Mosquitoes Affecting Animal Health

Importance

  • There are over 3,000 species of mosquitoes worldwide. Mosquitoes are an important food source for many animals. Some mosquitoes can also be beneficial as pollinators. However, some mosquitoes can transmit pathogens to people and animals.
  • Mosquito-borne diseases affect millions of people and animals each year throughout the world. Signs of mosquito-borne disease commonly include fever, lethargy, muscle aches, and headaches. Severe illness can lead to neurological damage, including encephalitis and death.
  • Foreign animal diseases (FADs) are not found in the United States and can threaten human and animal health. FADs can be introduced to the United States, so animal owners and veterinary personnel have a key role in recognizing and reporting FADs to animal and public health officials. Early signs of mosquito-related FADs may include:
    • Unusual mosquito appearance, abundance, or distribution
    • Large number of sick or dead animals
    • Unusual signs of illness (like abortion storms or neurologic disease)

About Mosquitoes

Mosquito species differ by where they lay eggs, what animals they feed upon, when they are active, and how far they can fly. Some mosquitoes don’t fly far, while others can fly several miles.

  • The mosquito life cycle has four stages: egg, larva, pupa, and adult.
    • Eggs are laid in or near water.
    • Larvae (wigglers) and pupae (tumblers) live in the water and feed on organic matter.
    • Adults live on land and feed on nectar from plants or blood from animal hosts (typically birds and mammals).
  • All mosquitoes require standing water to complete their development.
    • Some species lay single eggs on damp soil (that is later flooded by water) while others lay an egg raft (containing up to hundreds of eggs) on the water’s surface.
    • Some species lay eggs in larger water sources, like ponds and swamps. Other species may use small containers that collect water, such as a discarded tire or bottle cap.
  • Most eggs hatch within 48 hours, but some can remain dormant for years.
  • Mosquitoes typically live for two to three weeks. Some species in cold climates survive winter in the egg, larval, or adult stage.
Life cycle of a mosquito consists of a blood-fed adult female laying eggs singly or in rafts in the water which then hatch into a larva which then develops into a pupa and adult that emerges on the surface of the water.

Identification of Mosquitoes

  • Many mosquito species can be identified by a unique set of characteristics visible to the naked eye or with the help of a dissecting microscope.
    • Some mosquitoes, especially closely-related species, may be difficult or impossible to identify without the help of a trained entomologist or molecular testing.
  • Adult mosquitoes are slender, long-legged insects with one pair of wings, scales on wings, and long mouthparts (proboscis) used for sucking blood or nectar.
    • Antennae in males are bushier than in females.
    • Palps (sensory organs near the proboscis) may be long or short, depending on the species.
    • Coloration of hairs on the body, wings, and legs varies by species.
  • Identification of mosquito larvae and pupae uses different characteristics, but is more challenging than the identification of adult mosquitoes.
  • Identification keys and mosquito experts can be consulted for further details.
Diagram of a mosquito's basic anatomy pointing to features on the head: proboscis (mouthparts), antennae, and palps

Mosquitoes of Animal Health Concern

The mosquitoes listed below are commonly found in the United States. In certain areas, these mosquitoes may transmit pathogens. Endemic diseases in animals may or may not be reportable, depending on the jurisdiction. Foreign diseases listed below are Notifiable Diseases and Conditions by the United States Department of Agriculture (USDA). Learn more about recognizing and reporting FADs at CFSPH: FAD Prevention.

Close-up view of resting Aedes aegypti

Muhammad Mahdi Karim, GNU Free 1.2

Name: Aedes spp. (A. aegypti, A. albopictus, A. japonicus, A. vexans)

Characteristics: Distinctive black and white striping on legs and body, most active during dawn and dusk. Eggs laid individually near water, which hatch when they come into contact with flood water.

Habitat: Prefer small containers (tires, flowerpots, bird baths) or natural sources of standing water. Most abundant in southern U.S. but can live in temperate areas.

Endemic Diseases:

Eastern equine encephalitis
Fowl pox
Tularemia
West Nile virus disease
Western equine encephalitis

Foreign Diseases:

Akabane

Japanese encephalitis

Lumpy skin disease

Rift Valley fever

Venezuelan equine encephalitis

Close-up view of resting Anopheles merus

CDC Public Health Image Library/James Gathany

Name: Anopheles spp. (A. freeborni, A. quadrimaculatus)

Characteristics: Smaller than other mosquitoes, dark brown with spotted wings, hold body at angle (head down, abdomen up) when at rest. Individual eggs laid on water surface.

Habitat: Prefer clean, unpolluted water like ponds or slow-moving streams. Found in many parts of the U.S.

Endemic Diseases:

Dirofilariasis (heartworm disease)

West Nile virus disease

Foreign Diseases:

Akabane

Venezuelan equine encephalitis

Close-up view of resting Coquillettidia perturbans.

Jason Crockwell/inaturalist, CC BY-NC-ND

Name: Coquillettidia spp. (C. perturbans)

Characteristics: Medium-sized mosquito with a “salt and pepper” appearance of brown and white, wings have tear-drop shaped scales, most active early in the evening, persistent and painful biters, strong fliers. Eggs laid in rafts on surface of freshwater near aquatic plants.

Habitat: Prefer areas of low elevation and dense aquatic vegetation like wetlands or areas with cattails, widely distributed across eastern half of the U.S. and several areas of western states.

