Dance Fly

Dance flies form a large and diverse family, Empididae, found across temperate regions worldwide. They are predatory as both larvae and adults, hunting small soft-bodied insects, and are especially well known among entomologists for their elaborate courtship behavior.

Males of many dance fly species capture prey and present it to females before mating, sometimes wrapping the offering in silk to form a small "balloon." These nuptial gifts, along with the swirling aerial swarms males form at dusk to attract mates, give the group its common name.

Although related to biting flies in the broader fly order, dance flies pose no threat to humans; their piercing proboscis is used exclusively to subdue insect prey.

• Slender body with unusually long, spindly legs
• Elongated, tapering abdomen
• Downward-curving piercing proboscis adapted for capturing prey, not for biting humans
• Clear or lightly tinted wings
• Size ranges from about 3 to 10 mm depending on species
• Lookalikes: crane flies are much larger and lack a piercing proboscis; robber flies are stockier with a bearded face and stronger bristles

Dance flies are found throughout temperate regions worldwide, particularly in meadows, woodland edges, marshes, and vegetation along streams. Adults are often seen perched on foliage or forming loose aerial swarms in cooler, humid microhabitats during the warmer months.

Adult dance flies are active predators of small, soft-bodied insects such as midges and other small flies, which they capture in flight or pluck from vegetation. Many species are notable for elaborate courtship displays in which males offer captured prey, sometimes wrapped in silk, to females as part of a swarming mating dance performed at dusk. Larvae are also predatory or scavenging, living in soil, leaf litter, or decaying wood where they feed on small invertebrates.

Eggs are laid in moist soil, leaf litter, or decaying plant material. Larvae develop through several instars as predators or scavengers of small invertebrates in these habitats, then pupate in the soil or litter. Adults typically emerge in spring or summer. Most temperate species complete one generation per year, overwintering as larvae or pupae before adults appear the following season.