Curled Leaves on Baptisia

Blue false indigo is a large shrub-like perennial that provides year round interest in the garden. Though mostly pest-free this plant may occasionally develop curled black leaves.

The genista broom moth caterpillars are the culprit. These small green worm-like insects can be identified by the rows of black markings and white dots that encircle their bodies. The damage can vary from irregular trails or pin size holes to large sections missing from the leaf edges. Injured leaves will often curl and look somewhat scorched.

Damage caused by this caterpillar is minimal and control is usually not needed on established plants. You may decide to control this pest for aesthetic reasons or on young plants. Bt (Bacillus thuringiensis) sold as Dipel or Thuricide only kills caterpillars. This eco-friendly product is most effective when the caterpillars are small. Spray new growth where the caterpillars tend to feed for better results.

A bit more information: This insect is not a problem every season. Monitor plants as it is easier to control small populations of young caterpillars. And consider using the most eco-friendly control method; knocking the caterpillars into cans of soapy water to die.