Issue 3, June 7, 2023

Rose Slugs

Rose slug injury. Travis Cleveland, University of Illinois

We've had several reports of bristly rose slug causing rose foliage to be lacelike. The green larvae are more numerous on the undersides of the leaflets. Although causing window-feeding when young, the larger larvae eat holes in the leaflets and even cause defoliation.

The bristly rose slug is green, with fine, hairlike spines, and grows to about 1/2 inch long. Rose slug looks like bird manure when young but when older looks like the bristly rose slug without the bristles. Both are present at this time of year.

Bristly rose slug

Remove small infestations by hand. Although these insects look superficially like slugs or caterpillars they are sawfly larvae. They will not be controlled with slug baits or Bacillus thuringiensis kurstaki. Acephate (Orthene, Bonide Systemic Insect Control), bifenthrin (Talstar), and cyfluthrin (Tempo) are effective. Insecticidal soap will also be effective with very good coverage. Avoid getting the insecticide on flowers, although most rose varieties have had the nectar and pollen bred out of them and are not attractive to pollinating insects. Species roses and particularly some single-flowered varieties will attract pollinators, which could be killed by insecticide sprays on the blooms. Travis Cleveland (Originally published by Phil Nixon, April 30, 2010)

(Originally published by Phil Nixon, April 30, 2010)

Travis Cleveland

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