Survival and Mortality of Red Oak Borer Larvae1 on Black, Scarlet, and Northern Red Oak2 in Eastern Kentucky

Abstract

Survival and mortality of 3 generations of the red oak borer, Enaphalodes rufulus (Haldeman), were studied over a 7-year period. The borers showed a preference for black oak over red and scarlet oaks. Larval mortality was about the same on all hosts. Tree vigor and size did not affect larval mortality; however, both factors did influence attack density. Potential brood trees are less than 29 cm dbh, small and large pole size, and are growing slower than 5.1 mm in diameter per year. Larval mortality was 40% in the early instars, primarily because of woodpecker predation. In the mid-instar stages, there was 51% mortality of the surviving larval population. This was due mainly to a sequence of events at the attack site: wound sap—insect invaders—fermenting medium. Lepidopterous wood borer larvae (largely Prionoxystus spp.) invaded wound sites when the red oak borer was in the mid- or late-larval stages and caused mortality by apparent direct killing of 5—10% of the surviving larvae.