Species Mydas clavatus - Mydas Fly

25-30 mm length, wingspan to 50 mm or more

Large black fly with red/orange mark on top (dorsum) of 2nd abdominal segment. Body hairless, cylindrical. Eyes large. Antennae are distinctively clubbed in the Mydidae. This species flies rather boldly in the open. With the black-and-orange pattern, it resembles a wasp and fools the casual observer.

Throughout US and Canada--widespread.

Deciduous woodlands and adjacent fields and shrubby borders.

Summer, June-August (North Carolina)

Adults (just males?) take nectar (pers. observation, P Coin). Some sources say adults take caterpillars, flies, bees, and true bugs. Others are skeptical of this.

Eggs are laid singly in soil or rotting wood. (See video of oviposition--Flickr). Mydas larvae prey on beetle larvae, esp. those of June beetles. Larvae pupate close to soil (or wood?) surface. Adults are active only in mid-summer. Mating system in this species unknown. Different Mydas species apparently have different mating systems, including resource-defense polygyny and "hilltopping". (See Preston-Mafham, p. 99, (1))

Resembles a wasp of the family Pompilidae, and is presumably a Batesian mimic. One such wasp is Anoplius.

I have seen adults (males?) of this species taking nectar from several sources in Durham, North Carolina. I have seen a female ovipositing in a dead maple stump. Later, I found this stump was full of carpenter ants and large beetle larvae (probably Odontoaenius disjunctus). I have not observed the adults taking prey on the wing. Sources vary on the feeding habits of adults. Most say the adults are predatory, but this may be incorrect. Perhaps this is due to confusion with the somewhat similar Robber Flies (Asilidae)?

Arnett, American Insects, 2nd. edition (p. 876) gives 21 North American spp. in genus Mydas, says clavatus is widely distributed. (2)

Milne and Milne illustrate this species (plate 459) and give life history, including allegedly predatory habits of adults. (3)

Swan and Papp describe and illustrate the adult, larva, and pupa (fig. 1303). (4)

Deyrup has a photo of M. clavatus, p. 135. (5)

Borror and White illustrate M. clavatus, plate 13. (6)

Brimley, p. 335 (7)

Giff Beaton's page on flower flies has an image of Mydas clavatus.