Japanese Beetles that is! You might be familiar with them chewing away at your prize roses, shade-giving birch trees, or maybe even your veggies. Population numbers are expected to be very high this year as the soil moisture has been just right for high rates of larval survival. How very inconvenient.
What's their life cycle like?
Right now, we’re witnessing the adult form of the beetle and its main task is to eat, mate, and lay eggs. What a life...
Do you often see them congregating together, like they've set a 2 o'clock meeting on your raspberries? There's biology behind that. Female beetles release a pheromone to attract the males and beetle-damaged leaves also emit an odor, which causes them to aggregate. Adults can fly many miles to these scents and begin their feast, starting at the sunny tops of plants and working their way down.
At dusk, females fly to turf (that’s right – your lawn or local golf course) to lay eggs. The resulting grubs grow very quickly by feeding on grass roots and once soil temperature decreases to 60 degress Fahrenheit, the grubs move deeper. They typically remain 2-6 inches below the surface and this is where they stay all winter. In spring, once temperatures reach 50 degrees Fahrenheit, grubs feed until June rolls around and they move into the pupa stage. They emerge as an adult in late June and July to repeat the cycle all over again.
So what can you do to help manage this wanton destroyer of all things beautiful?
Let’s look at this from a more natural approach. For the brave, beetles can most easily be plucked (or shaken) from plants in the morning and when overcast since they're a little more groggy at these times. Just drop them into a container of soapy water to kill them quickly. Don't be tempted to squish them-- it will release the females' pheromones and attract every male in the neighborhood to your unsuspecting plants.
Do those Japanese beetle traps really work?
They contain a strong pheromone that lures beetles from a great distance. Think hard before deciding and be aware that you are calling in more than your share of beetles, not all of which will be caught in the trap.
To eliminate the grubs, you can try applying milky spore to your turf. Milky spore is a naturally occurring bacterium that targets and kills only the Japanese beetle. It must be applied when grubs are heavily feeding, which occurs in fall when soil temperatures are between 60-70 degrees Fahrenheit.
Another natural option to control adult populations is spraying your plants (not flowers) with Neem oil. The neem mixture is considered an "antifeed," which means the beetles won't want to eat once they've come in contact with it. Do your garden a favor...run out to our nursery to grab a bottle of Neem oil; our nursery gals are standing by to console any grief-stricken souls who have lost their rose leaves, coneflower petals, or raspberries to these pesky beetles.
What are Japanese beetles eating in your garden and what are you doing to eradicate them?
Or are you just throwing your hands up, grabbing a drink and enjoying the long summer days in your garden?