Species Trogus pennator

Trogus pennator (Fabricius, 1793)

From Latin penna a feather, or a wing (1).

circa 19 mm length, 33 mm wingspan (guide photo measurements)

T. pennator is an eastern, red species. True T. pennator is identified by the following combination: low, rounded scutellum (generally); supra-antennal area with two low ridges medially (rarely developed into denticles); and the fifth tergite of the female lacking prominent ridge. Both T. pennator and T. vulpinus share having long setae on tergites 2–6.(2)

Note: Those with a high, conical scutellum generally correspond to T. vulpinus.

eastern US and extreme southeastern Canada

Known larval hosts include: Eurytides marcellus, Papilio palamedes, P. polyxenes, and P. troilus.(2) It is worth noting that all of the above species are also parasitized by T. vulpinus.

Note: This species is not known to be reared from P. glaucus, P. brevicauda, or P. canadensis. Eastern red species reared from these hosts may correspond instead to T. vulpinus.

Trogus pennator is a parasitoid of swallowtail butterflies (Papilionidae), ovipositing in the caterpillars.

The solitary larva develops inside the caterpillar, allowing it to pupate before killing it. After metamorphosing, the adult wasp chews an irregular hole in the chrysalis to escape.

Perhaps a mimic of well-armed spider wasps, such as Tachypompilus ferrugineus:

  

T. edwardsii is a western species and does not overlap with T. pennator or T. vulpinus. It is further recognized by the following combination: scutellum elevated and conical; supra-antennal area with two developed denticles medially; transverse rugae on the petiole; tergites 2–6 with short setae; tergite 3 finely punctured.(2)

T. vulpinus is an eastern species that overlaps with T. pennator. It is separated by the following combination: scutellum elevated and conical (versus low and rounded); supra-antennal area with two developed denticles medially (versus ridges rarely developed into denticles); and fifth tergite with a prominent ridge separating the dorsal and lateral surfaces (versus no ridge throughout).(2)