Leaf Eating Columbine Sawfly
Your columbine seems to be growing fine then one day you check and most of the leaves are missing. This is most likely the work of the columbine sawfly.
This worm-like insect starts eating at the edge of the leaf and works its way inward, leaving only the veins intact. The columbine sawfly is completely green with no stripes or spots on the body. It has 6 to 10 pairs of little leg-like projections from the bottom of its body. If you see this pest, pluck it off the plant or knock it into a container of soapy water.
Most gardeners discover the damage after the insects have finished feeding, so control is not needed or effective.
Fortunately, healthy plants will survive the damage. Cut them back to the ground when they finish flowering. New healthy growth will sprout and grow throughout the season.
Mark your calendar to watch for this pest and manage it next year.
A bit more information: A skipper caterpillar also feeds on columbine. They eat holes in the leaves then eat outward toward the edges of the leaves. Consider tolerating their damage so the caterpillars can transform into important pollinating butterflies.
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