How to Get Rid Mexican Bean Beetles

Updated on August 8, 2019
OldRoses profile image

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.

Source

I had a problem with a rabbit making a buffet out of my vegetable garden this year. He tortured my beans. He nibbled, then let the plants grow a little before nibbling again. This was not the pest I was expecting in my beans. I thought that I would be battling the Mexican bean beetle.

What are Mexican Bean Beetles?

Mexican bean beetles are native to Mexico and the Eastern United States. They cannot survive in arid areas so they are only found in heavily irrigated parts of the West. They are relatives of lady bugs. They look a lot like them too. They have the characteristic black spots. In the case of the bean beetle, there are 16 spots, arranged in three rows of 6, 6 and 4. Their body color is usually described as orange, but can range from yellow to brown to even red. They are the only member of the lady bug family that eats plants, specifically legumes. Lady bugs usually eat other insects.

The adults overwinter in plant debris in your garden. They emerge in the late spring and immediately start feeding on the undersides of the leaves of beans, soybeans and cowpeas. They begin laying their eggs 1 or 2 weeks after on the undersides of the leaves. The eggs are easy to spot. They are bright yellow and laid in groups of 40 to 60. The larvae hatch in 1 to 2 weeks and begin feeding on the undersides of the leaves they hatched on.

All of this feeding by both the adults and the larvae results in the characteristic lacy appearance of bean beetle damaged foliage. The “lace” is actually the veins of the leaf which the beetles and larvae don’t eat. You are most likely to observe the damage in July and August.

After 2 weeks up to 5 weeks of feeding, the larvae attach themselves to the undersides of the leaves and pupate into the adults. The adults emerge in a week to 10 days and live for 4 to 6 weeks. Bacause their life cycle is so short, there can be 2 to 3 generations of Mexican bean beetles each growing season.

The larvae attach themselves to the undersides of the leaves to pupate into adults.
The larvae attach themselves to the undersides of the leaves to pupate into adults. | Source

How to Get Rid of Mexican Bean Beetles

Floating Row Covers

The best way to prevent the beetles from getting to your beans is to place a floating row cover over your plants. Floating row covers are lightweight fabric that can be laid over your garden or supported over hoops on row crops. The cloth allows sunlight and water in but keeps the beetles out of your garden. You can leave the cover on all season until harvest.

Handpick the Beetles, Larvae and Eggs

Since the adults, larvae and eggs are all found in one place, the undersides of the leaves, it’s easy to find them and destroy them. If you have a small garden and you aren’t squeamish, you can examine the undersides of your legumes and squish any beetles, larvae or eggs that you find. I’m squeamish so I knock them off of the leaves into a container of soapy water. If they don’t drown, the soap will kill them. You can use any kind of liquid soap. I use dish soap.

The adults, larvae and eggs are easy to spot on the undersides of the leaves.
The adults, larvae and eggs are easy to spot on the undersides of the leaves. | Source

Beneficial Insects

What’s a little cannibalism among family members? That’s right. Lady bugs eat Mexican bean beetles! If you don’t already have them in your garden, you can purchase them online to release into your garden. You can also purchase a parasitic wasp, Pediobius faveolatus, to dine on your beetles. Other insects that think the beetles are delicious are green lacewings and pirate bugs.

Insecticidal Soap or Neem Oil

When all else fails, you can spray. However, you must always be very, very careful what you spray on edible plants because whatever you spray on your vegetables, will end up on your dinner plate. Insecticidal soaps work by coating the insects and larvae and smothering them. Neem oil is always a good choice because it is non-toxic and breaks down within a few days. When spraying, be sure to coat the undersides of the leaves where the beetles, larvae and eggs are. Spraying on top of the leaves won’t harm the beetles, because they only feed on the undersides of the leaves.

Do a Thorough Fall Garden Cleanup

A great way to keep Mexican bean beetles out of your garden is to do a thorough fall garden cleanup. Remove all weeds and plant debris. The adult beetles hibernate in plant debris over the winter. If your garden is bare and there is no place for them to hibernate, they will fly away to find a more conducive environment.

Questions & Answers

    © 2019 Caren White

    Comments

      0 of 8192 characters used
      Post Comment

      No comments yet.

      working

      This website uses cookies

      As a user in the EEA, your approval is needed on a few things. To provide a better website experience, dengarden.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

      For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://dengarden.com/privacy-policy#gdpr

      Show Details
      Necessary
      HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
      LoginThis is necessary to sign in to the HubPages Service.
      Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
      AkismetThis is used to detect comment spam. (Privacy Policy)
      HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
      HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
      Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
      CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
      Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
      Features
      Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
      Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
      Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
      Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
      Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
      VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
      PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
      Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
      MavenThis supports the Maven widget and search functionality. (Privacy Policy)
      Marketing
      Google AdSenseThis is an ad network. (Privacy Policy)
      Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
      Index ExchangeThis is an ad network. (Privacy Policy)
      SovrnThis is an ad network. (Privacy Policy)
      Facebook AdsThis is an ad network. (Privacy Policy)
      Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
      AppNexusThis is an ad network. (Privacy Policy)
      OpenxThis is an ad network. (Privacy Policy)
      Rubicon ProjectThis is an ad network. (Privacy Policy)
      TripleLiftThis is an ad network. (Privacy Policy)
      Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
      Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
      Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
      Statistics
      Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
      ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
      Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
      ClickscoThis is a data management platform studying reader behavior (Privacy Policy)