Silent Spring

by Rachel Carson

Between 1920 and 1933, as a result of diligent searching throughout the native range of the beetle, some 34 species of predatory or parasitic insects had been imported from the Orient in an effort to establish natural control. Of these, five became well established in the eastern United States. The most effective and widely distributed is a parasitic wasp from Korea and China, Tiphia vernalis. The female Tiphia, finding a beetle grub in the soil, injects a paralyzing fluid and attaches a single egg to the undersurface of the grub. The young wasp, hatching as a larva, feeds on the paralyzed grub and destroys it. In some 25 years, colonies of Tiphia were introduced into 14 eastern states in a cooperative program of state and federal agencies. The wasp became widely established in this area and is generally credited by entomologists with an important role in bringing the beetle under control.