What’s Eating My Viburnum Bush?
Years ago I had beautiful large snowballs size flowers on my plant. I brought them in the house and put them in a vase. A few weeks later, I looked at my bush, and it seemed kind of bare. I let it go and didn’t think much about it. A few weeks later, I walked outside and half of my shrub from the bottom was completely defoliated! I was in shock! Upon closer inspection, I found that there were tiny little larva all over the bush! I found out that the Viburnum Leaf Beetle is all over! It is throughout Canada, and in the US from the East Coast to the Midwest from Pennsylvania and Ohio to Iowa and of course here in Illinois. You might see the same damage and wonder “What’s Eating My Viburnum Bush?” If the leaves are lacy looking and skeleton, chances are it’s the Viburnum Leaf Beetle, which is a super destructive bug! A few weeks later, after trying all kinds of things, including terrible pesticides and insecticides, my Viburnum bush was almost completely empty of leaves ! I really thought it was a goner. I started researching options, and I wanted to go with the least harmful to myself and the environment. I found a physical barrier, non-pesticide solution that has been working for me and I wanted to share with you. My method is a little more labor intensive and takes a growing season to two and upkeep, but it saved both of my big, beautiful Snowball Viburnum bushes.
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What is the Viburnum Leaf Beetle?
The Viburnum Leaf beetles is an annoying insect that loves to eat Viburnums. it lays it’s eggs on the very end twigs of your viburnum bush. The eggs overwinter, and then hatch in the early spring. The larvae crawl out to the end of the branches, and quickly start eating and defoliating the leaves. This may start to be noticed in Early May with small holes as It’s easy to overlook them at first. Once they have eaten, they will crawl down the branch into the ground where they will borough and then emerge as full adult beetles to start the cycle over again and continue the damage to your beautiful shrub. You can read more technical information about them here from the University of Wisconsin-Madison Horticulture Extension.
What do the eggs look like and how do they hatch?
The viburnum beetles egg sack looks like small, flat, oval raised parts of a branch on the very ends of the littlest branches. Those are the preferred egg laying sites. They are normally cluster together at about 5-8 at a time. Once all of the leaves have fallen in the fall, start manual control they going out and clipping all of those small and branches off and destroying them. Do not compost them! They need to be destroyed. Once the eggs hatch in early May to early June, the larvae crawl to the leaves, and start eating away. After they finish eating, they will crawl down the entire length of the branches to the trunk to the ground, and bury themselves in their world. Then they will emerge as full adult beetles around late June and keep on eating and laying and creating the lace -like leaves. The female Viburnum Leaf beetles will lay their eggs in July and start the cycle over again.
There are some Viburnums that are resistant the Viburnum Leaf beetle?
According to the Chicago Botanical Garden, The KoreanSpice Viburnum, Judd Viburnum and Double Fire Viburnum are more resistant to infestations of this awful pest. Of course they don’t have those gorgeous snowball like blooms either, though the Korean Spice Viburnum smells amazing (almost like lilacs to me!).
What kind of damage does the Viburnum Leaf Beetle cause?
The Viburnum Leaf beetle has a voracious appetite for the leaves and foliage. A large infestation of the beetle can easily skeletonize an entire large viburnum shrub in less than a few weeks. At first, with a small or new infestation you might only notice a few “chewed on” leaves that don’t seem that serious.
It rapidly becomes apparent that the shrub is in bad shape. The leaves have a “lacey” look to them and look brown and burned. The shrub may try to put out new growth in an effort to keep on going. Many of those leaves are also quickly eaten. It’s almost a helpless feeling and can kill your shrub by early July.
Can I control the Viburnum Leaf Beetle naturally without pesticide control?
For chemical control options, see the Cornell University Website
Yes, but It depends on when you discover them. You can treat the soil with chemicals and pesticides if you want to take that route. I discovered mine after the beetles were already doing damage, so I was only able to kill the them as they went along with an insecticidal soap by spraying daily. I also manually would drop them into soapy water. It was really hard and kind of like playing catch-up. I didn’t want to have to remove my gorgeous shrubs. Once I studied their pattern of how they lay eggs, hatch and complete their life cycle, I realized I would be able to use a physical control to help control the population the next calender year. I used an old-fashion product called Tanglefoot, and applied it on every trunk about 5 inches from the ground. This would ensure that a large portion of larvae never makes it to the ground to start the cycle over. The first year I did a ahard prune on my viburnums to make sure a large portion of egg-laying sites were removed. Then every spring, I carefully check the leaves every few days. If I see any looking a bit chewed on, I check the underside and look for the larvae and remove the entire branch. This is the third year and I only had 2 small branches near the bottom I needed to remove, the rest of my viburnum was clear. Every October, I carefully go over my Snowball Viburnum shrubs and remove and dispose of any questionable end branches with egg looking deposits. Insecticidal soap and horticultural oil can also be helpful to control the population as well while dealing with an infestation.
What is Tanglefoot?
The thought of using Tanglefoot was something that I got recalled my memory. My grandmother was a huge gardener and use this on a regular basis to control pests on her trees and shrubs. She would apply it to the trunks of her trees. I had a thought it might work because of the way the viburnum beetle larvae work. Upon looking into it more, I like the fact that it was non-toxic to humans and pets, and basically good for the environment. I did use it a little bit differently than recommended. They recommend to apply wrap to your tree first and then apply the product to the paper wrap. I applied mine directly to the branch so that there would be no gaps as to where the larvae could get through. It does leave a little bit of a stain appearance on the bottom of the branches, but it’s so close to the ground, and once the bus completely fills out, you don’t even notice a difference. To me, it was a small sacrifice to make for saving my viburnum bushes. Tanglefoot does say applying it directly to your tree/bush could harm it and recommend a paper wrap, so I would recommend you should follow their directions exactly as on the label on the container and not do as I am doing. It did read one place to use painter’s tape to wrap tree first and then apply it for a closer adhesion, so that’s an option too. You could remove it when the beetles yearly life cycle is over.
Tanglefoot for Viburnum Beetle control
You do want to apply Tanglefoot in very thin, coat because you want something larger like a bird, or a small wildlife to be able to free itself. That’s why I apply it close to the bottom of the trunks, where any birds would less likely to be to get it on their foot or feathers. You don’t need much to catch the larvae since they are so small.
Within 4 years of heavy pruning the end branches each fall, applying Tanglefoot in the spring before my Viburnum’s leafed out, and removing any suspect branches, this year one had no sign of damage at all and on the worst one I had two small branches that had active beetles on I removed and destroyed. My Viburnums are well over 10 feet tall, so it was definitely worth the effort to take the steps to save them instead of just ripping them out.
I know this is something that I’m going to have to constantly keep an on as long as I have viburnums, at least I know now I have a way I can control them and hopefully enjoy my Snowball Viburnum bushes from your year. For more information on growing Viburnum Bushes, check out this post. If you enjoy this gardening post, you might also like reading more about how to grow lavender in your yard, or planting an Oak Leaf Hydrangea.
