Viburnum Leaf Beetle Alert!

The Chicago Botanic Garden’s email newsletter is typically informative and sometimes entertaining, but today’s issue bore grim tidings. That is to say, the Viburnum Leaf Beetle (VLB) has now established itself in the Chicago area.

Viburnum Leaf Beetle. Photo from ohioline.osu.edu.
Viburnum Leaf Beetle. Photo from ohioline.osu.edu.

The VLB is originally from Europe but decided to summer in  Maine in 1994. Taking up residence, it has been marching westward ever since. It was first spotted in this area in 2009, and sightings have gradually become more numerous. In 2014 there were frequent sightings in a suburb not far from where I live.

Cranberrybush Viburnum, Viburnum trilobum
Cranberrybush Viburnum flowers

There are a quite a few Viburnums in my own garden, so this is worrying news. To make matters worse, a Cornell University entomologist has sorted Virburnum species according to their resistance to VLB. And guess what? Most of mine are Cranberrybush Viburnum (Viburnum opulus var. americana), which are in the “Highly Susceptible” category.

Cranberrybush Viburnum
Cranberrybush Viburnum with early fall color.

There are also two Blackhaw Viburnums (Viburnum prunifolium – “Moderately Susceptible”) and one Korean Spice Viburnum (Viburnum carlesii), which I planted just last fall. Fortunately the Korean Spice Viburnum is considered resistant to the VLB. Here’s a link to the whole list.

Cranberrybush Viburnum, Viburnum trilobum
Cranberrybush Viburnum fall color

According to a VLB fact sheet put out by Cornell University, the best way to fight this pest is to inspect newer growth for eggs, which look like this.

Viburnum twigs with VLB eggs. Photo from hort.cornell.edu.
Viburnum twigs with VLB eggs. Photo from hort.cornell.edu.

This is easiest to do before the plants leaf out. Any twigs infested with eggs should be pruned out.

VLB can completely defoliate a shrub, and after this happens for several years in a row the plant will probably die.

American Cranberrybush Viburnum fruit
American Cranberrybush Viburnum fruit

As soon as the snow melts I will inspect all my Viburnums for VLB eggs. It’s very aggravating because I just planted several Viburnums over the last couple of years. Some were planted to replace Serviceberry (Amelanchier x grandiflora) killed by bark-chewing rabbits.

Excuse me for a moment, will you? (AAAAAARRRRGH! GAAAAAH!) OK, that’s better.

Anyhow, do you have Viburnums in your garden? Do you have experience with Viburnum Leaf Beetle?

60 Comments on “Viburnum Leaf Beetle Alert!

  1. This is a good post and after planting 3 fatherless conundrum in the fall I was relieved to read they are in the resistant category. I am having issues with several of my roses so I understand your frustration.

  2. Apparently, VLB has been found in British Columbia and in at least one county (not mine!) in Washington. I wonder why control includes pruning the twigs that bear eggs instead of manually squashing the eggs? I have a few Viburnums that are currently on the resistant list.

  3. Ah crap….I was going to use some different words! This is beyond discouraging as I have so many in my garden and rely heavily on them for interest and privacy. Thanks for the heads up….you know where I will be tomorrow…checking all 7 of them! Nicole

  4. Thankfully this pest isn’t recorded in Australia, as I have quite a number of the susceptible viburnums in my garden. Good luck with destroying any eggs you see!

  5. I had never heard of this European pest before, but apparently it is bad in the UK. I had problems with vine weevils in my last garden and they sound similar except the larva overwinter in the ground. I was able to use nematodes to kill the larva and it worked, but I had to do it every year as they had free run in my neighbour’s garden! Maybe worth looking out for natural pest sprays or nematodes to water into the ground if you get an attack. Good luck!

  6. I think I’ve seen this in my garden and yes! I do have Viburnums. Is it my imagination or are there a lot more pests that are causing more problems than in the past. I’d hate to think it was because more gardeners garden organically or I suspect that it is rather due to those who use a lot of chemicals and destroy the balance to Good insects.

    • There are definitely more pests but I don’t think it is because of people gardening organically. It’s just that this is a smaller world, goods and people are travelling more than ever and pests are frequently hitching a ride.

  7. I had to remove 3 Viburnham opulus from my garden as I could not get on top of the VB. Despite pruning the defoliated leaves were a miserable sight. I also removed a V.tinus for the same reason. However, my neighbour used a ladybird nematode and had very good results. Its the larvae that seem to do the most damage and the adults finish it off. To deal with this organically I would research Ladybird nematode options.

  8. I have never even heard of the Viburnum Leaf Beetle. I have several viburnums in my garden. I have the High bush cranberry viburnum. UGH.. I will be inspecting for those eggs first chance. Thanks for the information.

  9. Yes, I have viburnums, some of the same species as you. 😦 Thanks for the heads-up and the photo. I will inspect mine for eggs as part of my March cleanup.

  10. We (MGs) get the nasty bug alerts from Cornell and were informed about this a number of years ago. Do you know it was first reported back in 1947 in the Niagara region (Ontario) in the park (right across from me) on native Arrowwood? Yes it did defoliate the shrubs. It moved across the border to our parks after that sometime in great numbers about six years ago. Here is one of the Cornell reports because it differs from where you reported the Leaf Beetle’s beginnings. http://idl.entomology.cornell.edu/files/2013/11/Viburnum-Leaf-Beetle-12g0ctu.pdf

    So it has reached Chicago now, that I did not know? It is more common in Canada and I know has reached large parts of NY, PA, ME, VT and OH. It has not been killing the plants outright to my knowledge, but with repeated attacks would stress it to that point is my guess. I don’t think it should worry you because it has been here a long time and my friend and associate, the grower and nurseryman (20 miles from me) grows all the susceptible Viburnum in great numbers and has not had the issue. My Viburnum (V. plicatum var. tomentosum) is less susceptible and never was affected. Hope your property is not one of the unlucky sites for Viburnum Leaf Beetle.

