Common Garden Pests

Bugs and critters bothering your garden? Learn how to identify common garden pests, along with simple solutions.

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Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Greg Thompson for The U.S. Fish and Wildlife Service at FWS.gov

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Courtney Celley for The U.S. Fish and Wildlife Service at FWS.gov

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Garden Slug

Garden slugs make their presence known by chewing holes in leaves and creating slimy trails over plants and pavers. They’re the bane of hosta lovers, with their non-stop chewing turning pretty hosta leaves into lace. Control slugs by placing boards or burlap bags throughout the garden overnight. Slugs will crawl beneath before daybreak—and you can scrape them into a bucket of soapy water. Slug baits, a resident toad and a healthy population of ground beetles also help control slugs.

Japanese Beetle

Japanese beetles love the soft tissue of flower petals, whether it’s butterfly bush, roses or purple coneflower. These eating machines can destroy beautiful blooms, turning pretty petals into raggedy, rotting messes. To get a handle on Japanese beetles, knock individual bugs into soapy water. They lay eggs in moist lawns, so cut back watering from late June to late July, when beetles are mating (check with your local extension office for precise timing for your area). Don’t hang Japanese beetle traps—they’ll only lure more beetles to your yard than you already have. Use caution with systemic pesticides, which you water into soil for roots to absorb and move through an entire plant. If the active ingredient is imidacloprid, this chemical has been implicated in bee colony collapse disorder.

Rabbit

Rabbits make quick work of plants—and they’re not picky. They’ll chow down on your peas, beans, lettuce, petunias and even potted plants. When they’re the culprits behind vanishing plants, you’ll often find leaves missing with stems intact or stubs where an entire plant used to stand. To keep rabbits at bay, try repellents, chicken wire, netting or a free-running dog (with an underground fence). Clean up yard debris that could give rabbits hiding places, and plugs any holes that lead under sheds, decks or porches.

Beetle Grub

Grubs are the precursor to various types of beetles. One of the most destructive grubs is Japanese beetle, which lives in turf. These critters chew through grass roots, creating dead patches in your lawn. The best time to control grubs is in early fall, when they’re young and feeding voraciously underground near the soil surface. Treat with parasitic nematodes, a microscopic worm that attacks grubs (Heterorhabditis bacteriophora is the best), or strap on a pair of lawn aerating sandals and spike the grubs to death. Concentrate your spiking steps on brown lawn areas and the green areas just outside the brown.

Four-Lined Plant Bug

The four-lined plant bug attacks perennials, creating 1/16-inch square dead patches in leaves as they feed. These bugs create more of a cosmetic problem that plants often outgrow, but when numbers are high, the damage can lead to browned, misshapen and dying leaves, which you might mistake for disease. Four-lined plant bugs emerge about the time that forsythia leaves unfold. They’re shy and crafty hiders, so you’ll likely see the damage long before you spot one of them. The best way to control these bugs is twofold. First, in midsummer, when the insects disappear, cut back plants that have been attacked, snipping below the damage. This should remove any eggs that have been laid inside stems. Pruning like this delays flowering on perennials, but the plants will branch and become bushy, which means more flowers. Second, in fall, clean up all stems and leaf litter in the bed. Take care to remove all stems of plants the insect attacked during the growing season. Eggs that will hatch the following spring are typically laid inside those stems, so don’t add them to your compost pile.

Earwig

Earwigs inspire terror with those giant pincer claws on their backside. Those claws are used to grasp prey, including slugs, aphids and insect larvae. They’re also used to fend off predators. Earwigs fill two roles in the garden. On the positive side, they scavenge and consume decaying organic matter and eat other plant pests. But when populations are high, they can damage desirable plants by feeding on the soft tissue of seedlings, new shoots and flower petals. One easy way to deter earwigs is placing rolled up newspapers around the garden as traps. The earwigs crawl inside, and you can shake them into a bucket of soapy water. Diatomaceous earth also works against earwigs. Sprinkle it at the base of plants, on earwig clusters or anywhere earwig populations are high.

Deer

Deer can wipe out a garden overnight, nibbling prize flowers, vegetables and plants. Telltale signs of deer feeding are torn or ragged leaf edges. Deer lack upper incisor teeth, so when they grab a plant, they jerk their heads up to pull a leaf free. This creates torn stems and leaves. Keep deer away from your yard with repellents (Plantskydd works well), an extra-tall fence (8 to 10 feet tall) or a double fence (3 to 5 feet tall, 3 to 4 feet apart). Toss plastic netting over individual plants or flowers you want to protect from browsing.

