Hello Gardeners, I’m Amanda McNulty with Clemson Extension and Making It Grow . A nearby stand of catalpa trees is kept pruned so that the owners can easily reach catalpa sphinx moth caterpillars that use the leaves as their larval food source. This stout but dully colored caterpillar is actually hard to find – most stands of catalpa I see don’t have them feeding on them. Their infestations seem to be sporadic; many other insects parasitize these creatures and some people actually purchase pupae