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Posts Tagged ‘controlling japanese beetles’

Japanese beetle on a morning glory leaf

Ewwwww! What was that that hit me in the head? Unfortunately, I knew what it was before I reached up to get it out of my hair – a Japanese beetle!

We have been lucky for the past two or three years – the Japanese beetles haven’t been bad at all. This year, they may be back in greater quantities.

They must be starting to emerge now because, just yesterday, I had three separate encounters with these nasty beetles.

A Japanese beetle chews holes in our morning glory leaves.

A Japanese beetle chews holes
in our morning glory leaves.

  1. In the morning I was enjoying coffee on our deck when I noticed a Japanese beetle on a leaf of our heavenly blue morning glories. Upon further inspection, I saw that there were holes in many of the leaves and a few big ones right next to this guy. Ugh! They’ve been feasting on the flowers!
  2. When I got to work, I had an e-mail waiting for me from someone whose 5-year old blueberry bushes were being attacked by Japanese beetles. They were wondering how to get rid of them because they were “beginning to do quite a bit of damage” to the plants.
  3. Then early in the afternoon, I was talking with a customer in the garden center and a Japanese beetle flew into my head and got stuck in my hair! Yuck!

They’re here!

Adult Japanese beetle

Adult Japanese beetle

Japanese beetles are native to Japan – as their name implies. They were brought over to the U.S. accidentally (as is the case for many of our alien pests) in the early 1900’s and are now a major pest throughout most of the eastern United States and beyond. They are about a half inch long with iridescent copper wing covers and a shiny green thorax and head. Their legs have rough spines that get caught in everything – including your hair! Nasty!

Japanese beetles feed on leaf tissue eventually leaving just the veins.

Japanese beetles feed on leaf tissue eventually leaving just the veins.

 

In our area of the Shenandoah Valley, adult Japanese beetles typically begin to emerge from the ground in early July. Almost immediately, they are up and flying around in search of food and mates. We are just starting to see them buzzing around the gardens.

Once they mate, the females will begin to lay eggs in the grass. These eggs hatch about two weeks later and the young larvae (white grubs) burrow down and begin to feed on the roots of the grass.

Beetle grubs devour the tender grass roots killing the grass.

Beetle grubs devour the tender
grass roots killing the grass.

From late August through October, the grubs grow, molt, and continue to feed heavily on the grass roots. This is the time when you will begin to see damage to the turfgrass if you have a heavy infestation. Patches of grass start to turn brown and die. Because the roots are gone, these brown patches can be peeled back easily to reveal the grubs underneath.

Once the weather turns colder in the fall and the soil begins to cool down, the grubs stop feeding and burrow down deeper into the ground where they spend the winter. In the spring when the soil warms a bit, the grubs begin to move up toward the surface and feed on the roots for a short time before they pupate near the surface. The adults emerge in early to mid summer and the cycle begins again.

Japanese beetles have ruined this beautiful Echinacea flower.

Japanese beetles have ruined this beautiful Echinacea flower.

As you can see, these annoying beetles are destructive in two stages of their life cycle; the adults can ruin flowers, foliage, fruits, and vegetables with their feeding and the larvae/grubs can kill large patches of turf as they consume the roots of the grass.

Controlling beetles in the garden

Hand picking is the safest method of control for beetles, however this is often difficult if not impossible to keep up with. If you carry around a small pail with soapy water, you can knock them off into the pail without ever touching them.

Pheromone traps can be used but be sure to place these at the edge of your property and not in or close to your gardens as the attractant will bring the beetles in from all around the neighborhood!

Japanese beetles consume Buddleia flowers

Japanese beetles consume
Buddleia flowers

Control with an insecticide is tricky since Japanese beetles often attack plants that are blooming; eating the foliage or worse, the flowers that the bees and other pollinators frequent.

Bonide Captain Jack’s Deadbug Brew is listed for controlling Japanese beetles and many other pests in the vegetable garden as well as on ornamentals. This product contains spinosad, an insecticide derived from a naturally occurring bacterium. The nice thing about spinosad is that it targets many different plant pests but spares most beneficial insects when used according to the label directions. It is similar in this way to Bt but it lasts longer in the garden and targets a broader range of insect pests.

Bonide Eight is also listed for control of Japanese beetles as well as many other destructive beetles and garden pests. Like Captain Jack’s, it can be used in the vegetable garden as well as on fruit trees and ornamentals. Always use according to the label directions.

