Well I've never seen this beetle before either and, of course, I was immediately concerned about our grapevines. Ugh, it seems there is a specific pest for everything!
So, I set off to do some research and find out exactly what to expect with this new (potential) pest. I did a LOT of reading about it, and here's what I learned...
First off, these beetles are hard to miss; they are HUGE. They're two-three times the size of a Junebug, YUCK!
Apparently they're not normally found in this part of the country. We had a very mild winter this year, so I wonder if that's why they are here this summer. Either that, or they are migrating. Great!
They are related to the Junebug, and are sometimes called a spotted June beetle. Like a Junebug, the grapevine beetle is nocturnal and is attracted to bright light. Their lifecycle is similar to the Junebug as well; they overwinter as larvae in the ground, and they emerge as beetles in June/July.
|Grapes on the vine|
I read that they can feed on other types of fruits too (like apples and raspberries...etc), although I didn't find much information about this.
The damage they cause is similar to the Japanese beetle; they skeletonize the leaves.
The recommended control for the adult grapevine beetle is hand picking the pest from the plant.
The larvae feed on rotting organic material, so they are said to be beneficial. Grapevine beetle larvae do not feed on grapevines. Learning this was a huge relief, my biggest fear was they would be a vine borer.
Even though the adult feeds on grapevines and other stuff, everything I've read about this beetle says that they don't cause major damage. They aren't considered major pests in vineyards, at least not that I could find. A large infestation of these beetles could cause damage, but it's pretty uncommon; one or two beetles in the neighborhood doesn't seem to be a concern. Whew, I feel much better.
Of course, now that I know they are here, I will continue to keep an eye on our grapevines and other plants they may harm. We will also continue to cover our grapevines to protect them from this and other pests. But, right now the Japanese beetle is my nemesis and the grapevine beetle seems like a minor threat. (Wouldn't it be great if the grapevine beetles ate Japanese beetles?)
Since learning about the grapevine beetle, I have seen a few of them flying around. They look like they're drunk when they fly, but they move pretty fast. The other day, one flew right into the side of the garage and almost fell on me. (GASP!) Their size and clumsy way of travel makes them easy to spot when they're buzzing around.
Since making the discovery, my neighbor reported spotting the bug to Dave's Garden, and Minnesota has been added to the regional list. Now I see Minnesota also shows in the list on Wikipedia. Wow, word travels fast!
After doing all this research, I feel like I can breath a sigh of relief. Since we cover our grapevines, I don't think I have to worry.
Have you ever seen this beetle? Has it caused any damage in your garden?
Photo Credits: The pictures of the grapevine beetles in this post were taken by my neighbor, and used with her permission. Forgive the blurry photos, these bugs react to the light from a camera flash.