How to Identify and Manage Aphids

Aphids are not often a common problem on the interior landscape, but occasionally they can show up. These tiny insects, also known as plant lice, can cause the leaves of plants to become deformed and sticky. If they are in high enough numbers, aphids can stunt a plants growth.

Why Are Aphids So Destructive?

Both immature as well as adult aphids feed on plants by sucking plant juices, which can distort the plant’s leaves. A quick growing infestation can drain the sap from a plant until it’s stunted or dying. Like other insects with piercing and sucking mouth parts (like a straw), aphids suck the sap out of the plant. Because of the nature of this feeding method, the aphids will secrete sticky fluid called honeydew. Honeydew can become a problem on the interiorscape; sticking to windows, planters and other surfaces. Over time the buildup of honeydew can allow for a black mold (sooty mold) to grow on the sticky surface. This soot can become unsightly. The honeydew can attract other insects such as ants, which like to feed on the sweet material. Honeydew can build up quickly because aphids reproduce at a very fast rate. Female aphids can reproduce without mating; giving birth to live immature aphids, skipping the eggs laying stage. In an outdoor setting, when temperatures drop in the fall, aphids will lay eggs but because of the warmer environment in the interiorscape environment there is no need to overwinter as an egg.

How to Identify this Pest

Aphids are tiny but easy to identify. They can vary a little in size, but aphids are generally pear-shaped and have two tubes at the tip of their abdomens extending backward. Colors vary depending on the species and host plant. Most aphids are wingless, but when population levels rise aphids can develop wings and relocate to a new plant. When looking for aphids, you can often find them on new growth. Also there are some species that can live and feed on the roots of plants.

The Life Cycle of an Aphid

Aphids can be a problem for indoor plants because of their sheer numbers. Female aphids reproduce without mating and give birth to live immature aphids which just look like smaller versions of the adults. The immature aphids begin to feed immediately, stressing the plants even more. The young aphids will molt (shed their skins) 4 times before becoming an adult. Once a plant’s sap has been nearly depleted or the population on a plant is very high some species will develop wings and search for new plants to infest. The common green peach aphid, Myzus persicae, under optimal conditions can complete its life cycle in 10-12 days.

Do You Have an Aphid Infestation?

Clear indicators:

Ants and aphids on snakeroot

  • Sticky honeydew is often an early indicator
  • As aphids molt they will leave their white skin flakes on the plant. Cast of skins may be confused with whitefly. These skins can also fall onto other plants or wall giving an unattractive look
  • Ants running up and down the stems of the plant, harvesting honeydew

A plant struggling with an aphid infestation can have curled, yellowed or mottled leaves, stunted growth of buds and branches, deformed buds, or even plant death. Watch for ants. If you see ants running up and down a plant that is often a good indicator that there is some kind of honeydew-producing insect present.

It’s Time to Take Back Control

Aphids might have strength in numbers, but it’s possible to mitigate the damage they cause and help prevent future infestations. Start by washing down the plant. Aphids can be easily knocked off. If necessary you can prune heavily infested parts of the plant. If washing and pruning is not an option there is biological control. Beneficial insects like lacewings larva can provide excellent control on the interior landscape. Not only will they feed on aphids but they will also feed on other soft bodied insects. You can buy lacewing eggs glued on a card to hang on plants that your customers will never see. There are also spray options available such as insecticidal soaps or horticultural oils. Always check to make sure that any compounds you select are labeled for use with the plant variety and location. Also be careful not to overspray because these compounds could make floors slippery or damage surfaces. Chemical insecticides like Safari (dinotefuran) and Flagship (thiamethoxam) can be used as a drench on the interior, and can be very effective. With drenching you do not have to worry about over spray. Another spray option is Endeavor (pymetrozine). This is a foliar-applied insecticide that paralyzes the mouth parts of aphids, preventing them from feeding. It is compatible with many biological control agents.

Pest control labels vary between states and the pesticide user bears the responsibility of consulting the pesticide label and adhering to the law. Always read the label before a pesticide is applied to make sure it is legal to apply on your site, in your state and the plant material.

Preventing Aphid Infestations

To prevent aphids, keep an eye on your plants and be sure not to over-water or over-fertilize them. Aphids thrive in environments with high nitrogen. Also inspect all new incoming plants. Aphids are a tough pest to control, but staying vigilant and using safe insecticides can help you beat the tiny bugs before they take over your landscaping.

Battling other common indoor plant pests? Check out my Professional’s Field Guide to Plant Pest Control for information on Spider Mites, Whiteflies, Thrips, Fungus Gnats, Mealybugs, and Scale insects.

 

“Ants and aphids on snakeroot” photo by Dendroica cerulea via https://www.flickr.com/photos/dendroica/6170146527/

Suzanne Wainwright-Evans is an Ornamental Entomologist specializing in integrated pest management. Suzanne has been involved in the Green Industry for more than 18 years with a primary focus on biological control and using pesticides properly. She is a graduate of the University of Florida with degrees in both Entomology and Environmental Horticulture. She has worked throughout the United States and internationally consulting to greenhouses, nurseries, landscapers and interiorscape companies.

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  • Clem Cirelli, Jr.

    Suzanne, we have found that most aphid infestations occur in residential interiorscapes where the homeowner decides to overwinter their summer tropicals, especially Hibiscus, in the house near their permanent indoor plants. As you pointed out, it only takes one female aphid, and then look out!

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