How to Manage Pests
Identification: Natural Enemies Gallery
Scientific name: Trioxys pallidus
DESCRIPTION Life Cycle
This wasp was introduced to California from France for control of walnut aphid. Since its establishment in the late 1960s it has virtually eliminated the walnut aphid as a pest in most orchards, except when disrupted by broad-spectrum pesticides applied for other pests.
The adult wasp has a shiny black head and thorax and a long, slender, yellowish or orangish abdomen. The adult is roughly 2 to 3 mm (0.08–0.12 inch) long. Trioxys pallidus undergoes complete metamorphosis. The female wasp lays an egg inside aphid nymphs. The egg hatches into a larva, which consumes the inside of the aphid and pupates in the mummified aphid. The adult wasps emerge through a small exit hole. To monitor for Trioxys pallidus, look for aphid mummies.