Every summer, Iowa gardeners look forward to colorful flowers and thriving gardens, but unfortunately, so do Japanese beetles. Japanese beetles begin their annual appearance in Iowa from late June through August.

With a little vigilance and the right approach, you can reduce damage and help your garden stay healthy throughout the season with these tips from the experts at Holubs Greenhouses in Central Iowa.

what are signs of japanese beetle damage?

Japanese beetles feed by eating the soft tissue between the veins of leaves, leaving behind a delicate, skeleton-like appearance.

You may notice:

• Leaves that appear lacy or transparent
• Ragged flower petals
• Damaged rose blooms
• Chewed grape leaves
• Fruit with feeding scars
• Beetles clustered together on plants

The damage can make otherwise healthy plants look stressed, but established trees and shrubs often recover if managed early.

How can i control japanese beetles?

Hand pick beetles daily

It may not be glamorous, but hand-picking is one of the most effective ways to reduce populations in home gardens.

In the early morning, when beetles are less active, knock them into a bucket of soapy water. Removing them before they attract additional beetles can significantly reduce damage.

Keep plants healthy

Healthy plants recover from insect feeding much better than stressed plants.

Continue watering deeply during dry weather, fertilize appropriately, and remove damaged blooms to encourage new growth throughout the season.

Use insecticides carefully

Several garden insecticides are labeled for Japanese beetles and can provide temporary protection for ornamental plants. Always read and follow the product label carefully, especially when treating flowering plants that attract bees and butterflies.

If you’re unsure which product is right for your landscape, stop by Holub Greenhouses. We’ll help you choose the best option for your plants while protecting beneficial pollinators whenever possible.

Don’t rely on beetle traps alone

While Japanese beetle traps catch thousands of beetles, they also attract beetles from surrounding areas. In many home gardens, traps placed too close to prized plants can actually increase feeding damage.
If you choose to use traps, place them well away from gardens and ornamental beds.

Protect pollinators while managing pests

Not every insect in your garden is a pest. Bees, butterflies, ladybugs, lacewings, and other beneficial insects play an important role in keeping gardens healthy.

Whenever possible:

• Spot treat affected plants instead of spraying entire landscapes.
• Apply treatments during the evening when pollinators are less active.
• Avoid spraying open flowers whenever possible.
• Choose products appropriate for your specific plants and pest problem.

A balanced approach helps protect both your garden and the beneficial insects that help it thrive.

Visit Holub Greenhouse in Ames for expert advice

Every Iowa growing season brings new challenges, and Japanese beetles are one of the most common pests we see each summer. If you’re noticing damage in your garden, stop by our Ames garden center. Our knowledgeable team can help identify the problem, recommend effective treatment options, and suggest plants that will continue to thrive throughout Iowa’s growing season.

Whether you’re growing roses, annual flowers, vegetables, or landscaping shrubs, we’re here to help you enjoy a healthier, more beautiful garden all summer long.