Brachycera

• Nematocera and Brachycera

  • No ptilinal sac, emerge from pupal case through T-shaped slit on dorsal surface
• Brachycera

  • Antennae shorter than thorax, with 6 segments (3 often present, last segment annulated)
  • Arista present in terminal antenna
  • Maxillary palps held stiffly forward (porrect)
  • 7 abdominal segments
  • Obtectate pupae
  • Represented by Family Tabanidae (with vet importance) only
• Brachycera


  Shortened horn, referring to their shortened antennae
• Defining features of Brachycera

  • Reduced antenna size (with 8 or fewer flagellomeres)
  • Maxillary palp having only 2 segments or less
  • Larval head capsule extending into prothorax
  • Two distinct parts of larval mandible
  • Epandrium and hypandrium of male genitalia separated
  • No premandible on lower surface of labrum
  • Distinct configuration of CuA2 and A1 wing veins

  
• Brachycera

  • Two major sections: Orthorrhapha and Cyclorrhapha
  • Many species are predators or scavengers
• Orthorrhaphous lineages

  • Many are scavengers, predators or parasitoids as larvae
• Cyclorrhapha or "higher" flies

  • Multiple major radiations of species diversity, feeding habits and habitat specialization
• Subfamilies of Tabanidae

  • Chrysopsinae
  • Pangoniinae
  • Tabaninae
• Proboscis

  Relatively short in Tabanus and Haematopota, longer in Chrysops, very long and projecting forwards in Pangonia
• Chrysops, Tabanus and Haematopota

  • Proboscis is soft and hangs down
• Chrysops

  • First and second antennal segments long, third segment has 4 annulations
• Haematopota

  • First antennal segment large, second narrower, third segment has 3 annulations
• Tabanus

  • First 2 antennal segments small, third has tooth-like projection and 4 annulations
• Horse flies, breeze flies, deerflies


  Also known as Tabanidae

  
• Tabanidae

  • Large and robust with powerful wings and large eyes
  • Eyes holoptic in males, separated by narrow space in females
  • Stout, heavily built varying in size from smaller than housefly to as large as hummingbird
  • Short, stout, anteriorly projecting antennae with 3 markedly different segments

  
• Two well-known types are the common horse flies (genus Tabanus) and the deer flies (genus Chrysops)

  
• Adult horse flies

  Feed on nectar and sometimes pollen, females require blood meal for reproduction, males lack mandibles for blood feeding
• Immature or larval horse flies


  Fossorial predators of other invertebrates in moist environments
• Females

  • Primary sense for locating prey is sight, have large compound eyes, attracted by motion
• Eyes of horse flies are generally brightly colored, used by entomologists to identify to species

  
• Male horse flies

  Usually holoptic, with eyes meeting and taking up majority of head
• Female horse flies

  Eyes separated by space called the frons
• Horse fly bite

  Extremely painful, they use mandibles like serrated scimitars to rip and slice flesh
• Horse fly bites


  Cause blood to seep out as they lick it up, they may carve out chunks to digest at leisure
• Horse fly's modus operandi is less secretive than mosquitoes, but still aims to escape before pain signals reach victim
• Pain of horse fly bite may mean victim is more concerned with assessing and repairing wound than finding and swatting the fly
• Horse flies

  • Seen in summer, most active in hot weather during daylight hours, prefer wet environments for breeding
• Horse fly breeding

  1. Females lay eggs on vegetation overhanging moist soil or on stones close to water

  2. Larvae hatch and fall into water or moist earth, feeding on invertebrates and small vertebrates until pupation

  3. Pupal stage lasts 1-2 weeks

  4. Adults are diurnal, strong flyers and very difficult to discourage

  5. Whole life cycle takes 4-5 months in favorable conditions
• Female horse flies

  Feed on blood about every 3 days, require blood meal before egg-laying
• Male horse flies

  Feed on honeydew and flower juices
• Some horse fly species are known to transmit disease and/or parasites
• Chrysops


  Intermediate host or vector of Loa loa filarial worm

  
• Horse flies have been known to transmit Anthrax among cattle and sheep
• Tabanids are very good vectors of Equine Infectious Anaemia Virus and some Trypanosome species
• Large numbers of horse flies can cause severe blood loss in animals, up to 300 mL in a single day, which can weaken or even kill them