Catalpas are the host plant for the Catalpa Sphinx moth (Ceratomia catalpae), the leaves being eaten by the caterpillars. When caterpillars are numerous, infested trees may be completely defoliated. Defoliated catalpas produce new leaves readily, but with multiple generations occurring, new foliage may be consumed by subsequent broods. Severe defoliation over several consecutive years can cause death of trees. Because the caterpillars are an excellent live bait for fishing, some dedicated anglers plant catalpa mini-orchards for their own private source of "catawba-worms," particularly in the southern states.
The largest living Catalpa tree is on the grounds of the Michigan State Capitol in Lansing, Michigan and was planted in the year of its dedication, 1879. The oldest is the 150-year-old specimen in the Minster graveyard of St Mary’s Butts in the English town of Reading in Berkshire, although this is soon to be replaced, passing the claim to Rochester's 140-year-old Catalpa situated in front of the town's Cathedral.
Catalpa is also occasionally used as a tonewood in guitars .