Spotting holes and brown spots on your rose leaves? You might have roseslugs or rose sawfly larvae. Here's how to stop these pests.
How to Prevent Rose Sawfly Larvae Damage
Updated Jul. 31, 2024
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Rose Sawfly Larvae Damage
“I have a miniature rose bush that produces red and yellow flowers. Something is eating away at the leaves, but no insects are visible. Do you know what may be causing this?” asks Birds & Blooms reader Rich Sereg of Merrimac, Wisconsin.
Gardening expert Melinda Myers says, “We often notice the damage after an insect has finished feeding on the plant. Gardeners bring me samples of plants marred by roseslug sawflies after the damage is done and the larvae, resembling caterpillars, have crawled to the ground to spin a cocoon to spend the winter in.”
Types of Rose Sawflies
Melinda explains, “The European roseslug sawfly secretes a slimy substance over its body so it resembles a slug, and it has a single generation alive and feeding early in the growing season. Another type, the bristly roseslug sawfly, has two to six generations living simultaneously throughout the growing season in the Midwest.
Watch for the European species on the undersides of the leaves beginning in mid-May and continuing through mid-June. These insects eat the soft leaf tissue between the veins, causing damage similar to Japanese beetles. The damage is usually not harmful to the plant’s health and longevity, but it does negatively impact its beauty. Mark your calendar and begin checking for the green larvae next spring.”
Curled rose sawfly larvae chew leaves along the edges.
How to Manage Rose Sawfly Larvae
Melinda says, “You can manage small populations by removing them from the plant and dropping them into a can of soapy water. Spray the underside of the leaves with organic insecticidal soap or horticulture oil to manage large populations. Confirm the insects are still present when you observe the damage and decide to treat. Spraying after the fact will provide no benefit.”
Learn how to get rid of rose chafer beetles.
What Does a Rose Sawfly Look Like?
Adult roseslug sawflies resemble common flies one might spot in their garden. They have two dark antennae and two pairs of wings. Larvae are yellowish green with an unmistakable orange-brown head, and they grow to three-quarters of an inch in length. Larvae do not harm humans, so there’s no need to worry about picking them off of plants by hand.
Learn how to treat black spot and rose rosette disease.
About the Expert
Melinda Myers is the official gardening expert for Birds & Blooms. She is a TV/radio host, author and columnist who has written more than 20 gardening books. Melinda earned a master’s degree in horticulture from the University of Wisconsin-Madison.
Sources
- Wisconsin Horticulture Division of Extension, “Roseslug sawfly“
- NC State Extension, “Roseslug or Rose Sawfly”
Originally Published: July 31, 2024
