Pest Alert: Viburnum Leaf Beetle

Tom Tiddens —  June 5, 2015 — 10 Comments

Viburnum leaf beetle is here, and he’s not a good neighbor!

Yesterday was an exciting (yet worrisome) day for me here at the Garden. We found viburnum leaf beetle here for the first time ever—although his arrival was not unexpected. Two separate discoveries were reported to me within just a couple of hours. One of our horticulturists made a discovery in one location, and one of our trained plant healthcare volunteer scouts found the beetle in another location. Both finds were on arrowwood viburnum (Viburnum dentatum), the beetle’s preferred host (and high on our watch list).

Click here to download the viburnum leaf beetle fact sheet with tips on managing the beetle.

If you live in the area, I suggest you monitor your viburnums for our new foreign friend. The sad thing about this critter is that once he moves in, he will become a perennial pest, just like Japanese beetles.

In ornamental horticulture (your home landscape plants), the viburnum leaf beetle seems to be on the verge of having a great impact in our area, as nearly everyone’s home landscape has viburnum. I’d like to take a moment to review this new critter.

Viburnum leaf beetle (Pyrrhalta viburni)

The viburnum leaf beetle (VLB) is native to Europe and was first found in the United States (in Maine) in 1994. It was first found in Illinois (Cook County) in 2009. In 2012 and 2013, the number of reports increased from Cook County and also from DuPage County. In late summer 2014, there were numerous reports from Cook County and some specifically from neighboring Winnetka, where complete defoliation was reported—only five miles from the Garden!

PHOTO: Leaf damage to Viburnum dentatum at the Chicago Botanic Garden by viburnum leaf beetle larvae.

Leaf damage to Viburnum dentatum at the Chicago Botanic Garden by viburnum leaf beetle larvae.

PHOTO: Viburnum leaf beetle (Pyrrhalta viburni) larva.

Viburnum leaf beetle (Pyrrhalta viburni) larva

PHOTO: Viburnum leaf beetle (Pyrrhalta viburni)

Viburnum leaf beetle (Pyrrhalta viburni) by Siga (Own work) [GFDL or CC BY-SA 3.0], via Wikimedia Commons

The VLB larva and adult both feed on foliage and can cause defoliation, and several years of defoliation can kill a viburnum. If you live in the area, I strongly suggest you begin monitoring your viburnums for this critter. There are many great university-created fact sheets for VLB that can be found online, or contact the Garden’s Plant Information Service for additional information. Please report new finds to the Illinois Natural History Survey, Illinois Department of Agriculture, or University of Illinois Extension Service.   

PHOTO: Plugged cavities on a viburnum twig containing egg masses of the viburnum leaf beetle (Pyrrhalta viburni).

Plugged cavities on a viburnum twig containing egg masses of the viburnum leaf beetle (Pyrrhalta viburni). Photograph by Paul Weston, Cornell University, Bugwood.org

Many people ask us: is it true that some viburnums will not be affected by the viburnum leaf beetle?

Viburnum leaf beetles prefer viburnums with little to no hair on the foliage. Plants grown in the shade also exhibit more feeding damage. The University of Illinois Extension has placed viburnums into four feeding categories: highly susceptible, susceptible, moderately susceptible, and most resistant. Viburnum species such as arrowwood (V. dentatum), European and American cranberrybush viburnum (V. opulus, formerly V. trilobum), wayfaringtree viburnum (V. lantana), and Sargent viburnum (V. sargentii) are in the highly susceptible and susceptible categories and can easily be destroyed by repeated infestations of the viburnum leaf beetle. Moderately susceptible species such as burkwood viburnum (V. burkwoodii), blackhaw viburnum (V. prunifolium), and nannyberry viburnum (V. lentago) may exhibit varying amounts of susceptibility, but are usually not killed, depending on the species. Other viburnums, such as Koreanspice viburnum (V. carlesii), Judd viburnum (V. x juddii), and doublefile viburnum (V. plicatum), are resistant to viburnum leaf beetle, will show little or no feeding damage, and are capable of surviving slight infestations. Please contact Plant Information Service at (847) 835-0972 or plantinfo@chicagobotanic.org for susceptibility questions on specific species.

