Tachinid Fly
Beneficial insect · Parasitoid
Tachinid flies are an important group of beneficial flies whose larvae develop in or on insect hosts. Many species help suppress caterpillars, beetles, and true bugs that damage crops and ornamentals. Adults are often overlooked because they resemble house flies or bristly bees.
How to identify it
Adults vary widely but are often gray, black, or patterned and may have strong bristles on the body. Some are stout and hairy, while others are more streamlined. Immature stages are parasitic maggots that develop within host insects after eggs are laid on or near the host.
How it helps your garden
Tachinid flies attack pests such as cabbageworms, cutworms, armyworms, squash bugs, Japanese beetles, and other plant-feeding insects depending on the species. Their larvae eventually kill the host, helping reduce future pest generations. Adults also visit flowers for nectar.
How to attract it
Plant nectar-rich flowers with accessible blooms, especially small clusters that are easy for flies to use. Keep flowering herbs and native plants in the garden so adults can feed while searching for hosts. Preserve some habitat complexity, including borders and mixed plantings, because host insects and adult flies both need resources. A shallow water source or moist sheltered areas can further improve their survival.
Tips
Because adults are so variable, it is often easier to notice their effect on pests than to identify every species. Flies that look plain or bristly are not necessarily harmful. Maintaining flowers through the full season improves support for these parasitoids.
General guidance for US gardens. Broad insecticide sprays harm beneficial insects along with pests; for a local pest-management plan, contact your Cooperative Extension office. Page updated Aug 4, 2026.