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They’re Back…

Since I last wrote about the Japanese beetle, there is still nothing to commend them – they haven’t suddenly developed a taste for ticks or mosquitoes and they are going to attack the roses — so this is a refresher course on dealing with the annual pest, a gift from Japan since the early 1900s, arriving in New Jersey, where we wish it had remained.

First a quick review of the life cycle: adults are emerging from the soil as we speak. Mated females drop to the ground during the afternoon and burrow into the soil to lay eggs; feeding resumes, mating continues and egg-laying happens on a daily basis. A single female can lay from 40 to 60 eggs in a season (30 to 45 days). The eggs develop into the familiar white grubs and remain in the soil for the next 10 months, emerging as beetles in late June to early July. The grubs feed on grass and plant roots and can do severe damage.

Japanese beetles have an educated palate and dine on many species of ornamental plants. Here is a smattering of their most favored flavors – rose, grape, hops, canna, crape myrtle, birch, linden, Japanese maple, Norway maple, flowering crabapples and about 300 other host plants. Both gourmet and gourmand!

In their native Japan there are some natural enemies that provide control, but here these do not exist so it is up to the human caretakers to get cracking.

Soapy water sprays (test first to prevent damage to the foliage), soapy water in containers held under the beetles in the early morning to catch the bugs as it drops to escape, squishing (yuck), chemical sprays – read the labels and follow instructions! Traps may attract more insects to the property from the neighbor’s yard, so be sure to locate them far away from any desirable planting.

Another strategy is to treat the lawn with milky spore disease to control the grubs, but this takes time (several seasons) to spread throughout the whole area. For those so inclined, there are a number of natural sprays that can be applied – try catnip, chives, garlic and tansy. Choose your weapons!

On another tack, the bagworm reared its ugly head again this week. If you have what looks like a pine cone hanging from your arborvitae, juniper, pine, spruce, black locust, honey locust or sycamore, you need some information about dealing with this pest. The photos accompanying this article, of both the Japanese beetle and the bagworm, help identify the culprit, and help is available both from the Master Gardener Hotline (Cooperative Extension) or me– I haven’t forgotten everything I ever knew… and I do know that the bagworm will eventually kill its host plant.

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Tina Clinefelter is a Penn State Master Gardener emerita and has received the President’s Volunteer Service Award from the Points of Light Foundation. She can be reached at tina36@comcast.net.

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