Freeloader Flies

Milichiidae

Classification

Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Diptera
Superfamily: Carnoidea
Family: Milichiidae

Pronunciation

How to pronounce Milichiidae: //mɪˌlɪkiˈaɪdiˌiː//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Summary

Milichiidae, or freeloader flies, are a family of small, predominantly dark flies known for their kleptoparasitic behavior, often associating with predatory invertebrates and feeding on their prey's bodily fluids. They have a global distribution and primarily inhabit open environments and forests.

Physical Characteristics

Small-to-very-small flies, usually 1 to 5 mm in length; typically black or at least dark; some species have a silvery abdomen due to fine hairs, especially in males (e.g., Milichiella argyrogaster). The eyes are often red, with a long, geniculate proboscis that is concealed when not in use, and a short, broad abdomen that may distend after feeding.

Identification Tips

Look for small flies with disproportionately large heads and long proboscises, often found near predatory invertebrates. They may appear to lick their prey, which is a sign of kleptoparasitic behavior.

Habitat

Open landscapes, forests and forest edges, forest canopy, stables/houses, and caves.

Distribution

Worldwide, except Antarctica; some species have spread globally through human commerce.

Diet

Larvae are generally saprophagous, feeding on decaying plant matter, manure, and carrion. Adults are kleptoparasitic, feeding primarily on the fluids of predatory insects' prey.

Life Cycle

The larval stage lasts generally about 2-3 weeks in temperate climates, maturing from saprophagous stages.

Ecosystem Role

Kleptoparasites often found near predatory invertebrates, playing a scavenging role and aiding in nutrient cycling.

Health Concerns

Some species are associated with decay and filth, earning them the common name 'filth flies'.

Collecting Methods

Net capture near predatory insects
Light traps

Preservation Methods

Ethanol
Pinned specimens

Evolution

Once included in the family Carnidae, Milichiidae has been reassigned to various superfamilies including Carnoidea, Chloropoidea, and Agromyzoidea based on morphological traits.

Similar Taxa

Misconceptions

Misidentified as solely filth flies due to their breeding sites; some are kleptoparasites and not just scavengers.