A word of caution: Even natural or organic products can be deadly to pollinators like bees. If possible DO NOT spray when plants are in bloom. If this is not possible, spray early in the morning or later in the evening when bees are less active and ALWAYS read and FOLLOW the label directions! Sometimes, for a plant like Buddleia that blooms all summer, Andre will shear off all the flowers before spraying an insecticide.

Of course, controlling the larval stage will help prevent infestations of adult beetles to some extent. Here are some tips for controlling the beetle grubs in your lawn. For these guys, timing is everything!

Hopefully the beetles won’t be too bad this year. We will definitely know soon!

Until next time – Happy Gardening!

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Japanese beetles crawl over Buddleia flowers

Just the other day this question was posted on our Discussion Board:

I’m having a problem with my Heliopsis helianthoides ‘Summer Sun’. It appears that the petals are being “cut” off. For example this morning when I looked at the flowers I had two in full bloom. When I looked a few hours later, some petals were missing. Now when I looked at roughly 7:30 pm the one bloom only has one petal left and the other bloom is denuded of petals about 75% of the way around the center. This is not the first day that this has been happening. It’s not that petals are dropping off as there is a remnant of the petal around the center of the flower; it appears as if the petals have been cut off.

Japanese beetles shred a beautiful hibiscus flower.

Japanese beetles shred a hibiscus flower.

Hmmmm – I’ve seen this before with Echinacea (coneflowers), Hibiscus, Chrysanthemum, and many other plants. The culprit is beetles. In our area it’s probably the Japanese beetle that does the most damage to flowers, foliage, and fruit at this time of year. Although bean beetles, Colorado potato beetles, and stinkbugs are right up there in terms of damage to plants, Japanese beetles seem to do the most damage to ornamentals, particularly to the flowers, flower buds, and foliage.

Adult Japanese beetles began emerging from the ground in early July and have since been flying around in search of food and mates. I think they were a bit later than normal this year because we had such a late spring. I haven’t seen very many in my garden – just a few on the Rattlesnake and Kentucky Wonder pole beans. I hope this trend continues!

Japanese beetles devour a mandevilla flower bud

Japanese beetles swarm over and
devour mandevilla flower buds

A few years ago they were really bad and devoured most of our young apples, the corn silk, and the foliage of our pole beans. How very annoying! Perhaps the excess rain this year has contributed to their lower numbers – at least in my gardens. Our 5″ of rain (in one day) may have come right about the time the adults were beginning to emerge from the pupae so a bunch may have drowned. Can’t say I’m sad about that!

There are several different ways to control Japanese beetles in the flower garden and in the vegetable garden. I remember when I was growing up, my grandfather used to have a small bucket of creosote that he would keep in the garden by the Kentucky Wonder beans. Every time we went into the garden we would have to take the bucket and knock the beetles off the beans into the creosote. We now do this with a bucket of soapy water – same results.

There will be nothing left of this Rose-of-Sharon flower when these beetles are through!

Japanese beetles attack and destroy
a Rose-of-Sharon flower

Control with an insecticide is tricky since Japanese beetles are often attacking plants that are blooming; eating the foliage or worse, the flowers that the bees and other pollinators frequent. Our bees have enough trouble these days without being poisoned by the careless spraying of insecticides.

That’s why it is so important to read and follow the label directions whenever you spray any pesticide. There are specific “Precautionary Statements” on the label which include “Environmental Hazards”. You should always read this section before spraying.

Japanese beetles love corn silk. Daren Mueller, Iowa State University, Bugwood.org

Japanese beetles love corn silk.
Daren Mueller, Iowa State University,
Bugwood.org

Bonide has developed an organic insect control called Captain Jack’s Deadbug Brew which is listed for controlling Japanese beetles and many other pests. It can be used in the vegetable garden as well as on ornamentals. Captain Jack’s Deadbug Brew contains spinosad, an insecticide derived from a naturally occurring bacterium. The nice thing about spinosad is that it targets many different plant pests but spares most beneficial insects. It is similar in this way to Bt but it lasts longer in the garden and targets a broader range of insect pests.

The Captain Jack’s label states that the product is toxic to bees if they are exposed to the treated plants during the first 3 hours following application (while the spray is still wet). Once it dries, spinosad is relatively harmless to bees. Because of this, you should spray your plants in the evening when the bees are less active. This will allow plenty of time for the spray to dry before the bees and other pollinators visit the plants that have been treated.

Here’s hoping the beetles stay out of your gardens this summer!

Until next time – Happy Gardening!

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