Parasitology - Nuisance & Biting Flies Flashcards
Aside from fleas & lice, what are the other types of insects (Phyla: Insecta) that qualify as parasites of the skin? What is their order?
Diptera - flies
In what family of Diptera insects do nuisance & biting flies fall?
What are the main nuisance & biting flies species or genera?
Family: Muscidae
Nuisance flies:
- Musca domestica* - house fly, standard fly
- Musca autumnalis* - face fly
- Hydrotaea -* head fly
Biting flies:
- Stomoxys* - stable fly
- Haematobia* - horn fly
What family of Diptera contains the nuisance & biting flies?
Muscidae
What are the species or genera of nuisance flies?
Musca spp: M. domestica, M. autumnalis
Hydrotaea irritans
Musca domestica is also known as house fly or standard fly. Its morphological features are the “standard” against which all other flies are compared.
Describe M. domestica’s appearance in terms of:
size
thorax
abdomen
mouthparts
Size: ~7.6 mm
Thorax: Grey with longitudinal stripes
Abdomen: Yellow with one black stripe
Mouthparts: No forward-pointing proboscis. Rather, a sponge-like labellum to suck up food broken down by vomited enzymes
What is M. domestica’s life cycle? How does this life cycle contribute to M. domestica’s ability to transmit disease?
Life cycle (12 days mimumum): Eggs laid in dung → Hatch into larvae → Pupate in manure → Adults (can survive overwintering by hibernating)
The fact that the fly is hatches and pupates in manure means it can easily pick up enterobacteria and other bacteria found in faeces such as E. Coli, Shigella, Salmonella. It can also transmit enteroviruses and some helminths.
Aside from disease transmission, what other pathogenic significance do houseflies (M. domestica) have?
They cause “fly worry” in cattle, which can cause production losses in terms of reduced weight gain, reduced milk yield, etc.
What is the most numerous nuisance fly causing fly worry in cattle?
Musca autumnalis, aka face fly
What is Hydrotaea irritans and what species does it bother the most?
H. irritans is a nuisance fly in the Musca family that mainly bothers sheep. It is also found on cattle in some areas.
How does H. irritans differ from the domestic house fly, M. domestica, in appearance?
H. irritans has a green abdomen
Why is H. irritans especially bad for sheep?
H. irritans, aka “head fly”, swarms around the sheep’s head, rasps the skin before sponging up secretions and exudate with its labellum.
This can drive the sheep to self-injury called “broken head”, leaving it susceptible to secondary infection & blowfly strike.
What is the difference in life cycle between the M. domestica and the H. irritans?
Where do they lay their eggs?
Life cycle of M. domestica is about 12 days. They lay eggs in dung.
Life cycle of H. irritans is one year because the larvae overwinter, pupate in spring and emerge as adults in summer. They lay eggs in rotting vegetation.
What are the biting flies in the Musca family?
- Stomoxys calcitrans* - “stable fly”
- Haematobia irritans* - “horn fly”
How do the mouthparts differ in nuisance flies and biting flies in the Musca family such as Haematobia irritans and Stomoxys calcitrans?
Haematobia irritans and Stomoxys calcitrans both have forward-pointing proboscis, like a hypodermic needle.
What is the distinguishing behaviour of the stable fly, Stomoxys calcitrans?
It attacks all animals and humans. It “visits” (feeding on) hosts, but flies away and rests elsewhere.
How does the stable fly differ in appearance from the M. domestica?
Instead of a grey thorax with black longitudinal stripes, it has a grey thorax with grey longitudinal stripes, and its abdomen is grey with black spots.
How does the stable fly’s life cycle differ from M. domestica’s?
Its life cycle takes about one month instead of 12 days, and it lives for another month as an adult.
Like Hydrotaea irritans, it lays its eggs in rotting vegetation, like straw & hay.
How does the behaviour of the biting fly Haematobia irritans (aka Lyperosia) differ from that of *Stomoxys calcitrans? *
“Resident” fly: spends most of time on host (usually cattle). Rests along back, shoulders & side, feeds on dewlap, udder & belly where skin is thinner.
- tend to “face downward” on back.
S. calcitrans is a “visiting fly”.
Haematobia irritans (Lyperosia) & Stomoxys calcitrans look similar, but their life cycles are different in terms of where they lay their eggs. Haematobia, also known as “horn fly”, prefers to lay its eggs in a similar environment as M. domestica & M. autumnalis. Where is that?
In dung.
Haematobia irritans prefers FRESH cattle dung and emerges after just one week.
Recap all the nuisance & biting flies in the Musca family.
