Japanese Beetles

The day has come…. Japanese Beetles have emerged from their underground hibernation and resurfaced here in Cedar Rapids/Marion. These garden pests can cause immense unsightly damage to your plants and ruin your garden harvest.

Keep a close eye on your Roses, Grape Vines, Raspberries, Crabapples and Japanese Maples as these are especially enticing to these hungry little bugs. If you notice your leaves look skeletonized or lacey, that is evidence that you’ve had a swarm of visitors.

jb grub cycle

In Iowa, Japanese Beetles typically emerge from the soil between June and July and stick around through the end of summer. The adults creep out of the ground each morning to feed on your garden. While above the surface, they lay eggs which hatch into grubs that immediately begin to consume the roots of turf grasses and other plants.

Before the first fall frost the adult beetles die off and the grubs bury deeper into the soil where they hibernate until spring. Come April or May, the grubs start feeding on roots once again until early June when they grow into adults and emerge with hungry intent.

As the adult beetles feed, they emit a chemical hormone that sends a signal to other beetles that a food source has been found. This signal brings in countless more beetles that will strip your leaves and plants. Because of this, handpicking is the most effective method of controlling these pests and minimizing the destruction. By plucking them and dropping them into a bucket of soapy water you not only stop them from eating but also from producing the attracting hormones. Japanese Beetles are typically most active during mid-day so the best time to handpick is in the morning or evening when they are a bit slower.

In addition to tedious hand picking, there are both chemical and organic methods to control Japanese Beetles. We carry a wide range of these products including:

Eight® Yard and Garden Spray - provides economical contact and residual insect control for up to 4 weeks. Eight® kills over 100 insects which destroy lawns, roses, flowers, trees, vegetables, and fruits. It may be applied to homes, foundations and other areas to stop infestation of flies, ticks, fleas, mosquitoes, ants … all flying, crawling and hopping insects.

Bonide® Systemic Insect Control - is made for use on flowers, shrubs, trees and turf. A contact and systemic action protects the plants from a multitude of insect threats, above and below the ground.

Bonide® Fruit Tree Spray Concentrate – A liquid fruit tree spray. Simple to use. No plugged nozzles. As little as 1½ tablespoons per application. Excellent for the home orchardist.


Fruit Tree & Plant Guard - This goofproof, water-based combination is economical, versatile and has a very broad spectrum. Only 2 ounces/gallon treats not only a comprehensive listing of fruits, but also flowers, shrubs and ornamentals.

Rose Shield®  – This is a great solution for insect and disease problems of roses, flowers, landscape plants, trees, shrubs and ground covers. Lasts up to 30 days. Rainproof within 60 minutes. Rose Shield®  is absorbed by the plant and moves rapidly throughout, killing insects from within.

Rose Rx®  Systemic Drench – Is a six-week, systemic insect and disease control drench. Simply measure, mix and pour around the base of roses and shrubs, or sprinkle over the top of entire flowerbeds. 1 quart treats up to 16 roses or other shrubs or a 200 sq. ft. flower bed.


Neem Oil – An all-purpose insecticide, miticide, fungicide for organic gardening. Derived from the Neem seed, Neem Oil is an excellent choice for use on virtually any plant. It kills all stages of insects- eggs, larvae and adults.  It works on a wide variety of pests including Japanese beetles, aphids, mites, whiteflies, flea beetles and earwigs.  Important: Neem works best when applications begin at first sign of attack.

Captain Jack Deadbug Brew® (Spray & Dust) - contains Spinosad. Deadbug Brew kills bagworms, borers, beetles, caterpillars, gypsy moth, loopers, leaf miners, spider mites, thrips and more. A convenient, economical and perfect way to spot treat vegetables and flower gardens.

Japanese Beetle Killer Spray - Pyrethrin-based insecticide is a safe and effective way to control these pests on vegetables, grapes, raspberries, flowers, roses, trees and shrubs. In addition to controlling Japanese beetles, it also controls cucumber beetles, flea beetles, cabbageworms, Colorado potato beetles, and more.

Bonide® Garden Dust  - A specially formulated, general purpose product for convenient use on vegetables, fruits and flowers.

Bonide® products that have a tan band on the front label are made from all natural ingredients. If you are doing organic gardening, look for the 3-leaf logo and statement “For Organic Gardening” to assure they meet the USDA’s National Organic Program.

Give us a call or stop by if you are having problems with Japanese Beetles. Our expert staff would love to help you find a method or product to control these pests in your yard!

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