[9][12] Trichopoda pennipes first appears in the late spring or early summer and feeds on nectar sucked from flowers such as Queen Anne's lace and meadowsweet.

The female fly lays several small, pale-coloured, oval eggs on a large nymph or an adult bug.

After feeding on the bug's tissues, the cream-coloured larva emerges and falls to the ground where it pupates in a reddish-brown puparium formed from the last larval skin.

One of the principal host species for T. pennipes is the southern green stinkbug, Nezara viridula.

This is a crop pest that originated in Ethiopia but now has a worldwide distribution and is named for the foul-smelling defensive secretion it exudes from a gland on its thorax.

This exudate appears to be fairly effective in preventing predation by birds but is well tolerated by T. pennipes[15] which seems to be highly attracted by an aggregation pheromone produced by the male bugs.

Their eggs are now found deposited on nearly 50% of the squash bugs in the area but it is unclear how effective this is in controlling the crop pests.

However, T. pennipes does not prevent all crop damage as the bugs continue to feed and reproduce after being parasitised, though the reproductive organs begin to atrophy when the parasitoid reaches the second instar stage.