Q: Something is eating roses, there is almost nothing left of the leaves. What causing this and what to do about it?

• Beth from Youngstown

A: Several pests can skeletonize rose leaves to the point of nothing being left of the leaf but the veins. Japanese beetles, rose chafers and sawfly larvae are common pests that can cause this type of damage. But which one is it?

One tool we use to narrow down the culprits when we don’t have a sample to identify is Growing Degree Days (GDD). GDD is a measure of heat accumulation during the growing season.

Pest development (also plant development) is largely dependent on temperature. Some pests need more exposure to warm temperatures to develop that others. And GDD can tell you how much heat has already acclimated by a calendar date.

For example, Japanese beetles need a lot of warmth before they emerge as adults, and GDD tells us it’s a little too early for them. This leaves rose chafers and sawfly larvae as the most likely suspects.

As adults, sawflies are small, nonstinging wasps. It’s when they are in the larval stage that they are a pest of roses. The larvae are also called roseslugs.

There are three types of rose sawflies in Ohio — European sawfly, the curled sawfly and the bristly sawfly. Sawfly larvae look like small caterpillars. Rose chafers are 1/2-inch pale green to brown beetles. Unlike the sawfly, the rose chafer causes its damage to roses as an adult. Without a sample we can’t tell you which one you have but, the control methods are the same for both insects.

Inspect the leaves on your roses, including the undersides of the leaves. If you see either one of the pests, you can either pick them off by hand or wash them off with a hose. If you had pick them, drop them into a container of water with a couple of drops of soap. If these methods are not effective, you can use an insecticidal soap or a horticultural oil.

As a last resort you can use an insecticide. If you use an insecticide, be sure to read and follow the directions in regards to bees and pollinators. Pay special attention to systemic insecticides because the chemical can persist in the bloom and affect bees and pollinators.

Our OSU pollinator expert says, “Avoid applying systemic neonicotinoid insecticides to the soil around bee-attractive plants any time before bloom in the spring. Wait until the petals have dropped or use a bee-friendly product.”

For details on all things roses and to learn about protection your roses: http://go.osu.edu/roses.

For more on Growing Degree Days, go to: http://go.osu.edu/growingdegreeday.

Sprague is an Ohio State University Mahoning County Extension Master Gardener volunteer. Call 330-533-5538 to submit your questions to the plant clinic. Live clinic hours are 10 a.m. to noon Mondays and Thursdays. Or visit go.osu.edu/mahoningclinic for details.