The reproductive success of the twig girdler Oncideres cingulata (Say) was examined relative to twig morphology of the host tree species used for oviposition. There were significant differences in twig morphology between hosts, in twig length, volume, and surface area. Ovipositing beetles appeared to adjust reproductive efforts to these host differences, as reflected by egg density. Twig length was strongly correlated with the number of eggs laid across all host species, although regression analysis found that a model consisting of twig diameter and surface area best accounted for the total number of eggs per twig. Adult emergence was not related consistently to any aspect of twig morphology across host species. However, emergence rates varied between hosts, ranging from 6.1% from eggs laid on birch (Betula nigra L.), 7.7% from American elm (Ulmus americana L.), 10.0% from pecan (Carya illinoensis (Wangenh.) K. Koch), to 28.2% on honey locust (Gleditisia triacanthos L.).