mouse bot fly

Mouse bot fly is a large parasitic fly. It occurs in the United States and southern Canada east of the Great Plains and in the Pacific Northwest. Adults are found in hardwood forests and other habitats where their preferred host is found. They are rarely seen. They do not feed, and they have short lives. The larvae are parasitic mostly on the white-footed mouse, but sometimes on other species. They create swellings, known as warbles, under the skin near the anus of the hosts.

Adults are superficially bee-like and about 1¼″ (30 mm) in length. The body is black, shiny, and covered with black and pale hair. The pale hair on males is yellow, on females is yellowish white, almost – but not – white.

The front of the head is covered with pale hair, and there is usually a small black spot on each side. The compound eyes are entirely black, with no red spots. The antennae have three segments. On the second segment there is a longitudinal, line-like groove (suture). The mouth opening is very small.

The large plate on the front portion of the thorax (scutum) is black, shiny, and covered with a mixture of black and pale hair. There are several plates on each side of the thorax. There is a black spot on the plate at the upper front (anepisternum). The exoskeletal plate between the abdomen and the thorax (scutellum) is very short. The area just behind the scutellum (postscutellum) is well developed.

On the wing the terminal cell (R₅) of the radial sector (Rs) is closed or narrowed toward the end (distally).

Total length: about 1¼″ (30 mm)

The habitats where its hosts are found

The female lays eggs on vegetation near the burrow of its host. The eggs hatch almost instantly when they sense a passing warm body and the larvae attach themselves to the body. The larvae bore under the skin and feed on the flesh of the host. They produce boil-like swellings called warbles. Several larva may inhabit a single host. After the host dies, the larva emerges, burrows into the ground, and pupates.

white-footed mouse (Peromyscus leucopus)

The preferred host is white-footed mouse, but mouse bot fly has been known to infest other species.

Sources

24, 30, 82.

The location of the sighting in Anoka County (light green on the map), is “Twin Cities”, “Location not precise.”

Unknown insect found in the grass... some sort of bee or fly? Any ideas?? The dust on it is from the bird seed container I used to save it from the lawn mower. I hope that doesn’t hinder identification!

Location: Scott County

Unknown insect found in the grass... some sort of bee or fly? Any ideas?? The dust on it is from the bird seed container I used to save it from the lawn mower. I hope that doesn’t hinder identification!