Genista Broom Moth Caterpillar

Genista Broom Moth Caterpillar on a leaf at Crow’s Nest Preserve

By Daniel Barringer, Preserve Manager.

Yesterday on the blue false indigo (Baptisia australis) plants I saw this pretty caterpillar. I had left my camera at my parents’ house over the weekend so I borrowed Pete’s camera for this closeup:

These caterpillars are the larvae of the genista broom moth (Uresiphita reversalis), also known as the sophora worm moth. I’ve never seen any damage on our Baptisia before, and its perfect foliage is one reason people grow it. No longer the case, though I am okay with the damage if the caterpillars provide some bird food. After all, we plant native species to support indigenous insects to feed local birds.

The webbing you see in the photo will become the pupa for the moth. This caterpillar is also commonly found on non-native broom plants (Cytisus sp.) or on bluebonnets (Lupinus) and is found from Nova Scotia south to Florida and Texas, though I suspect it’s more common to the south. Its population also reportedly irrupts in cycles so I don’t expect it will be a constant pest. I have several options for managing the damage if it becomes too great: picking off the caterpillars, cutting back the plants (they need it anyway), spraying with a sharp stream of water to see what that does…but the bottom line is that we have planted a diversity of species so that a pest on one of them does not ruin the garden.