How To Get Rid Of Aphids, According To Experts

Aphids are tiny soft-bodied pests that feed on a variety of plants, including vegetables, ornamentals, trees, shrubs, and houseplants. Because they reproduce quickly and have multiple generations per season, their populations can explode within a few days.

Aphids inject their mouthparts into the plant tissue to feed on the sap. “When there are a large number of aphids, you may see deformed or discolored leaves or stunted plant growth,” says Rafia Khan, PhD, assistant professor and extension entomologist at Texas A&M AgriLife Research and Extension Center. “Some aphid species are specialists that feed only on certain plants, while other are generalists that feed on many different types of plants.”

Aphids also can vector, or transfer, pathogens to some plants. “Unfortunately, by the time you notice them feeding, they’ve already transmitted the disease,” says Matt Bertone, PhD, entomologist and director of the NC State Plant Disease and Insect Clinic. “They also excrete honeydew, a sticky substance that attracts ants, which also keep aphids’ natural predators away.” Honeydew also may lead to a build up of sooty mold, a type of fungus. If the plant becomes covered, the fungus can interfere with the plant’s ability to photosynthesize, which can affect its growth, says Khan. 

How To Get Rid of Aphids

There are a few ways to manage aphids in your garden and on houseplants, but you’ll need to combine these techniques for the most effective control, say Khan and Bertone:

• Inspect your garden for aphids every few days. “Things can get out of hand quickly if you’re not paying attention,” says Bertone. Check the undersides of foliage, where aphids hide, and keep an eye out for sooty mold.
• Use the garden hose sprayer to blast them off, says Khan. Repeat over several days to reduce the population.
• Snip off affected foliage and discard if aphids are present on only a few leaves or stems, says Khan.
• Plant flowers to attract beneficial insects. Bringing in natural predators can help manage aphid populations, says Bertone. For example, plant pollinator-friendly flowers to attract beneficials such as lady beetles, which love to dine on aphids.
• Use row covers on susceptible crops to protect them, suggests Khan.
• Avoid over-fertilizing because high nitrogen levels trigger tender, new growth which aphids prefer, says Khan.
• Try neem oil or insecticidal soap if other methods aren’t working, says Khan. These products work by contact, so you must cover the aphids in order to suffocate them. But be aware these products can kill beneficial insects, too, so be careful about application. A systemic insecticide, absorbed through the plant’s roots, is another option.
• Before bringing in outdoor plants for winter, treat them for aphids and other insects. Spray them off with the hose, and consider using a preventive spray of neem or insecticidal soap to knock down any hitchhikers, says Khan.
• For houseplant infestations, follow the same steps as above. But if you’ve tried everything and still are struggling with a large population, discard the plant to prevent spread to your other houseplants, says Khan. 

How To Identify Aphids

These insects are found in colonies, clustered on the undersides of leaves and stems. They’re oval or pear-shaped, usually about 1.5 to 2.5 mm in length. They have three pairs of legs, antennae, and a pair of tailpipe-like structures, called cornicles, on their back ends, says Bertone. They may be yellow, pale green, dark green, red, black, or covered with white, waxy filaments that resemble wool.

How Aphids Reproduce

Aphids have a complex life cycle, which is why the population can skyrocket within days. The eggs, which are miniscule, overwinter and hatch in spring when temperatures warm up. All of these aphids are females that give live birth to other females. When food runs out or things get overcrowded in a location, winged females are born and fly off to other plants. As cold weather approaches, both female and male aphids are produced to mate, with females laying eggs that start the cycle all over again.