Stink Bug

Brown marmorated stink bug has been in the United States 20 years, and in that time it’s spread throughout the Mid-Atlantic, Upper Midwest and along the West Coast. Stink bugs attack many home garden crops, including beans, corn, tomatoes peppers, apples and raspberries. Their feeding wounds fruits and veggies, resulting in corky spots that are inedible. Stink bugs spend winter inside, invading home voids and attics. With their stinky personalities, these bugs stir up drama indoors when they emerge from hiding in hordes, usually in winter. In the garden, knock stink bugs into soapy water to kill them. Indoors, the same method works, or you can try vacuuming up the stinkers (which might make your vac stink). Another indoor option is using a dry-mop cleaning tool (think Swiffer-type) that you cover with duct tape, sticky side out. That device gives you reach to grab stink bugs climbing curtains, walls and ceilings.

Rose Slug

A rose slug is the larvae or immature stage of a rose sawfly. It’s easy to overlook on roses, until its feeding begins to damage leaves. Rose slugs feed on leaf undersides, out of sight, nibbling on leaf tissue—the part between the veins. When they’re done eating, leaves resemble skeletons. Usually when gardeners spot rose slug damage, they think their roses have a disease because leaves are speckled and have holes in them. Sawfly larvae are not slugs or caterpillars, but a different type of critter. Blast them off roses with a spray of water, or spray them with spinosad, a bioinsecticide made from soil bacteria.

Grasshopper

When grasshoppers hit your garden, nothing is safe. These insects chew their way through leaves, flowers and fruits without stopping, eating up to half their body weight per day. Kill grasshoppers when they’re young anytime you can. Create a garden where bluebirds feel at home, because they’ll help eat these pests, as will toads, snakes and shrews. Explore the world of grasshopper baits to discover bioinsecticides that kill these insects using various strains of fungi or bacteria. Don’t just ignore grasshoppers, because if you have a severe problem one year, you will continue to have issues in future.

Aphids

Over 4,000 different types of aphids exist and attack plants. If their numbers are low, they might be unsightly, but won’t actually harm plants. It’s when populations boom that their feeding damages plants, causing leaves to curl or flower buds to fail to open. As aphids feed, they release a sticky honeydew, enriched with plant sugars. These sugars grow mold, attract ants and create another layer of problems. Ants will actually guard aphids to protect them from predators so the ants can harvest the honeydew. When you spot a cluster of aphids, remove them with a spray of water from the hose, or kill them with insecticidal soap or a sprinkle of diatomaceous earth. Birds and predatory insects eat them, including ladybugs and lacewings. Avoid using pesticides in your garden and let these natural controls help take care of aphids for you.

Chipmunk

You may not think of a chipmunk as a pest, but when it starts digging under shrubs or patios, your view may change. Chipmunks actually cause the costliest damage to established landscapes, unseating retaining walls, destabilizing walkways and even killing roses (by digging directly under the trunk). Once chipmunks dig tunnels, other critters arrive to set up housekeeping in those tunnels, including voles, shrews and snakes. Chipmunks visit gardens with bird feeders and other ready sources of food or water. An outdoor cat or dog can help keep these critters at bay, as can garlic oil pegs you toss into tunnels or various repellents you sprinkle onto flower beds or near tunnel openings.

Whitefly

The name whitefly is fairly descriptive of what these pesky insects look like: tiny, white, flying bugs. Whiteflies cluster underneath leaves usually starting in mid- to late summer. When you disturb plants, the insects fly up, forming white clouds. It’s dramatic and horrible at the same time. They love tomatoes, perennial hibiscus, fuchsia and anise hyssop. The adults and young suck plant sap, damaging leaves as they do so and releasing sticky honeydew. Controls include ladybugs, lacewings and a naturally occurring tiny parasitic wasp. You can also control whiteflies using horticultural oils, soaps or bioinsecticides containing fungi that parasitize whiteflies.

Bagworm

Bagworms are the larval form of a moth that attacks evergreens and other trees. The worm inside each bag feeds on the evergreen bush or tree, building a case around itself for protection from predators. The case is made from bits of the plant the insect is feeding on and slowly enlarges over time as the insect grows. Females lay eggs in the bags in late fall. The best control, if you only have a few bagworms, is to handpick the bags and drop them into soapy water or put them out with the trash. Predatory insects including wheel bugs or insect-eating birds will attack these insects, even inside their bags. You can also spray traditional or bioinsecticides. Follow directions carefully on timing. Once larvae are more mature and tucked into thicker bags, the chances of a spray reaching the worm itself are small.

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