Endemic Diseases:

Eastern equine encephalitis

West Nile virus disease

Close-up view of resting Culex quinquefasciatus

CDC Public Health Image Library/William Brogdon

Name: Culex spp. (C. tarsalis, C. pipiens, C.  quinquefasciatus)

Characteristics: Uniform brown color, no distinctive markings, hold body parallel to surface when at rest. Eggs laid in rafts on water surface.

Habitat: Prefer stagnant, polluted water like water in drainage ditches. Different species found in all parts of U.S.

Endemic Diseases:

Eastern equine encephalitis

Fowl pox

St. Louis encephalitis

West Nile virus disease

Western equine encephalitis

Foreign Diseases:

Akabane

Bovine ephemeral fever

Japanese encephalitis

Rift Valley fever

Venezuelan equine encephalitis

Close-up view of resting Culiseta incidens.

CDC Public Health Image Library/Gary Alpert

Name: Culiseta spp. (C. melanura)

Characteristics: Chocolate brown, medium-sized mosquito. Eggs laid in rafts on water.

Habitat: Prefer cool, acidic water like lowland swamps or flood plains. Found in eastern U.S. from Great Lakes to Florida.

Endemic Diseases:

Eastern equine encephalitis

West Nile virus disease

Close-up view of resting Mansonia titillans

Flickr (Sean McCann, CC BY-NC-SA 2.0)

Name: Mansonia spp. (M. dyari, M. titillans)

Characteristics: Medium-sized, brown mosquito, most active at dusk and dawn, strong fliers. Eggs laid on underside of leaves of aquatic vegetation where larvae attach to plant roots to obtain oxygen.

Habitat: Prefer large, permanent bodies of water, like retention ponds, with dense floating vegetation. Found in Southeastern states.

Endemic Diseases:

West Nile virus disease

Foreign Diseases:

Rift Valley fever

Venezuelan equine encephalitis

Close-up view of resting Psorophora ferox

Wikipedia (Katja Schulz, CC BY 2.0)

Name: Psorophora spp. (P. ciliata)

Characteristics: Larger mosquito, aggressive biters, active day and night, and strong fliers. Eggs remain dormant until water pools formed after rain.

Habitat: Prefer floodwaters. Found in tropical, warmer climates, southern U.S.

Endemic Diseases:

Leucocytozoonosis

West Nile virus disease

Foreign Diseases:

Venezuelan equine encephalitis

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Collection and Submission of Mosquitoes

  • Mosquitoes of concern should be collected for identification to ensure effective control measures are used to target the correct mosquito species in the intended way. Testing may be available to determine if pathogens are present or insecticide resistance is developing.
    • Adult mosquitoes are fragile, so care should be taken not to crush or damage the insect. They should remain dry so as not to mold.
    • Mosquito eggs, larvae, and pupae can be collected from water with a dipper, net, pipette, or turkey baster. Immature mosquitoes can degrade in water if not shipped quickly and kept in the refrigerator.
  • Laboratories and shipping companies may have specific instructions for you to follow.
    • Place adult mosquitoes in a labeled, sealed, hard-sided container and keep dry and cool in a refrigerator or freezer.
    • Place larvae and pupae in a labeled, sealed, leak-proof container submerged in 70-90% ethanol. Rubbing alcohol, hand sanitizer, or clear cocktail alcohol (80 proof or higher) will also work, if needed.

For additional tips, visit How to Submit Vectors for Identification.

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Control and Prevention of Mosquitoes

  • Mosquito populations can be managed by disrupting their life cycle and habitat.
    • For prompt detection and control, continuously monitor areas in and around animal housing for adult mosquitoes and mosquito larvae habitats.
    • Reduce mosquito larvae habitats in and around animal areas by draining, agitating, or replacing water-holding containers at least weekly.
    • Consider ways to encourage natural predators like birds, bats, and fish to help reduce mosquito populations.
  • Prevent mosquito bites to avoid pathogen transmission.
    • A variety of mosquito bite preventatives are available for animals, including topical pour-ons, sprays, and collars. Be sure to choose a product with an EPA registration number. Read the product label carefully to make sure it is effective against mosquitoes and safe for the species and age of animal to be treated.
    • Install and maintain screens on doors and windows to keep mosquitoes out of homes, barns, and other animal areas.
    • Plan outdoor activities during a time of day or time of year when mosquitoes are less active in the area.
  • Avoid moving mosquitoes from one site to another.
    • Drain and remove eggs, larvae, and pupae from water-holding containers prior to movement.
    • Inspect vehicles and other equipment that may harbor adult mosquitoes before movement, and clean and disinfect as needed.
  • Prevent mosquito-borne diseases in livestock and pets.
    • Vaccines are recommended for horses to protect against West Nile, eastern equine encephalitis (EEE), and western equine encephalitis (WEE) viruses.
    • Heartworm preventatives are recommended for dogs and cats at risk of mosquito bites.
  • Mosquito control products should only be used after consulting with experts to prevent unintended harm to wild animals and invertebrates, like frogs and honey bees. These products can also contaminate water sources.
    • Larvicides (e.g., dunks) are used in rain barrels, small bodies of water, and other water sources that cannot be drained or frequently replaced.
    • Adulticides are used to quickly reduce adult mosquito numbers in an area.

For additional guidance, visit Considerations When Managing Vectors.

Learn More

Additional information on mosquitoes, their impacts on animals, and control can be found below.

Mosquitoes

Mosquito control and bite prevention for animals

Note: This webpage shows some of the most significant vectors of concern to domestic animals in the United States. It is not meant to be a complete resource of all arthropods, their associated diseases and conditions, or used as a diagnostic tool. Veterinary consultation is advised for clinical cases.