It s metallic black and copper colored, fast, and will grab your attention as it flies by. No it s not the latest German sports car, but the Japanese beetle. Japanese beetles are the nemesis of many gardeners trying to grow roses, grapes, beans, hollyhocks, evening primrose . Well, you get the idea. They re not fussy eaters. First introduced by accident into the U.S in New Jersey in 1916, their range extends west to the Mississippi River.
But fear not, there are ways to limit the damage from these pesky beetles and still enjoy your gardens. Here’s a Japanese beetle tutorial.
The Japanese beetle overwinters in the soil as a whitish-gray, c-shaped grub. It slowly migrates to the soil surface in spring. The adult beetle emerges in late June and early July in our area. After emerging, Japanese beetles have only two things in mind: eating and mating.
Beetles congregate on leaves and flowers to feed and mate. They’re attracted to each other by pheromones (chemicals emitted to attract a mate). After, mating females drop to the ground to lay eggs in the soil, often in the lawn, and start a whole new generation for next year. You can use their penchant for food and sex to aid in their downfall.
First reduce the number of grubs in the soil. These grubs are one reason skunks will visit your lawn tearing it up looking for a tasty treat. The best organic control of Japanese beetle grubs in the North is beneficial nematodes. These microscopic worm-like critters are sprayed on lawns in June. They migrate into the soil with watering and parasitize the grubs. They can greatly reduce the grub population and therefore the number of adult beetles emerging a little later.
Control adult beetles in the morning. Maybe it s because of their carousing and feasting the previous day, but adults tend to be sluggish before noon. Simply place a bucket of soapy water under the plant and shake the branches. The natural defense for sluggish beetles is to roll over and drop to the ground. With bucket in hand you can catch many of these beetles and let them drown.
There are organic sprays available as well. Neem oil is touted to repel Japanese beetles and disrupt their feeding and mating. It works best reapplied after rains.
Japanese beetle traps are also popular. They have sex pheromones that attract beetles looking for a mate. Once they hit the plastic shield containing the bait they fall into the bag and are trapped. However, if you re the only one in the neighborhood trapping, you ll be luring all your neighbor s beetles to your yard. Many will avoid the trap and find your plants, so it’s best to use traps en masse with neighbors.
Patience and diligence are needed to control Japanese beetles. It takes a number of years for them to build up in your yard and it ll take a few years to get them under control.
This is Charlie Nardozzi from Hinesburg.
Charlie Nardozzi is an all-around gardening expert with a special fondness for tomatoes and roses.