BIOMI 3310 Lecture Notes - Lecture 22: Halteres, Louse, Nematocera
Lecture 22 - Dipera
Diptera: flies
• 2 wings - 1 on the 1st thoracic segment, 1 on the second segment that's modified into a haltere
and used for balance
• Holometabolic (complete/complex metamorphosis)
• Species that are parasitic as adults:
o Feed on blood
o Good vectors
• Species that are parasitic as larvae cause myiasis (disease caused by flies invade living tissues)
Groups of Diptera:
• Nematocera
o Only adult females suck blood
o Culicidae: mosquitoes
• Two Types:
▪ Culicine Mosquitoes: short palps; vector of Yellow Fever
▪ Anopheline Mosquitoes: long palps; vector of Malaria
• Feed by inserting the stylet of the mouthparts and sucking blood out of a small vessel
▪ Inject saliva that contains clotting inhibitors
▪ An immune reaction to the saliva causes the itching/swelling/redness at the site
▪ Have stretch receptors in their abdomen, so you can't make one leave by
making a muscle or stretching your skin. It will only leave when it's full.
• Feed on birds, mammals, and fish
• Most require blood meals to feed their eggs.
• Take more than one blood meal
▪ As a result, they're vectors of malaria and filariasis
• Life Cycle
▪ Female lays eggs in calm water
• Some lay eggs as rafts on the surface of the water
• Some lay single eggs with small floats on each side of the shell
• Some glue their eggs just above waterline so the eggs hatch when the
water rises - guarantees that the larvae will emerge when water is present
▪ Larvae are filter feeders that swim around. They often hang from the surface of
the water by their breathing tube, which is held in place by surface tension.
• Larvae are called "wigglers"
▪ Larvae undergo 2 molts, then pupate.
▪ Pupal stage is free-swimming and has a series of breathing tubes that extend
out of the thoracic area.
• Pupae are called "tumblers" because they tumble as they move around in
the water
▪ When the adult is ready to eclose, the pupa will rise to the surface and be held
in place by surface tension. The adult works its way out of a linear suture on the
back of the thorax of the pupal case.
▪ The eclosed adult stands on the pupal case until it pumps its wings full of
hemolymph. Then, it flies off to mate.
o Simuliidae: black flies
• Vectors of river blindness in Africa (onchocerciasis) and avian malarias
• Females take a blood meal for energy to develop eggs
▪ Tears a hole in the flesh with a set of small, lacerating mouthparts
▪ Laps up blood from the bite wound
▪ The lesions are small, bleeding spots.
• After the female takes a blood meal, she lays eggs in fast moving water.
• A larva hatches and maintains its position within the stream by secreting a silken
thread of saliva.
• Larvae pupate to form a small stage with large gills.
▪ This stage is also suspended in the water (like a cork on a string)
▪ When it's time to eclose, the cork moves up to the surface and the adult pops
out of the pupal case.
o Ceratopogonidae (Heleidae): biting midges
• Look like a cross between mosquitoes and black flies.
▪ Mouthparts are similar to black flies.
▪ When they feed, they sit like black flies.
• Most have terrestrial life cycles.
• Females lay eggs → maggot-like larvae → pupal stage → adult
• Wings have patches of dark hair
o Psychodidae: phlebotomine sand flies
• Life Cycle:
▪ Lay eggs under rocks, in cracks, etc.
▪ Small larva molts several times, then turns into a pupa.
▪ Adults eclose and fly off to mate.
▪ Females suck blood to produce eggs.
• Mouthparts are short.
• Tear small holes in the skin
• Bite only at dawn and dusk (when there's not much wind, because they're
weak fliers)
• The wings have very simple venation (veins are parallel to each other from the base to
the tip) - considered primitive.
• Brachycera: horseflies and deerflies
o Also includes several groups of non-blood-feeding snipe flies
o Only adult females suck blood.
• Vicious daytime biters
• Adults are very strong fliers and will travel many miles to bite.
▪ Attracted to CO2 exuded by hosts
▪ Attracted by the motion of large black objects
• Mechanical vectors, because they induce interrupted feeding
▪ The bite hurts so much that the host intervenes, causing the fly to jump off.
▪ The partially fed fly moves to a new host.
▪ Mechanically transmit anthrax, tularemia, equine infectious anemia, and
Trypanosoma evansi
• Biological vectors of filariid nematodes.
o Males DON'T feed - serve only as insemination devices.
o Brightly colored eyes
• In males, the eyes meet in the middle of the head.
• In females, the eyes are separate.
o Tabanus: horse fly
• Wings are clear
Document Summary
Diptera: flies: 2 wings - 1 on the 1st thoracic segment, 1 on the second segment that"s modified into a haltere. Lecture 22 - dipera and used for balance: holometabolic (complete/complex metamorphosis) Species that are parasitic as adults: feed on blood, good vectors. Species that are parasitic as larvae cause myiasis (disease caused by flies invade living tissues) Groups of diptera: nematocera, only adult females suck blood, culicidae: mosquitoes. Two types: culicine mosquitoes: short palps; vector of yellow fever, anopheline mosquitoes: long palps; vector of malaria. Feed by inserting the stylet of the mouthparts and sucking blood out of a small vessel. Inject saliva that contains clotting inhibitors: an immune reaction to the saliva causes the itching/swelling/redness at the site, have stretch receptors in their abdomen, so you can"t make one leave by making a muscle or stretching your skin. Feed on birds, mammals, and fish: most require blood meals to feed their eggs.
