the plague of japanese beetles

japanese beetle.  image courtesy of University of Minnesota Extension Service

 I was weeding the garden tonight, cutting down the fava beans which have wilted in the heat.  Favas like cool weather, and thrive in the spring, then tend to get a black fungal disease as the Minnesota summer turns humid and hot.  So I cut them down about this time of year.  The storm last week knocked most of them down anyway, so I was just finishing what Mother Nature started.



So I was weeding and cutting, and Gita was sifting through the favas and peas to find all the pods I had missed (She's very good at that by the way.  I don't know if it's cause I miss so many or if she just has really good eyes).  The kids were playing on the swingset and yelling for me to look at them every 30 seconds or so.

About that time, Joan, another gardener at our community garden rushed into our yard breathlessly to tell me about the japanese beetles.  "There's hundreds of them in the bag and they're getting out and they're all over the beans- and they're so gross- and.. and.."  she said.

I had just picked a few off of my new apricot and plum trees.  It wasn't too surprising because this is prime weather for japanese beetles, and pretty much the peak time for the adult stage.

Joan was pretty worried, and pretty grossed out, so we talked for a while and I promised that I'd go down and take a look after the kids were in bed.

So I headed down about 9:30 or so with my flashlight, a 5-gallon bucket and a couple of bottles of soap to see how bad it was.

Another gardener, Pat, who has planted 20 or so fruit trees at the community garden had put a pheromone trap in one of his fruit trees to catch the beetles, and there must have been thousands of them in there.  A mass about the size of a hot water bottle, of wiggling little japanese beetles.

Abdel, another gardener was out there and we talked a bit, and went to look at his beans, which were being eaten by the beetles.  They weren't so bad, but the plot next to mine, where the woman with the plot planted mostly soybeans, was teeming with them.  I reached over the fence to squash about a dozen of them by hand, but I could have stayed a lot longer.  I didn't see any on my plot, so I said goodbye to Abdel and went home.

Japanese beetles are still relatively new to Minnesota, and aren't yet found in all parts of the state.  They were brought here from Japan in horticultural materials in 1916 and have worked their way steadily west since then, with the help of trains and cars and airplanes.

Now that they're here, they'll probably outlast the era of train and car and airplane travel.  They're persistent little buggers, and like the warming climate of the state a lot.  This last hot, humid week was perfect for them.  Now the question is what to do.

I'll probably start by handpicking the cherry, plum and apricot trees.  Supposedly if you shake the trees in the morning when it's still chilly out, they fall easily and you can squash them.  If we had chickens, they'd be great chicken feed, but we're not there yet.  I may treat the turfgrass with milky spore disease to bring their numbers down over the long term.

I suppose, for the most part, I'll have to learn to live with them.  I could spray pesticides, but the long-term degradation of my little piece of land isn't worth it.  I'd rather live with a few beetles than poison my family and property.   See this U of MN Extension Bulletin if you are having issues with Japanese beetles.  A lot of their advice is chemical, but they give some good non-toxic tips as well.  Take them for what they are worth.

The good news is that this is the worst it will be.  The adults are laying their eggs and soon will be dying off.  Then the grubs are born in August and they feed on nothing but turfgrass until next June.  I suppose if I cared about turfgrass that would bother me, but I really don't.  I'll squash a few and say sayonara until June 2012.