Influence of Feeding Habits of Tiphia vernalis on the Parasitization of the Japanese Beetle

Abstract

Limited surveys here reported indicate that the feeding habits of T. v. adults are important factors in the spread and efficiency of this parasite against the Japanese beetle. When the distr. of honeydew is limited or concentrated, the Tiphia are attracted from the surrounding area and congregate on the infested trees and shrubs for their food supply. The spread and efficiency of the parasite are thereby lowered through lack of its dispersion, and superparasitization results, especially in areas where the host population is not dense enough to accommodate the parasite. Colonies liberated in areas where the adult food supply is absent or limited rarely become established. Japanese beetles disperse readily and deposit their eggs over a wide area, but the grubs are usually more abundant near the trees and shrubs on which the adults feed. This condition is favorable for the parasite and tends to increase its efficiency by lessening superparasitization, especially in areas where the Tiphia are attracted to the same trees and shrubs for their food supply.