Dogwood infestation, naughty or nice bug?

A:

These are the sort of questions we love to get. Too often people see unfamiliar insects on their plants and their first reaction is to grab an insecticide and spray before determining if the insect is a pest or not. In your case this insect is NOT a pest and is actually beneficial. 

Although it is white and black, this beauty is in the genus Psyllobora and is therefore a species of ladybird beetle. I checked with Jim LaBonte who is a beetle expert with the Oregon Department of Agriculture and he confirmed my ID however he was hesitant to put a species name to it without the actual specimen as their markings are highly variable. The “small white grubs” are the larval stage.

They are known to feed on fungus, particularly the mildew type and possibly arthropods such as mites, aphids, and scale insects. I cannot tell you what they are feeding on in your case, however they are helping to keep your dogwood healthy and therefore should not be sprayed.

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