The Garden is a member of the Sentinel Plant Network, a group that unites botanic gardens in monitoring and providing education on exotic plant pests and pathogens, and works in partnership with the National Plant Diagnostic Network (NPDN).

If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic invasive plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!

©2015 Chicago Botanic Garden and my.chicagobotanic.org

Tom Tiddens

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Tom Tiddens is plant health care supervisor at the Chicago Botanic Garden. The Plant Health Care (PHC) Department monitors the Garden for insects and diseases on a weekly basis, as well as other plant health concerns, to discover, evaluate, and treat pest concerns in their early stages.

10 responses to Pest Alert: Viburnum Leaf Beetle

  1. Thanks for the information on the VLB. I have several beautiful viburnums in my yard and would hate to lose them. Of course they are arrowwoods – the species most affected.

  2. Russ Carpentet June 5, 2015 at 12:59 pm

    What can one do to get rid of them?

    • Great question Russ, below you will see some management options:

      Monitoring
      • Inspect viburnums in the winter for visual signs of egg laying.  Look for off-color bumps on smaller twigs all in a straight line.
      • Inspect viburnums for larva just after leaf-out.  Look for very small larva on the underside of leaves.
      • Inspect throughout the season for signs of feeding damage and defoliation.

      Natural control / non spray options
      • Plant resistant viburnum types.
      • Tolerance – Low levels of VLB are not very damaging.  Remember that high levels, along with defoliation, can kill a viburnum if it happens year after year.
      • Prune out branches in the winter that are found with egg laying evidence.
      • Encourage or release natural enemies, such as ladybugs and lacewings that will feed on the young larva.
      • Pick them off by hand.  Only practical if you have a small number of shrubs.
      • Knock off adult beetles into a container of soapy water.  When a branch is disturbed the beetles react by falling off, so hold a bucket of soapy water under the branch and then gently shake it.

      Applied control (Organic options)
      • Spray the young larva very early on with an insecticidal soap (follow label directions carefully).  Don’t expect 100% control with a soap spray.
      • Spray the young larva very early on with a pyrethrin (follow label directions carefully).
      • Spray the young larva with a microbial product called Spinosad (follow labeled direction)

      Applied control
      • Spray a synthetic insecticide when larva is beginning to feed and cause damage (follow label directions carefully).  Insecticide spray treatments for adults are not recommended for management.
      • Avoid using systemic neonicotinoid product as they may affect the pollinators, such as bees.

  3. So what are we supposed to do??!!!

  4. Roberta Morris June 19, 2015 at 11:36 am

    Tom, don’t think this is new this year. I am in northeast Deerfield and began to see defoliation and damage to my viburnums last fall! Couldn’t find any answers to what was attacking them until I read the Trib article. This could be massive….

  5. Roberta Morris June 19, 2015 at 11:38 am

    Any idea what’s attacking knock-out roses? First holes, then severe leaf browning. HELP!

  6. I read this article at the right time. I wanted to plant Viburnum shrubs in my garden and was researching about it. I am glad that I came across this article. And is it true that they can grow in any soil type?

  7. I live in LaGrange, IL and have 7 Blue Muffin Vibernums that were planted 3 years ago as a hedge in the back of my yard. They are mostly in the shade. Last summer I noticed most of the leaves on all the shrubs had many holes in them – and I then read about this nasty beetle. Recently I removed many twigs that had egg infestation on them. There are so many, I am sure I have missed some. ALOT of eggs on the twigs. They were mostly on the new growth. I will be watching this spring as leaves emerge with insecticide soap as recommended. Not good! I had thought Vibernums were the tuffest shrub on the block…

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