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You are here: Home / Fruits & Vegetables / Vegetables By Name A-M / Beans / Bean Pests: How to Identify and Control

Bean Pests: How to Identify and Control

12 Comments

Avoiding and Preventing Common Bean Pests
Green beans are one of the simplest garden vegetables to grow, producing a bountiful crop with very little care. Most bean pests are easily controlled through natural means and rarely require the use of pesticides. Watch for the following pests in your bean patch:

Aphids

Aphids are small, green, red or gray insects that are most prevalent during the early summer, but can appear anytime. They don’t eat holes in the leaves, but pierce leaves and stems, sucking the juices from the plants. Plants may droop or leaves may turn yellow during aphid infestations. You may also notice honeydew, a sticky substance secreted by aphids, on the leaves and soil. An increase in ant populations also indicates aphid infestations because the ants feed on honeydew. Look on the undersides of the leaves for the aphids themselves.

Aphids tend to appear cyclically so they’ll probably move on by themselves in a few weeks. Ladybugs, predatory wasps and lacewings prey on aphids and may keep populations under control without any help from you. If, however, the aphids are damaging your bean plants, spray them with a steady stream of water from the hose or apply insecticidal soap to the leaves, coating both the tops and bottoms well to cover the aphids.

Thrips

Thrips, like aphids, are small, barely noticeable insects that suck the juices from bean plants. If they appear while beans are flowering, the beans may fail to pollinate or the resulting pods may be deformed. Lay aluminum foil on the soil after planting to repel thrips or treat them with insecticidal soap.

Beetles

Mexican bean beetles look like large, brown ladybugs, and although they may appear early in the summer, they cause the most damage in mid-to-late summer. You may also notice Japanese beetles, which are shiny and green, or brown-spotted bean leaf beetles munching on your plants. These voracious insects usually feed on the undersides of the leaves, leaving the veins intact. Occasionally, beetles may also feed on pods and stems.

Outwit beetles by planting fast-growing varieties that mature before they appear. Hand-pick beetles off bean plants and drop them in a bucket of soapy water to destroy them. Watch for their yellow, fuzzy larva and yellow eggs, and destroy them, as well.

Caterpillars

Corn earworms and cabbage loopers aren’t as picky about their diet as their names imply. Both insect pests eat beans, as well as corn and cabbage. These pests are most troublesome in late-planted crops and can quickly decimate an entire row of beans.

Spray the bean plants with Bacillus thuringiensis, also known as Bt, to control feeding caterpillars. Bt is a natural soil bacterium that paralyzes the gut of these insects, slowly starving them. The process takes three or four days, but the insects stop feeding almost immediately. Bt doesn’t damage bean plants and is safe for other animals and insects.

General Recommendations on Bean Plant Pests

Pest problems tend to vary from year to year, but good cultural practices can minimize their appearance and also ensure healthy bean plants that are more able to survive insect infestations. Till the soil in early spring if you’ve had problems with bean pests. Tilling will destroy any overwintering insects. Rotate bean crops from year to year to confuse and thwart bean pests.

Plant beans in full sun in late spring, two weeks after the last frost. Bean seeds do not tolerate cold, soggy soil and may be stunted or fail to appear altogether. Plant bean seeds 1 inch deep and 2 to 4 inches apart. Thin them so they stand 12 inches apart after true leaves emerge. Water them to keep the soil evenly moist, and monitor the garden often for insect pests.

For Further Bean Pest Control Reading

Clemson University – Bean & Southern Pea Pests

Penn State University – Beans: Insect Identification and Control in the Home Garden

mexican bean beetle green beans harvested and growing in garden with text overlay identify and control bean pests aphids thrips beetles and more

Related

Filed Under: Beans, Garden Pests Tagged With: bean bugs, bean insects, bean pests, Beans, Green Beans

Comments

  1. Annie Gaddis says

    June 27, 2015 at 8:18 am

    Would have been nice to have had PHOTOS for each of those!

    Reply
    • sheila says

      May 22, 2022 at 5:37 pm

      totally. no help here…. what a waste of time….ugh

      Reply
    • New Green Thumb says

      June 26, 2022 at 11:58 am

      Wanted to comment the very same.

      Reply
  2. Conniue Gettle says

    July 11, 2019 at 11:13 am

    I have a yellow, no black spots, beetle- like looking critter, easily squished , with several hairy , little leg pairs on the front of its body. It ruined my yellow beans and I just found a couple which have moved to my red beets. Any identification and how to get rid of them?

    Reply
  3. John says

    June 7, 2020 at 10:53 am

    Good information but pictures would be great.

    Reply
  4. Vi Wawrykow says

    June 26, 2020 at 11:14 pm

    Something is eating my scarlet runner beans. Leaves are chewed full of holes and some beans are cut off. There are no visible mites or aphids or caterpillars. Help.

    Reply
    • Kim Cozort Kay says

      February 13, 2021 at 2:09 pm

      Mine too! The leaves are curling up and inside the curled up leaves are these caterpillar like worms.. Help.

      Reply
  5. Jacob C Crowley says

    July 4, 2020 at 1:35 pm

    To the lazy commenters, do some work and type into google these pest and see the photos. Good god people want everything spoon fed to them these days..

    Reply
    • Mr Baffelator says

      September 15, 2020 at 5:24 pm

      You don’t appear to have enough intelligence available to comment on the “lazy commenters”.. Are you a big fat do nothing yourself
      ..???

      Reply
  6. Needra says

    July 9, 2020 at 10:32 am

    These dark brown bugs are eating the stems of my bean plants. Sometimes they eat the leaves too. They crawl around on the soil. They are about 3 centimeters long. What are they? Should I send a picture?
    Thanks!

    Reply
  7. Larry says

    May 12, 2022 at 2:07 pm

    My bean pods have hundreds of lil black bugs, but none on the leaves or stems. Sprayed twice w/ bioneem, but doesn’t bother them much. Will try water sparay.

    Reply
  8. Maryanne says

    July 10, 2022 at 7:12 pm

    Try cinnamon powder and sprinkle it on the ground and reduce if it rains

    Reply

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