I'm beginning to see adult Japanese beetles on my dahlias and other flowers. It doesn't look like a heavy infestation but I am wondering what are some non-chemical control methods. I've read that nematodes are one option. Are they effective? Are there others?

1 Answer 1


Milky Spore is another option. Apparently, it is very effective for some, not at all for others. I hear it is most effective if you can convince your neighbors to use it, as well, so a larger area is infected with the disease (which kills the grubs).

I put it down in my yard two years ago, as did a few of my neighbors, and I have noticed less beetles since, HOWEVER I put it down at the end of a boom season for the beetles (they almost completely defoliated all of the linden trees in the town I live in and the neighboring town, too), and I notice less damage all around. We had a record-breaking drought last year, too, which I'm sure killed a lot of the grubs. When I dig in my yard, I'm not finding many grubs at all, and have found none that appear to be infected, so I have no evidence that the milky spore is doing anything. I think we may be at in a "bust cycle" following the boom. I'll be interested to see how many beetles we have in a few years.

For smaller numbers of beetles, I hand pick into a bucket of soapy water. That seems to reduce the amount of damage I see in my yard, but during the boom year it was hopeless.

  • 1
    I'm finding about 20 per evening over the last couple days. I'll try the hand picking for now.
    – dkackman
    Commented Jul 15, 2013 at 22:46
  • Hope they don't get much worse for you this year!
    – michelle
    Commented Jul 16, 2013 at 17:23
  • 1
    Chickens worked for me...
    – Tim
    Commented Jul 17, 2013 at 16:33
  • They have not been terrible this summer, either. My hollyhocks all have lacing on their leaves. My grapes have some, as do my roses, but nothing is looking bad enough that I'm worried it won't make it. My hazels and lindens have no damage at all, which wasn't the case before the bust. I still have not dug up a single grub that appears infected, and I don't see damage in my neighbors' yards either.
    – michelle
    Commented Aug 4, 2014 at 16:38
  • @Tim can you elaborate on the chickens? I have fruit trees so I'm wondering if the chickens would be able to reach them. I had been planning to get chickens anyway but maybe I should get them earlier if they can help with pest control Commented Jun 30, 2018 at 16:03

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