How to Kill Aphids Organically

Control a colony of aphids by attracting beneficial insects. Plus, learn to recognize aphid damage as soon as it appears.

| January 18, 2013

This article is part of our Organic Pest Control Series, which includes articles on attracting beneficial insects, controlling specific garden pests, and using organic pesticides.    

Small sucking insects commonly called “plant lice” are usually aphids. Numerous species inhabit vegetable gardens, where they are a primary food source for important beneficial insects including lady beetles and lacewing larvae. Aphids become a problem when a species finds exactly the plant they desire, as often happens with cabbage aphids on fall crops of broccoli, kale or Brussels sprouts. Peas, beans, potatoes, tomatoes and other crops also can be seriously damaged when aphid colonies grow to a damaging size. Some aphids can transmit viral diseases in cucumber and tomato family crops. Learning how to kill aphids naturally is an important part of organic pest control.

What Are Aphids? 

Small, soft-bodied sucking insects, aphids typically have a pear-shaped body one-tenth of an inch or less in length. They may be winged or wingless, and often have colors that blend in with the leaf or stem being damaged. Young, tender growth is often preferred, because aphids feed by sucking plant juices through straw-like mouthparts. Aphids commonly feed in groups, and numerous species are found in gardens around the world.

What Does Aphid Damage Look Like? 

Curled, mottled leaves are a sign that aphids (or similar insects) are at work. In time, infested plants become stunted and sickly, and a great deal of chlorophyll may be lost when leaves are devastated by aphid feeding. When aphids infest a young stem it often curls and stops growing. Gray-green cabbage aphids often cluster in the sheltered spot where leaves join the stem, or inside broccoli heads or the outer leaves of Brussels sprouts.  

When you see ants moving up and down a plant, aphids are likely to be present. Many aphid species excrete copious amounts of a sweet fluid called honeydew, which ants relish and readily gather up. In fact, some ants “milk” their aphid herds and in exchange help protect the aphid colonies.

Aphid Reproduction 

One key to the enormous success of aphids is their amazing reproductive capacity, which is higher than that of any other garden insect. It is estimated that a single aphid could have 5 billion descendants between spring and fall! Each female produces 50 to 100 offspring, and there may be over 40 generations annually in mild climates (and even more in greenhouses). Fortunately, a wide variety of predators, parasites, and pathogens keep the aphid population in check, but not always well enough to prevent serious damage.

6/27/2016 8:00:46 PM

I'm in need of help with aphids that are all over my catnip plant. How do I get rid of them? I sometimes use the catnip for tea. The rest of the time I occasionally give some to my cats.

7/22/2014 7:48:00 AM

I am finding A Lot of Aphids on my Petunias and other landscape flowers. I am wondering, when fighting the Aphids Should the insecticidal soap or dish liquid mixture be applied every few days? Thank you Have a great day:-)

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