Japanese Beetles

By: Jennifer LaMontagne-Horticulturist-Bloch’s Farm-Green Lake, WI

It’s the time of year to observe your plants closely for diseases and pests. Have you noticed groups of iridescent green bugs with brownish-gold wings chewing on your plant leaves lately? The culprit could be Japanese Beetles (Popillia japonica). 

These insects have been rapidly increasing in number in Wisconsin ever since their arrival to the United States in 1916. They are about ¼ inch in length, have shiny bronze wings, and a green patch above their head. The adult beetle lifespan lasts about four weeks, from June to August, sometimes lasting into September. Japanese beetles feed on over 275 different species of plants, and can cause varying degrees of damage. They chew on leaves, avoiding the veins, leaving a skeleton-like look on the leaves. They eat the bud and flower parts, as well. Japanese beetles can sometimes transmit diseases into the plant while they are chewing. When they are in the grub stage, they will feed on the roots of the plants, which can be a serious problem in turf grass establishments. 

Luckily, there are a few ways to stop these beetles from attacking your yards. If they are a problem in your turf grass, there are a variety of granular products, such as Milky Spore Powder, that can be spread across the lawn to kill the grubs. It’s best to start implementing treatment against the beetle grub in late June or early July. 

Other options include systemic insecticides for trees and shrubs that kill adult beetles. Deterrents, such as hot pepper wax spray, make the plants taste bad; therefore, repelling them. Japanese Beetle Traps may also be useful. A pheromone attracts the beetles, and then they become trapped inside a bag. The traps should be placed 20 to 50 feet away from the susceptible plants. There are also a number of different sprays that are effective against Japanese beetles; these include Eight and Captain Jack’s Deadbug. Some of these come with a hose end attachment that works great for reaching the tops of large shrubs and trees. We recommend a combination of these products to control the beetles. 

Bloch’s Farm is open 8 am to 5 pm Monday – Saturday, and 10 am to 4 pm Sunday. We have Japanese Beetle traps, spray, and granules available. You can also check out our huge selection of perennials, trees, and shrubs! Stop in today and our knowledgeable staff will be happy to help you! Feel free to call 920-294-6000 or e-mail jlamontagne@blochsfarm.com with any questions. Visit our website online at www.blochsfarm.com and follow us on Facebook and Instagram. Join us for this weekend’s sale: June 23rd – June 25th : 25% Off One Item of Garden Decor!

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