How to Get Rid of Iris Borers

Updated on April 9, 2018
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.


If you live west of the Rocky Mountains, right now you are scratching your head and wondering what the heck an iris borer is. For gardeners east of the Rocky Mountains, the iris borer is the scourge of the iris garden.

Know your enemy

The iris borer is actually the larvae, or caterpillar, of a brown nocturnal moth which lays its eggs on the dead leaves and other debris surrounding your iris at the end of the summer, typically late August through September. A female moth can lay up to 1,000 eggs before she dies. Fortunately, there is only one generation of moths each year.

The eggs over winter in the plant debris in your garden, hatching in the spring when warm weather arrives in April or May depending on your climate. The larvae are the iris borers. They are easily identified by their pink bodies and brown heads. They head for the nearest iris, climb to the tops of the leaves and burrow into them. Iris foliage at this time of year is usually only about 6 inches tall making it easy for the caterpillar to climb them.

During the spring months, the borers munch their way inside the leaves down to the rhizome which is their ultimate target. Once in the rhizome, usually in July, they take up residence, eating it to a hollow as they grow to their adult size of 1 to 2 inches. Then in late July or early August, they emerge from the now dead rhizome and burrow into the soil to pupate into moths which will then lay eggs and begin the cycle again.

Iris Borer Moth
Iris Borer Moth | Source

Cleanliness is king

Obviously, the best way to rid your garden of iris borers is to keep it very clean. Remove all weeds, plant debris and dead or damaged leaves immediately. This makes your garden uninviting to the moths who will look elsewhere for a place to lay their eggs. When the foliage on your iris dies after the first frost, cut it down to the rhizome and remove it. Don't forget to remove all the dead foliage from your other annual and perennial plants. Don't leave any plant debris for the eggs to overwinter in.

Try a natural insecticide

You can try spraying your iris with any spray that contains pyrethrin. Pyrethrin is a naturally occuring insecticide that can be found in chrysanthemums. Pyrethrin is considered safe to use because it is biodegradeable. It has been used for thousands of years as both an insect repellent and an insecticide. It kills insects by destroying their nervous systems. Check the ingredients label of the insecticides at your local nursery to see which ones contain pyrethrin.

Another alternative is to create your own insecticidal soap. Simply mix 1 part Murphy's Soap and 9 parts water and spray it on your plants. You will need to re-spray after any rains. Insecticidal soaps work by smothering insects. The soap adheres to their bodies and covers the holes they use for respiration.

Both have been effective in killing the larvae as long as they are used before they have a chance to burrow into the leaves in April or May, depending on your growing zone.

Squeeze 'em til they scream

If you examine the foliage on your iris closely, it's easy to see where the borers have entered them. Simply squeeze the leaves between your fingers to destroy these pests. If you are squeamish like I am about actually touching the borers, this is a fun and easy way to kill them without having to touch them. If even just squishing the leaves bothers you, have your kids do it for you if they like squishing bugs.

Kill 'em with kindness

Sprinkle diatomaceous earth liberally around your rhizomes. Diatomaceous earth is made up of the skeletons of diatoms that lived in ancient seas that dried up eons ago. The skeletons are ground into a white powder that has sharp edges that will tear up the abdomens of the borers, killing them, as they crawl over it to get to your iris.

There are two problems with diatomaceous earth. It is expensive and it's a non-renewable resource. My own preference is to use crushed eggshells. They are free, a renewable resource and organic if you use organic eggs like I do.

Wash your eggshells and then crush them up. You can use your hands, a hammer or a coffee grindeer. Sprinkle them around your iris. In addition to killing the borers, they have the added benefit of releasing calcium, an essential nutrient, into your soil as they decompose into the soil.

Eggshells are also an excellent addition to your compost making it rich in calcium. They will break down faster if you crush them before adding to your composter.

Preventing iris borers from destroying your iris is easy if you keep your garden debris free and keep a close eye on your iris foliage in the spring to spot any signs of borer infestation.

Questions & Answers

© 2015 Caren White


    0 of 8192 characters used
    Post Comment

    • OldRoses profile imageAUTHOR

      Caren White 

      3 years ago from Franklin Park, NJ

      Thanks, Flourish. I like to have different ways to deal with things myself. Thanks for reading and commenting.

    • FlourishAnyway profile image


      3 years ago from USA

      I like that you provide a couple of options (and poetryman perhaps provides a fourth, haha).

    • OldRoses profile imageAUTHOR

      Caren White 

      3 years ago from Franklin Park, NJ

      Poetryman, why don't you start the trend? I bet they pop when you cook them! Thanks for reading and commenting.

    • poetryman6969 profile image


      3 years ago

      Sounds like you know of good ways to take care of the problem. I keep thinking that someday they will tell us that some or all of our garden pests are good for us and that it is our civic duty to eat those bugs!!!


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, 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:

    Show Details
    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 or domains, for performance and efficiency reasons. (Privacy Policy)
    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)
    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.
    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)