  11. Try Viburnum ‘Summer Snowflake’ – it’s spectacular, most of the summer,
    and appears to be resistant.

  12. Good grief! It seems like there’s always some new pest that threatens some of our favorite plants. We have been trying to choose a new tree to replace two horse chestnuts in the nursing home garden where I volunteer and really liked the Chinese fringetree. Then we saw the report that the Emerald Ash Borers had been found on these as well as ashes–aarrgh! Thanks for the warning, Jason; I have only one viburnum right now, but I will be sure to inspect it carefully before it leafs out.

    • Tell me about it! I planted two American fringe trees just a couple of years ago and right afterwards they announced that EAB likes fringe trees. You’re right about new pests popping up on a regular basis.

  13. The planet has shrunk now and we alll share our plants. Unfortunately we share our pests too. Every year there is a new horror attacking our shrubs and trees. I suppose it is the fault of greedy gardeners; we want plants from all the corners of the world and inevitably we get the pests and pathogens too. The Viburnum beetle is in the UK, so far he has kept away from my garden but I suppose it is only a matter of time.

    • Shipping plants around probably contributes to the problem but pests will hitchhike on all kinds of materials. The Emerald Ash Borer came here from China in shipments of lumber.

  14. My fingers are crossed for your plants’ continued health. I have a viburnum hedge that I use as walls for my secret garden. =/ The hedge is evergreen and huge so inspection isn’t going to be an easy (read possible) thing. This latest invasion highlights to me one of the problems with importing ornamental plants and calling them ‘pest-free.’ Eventually the insects that normally accompany them come over, too. But rather than merely limiting the ornamentals they co-evolved with they can viciously attack native plants that may have zero strategies to protect themselves. And pests that overwinter under bark are a PITA. ugh

  15. Oh no! One more blight to worry about. I, too, have several Viburnums. Always thought of them as pretty foolproof plants. Thanks for the heads-up.

  16. Dang! If it’s not one pest, it’s another! I have no viburnums at Longview Ranch, and this post makes me sure I won’t be adding any. In Portland, we are and have been dealing with the miserable Azalea Lace Bug, which is decimating azaleas and some rhododendrons all over the place – fast. And there’s no real “cure”. Good luck keeping your viburnums healthy!

  17. Well, I was going to curse something much worse, but I guess ARGH will have to do. (#$^*O!!Y*^R&%R&%FT!) I, too, have several Cranberrybush Viburnums. I suppose it won’t be long before it gets to Wisconsin (if it isn’t there already). Ugh. Dang. I love Cranberrybush Viburnums. Drat.

  18. Thank you for the warning. That is bad news indeed. No doubt they will soon get here if they are not already.

  19. I am not sure how prevalent they are here in Scotland but I’ll be on my guard now. I have 3 viburnum and none from the highly susceptible list. Guess what I’ll be doing at some point over the weekend.
    I hope you are able to at least get a bit of control over it if you find it in your garden Jason.

  20. We have it here and last year there seemed to be thousands of them……fortunately they haven’t done too much damage to date, I shall inspect the branches now though. Gosh, poor you still having snow! xxx

  21. Thanks for the info. Definitely not good news. I have quite a few viburnums, but luckily mostly on the safer end of the scale. Haven’t heard anything about it from the Morton Arboretum, so maybe it’s currently up to the north by you. Nope, it’s been found here in DuPage county as well. It’s definitely a pest to be at watched for and reported.

  22. I am not familiar with this beetle. I hope it doesn’t make it’s way southward. We have plenty of other introduced problem insects to deal with. We have lots of viburnum in our garden. One of my favorite shrubs.

  23. Jason, thank you for such useful information. I had this VLB last summer and my Cranberrybush Viburnum was awful! More problem I had when these beetles moved from viburnum to blackcurrant bush. I could lose the harvest of these bushes. So I used chemical methods against VLB.

  24. I noticed a mild infestation of little round black squishy things on the underside of the leaves of a potted Japanese snowbell (styrax japonicus) bought one year ago that was awaiting planting. I picked off about 100 of them last Tuesday, and 30 more Wednesday, as well as scraping off the increasing rows of bumps on branches and the stalk/trunk. After the cleanup, except for a few dead branches, the tree appeared in good shape. I finally looked up the pest and identified viburnum leaf beetle. Unfortunately, I had been flicking these round things in the general direction of 3 old viburnums (70+ years) assuming they would dry up when they hit the hot ground. There were a few other young potted trees sitting on the same stump (stewartia, current) that were completely unaffected, so I didn’t think twice. After mulling it over, I cut up the 8 ft. tree, bagged it up, and put it in the trash – pot, soil, and all. Not sure what will happen to the large viburnums now (10 – 20ft), or whether adult beetles are present in my garden. All this to say that we have this beetle in BC, and it definitely impacts styrax japonicus.

    Interestingly, a large snowbell I have on the east coast appears to have died back this year. I consulted Behnke’s Nursery about the tree, specifically to ask about cicada Brood 2 that was supposed to hatch in the summer of 2013 and might have caused the damage, but was told that though the insects were expected, they didn’t reach our area, and that my showstopper snowbell had been damaged when the temperature plummeted to 4 degrees in February. The nurseryman recommended removing all the dead branches and said that, barring a cold spell next winter, the tree would recover. Dumbarton Oaks garden has a lot of large Japanese snowbells. I would be curious to know if they were damaged as well.

    • Still no sign of the beetles on my Viburnums, knock on wood. Though something is eating holes in the cranberrybush viburnum leaves.

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