13: Biting and Nuisance Flies

Type of general fly life cycle

Complex metamorphosis: juvenile life stages look very different from adult life stages

What do mosquitos feed on

Males feed on plants, females feed on blood

Mosquito genera of veterinary concern

Aedes, Anopheles, and Culex

What is required for mosquito larval development

Water

CS of mosquito infestation

• Nuisance/painful bites → annoyance → less time eating → lower production

• ± Hypersensitivity

• Severe: anemia

• Vector borne diseases

Common name for Culicoides spp.

Biting midge or no-see-um

Size of Culicoides spp.

SMALL

Breeding site of Culicoides spp.

Stagnant water and tree holes, egg in decaying and wet vegetation

What is required for Culicoides spp. larval development

Water

Control for Culicoides spp.

Bring the horses/LA in before dusk, Culicoides spp. are most active at twilight and at night

CS associated with Culicoides spp. in horses

• Painful/annoying bites

• Hypersensitivity → “sweet/summer itch”

• Pruritis → alopecia

Common spots of alopecia in horses affected by Culicoides spp.

Mane and tail; also ears, poll, face, chest, and ventral abdomen

Parasite that is borne by Culicoides spp.

Onchocerca cervicalis

Common name for Simulium spp.

Black flies

Size of Simulium spp.

Small

Breeding sites of Simulium spp.

Fast running water in northern North America

CS associated with Simulium spp.

• Painful/annoying bite → loss of production

• Anemia (these guys are blood feeders!)

• Hypersensitivity

Parasites borne by Simulium spp.

Onchocerca spp. in large animals

Flies that are grouped as Tabanids

Tabanus and Chrysops

Size of Tabanids

Large

Common name for Tabanus

Horse fly

Common name for Chrysops

Deer fly

How do you tell the Tabanids apart

Chrysops has striped wings

Breeding site of Tabanids

Underside of vegetation near water

What is required for Tabanid development

Water

Seasonality of Tabanids

Emerge in late spring/early summer and peaks from June to September

CS associated with Tabanids

• Painful bites → loss of production

• Hide damage (“messy eaters”)

Cattle parasite of most significance borne by Tabanids

Anaplasma marginale

Common name for Stomoxys calcitrans

Stable flies

Size of Stomoxys calcitrans 

Medium

Breeding site of Stomoxys calcitrans 

Decaying organic material

Location where Stomoxys calcitrans usually feeds

Lower legs or underside, then leaves the host

Economic threshold

The amount of flies needed to decrease the feed intake and production parameters of an animal

Parasite that is borne by Stomoxys calcitrans 

Habronema spp. in horses

Control for Stomoxys calcitrans 

Put your leaf or manure pile away from the barn

Common name for Haematobia irritans

Horn fly

Breeding side of Haematobia irritans

Fresh cattle feces

Where do we find Haematobia irritans

On the animal (cattle) all the time

Parasite borne by Haematobia irritans

Stephanofilaria stilesi

How common are Haematobia irritans

So common, someone did the math to estimate the economic impact in the cattle industry

Economic threshold for Haematobia irritans

200 flies

Treatment threshold for Haematobia irritans

100 Flies

Why does Haematobia irritans have the most drug resistance out of all the flies we discussed

They feed so many times a day that the gene pool quickly adapts

Specific fly control mechanism that works due to the unique behavior of Haematobia irritans

Walk-through fly traps

Common name for Melophagus ovinus 

Sheep ked, louse fly

Why are Melophagus ovinus often confused for lice

Wingless and dorsoventrally flattened

Breeding site of Melophagus ovinus 

On their host sheep

Clinical signs associated with Melophagus ovinus in sheep

• Inflammation → loss of wool production

• Anemia

Vector borne by Melophagus ovinus 

Blue-tongue virus

Important factor when treating sheep for Melophagus ovinus 

The treatment needs to penetrate the wool

Stage of Melophagus ovinus susceptible to treatment

Adults (not pupa)

Common name of Musca spp.

Filth flies or nuisance flies

Nutrition for Musca spp.

Secretions

How do Musca spp. feed

They sponge up secretions

Breeding site of Musca spp.

Animal feces

Musca spp. that is a vector for Habronema and Draschia

Musca domestica (house fly)

Musca spp. that is a vector for Thelazia

Musca autumnalis (face fly)

General fly control principles

• Stable animals away from the flies

• Barriers

• Target breeding sites

• Eliminate standing water

• Open pasture for airflow

• Insecticides on premise

Principles to minimize fly breeding sites

Remove water and fresh feces

Why does fly control fail so often

Your fly control is only as good as your neighbor’s

Common fly control mechanism in horses

Pyrethroid sprays

Common fly control mechanism in cattle

• Ear tags

• Dusts

• Pour-ons, spot-ons

• Injectables

• Back and face rubbers

• IGRs

IGR

Insect growth regulator; feed through product that inhibits larval growth in feces