Hi Paula,

Thank you for reaching out to the UNH Extension Infoline. I am sorry to hear that your David Austin rose is experiencing severe leaf damage! Rose slugs, also known as rose sawfly, are an extremely common insect issue with roses at this time of year. We have received a few other inquiries on this subject this week. 

It is tricky to be 100% without photos to reference, but from the details provided here it does sound like it could be rose sawfly (rose slug) or Japanese beetle infestation. If they are rose slugs, they are typically found on the underside of leaves. "Small numbers of rose slugs can be hand-picked from leaves and either squished or drowned in a bucket of soapy water. Heavier infestations may warrant the application of a registered insecticide such as insecticidal soap or Spinosad." Here is the link to read more about rose slugs and Japanese beetle issues on roses: https://extension.unh.edu/blog/2019/06/whats-eating-leaves-my-roses

Additional links for reference:
https://hort.extension.wisc.edu/articles/roseslug-sawfly/
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/insects/sawflies/rose-and-pear-slugs-sawflies
https://ecoipm.org/2015/05/04/rose-leaves-eaten-by-sawflies/
https://extension.unh.edu/sites/default/files/migrated_unmanaged_files/Resource000543_Rep565.pdf

You can also always send plant sample and/or insect samples to our UNH Extension diagnostic labs for further diagnostics.

Here is the link for the insect ID: https://extension.unh.edu/agriculture-gardens/pest-disease-growing-tools/insect-other-arthropods-identification and here is the link for our plant diagnostic lab form: https://extension.unh.edu/agriculture-gardens/pest-disease-growing-tools/plant-diagnostic-lab

Good luck and have a great weekend!

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