Flies

Question 1

• What are flies of veterinary importance?

Answer 1

Direct effects – bites, irritation, anaemia, hypersensitivity & Myiasis causing flies & indirect effects – vectors of disease

Question 2

• What are the two suborders of flies?

Answer 2

Brachycera & Nematocera (blood feeders)

Question 3

• What are the four main types of Nematocera?

Answer 3

Simuliidae (black flies), Culicidae (mosquitoes), Ceratopogonidae (biting midges) & Psychodidae (sand flies)

Question 4

• What is significant about a mosquito’s life cycle?

Answer 4

Require still water

Question 5

• What is a biological vector?

Answer 5

When the organism carries out a developmental cycle or multiplies within the vector e.g. Dirofilaria immitis – first stage larvae acquired by mosquitoes through feeding, development of the microfilariae to the infective third stage occurs within the mosquito, infective larvae move into the bite wound and migrate through the tissues to the heart

Question 6

• Categorise the Brachycera depending on if the larvae cause problems of if the adult blood meal does?

Answer 6

Larvae cause problems – Oestridae, Sarcophagidae, Calliphoridae, some Muscidae – house flies, head flies
Adult blood meal causes problems – Tabanidae, Hippoboscidae, Glossinidae, some Muscidae – stable flies, horn flies

Question 7

• What are Tabanidae?

Answer 7

Horseflies, deer flies and clegs

Question 8

• What are Hippoboscidae?

Answer 8

Obligate blood-feeding ectoparasites, with both males and females feeding on blood, adenotrophic viviparity

Question 9

• What does adenotrophic viviparity mean?

Answer 9

A single egg hatches inside the female and the larva is retained until it is ready to pupate

Question 10

• What is Melophagus ovinus?

Answer 10

A member of the family Hippoboscidae, the sheep ked – wingless fly

Question 11

• What are some of the common features of Glossinidae?

Answer 11

Tsetse flies – reproduce via adenotrophic viviparity, vectors of the parasitic protozoan which causes trypanosomiasis

Question 12

• List the obligate and facultative myiasis flies?

Answer 12

Obligate – Sarcophagidae (flesh flies) & Oestridae (bot flies)
Facultative – Calliphoridae (blow/bottle flies) & some Muscidae (house flies – Musca domestica)

Question 13

• What are the three genus of the family Oestridae of particular veterinary importance?

Answer 13

Gasterophilus – horse botfly
Oestrus – sheep nasal botfly
Hypoderma – heel flies, warble flies, cattle grubs

Question 14

• What are the three significant species of the genus Gasterophilus?

Answer 14

A Gasterophilus intestinalis, female lays eggs around the knees
Gasterophilus nasalis, females lay eggs under the jaw
Gasterophilus haemorrhoidalis, female lays eggs around the lips

Question 15

• What are the effects of the genus Oestrus?

Answer 15

Cause a profuse discharge and thickening of the nasal mucosa that impairs respiration, larvae present in the sinuses are sometimes unable to escape; they die and lead to septic sinusitis

Question 16

• What is the most common problem of Calliphoridae?

Answer 16

Flystrike – blow/bottle flies are the primary cause e.g. Lucilia sericata

Question 17

• Lucilia sericata is anautogenous, what does this mean?

Answer 17

They must acquire a protein meal before maturing their eggs

Question 18

• What are flesh flies (Sarcophagidae)?

Answer 18

An obligate larval parasite of warm blooded vertebrates that causes rapid and severe myiasis in most livestock particularly sheep – not present in the UK

Question 19

• What is Hydrotaea irritans?

Answer 19

Sheep head fly – feed on secretions from the eyes, nose and debris at horn base, feeding causes irritation and scratching resulting in wounds

Question 20

• What is Haematobia irritans?

Answer 20

Horn fly – takes blood meal (most often from cattle), causes painful bites, one of the most economically important pests of cattle worldwide

Question 21

• How can flies be controlled?

Answer 21

Chemical control applied to animal and/or the environment, husbandry/management, barriers, trapping, biological control

Question 22

• What are behavioural responses?

Answer 22

The stress caused by flies can result in a failure to graze normally, resulting in decreased milk production and reduced weight gains, further losses can occur when animals injure themselves in their efforts to escape the flies – gadding, bunching

Question 23

• What is flystrike?

Answer 23

A type of myiasis caused by flies which lay eggs into wounds, orifices or rotten fleeces

Question 24

• Unless the process is halted what might happen to the animal?

Answer 24

The infested animal may die from shock, histolysis or infection