Article pulled from Extension note created by Pamlico Master Gardener Volunteer Lori Gaskins.

Aphids are tiny insects that often go unnoticed in the home garden. They are very common and are present almost year-round. However, on occasions where populations build up quickly, aphids can cause damage to plants that may require gardeners to take control measures. To better help you understand what aphids are, the damage they create, and how to manage them, this article provides helpful information and tips for home gardeners.

What Are Aphids?

Aphids are insects that have many plant hosts. Most aphids are less than 1/8 inch long and commonly light green or yellow, but they also may be white, black, red, brown, or gray. They may be winged or wingless. The most common ones in home gardens are the green peach aphid (Myzus persicae), the oleander or milkweed aphid (Aphis nerii), and the melon or cotton aphid (Aphis gossypii).

The green peach aphid (Myzus persicae) is a common garden pest that can damage leaves and transmit plant viruses.

How Aphids Damage Garden Plants

There are many different species of aphids affecting many different species of plants. Vegetable garden host examples include peppers, tomatoes, leafy greens, cabbage, kale, and basil plants. Aphids can usually be found on the undersides of leaves or on the plant stems. Most of the time, they cause no problems for the plant and can largely be ignored by the gardener. But they do have sucking mouthparts that pierce the plant, sometimes causing deformities in leaves. If signs of damage are seen, it is usually in the form of curled, yellow or deformed leaves, or poor plant growth. Aphids can transmit plant viruses that may be of concern, and their feces, called honeydew, can be a growth medium for black sooty mold.

Aphid Life Cycle and Behavior

Aphids have a complex life cycle, producing offspring both sexually and asexually. They can cycle through many generations per season and they mature quickly, so populations can increase rapidly. In fact, in hot weather, it may only take a week or two for a new generation to be produced. In the fall, males and females mate to produce eggs. These eggs can overwinter on plants, hatching the following spring. These newly hatched eggs may be females, who again can reproduce without male fertilization.

Adult aphids can produce multiple generations quickly. Young aphids cluster around the parent as they feed on plant sap.

Why You Might See Ants on Aphid-Infested Plants

Gardeners may see, feel, or smell honeydew on aphid infested plants. Honeydew is the shiny, sticky, sweet smelling feces of the aphids which results from them eating the plant’s sap. Honeydew accumulates on plant parts and can attract other insects. In fact, some ants may tend to aphids and protect them from predators. In return, aphids provide the ants with honeydew as a food source.

How to Control Aphids in Your Garden

It may not be necessary for the plant’s health to treat an aphid infestation. If treatment or control is deemed necessary, consider an integrated management scheme using the recommendations listed below. Be aware that aphids can be difficult to control due to their fast reproductive rates and the fact that they are often found in the unfurled leaves of plants and are therefore protected from many treatments.

Cultural Control for Aphids:

Resist overfertilization with nitrogen as this promotes leafy growth which is the preferred food source of aphids. Use reflective mulch or an aluminum item like a pie pan around the base of plants, as these interfere with the insect’s ability to find the host plant. Anti-aphid mesh netting can also be used. Companion planting with flowers may also help to attract natural enemies (example: yellow flowers attract lady beetles).

Mechanical Control for Aphids:

Dislodge aphids with a forceful water spray, physically rub them off leaves, or prune and destroy affected plant material.

Biological Control for Aphids:

Lady beetles (Coccinellidae family), green lacewing larvae (Chrysoperia rufilabris), parasitic wasps (Aphidius species), flower flies (Family: Syrphidae) may all decrease aphid populations. Attracting these insects to the garden or purchasing these insects to release into the garden is also an option.

Chemical Control for Aphids:

If all other controls fail and treatment is warranted, insecticides may be considered. Topical insecticides such as insecticidal soap or horticultural oil, pyrethrins, or insect growth regulator azadirachtin should be sprayed directly on the aphids. Systemic insecticides, such as imidacloprid or dinotefuran, should be applied to the plant roots.

Learn More About Aphid Management

For more information on controlling aphids, please contact the Pamlico County Extension office at 252-745-4121 or Daniel_simpson@ncsu.edu.

Pesticide and Chemical Use Disclaimer 

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services does not imply endorsement by NC State University or N.C. A&T State University, nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your local N.C. Cooperative Extension County center.