Horse and Deer Flies

Pronunciation

How to pronounce Tabanidae: //ˌtæbəˈnɪdiː//

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Summary

Tabanidae, commonly known as horse-flies and deer flies, are a family of true flies characterized by their large size, blood-feeding behavior of females, and predaceous larval stage. They are found worldwide, except for polar regions, and play significant roles in ecosystems as pests to livestock and vectors for diseases.

Physical Characteristics

Adult tabanids are large flies with prominent compound eyes, short antennae composed of three segments, and wide bodies. Males have eyes that are almost touching, while females have widely separated eyes. They possess a stout stabbing organ with sharp cutting blades for biting and lapping blood. Their larvae are long, cylindrical or spindle-shaped with small heads, rings of tubercles around segments, and a breathing siphon at the posterior end.

Identification Tips

Species recognition is based on details of head structures (antennae, frons, and maxillae), wing venation, and body patterning. The notched posterior margin of abdominal tergite 1 is a unique characteristic. Adult size ranges from 8 to 28 mm, with distinctive features such as coloration and patterns of wings and bodies.

Habitat

Larvae grow in semi-aquatic habitats, mostly in wet soil in marshes, bogs, or at water margins, with some in drier soils and environments such as deserts and alpine meadows.

Distribution

Found worldwide except in polar regions and some islands including Greenland, Iceland, and Hawaii. Specific regional distributions include about 350 species in our area, 145 species in Canada and Alaska.

Diet

Adults feed on nectar and plant exudates; females require a blood meal for reproduction, which they obtain by biting land vertebrates, including humans. Larvae are predaceous and consume insects and worms.

Life Cycle

The larval stage can last up to 2 or more years (especially in northern regions), and they pupate in dry soil. Eggs are laid in clusters of up to 1000 near water and hatch after about six days. Pupation lasts about two weeks and adults emerge after metamorphosis.

Reproduction

Mating occurs in swarms, with females requiring a blood meal before laying eggs. Eggs are white then darken with age, hatching into larval grubs that are legless and develop through multiple moults.

Predators

Eggs are attacked by parasitic wasps; larvae are consumed by birds and parasitized by fungi and nematodes. Adults face predation from birds and specialized wasps.

Ecosystem Role

Larvae contribute to nutrient cycling in aquatic ecosystems, while adults serve as pollinators and are significant in food chains as both predators and prey.

Economic Impact

Horse-flies and deer flies can be pests to livestock, reducing growth rates and milk output. They can also cause blood loss and transmit diseases.

Cultural Significance

Horse-flies have been referenced in classic literature, highlighting their historical significance in both human culture and mythology.

Health Concerns

They are known vectors for blood-borne diseases, such as the equine infectious anaemia virus and various species of Trypanosoma, leading to health issues in humans and animals. Bites can provoke allergic reactions and may result in complications if left untreated.

Collecting Methods

• Malaise traps
• Modified Manitoba traps with baits and attractants

Evolution

The oldest records of the Tabanidae family date back to the Early Cretaceous. They may have co-evolved with angiosperms and show a complex evolutionary history focused on blood-feeding habits that likely evolved from predation.

Similar Taxa

• Oestridae (botflies)
• Bembicinae (horse guard wasps)

Misconceptions

Commonly mistaken for other biting flies; not all species are pests to humans directly, as some may primarily feed on livestock or wildlife.

Tags

• Tabanidae
• Horse Flies
• Deer Flies
• Pests
• Insect Vectors