Minnesota Flies

Band-winged crane fly (Epiphragma fasciapenne) is a common, easily identified, moderate-sized crane fly. It occurs in the eastern United States and adjacent Canadian provinces east of the Great Plains. Eastern Minnesota is at the western edge of its range. It is found in floodplain woodlands and wooded areas adjacent to swamps.

Like all crane flies, the body is long and slim, the wings are long and narrow, and the legs are very long, very thin, and very fragile. The thorax has a distinct, V-shaped groove on top. The lower jaws each have a very long, antenna-like extension.

Band-winged crane fly is distinguished by the distinctive wing pattern with four bands of bordered brown spots, and by a dark brown band at the very tip of the third leg segment.

Eumerus is a genus of small hoverflies in the family Syrphidae. With 281 known species, it is one of the largest genera of flies. It is found throughout the Palearctic realm, which includes Europe, Asia north of the Himalayas, North Africa, and the northern and central parts of the Arabian Peninsula. Several Eumerus species have been introduced into North and South America. Three of these are known to occur in the United States: lesser bulb fly (Eumerus funeralis), narcissus bulb fly (Eumerus narcissi), and onion bulb fly (Eumerus strigatus). Collectively, they are known as lesser bulb flies.

Adult lesser bulb flies are black tinged with bronze. They have pale longitudinal stripes on the thorax and silvery-white stripes on the abdomen. The larvae are considered pests. They tunnel into plant bulbs, causing the bulbs to rot. The bulb either dies or produces stunted growth in the following growing season. In some areas, up to 25% of narcissus bulbs are infected.

Long-tailed dance fly (Rhamphomyia longicauda) is a small, black, long-legged fly. It is commonly found from May to July in deciduous woods near water. The wings are long and black. The head is round with large bright orange or red eyes. On the female, the middle and hind legs have a fringe of long, black, bristly hairs.

Every evening around sunset, males and females collect in same-sex swarms. Females and fly up and down, the behavior that gives this family its common name “dance-flies”. Females cannot hunt for prey. They receive protein from males as gifts in exchange for copulation. They swallow air, filling and extending their abdomen outward, saucer-like, falsely signaling males that their eggs are nearing maturity. The long hairy legs wrap around the abdomen, making it appear even larger. Males are attracted to females that have largest swollen abdomens and hairiest legs. An individual will break off and join the other swarm to select a mate.

With 7,003 species in 530 genera worldwide, robber flies are one of the largest and most abundant families of insects alive today. Bee-like robber flies, as the common name for the genus suggests, resemble bees. There are 240 species of bee-like robber flies, 62 species in North America north of Mexico. Few of the species have been given a common name. Laphria sacrator is one of several species famous for being a bumble bee mimic, so “bumble bee mimic robber fly” will stand in for the common name.

Bumble bee mimic robber fly (Laphria sacrator) is a short, robust, medium-sized, bee-like robber fly. It is fairly common in northeastern and north-central United States, including Minnesota. It has a stout thorax and a short abdomen, both partially covered with long yellow hairs making it resemble a bumble bee. It is one of the hairiest of the bee-like robber flies. Adults are ⅝″ to 1″ long.

Many insects that form detachable galls on oak. All but two of these are cynipid wasps. The two exceptions are the oak gall midges Polystepha pilulae and Polystepha globosa.

Oak leaf gall midge (Polystepha pilulae) is a long-legged, 1 ⁄16″ to ⅛″ long, mosquito-like fly (midge). Adults are impossible to identify by appearance in the field. However, the species can easily be identified by the gall it produces. Galls appear always on the upper surface of northern pin oak, northern red oak, and possibly black oak leaves. They are hard, 1 ⁄16″ to 3 ⁄16″ in diameter, and irregular in shape. They are green when they first appear in the spring, soon turning red or magenta. As they age they become brown and crusty. They can be easily detached from the leaf surface.

Oak leaf gall midge (Polystepha globosa) forms similar spherical galls on the undersurface of the leaves of black oak and possibly other oaks in the red oak group.

midge (Axarus festivus)

bee-like robber fly (Laphria index)

bumble bee mimic robber fly (Laphria thoracica)

hoverfly (Chalcosyrphus chalybeus)

orange-horned hammertail (Sphegina campanulata)

bee-like robber fly (Laphria sp.)