Fall Japanese Beetle 2017 Update - Are They Gone Yet?

September for gardeners can be bitter sweet knowing fall frosts and winter snows are weeks away instead of months. Others are joyful that the monotony of weekly lawn mowing or the constant hand flicking to a drowning end for Japanese beetles is over. I'm somewhere in between both emotions.

I am more than over the unwelcome visit by the hundreds of Japanese beetles that arrived in June and stayed for three months of breakfasts, lunches, dinners and Sunday brunches. They didn't send a thank you for the meals or bother to apologize for their destructive mess. Their numbers seem to be dwindling - many can be found dead on sidewalks or alleys. Bye bye beetles, please don't come back anytime soon, but that is false hope, they know it, we know it.

Their young are now hatched and dining on grass roots as we head in to pumpkin season. Is there anything that can still be done this month or this fall to kill the next generation of beetles? Yes, but you need to act right now.

First, the horticulture and entomology experts recommend treating the lawn for eggs and grubs from June through early August, almost as soon as adult beetles arrive to your garden. The reason - chemical granules generally have a four month control period, so grubs will be killed from egg laying to grub stage during the period adults are flying.

Internet Photo from Bayer Advanced

The list of summer grub control products to use can be found on the highlighted link below. 

However, if you missed that window you can act right now, there are two organic lawn grub controls that can be applied while soils are still warm this fall. These include Milky Spore and Beneficial Nematodes. Milky Spore takes a few years to establish and has found to not be that effective. It is available in a powder formulation or granular (granules are much easier to use). Beneficial nematodes have a much better larvae kill rate than milky spore. Read all application labels for storing, mixing and applying for both products.

Chemical GRUB Controls - applied from June to mid-August

Milky Spore - apply now - a powder that needs to be applied where grubs are active (if you have dead patches in the fall and lots of previous adult beetles, this is a good indicator). It causes a bacterial disease in the grubs, reducing their chances to survive the winter. Keep in mind that control (kill) of grubs is less than 5%, so don't expect great results from Milky Spore.

Beneficial Nematodes - apply now known as predator nematodes that target lawn grubs, they are shipped to your house and must stored properly and applied according to package instructions. Click here for names of beneficial nematode products to try (page 8).  

FAQ on beneficial nematodes  

Mail Order Information on beneficial nematodes (again, call local garden centers to see if they carry).

Now that the metallic orange adult beetles have died off, try to enjoy the rest of the fall season. It goes without saying that our current weather conditions are very challenging to many people in the country. Fires out west are causing so much damage, smoke and concern. My heart is crying for my home state - Montana, where more than a million acres are burning. Texas, Florida have too much rain and the hurricane destruction is beyond imaginable. 

Internet Photo from Montana Public Radio