Tachinid Fly – Trichopoda pennipes

Tachinid Fly – Trichopoda pennipes
Family Tachinidae / Subfamily Phasiinae

Phasiinids are among the most primitive tachinids; they deposit undeveloped eggs onto their hosts
Tachinid Fly - Trichopoda pennipes
Trichopoda pennipes is about the size of a housefly, and is primarily a parasite of insects in the families Coreidae (squash bugs and leaf-footed bugs) and the Pentatomidae (stinkbugs). Although several species of Tachinid flies have been imported as biological control agents of agricultural pests, this distinctively colored fly is native throughout much of the United States.

Female flies in the subfamily Phasiinae lack a uterus, or ovisac, in which to store eggs while they develop. They attach an undeveloped eggs directly to the exterior of the host (below). These eggs make take a few days to develop and during this time they are subject to removal by the victim, or may be lost when the bug molts. A few species have developed complex sclerotic mechanisms for inserting the egg partially or fully into the host's cuticle [2].

Undeveloped eggs are cemented to a bug's pronotum

T. pennipes appears to have different biotypes across the country, preying on very specific hosts in different regions. In California, a population of the fly was reported attacking the bordered plant bug Largus succinctus , but the same flies never attacked the squash bug. [1] Recently, T. pennipes were collected from fields of squash in New York state and released near farms growing squash in northern California. They have now established permanent populations, and now nearly 50% of the squash bugs preying on the plants are found with fly eggs deposited on them. However, it is not known how effective is this control, or whether the flies have managed to reduce populations of the voracious crop pests.

Tachinid Fly

The female fly lays oval eggs on large nymphs or adult bugs. The larvae burrow from the egg directly into the bug's body. Only one larva survives within each bug. A large, cream-colored maggot exits from the body of the bug, drops to the ground, and pupates in a dark reddish-brown puparium. The bug soon dies. A new generation of adult flies emerges to lay eggs about two weeks later. Each female fly may lay several hundred eggs, and there may be three generations each year, depending on location [1].

  1. Weeden, C.R., A. M. Shelton, and M. P. Hoffman. Biological Control: A Guide to Natural Enemies in North America
  2.  D.M Wood, Manual of Neararctic Diptera Vol. 2, Tachinidae
Flies of North America – Order Diptera. Flies are prevalent in virtually all habitats, with over 16,000 species in North America. Flies can be distinguished from all other insects in that they only have one pair of normal wings. Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids.
Syrphidae | Flies Index | Tachinidae | Bee Flies | Robber Flies