Hello Fred,

This is the larva of a Dogwood Sawfly, a common and native insect that feeds on the foliage of a variety of dogwood species. The damage might be an eyesore but it should not seriously affect the long-term health of the shrub. If you are not able to hand-pick off the larvae, then there are a few lower-toxicity insecticides that can help manage them, assuming there are enough leaves left to spray (though sprays must be thorough and contact the larvae themselves and upper and lower leaf surfaces).

Neem oil is one type of horticultural oil, and it can work well as a topical insecticide but only if it directly contacts the insect. Older larvae, as these are, are sometimes more resilient than younger larvae and might not be as easily impacted by a single application. More than one treatment might be needed, and in that case, follow product label directions as to how long to wait between sprays. Do not spray while temperatures are above 85 degrees as this risks causing damage to the plant itself (called phytotoxicity).

Miri

Thank you for your prompt reply!

You're welcome!