attractive to some pests is also effective.”
For animals, this might involve:
- Removing debris and other potential habitats in order to deter rodents.
- Relocating compost piles.
- Storing pet food and bird seed inside.
- Harvesting ripe fruits and vegetables and picking up any that have fallen to the ground.
For insects and disease, this might involve:
- Keeping plants trimmed for better air flow to prevent disease.
- Drying out infested areas.
- Swapping the food-source plants with ones that don’t attract pests.
Mechanical pest removal
“Using physical devices to deter larger pests from attacking your garden often can be the easiest method of control,” says Bell. These can include:
- Creating raised beds;
- Installing fencing;
- Making a hanging garden;
- Placing traps to catch and relocate smaller animals.
For insects, a mechanical solution is pheromone traps. These are effective for many species including ladybugs and Japanese beetles, says Holst. Set up several traps to lure insects out of the garden and place them a good distance from your garden.
“The last thing you want to do is pull more destructive insects into the garden,” says Holst.
Biological pest removal
Biological pest removal involves using other insects to control pests. “The most common example is the use of ladybugs to control aphids,” says Bell. Another example are nematodes, a small worm-like creature that can control grubs.
But biological control comes with consequences, like potentially throwing ecology out of whack. “Ladybugs are cute and harmless to humans,” says Holst. “Hundreds or thousands of ladybugs, however, are not so cute, especially if as the temperatures change they try to enter your home or business in order to survive the winter.”
Chemical pest removal
“If all else fails, a product may be necessary to keep your garden looking beautiful or producing the food you desire,” says Holst. “Fortunately there are many to choose from.”
For insects, some are applied to the plant, some to the soil and some as a barrier repellant around the garden. “Repellents work best if you use them before an animal problem starts,” says Ward. “Most repellents require multiple applications.”
A few common chemical treatments that are considered low or non-toxic to humans are:
- Neem oil. Neem oil is a naturally occurring pesticide that comes from the seeds of the neem tree, an evergreen from India. Sprayed on, it suffocates insects on contact. It’s particularly good for soft-bodied insects like aphids, mites and thrips, and considered safe for birds, bees and mammals.
- Diatomaceous earth. Usually used as a powder, diatomaceous earth is made from tiny aquatic fossils. Because it kills by breaking insect exoskeletons, it’s best for killing larvae, slugs, ants and cutworms. It is generally considered OK environmentally.
- Soaps and essential oils. Various insecticidal soaps and oils kill on contact and are considered mostly safe for beneficial insects. Most are good for aphids, thrips and mites. Best to buy pre-made, as homemade ones could cause foliage burn.
- Pyrethoids. These are a man-made form of the naturally occurring insect control pyrethoids created from chrysanthemum. They must be applied directly to insects, which they quickly paralyze. They’re effective on moths, ants and mosquitos, but also kill lots of beneficial species.
- Neonicotinoids. These widely used pesticides target sap-sucking and leaf-chewing insects like aphids. They’re effective because plant tissues absorb them. Use these as last resort since they’re lethal to bees, butterflies and birds.
For best results and safety, always follow the instructions on the label and use organic solutions on food gardens.
Call the Pros
A lot of pest problems can be fixed through DIY, but some require a extra help. When all else fails, call your local landscapers and tree-care pros. They know the right treatments and how to comply with state pesticide applicator regulations.