Save the bees, not the beetles!

July 3, 2008 12:16 PM

How do I rid my roses of Japanese Beetles without killing the bees?

My dwarf roses are crawling with japanese beetles. Seriously - on some flowers there are 3 or 4 beetles clustered on top of each other. When I shake the bush, it explodes into flight like a 3-day-old fly-covered corpse.

I don't use chemicals in the garden. My neighbor has suggested a very low-strength combination of water and dishwashing liquid with a wee bit of baking soda. But I'm worried about the bees, which are also feeding (where they can get some space!). I don't want to kill them off as well. Is there anything I can do to get rid of the beetles without killing the bees as well?

posted by media_itoku to home & garden (8 comments total)

My friend who is both a gardener and an entomologist picks japanese beetles off the plant manually. She drops them into a can filled with soapy water. Presumably they die in the soap water, but I never really asked her about that part!
posted by subatomiczoo at 12:38 PM on July 3

Manually picking bugs into water (short term) and milky spore (long term).
posted by pullayup at 12:41 PM on July 3

Yeah, soapy water, per subatomico, sorry!
posted by pullayup at 12:43 PM on July 3

Yeah, it's all about the manual picking off the buggers.
posted by Stewriffic at 12:44 PM on July 3

This has a pretty good rundown of your options.

If you decide to use the standard japanese beetle trap, make sure you put it away from the plants you'd like to protect, since not only does it attract the beetles you have, it attracts new beetles as well. These traps don't use pesticides, they just imitate the beetle's pheromones and lure it into the bag where they get stuck.
posted by electroboy at 12:45 PM on July 3

Japanese beetles don't like garlic, and it is also a good companion plant for roses. Garlic is easy to grow, so it can't hurt to try.
posted by idiotfactory at 3:55 PM on July 3

Don't use the japanese beetle traps; they attract beetles from all over. The year I used them was a terrible disaster and nearly killed my roses even though I was out there hand-picking several times a day (hence my blog rant). Plus, the bugs fall in and rot and then those things REEK of death.

It's a bit late now, but I think in the fall you can apply some beneficial nematodes, followed by milky spore, in the Fall. That will kill the lawn grubs, which are the Japanese Beetle's larvae stage.

Go get 'em!
posted by GardenGal at 7:16 PM on July 3

A bit late to this thread! I was just reading up on these bastards after finding a few chewing on my basil.

I'm not 100% sure if the information is accurate (especially the last item) but here's a few things that turned up in my searching:

Manually picking them off is supposedly easier early in the morning. Spread a sheet or something under the plant and shake it. If done early in the morning when it's cooler and dew-y, the beetles will fall rather than fly off.

The remains of dead beetles is claimed to act as a repellent. No idea if drowning in soapy water alters the repellent nature of the bug corpses. I'd prefer to crush them; it's cathartic.

From here, among other things:

Use interplantings of four o'clocks (Mirabilis), larkspur, white geraniums, red (and dwarf) buckeyes whose flowers attract and poison the beetles. The leaves of the castor bean plant also poison them. These plants are poisonous to people to so be careful using them around children or pets!

posted by CKmtl at 7:45 PM on July 29