Aphids, Spider Mites and 7 Other Bugs That Are Killing Your Plants (& What to Do About ‘Em)

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It’s such a joy to see your houseplants, vegetable garden, flowers—or whatever greenery you have, no matter how small—thrive and bloom. But occasionally, you discover a nasty little surprise: What the heck is that weird bug? And what is it doing to my plant? Before you panic, take stock of what’s going on. Sometimes you see the damage first, sometimes the bug. To accurately ID the problem, look for other clues such as webs, sticky sap-like substances and holes in the leaves. For houseplants, it’s also smart to isolate the affected plant from others before they all get infected.

Of course, outdoors, you’ll encounter bugs on your plants regularly. But the most common way a houseplant gets infected is when you bring a new plant home from the nursery, or if you let them spend the summer outdoors. Either way, inspect the plant before bringing it into your home, give it a once-over with an insecticidal soap before taking it indoors for the winter, and keep it away from your other plants for a few weeks once it’s inside.

Finally, be real about your plant’s health. Sometimes you try everything and a plant still is a little sad-looking. If you’ve made several attempts to get rid of the bugs and haven’t succeeded, give yourself permission to toss it! Sometimes you have to exercise a little tough love to protect your other plants.

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Here are the most common bugs that affect both indoor and outdoor plants:

plant killing bugs aphids
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1. Aphids

These teeny-tiny, pear-shaped bugs often show up in huge numbers and may be green, pink, black, brown or yellow. Adult aphids may have wings. They’re found on new leaves and under leaves and stems. You also may see honeydew, a sticky substance they leave behind, as they suck the plant’s sap.

What to do: Knock down the aphids with a spray from your hose. Indoors, put the plant in the sink and use the sink sprayer to wash it clean. You’ll probably have to do this a few times on a regular basis. Or use a cotton swab dipped in alcohol to rub away individual insects. Your last resort is to spray with insecticidal soap or neem oil.

Treat it with: Insecticidal soap, $10

plant killing bugs spider mites
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2. Spider Mites

Related to spiders, these minute insects are about the size of a period on the page. You may not see them until the plant is sickly or has silky webs on the leaves. All life stages of spider mites suck sap and will kill the plant in time.

What to do: We’re not going to lie—these are some extremely difficult pests to control. You can spray the plant off with water, as above, or use an insecticidal soap. But you’ll need to repeat in about a week. For bad infestations, you may be better off tossing the plant.

Treat it with: Insecticidal soap, $10

plant killing bugs whiteflies
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3. Whiteflies

Whiteflies look like tiny moths that may fly up when a plant is disturbed. Babies and adults suck sap and leave behind honeydew.

What to do: Spray the plant with insecticidal soap, especially under leaf surfaces. Repeat in a few days, but sometimes, your only option is to dispose of the plant.

Treat it with: Insecticidal soap, $10

plant killing bugs scale
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4. Scale

Scale looks like a waxy substance or fish scale on stems and under leaves. The adults are stationary, but the babies crawl around.

What to do: Use a nail file or toothpick to pick off early infestations. Or spray with neem oil to smother the adults, which are somewhat protected by the waxy coating. Insecticidal soap will kill the immature forms.

Treat it with: Neem oil, $11

plant killing bugs mealybugs
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5. Mealybugs

Mealybugs are about 1/8-inch long or longer, and they move very slowly. The adults have a cottony appearance. The babies look the same but are smaller. They also leave behind honeydew.

What to do: Clean off individual insects with a cotton swab dipping in rubbing alcohol, or use an insecticidal soap. Bad infestations usually mean it’s time to say buh-bye to the plant.

Treat it with: Rubbing alcohol, $2

plant killing bugs cucumber beetles
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6. Cucumber Beetles

Watch for these 1/5-inch-long beetles if you’re growing cucumbers, squash, melons or pumpkins—they’ve got a black head and a yellow-green body with three black stripes or black spots. A single beetle can damage the entire plant by eating the lower leaves or the flowers, preventing pollination. Cucumber beetles also spread a disease that can kill your plants.

What to do: Check your plants daily, because they show up overnight. Use row covers to keep beetles off your plants, or a pyrethrin-based insecticide labeled for vegetables.

Treat it with: Insecticidal Spray, $15

plant killing bugs flea beetles
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7. Flea Beetles

Tiny holes in the leaves of eggplant, pepper, potato and tomato plants may be a sign of flea beetles, 1/16-inch-long shiny black, striped or greenish beetles with hard bodies. They can stunt the growth of young plants, and they’re most often an issue in spring.

What to do: Row covers can protect young plants. If it’s a bad infestation, look for pyrethrin-based insecticides that are safe for the vegetable you’re growing.

Treat it with: Pyrethrin insecticide, $15

plant killing bugs slugs
Joseph De Sciose / Aurora Photos/Getty Images

8. Slugs

These are not insects but rather mollusks, which are half an inch to a few inches long. Slugs like chard, lettuce, peas and spinach. They’ll typically make holes in older plants or may eat young plants completely, except for the stem.

What to do: Sprinkle a little organic slug bait around plants a once or twice a week in spring and keep fallen leaves cleaned up so they have no place to hide.

Treat it with: Slug bait, $11

plant killing bugs fungus gnats
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9. Fungus Gnats

Fungus gnats are the only bugs on our list that won’t harm your plants, though the larvae in large numbers may stunt the growth of seedlings. But they’re mainly just super annoying because they fly around or hang out on the surface of houseplant soil and flutter by your face when you’re in the vicinity.

What to do: The larvae feed on organic material such as peat moss, so use a product containing Bacillus thuringiensis var Israelensis (BTi) on top of soil. This naturally occurring bacteria attacks the larvae’s digestive system and stops the reproductive cycle. You can use yellow sticky traps, but that doesn’t halt the source of the infestation.

Treat it with: BTi, $41

purewow author

Freelance Gardening Editor

Arricca Elin SanSone is a gardener with more than 15 years of experience. In addition to PureWow, she writes for Prevention, Country Living, Veranda, The Spruce and many other...