Nuisance: labellum mouthparts
Musca domestica - house fly
Musca autumnalis - face fly
Hydrataea irritans - head fly, causes broken head in sheep
Biting: forward-pointing proboscis
Stomoxys calcitrans - grey stable fly, “visiting” fly
Haematobia irritans (Lyperosia) - horn fly, “resident” fly
What are the biting flies that fall under the “forest flies & keds” category? They are also called “louse flies” because they look like lice.
Forest Flies:
Hippobosca bovis & Hippobosca equina - only attack cattle & horses
Sheep ked:
Melophagus ovinus - attacks sheep
What is bad about the louse fly, Hippobosca equina, in terms of where it is found around horses and where it lives in the UK?
It tends to swarm around the perineal region of the horse.
What is the difference between the sheep ked’s (Melophagus ovina) life cycle and the forest fly’s (Hippobosca bovis & H. equina) life cycle?
Sheep ked lifecycle is completely on host. Adult female ked deposits single larva in fleece → larval ked pupates in fleece → adult emerges a few weeks or months later, depending on temperature.
Forest flies’ lifecycle is mostly off the host. Adult fly deposits larva in soil → Larva pupate in soil → adult
What are Tse Tse flies and where are they found?
What disease do they transmit?
Tse Tse are biting flies of the Glossinidae family. Both male and female leave painful bites.
They are found only in Africa.
They transmit Trypanosomes to cause fatal disease, “nagana”, in animals and “sleeping sickness” in humans.
What is the appearance of the Tse Tse fly in terms of size, colour and wing venation?
See photo
Size: 6-13 mm (medium-sized)
Colour: Greenish thorax with yellow-brown abdomen
Wing Venation: “Butcher’s Cleaver”
What is special about horse flies in terms of size, wing venation, mouthparts, life cycle & behaviour?
Size: They are BIG biting flies ~ 2.5 cm long (3x M. domestica)
Wing venation: Closed “discal” cell
Life cycle (one year): Eggs laid on leaves over H2O →larvae fall into H2O →return to land to pupate
Mouthparts: short, strong & down-pointing for slashing & sponging
Behaviour: only FEMALES suck blood
What family of Diptera (order) do horse flies belong?
Tabanidae
Besides Tabanidae (horse flies), which other biting flies lay their eggs on or near water?
Culicoides (midges), Simulium (black flies or buffalo gnats) & Culicidae (mosquitoes)
Culicoides midges - Eggs laid on plants near H2O → larvae → pupae → adults
Simulium black flies/buffalo gnats - Eggs laid underwater → larva emerge & attach to water vegetation → pupate, floating to surface → adult emerges
Culicidae mosquitoes - Raft of eggs laid on water → larva hatch on water → pupate in water → adult
What is the most important genus in the family Ceratopogonidae?
Ceratopogonidae are midges.
The most important genus is Culicoides, which cause sweet itch in horses and are vectors for viral diseases such as Blue Tongue and African Horse Sickness.
How do Culicoides, in the family Ceratopogonidae, differ from appearance from M. domestica?
See photo.
They are very small, aka “noseeums” at 2-5 mm.
They are dark with humpbacked thorax.
They have mottled wings.
These are midges.
Simulium are also known as black flies or buffalo gnats, even though they are very small (2-4 mm). Like midges (culicoides), they have arched, humpback appearance.
What is unique about their biting behaviour?
What is unique about their wings?
Only females suck blood.
They have clear wings with weak venation.
The family Culicidae includes mosquitoes, which are always born on water (think of stagnant water!). What are three important genera?
Culex
Aedes
Anopheles
What do mosquitoes (Culicidae) have in common with black flies & buffalo gnats (Simulium); and sandflies (Psychodidae) in terms of biting behaviour?
Only females suck blood.
What are some diseases transmitted by Culicidae (mosquitoes)?
Human:
Malaria - plasmosis
Dengue fever
Animal:
arboviruses - eg., rabbit myxomatosis, equine encephalitis
parasites: Dirofilaria immitus
Psychodidae is the family of sandflies. What are the two main genera of sandflies and why are they very important to vets in warm climates?
Phlebotomus (Old World)
Lutzomyia (New World)
They’re vectors for the protozoan parasite Leishmania, which causes the blood disease Leishmaniasis.
Leishmaniasis is an intracellular protozoal-parasite invasion of macrophages; the protozoan’s amastigote (later) stage transforms into promastigotes in sandfly’s gut.
Which nuisance fly has the olive-green abdomen?
Hydrotaea irritans - head fly, affects sheep especially.
