The unusual damage caused by the native redbud leaffolder (Fascista cercerisella, family Gelechiidae) on its namesake host (Cercis canadensis) is becoming evident in southwest Ohio as caterpillars develop through the first generation. Thus far, populations appear to be sporadic and highly localized. However, population densities and distribution may change with the appearances of the second and third generations.
The nest-making caterpillars are commonly found on wild eastern redbuds but infestations tend to be light and irregularly distributed throughout the canopy. I've never seen appreciable damage. However, I have commonly observed obvious, damaging populations on weeping redbuds. Whether this is due to host preference or simply because the vertical orientation of the leaves makes the damage more obvious is an open question. I'm not aware of any host preference studies for this native moth. Regardless, it's important to closely monitor the weepers.
The caterpillars use silk stitching to produce two types of nests. Leaf edges may be folded over to produce nests that conform to the "leaffolder" common name that's approved by the Entomological Society of America.
However, the nonconformist caterpillars also make nests like a "leaftier" by stitching together neighboring leaves. In fact, various online resources may inaccurately refer to the caterpillars as the redbud leaftier.
The caterpillars reside in heavy silk tubes within both types of nests. They partially emerge out of their tubes to feed as skeletonizers, consuming the upper and lower leaf surfaces. The affected areas turn orangish-brown which sharply contrasts with the normal dark green color of the foliage.
Early instar caterpillars are cream-colored and have no discernible markings. As the caterpillars mature, markings begin to develop with alternating segments darkening to produce a striking appearance of black and light-green bands running the length of the body. They resemble tiny banded sea kraits (snakes). When disturbed, the caterpillars wiggle back and forth violently further enhancing their tiny snake impersonation. They have great entertainment value!
Like fall webworms (Hyphantria cunea), the velvety black female leaffolder moths tend to lay their eggs on or near the leaves from which they developed. So, the nests are expanded with each successive generation. The tree generations also overlap meaning that it's common to find both early and late instar caterpillars in the same nest.
Populations tend to build with each generation meaning that the most significant damage occurs late in the season. The moth spends the winter as pupae in debris and fallen leaves beneath infested trees.
The leaffolder seldom causes enough damage to redbuds in landscapes to significantly affect the overall health of infested trees. Of course, heavy leaffolder activity can affect tree aesthetics.
However, using insecticides to manage this leaffolder is problematic. The protection provided by folded or tied leaves place the caterpillars out of the reach of topical insecticides. I could find no data on the efficacy or application timing of systemic insecticides.
Where practical, populations can be reduced by pinching nests to kill caterpillars. Raking and destroying fallen leaves will also reduce localized numbers by eliminating overwintering moth pupae.