I was introduced to Suzanne Wainwright-Evans, an ornamental entomologist, on Joe Lamp’l’s terrific podcast. She helps nurseries and garden centers with their bug problems, so she has to know what works and what doesn’t. 
Her approach to destructive insects:
- Grow pollen-producing plants to attract beneficial insects, the ones that feed on the destructive ones.
- And conserve the beneficials by avoiding pesticides, especially the synthetic ones like Pyrethrin.
What about buying ladybugs or praying mantis?
First, she calls ladybugs "ladybird beetles". Okay. But the take-away message is that the ones we buy often carry disease and parasites, so avoid them. And most will immediately fly away, anyway. So save your money.
And those praying mantis end up eating all sorts of critters we want, like butterflies, beneficial insects, and even hummingbirds!! They’re also not native anywhere in the U.S., and bottom line, are not effective.
What does work?
Nematodes. She says these microscopic worms are very effective at controlling soil-borne pests.
Suzanne, any advice about Japanese beetles?
- First, don’t use traps – they end up just attracting them to your garden.
- Plant resistant varieties of plants
- Use Neem Oil. She sprays it "every few days"
- Apply insecticidal soaps – repeatedly.
Uh, that repeated spraying sure doesn’t sound like sustainable gardening to me. I’m sticking with choosing the right plants.
Read much more of Suzanne’s wisdom at her website: Bug Lady Consulting.
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Interesting information from Suzanne – thank you!
There is a ton of advice out there on Japanese Beetles. In my experience, traps don’t do anything except attract more. AND – the best preventative is hand removing the beetles and dumping them in a bucket filled with a mix of water and green dish soap – Palmolive works the best for me – I have no idea why. I use about a cup and a half of dish soap per bucket of water.
I dump the beetles in live and sometimes squish them before I dump them in – yep, gardening is not for the squimish, so stop your cringing.
After that, leave the dish soap buckets filled with the beetles in the area where they are infesting. I swear that all that death and carnage seems to chase the other beetles away. The trick seems to be in doing this early in the season, usually around Mid-June. I have very little problem the rest of the season.
I also took out all my hot pink colored roses. These were the prime attractants in my garden and without the roses, I don’t have too much of a problem with the beetles.
Good luck and thanks for the on-going awesome information!
Take care, Shawna Coronado
Oh, that previous comment was meant for here but I also noted that she stated that neem oil can help with Japanese beetles in that it repels them from feeding on plants.
Suzanne,
Just found your blog I’ll be adding it to my feed. This is good reading as I’m a bug guy too! BTW our Carolina Mantis is native. I found a hummingbird dying that a Chinese Mantis caught, it was one of my most visited photos at http://www.rlephoto.com
When I used to have fish in the pond, a drought killed them when it dried up. I used to toss the Japanese Beetles in the pond and they were quickly eaten.
Looking forward to more articles here.
I plan on using ladybugs in my Fort Bragg garden this year. Lots of good info in your post. I look forward to seeing how the “ladies” do their job in the country. Thanks for a fabulous post. BTW I’ve had many ladybug visitors on my 12th flr terrace here in SF and believe it or not I think they ate all the mites off of my ivy. Simply amazing. I’ve done a couple of good bug posts but none as informative as yours. I will definitely link to your post. KUDOS
iona
OMG – I have never heard of a praying mantis killing and eating a hummingbird! How does that happen? If they are not native to this country, where in God’s name did they come from? The Japanese people cherish the praying mantis – Japanese beetles – hmmmm….. Will check your blog for further information.
Thank you for your time and information. You are appreciated. I learned some things I didn’t know. Yeah! I am still not too old to learn!
FM2YO,
I hope my answer to your question won’t be to frightening. The mantis perches on a flower then grabs the hummers and in the case that I saw it rips open the throat and holds it until it dies. I was going to rescue the poor bird but once I saw this I know there was nothing to do, you could have placed a finger in the opening the mantis made.
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