limit Asiatic garden beetle damage now

Asked July 12, 2020, 2:43 PM EDT

Hi, In the last couple weeks, Asiatic garden beetles have moved into parts of my small garden. They are the copper colored nocturnal beetles slightly smaller than a Japanese beetle. They hide under ground in the day and ravage my plants at night. I first noticed them swarming in the night a few weeks ago. then a couple weeks ago, they stripped my sunchokes down to the stalk/veins. I moved the sunchokes out of the main garden attempting to limit the damage. When i dug up the sunchokes, i found tens of beetles, probabbly 30 or 40 all over the root ball. Since them, they appeared across my yard and totally stripped the leaves from my sage and a hummingbird bush. They are working on a second humming bird bush, some zinnias, and my luffa. i've been picking them off, smashing them, burning them. But there are just too many. Every morning, I find more damage. I know i can break their life cycle this fall/spring by killing their grubs. That's what I plan to do. But, what can I do now to get rid of them and limit the damage this year? I don't want to spray poisonous chemicals.

Washtenaw County Michigan

3 Responses


For a non insecticidal control try the light over a bucket idea here-

Also, for some plants, protecting them with floating row cover, cheese cloth or fine netting( such as tulle sold by the yard at fabric stores for bridal veils) may work if you are careful to gather the covers at the base of the stems.

These methods will be necessary during the adult beetles life span, or at least during their highest population in July and August-

I hope this helps!

Hi Laura, Thanks for the quick response. I went out last night during dinner time and found they everywhere. Every leaf of my butter fly bushes, every leaf of my mint, all of my 48 pepper plants had 2 or 3 beetle each, zinnias were covered.... I put a light over a bucket for a while, but that didn't seem to attract them. Maybe it was too far away or not bright enough. (What do you think?) Upset and desperate, i spent a couple hours burning them one by one with a lighter. Some of them were toast, others raced underground for cover.... Reading this morning, I see there is a Bacillus thuringiensis galleriae (BTG) product that may work on adult beetles if sprayed on the leaves. The beetles ingest this bacteria, and it kills them. Are you familiar with this? Seems beetle specific and "natural" enough. It comes in two varieties. One BTG works on grubs. The other works on adults. I'm having trouble locating the one for adults. I've only seen literature about it but no product for sale. Do you know where to find it?

MSU Extension is not permitted to recommend retailers or brands. Therefore we do not maintain lists of retailers for products. Various species of Bt are used to control different insects. The one you reference is relatively new.

I would leave the bucket with a light on it out all night and see if any dropped in by morning.

Here are some extension links I pulled for you about the BTG organism. This information, as always, is based on the science and research results. Any mention of brands is for example, or is listed as the brand used in research. Extension doesn’t endorse any brands or retailers. If you search each of these documents for “asiatic” it will bring you to the section of he document that addresses the beetle you are trying to control.