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Archive for Thursday, July 25, 2013

Garden Calendar: Identify which shiny green insects are friends, foes

July 25, 2013

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This summer certainly is the year for green insects — with Japanese beetles making their presence known, emerald ash borers knocking on our door, and the usual suspects just seeming to be more visible than usual.

Here are some tips for identifying which of the green insects you should worry about and what to do if control is warranted.

Japanese beetle

The shiny green beetle that is getting the most attention right now is the Japanese beetle.

We have been seeing these insects in Douglas County the last few years, but this is the first year that people have carried jars of them into my office. They look a lot like the insects commonly referred to as June bugs, except the Japanese beetle is metallic green with coppery-colored wings.

Clockwise from top, a Caterpillar hunter, emerald ash borer and Japanese beetle are pictured. The Caterpillar hunter is actually a beneficial insect, not to mention a beautiful one, but the other two are harmful to plants.

Clockwise from top, a Caterpillar hunter, emerald ash borer and Japanese beetle are pictured. The Caterpillar hunter is actually a beneficial insect, not to mention a beautiful one, but the other two are harmful to plants.

You will have to get up close and personal to see them, but the major distinguishing characteristic is a row of patches of white hair along each side of the abdomen. The patches look like a string of pearls or beads.

Japanese beetle adults love roses, raspberries and grapes, but they will devour a number of other landscape and garden plants if given the opportunity.

They also like to aggregate, so if one Japanese beetle finds your roses you can bet his or her friends will be along soon. In the evenings, mated females will lay their eggs in the soil in your lawn. A Japanese beetle female can lay as many as 40 to 60 eggs in her four- to eight-week lifespan.

In addition to the adult beetle feeding, Japanese beetle larvae cause damage as they feed on turf roots in August and September. The larvae overwinter in the lawn and adults will emerge next summer to start the cycle anew.

To control Japanese beetles, handpick and destroy small populations. Neem-based products that contain azadirachtin are effective for a few days and are a good choice for plants that pollinators are visiting. A number of conventional insecticides provide control for two to three weeks.

Read and follow label instructions with any type of pesticide and make sure that it lists the insect you want to control and plant you want to protect.

Green June beetle

The larger cousin of the Japanese beetle is the Green June beetle. They have similar feeding and congregating habits, although the Green June beetle’s favorite treat is overripe fruit. Control is also similar. Fortunately, Green June beetle is a less voracious feeder and reproducer than the Japanese beetle.

Emerald ash borer

You will have a hard time actually finding this one, but if you do, I hope you will contact me. Emerald ash borers are very small — a half-inch long and one-eighth inch wide at maturity, and they spend most of their life as a worm-like larva feeding under tree bark.

The insect was found in one tree in Wyandotte County last summer and a single adult was found in a trap in Johnson County earlier this month. It has yet to be confirmed in Douglas County or Lawrence.

Because emerald ash borer has devastated ash forests in Michigan and many surrounding states, owners of ash trees are rightfully excited about its impending arrival.

The primary identifying characteristics for emerald ash borer are exhibited on the trees they infest. If your ash tree has lots of sprouts along the trunk and appears to be declining, it is a candidate for inspection.

The D-shaped exit holes are only one-eighth inch in diameter, so they are almost impossible to see in the ash’s furrowed bark. Larger holes on the trunk indicate the presence of our native borer species: the ash-lilac borer and redheaded ash borer.

Protection for ash trees requires preventative measures. Professional landscape and tree care companies can provide advice on the various options and associated costs, or more information can be obtained through the USDA Forest Service’s informational website, emeraldashborer.info.

In research trials, commercial products are generally more effective than those available to homeowners.

Caterpillar hunter

This large ground beetle has a coppery border to its metallic-green wing covers, with a shiny black head and thorax. I think it is one of the most beautiful beetles that live in our area.

Caterpillar hunter is considered to be a beneficial insect and control is unnecessary. They are reported to be attracted to lights.

There are a few other shiny green insects that may be beneficial or detrimental to your garden plants, but these are the most common in this area right now.

For confirmation about identification or control strategies, remember the Master Gardener Horticulture Hotline, Monday-Friday, 1 p.m. to 4 p.m. at 2110 Harper St., or stop by the Master Gardener booth at the Saturday morning’s Downtown Lawrence Farmers’ Market.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. Contact her or an Extension Master Gardener with your gardening questions at 843-7058 or mastergardener@douglas-county.com.

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