Flea, Tick & Mosquito Seasonality & Geography

While it's true that flea, tick and mosquito activity spikes in the spring and summer months, they can pose health risks for your pet year-round.  By the time spring rolls around, these tiny bloodsuckers may already be in full bloom.

U.S. flea population map

Flea season has no off-season

Fleas don’t check the weather forecast. As long as they have a warm host like your family pet to live on, they’ll make themselves at home.

  • When is flea season? When thinking about flea season, think about more: more fleas, more active. Fleas tend to be more active during warmer months. Ideal conditions feature damp, humid weather and temperatures from 60-69˚ F — which can be as early as late February in some parts of the U.S. and even result in a fall “second season” throughout the country.

To learn when flea season kicks into high gear, look for your state on the flea map above. *Data as of June 16, 2014. This information changes frequently as more cases are diagnosed. For the most up-to-date information, click here.

  • Where are fleas found? Fleas are found in the spots where you and your pets spend the most time — such as pet beds, furniture and carpets. Hitchhiking fleas can hop a ride on people and pets as they move in and out of your house. And once inside, fleas lay eggs which can quickly develop into an infestation.
  • What can you do? Washing bedding and vacuuming floors and furniture regularly is an easy way to help keep fleas from waging war in your home. But a great way to help prevent an infestation on your pet or in your home is to routinely use prevention products. Many effective products that fit your lifestyle are conveniently available at local and online pet specialty retailers.

U.S. tick population map

Ticks are always in season

On their own, ticks live and breed in temperatures above 40˚ F. Several tick species are active all year long, regardless of temperature. Ticks transmit a variety of harmful diseases that affect pets and people alike, making year-round prevention imperative.

  • When is tick season? Typically from mid-spring through late-fall — peak tick season varies depending on where you live in the U.S. and the types of ticks most prevalent in your area.

For an estimate of where multiple species of ticks and their numbers may be highest in your area, look for your state on the tick map above. *This information changes frequently as more cases are diagnosed. For the most up-to-date information, click here.

  • Where are ticks found? Ticks hang out where they can easily feed on live animals, most notably in wooded areas and grassy spots like your own backyard, a park or a field. Adult ticks cling to tall blades of grass or lower-hanging foliage until they can attach themselves to passing animals.

Are city dwellers safe? Ticks love urban areas, too! It’s often warmer in cities. You can find them in everyday places such as planters, trees and parks.

  • What can you do? Because ticks love long grass and low-hanging bushes, keep your yard mowed and your foliage trimmed. Treat your yard with products that offer additional tick protection for your home, deck and patio. Check your pet for ticks on a regular basis and get in the habit of doing daily tick checks when tick activity or your pet’s outdoor access is higher. Find prevention products at local or online pet specialty retailers and then remember to apply them properly and routinely.

U.S. mosquito population map

Mosquito season bites

Unlike fleas and ticks, mosquitoes are temperature sensitive and have more of a traditional season throughout most of the U.S. Their buzzing, biting and resulting itch are bothersome enough, but the main concern with mosquitoes is that they can transmit heartworms, leading to a potentially fatal disease for your cat or dog. Luckily, there are protection products for dogs that kill mosquitoes through contact, plus heartworm prevention products for both cats and dogs.

  • When is mosquito season? Mosquitoes thrive in 75-80˚ F weather and aren’t as active when temperatures drop. Traditionally, that means most of the U.S. sees an increase beginning in May with heightened activity well into August.

Heartworms and mosquitoes go hand in hand. For a better idea of where mosquitoes are found and affecting dogs, follow the forecasted heartworm disease prevalence map above and look for your state, or click here and select Heartworm on the Parasite Prevalence Map. *This information changes frequently as more cases are diagnosed.

  • Where are mosquitoes found? Mosquitoes require stagnant water to breed, so areas with puddles, storm drains, water troughs, bird baths or any kind of container where water can collect are a potential nursery. When ready to feed, mosquitoes are attracted to people and animals, sensing a meal from as far as 100 feet away. Small and quick, they easily find their victims indoors and outdoors.
  • What can you do? Because mosquitoes can transmit deadly diseases, it is important to eliminate or avoid areas where they like to breed. Fortunately for our pets, there are a number of highly effective and safe heartworm disease prevention products available. Speak with your veterinarian about finding the right one for your dog or cat. Additionally for dogs, there are products that offer mosquito protection by killing them through contact. Products that kill through contact do not require mosquitoes to bite in order to die.

Prevention season starts now!

Bayer offers a wide range of effective flea, tick and mosquito prevention and treatment products, and heartworm prevention products. Find them at pet specialty stores and veterinarian offices.

Related articles:
Flea Diseases in Dogs
Tick Diseases in Dogs
Heartworms in Dogs
Mosquito Diseases in Dogs

Disclaimer: This is provided for your information only and is not intended to diagnose or treat any medical condition. Should you have any symptoms or concerns, please contact your veterinarian.

Bayer Products

  • K9 Advantage® II for extra large dogs and large dogs packing

    K9 Advantix® II

    A once-monthly topical application that kills and repels fleas, ticks and mosquitoes.

    Do not use on Cats.

    K9 Advantix® II

    Indicated for:


    Do not use on Cats.