Using sticky bands to reduce defoliation of urban trees by cankerworms

Defoliation by insects can reduce tree growth, increase mortality, and increase herbivory of neighboring plants. In North Carolina, fall cankerworms (Alsophila pometaria) and spring cankerworms (Paleacrita vernata) are important early season defoliators and have become more common in recent years. Female fall and spring cankerworm adults are wingless and climb tree trunks to mate and deposit egg masses. Therefore, sticky bands made by wrapping paper bands around trees and covering them with TangleFoot^TM can intercept female moths as they climb preventing oviposition and reducing subsequent larval abundance and defoliation.  Our hypothesis was that sticky bands would reduce cankerworm larvae and defoliation in the canopy when compared to unbanded trees. To test this hypothesis, we measured cankerworm abundance and defoliation on willow oaks with zero, one, and two-bands. We found that trees with two bands captured an average of 38.69% more moths than single banded trees. As a consequence, two-band trees had the least larvae in the canopy.  We found that larval abundance sampled early in the season with trays of soapy water was correlated with canopy defoliation at the end of the season. However, tree bands did not affect total canopy defoliation.  Although many cities use sticky bands as part of cankerworm management we did not find evidence for their efficacy when defoliation is low.