Do ticks and mosquitoes transmit COVID-19? And how is wet weather affecting pest activity?

by Brianna Crandall — April 20, 2020 — The National Pest Management Association (NPMA) released a clarification about pest transmission of COVID-19 and other diseases this week, and issued its bi-annual Bug Barometer forecast for the continental United States.

Transmission of COVID-19 and other diseases

In times of crisis, an overabundance of news, opinions, facts and myths starts to circulate, leading to a heightened level of panic and uncertainty. According to new research, there were over 4 million online conversations in March on the topic of pests and their ability to transmit COVID-19. Because the gravitas of the current COVID-19 pandemic is already at an apex without the addition of speculation, the National Pest Management Association (NPMA) has set out to dispel at least one misconception about pests and how the disease is being spread.

Jim Fredericks, Ph.D., chief entomologist for the NPMA, remarked:

The amount of information people are receiving right now, whether fact or fiction, is enough to make anyone’s head spin. At this time, there is currently no evidence to suggest that pests like mosquitoes and ticks can be implicated in the transmission of COVID-19. They are, however, able to transmit other serious diseases such as West Nile virus and Lyme disease. With summer right around the corner and people spending more time outdoors than ever before, vigilant pest prevention efforts will be paramount to public safety.

To help Americans decipher the true threats associated with pests, NPMA is breaking down the most common culprits of disease transmission and how to protect against them.


Mosquitoes are vectors of numerous diseases, including West Nile virus, Zika virus, Eastern Equine Encephalitis, malaria, yellow fever, dengue, chikungunya and more. Symptoms range from mild to severe, and all can be life-threatening if not treated quickly.

Where they’re found: Outdoors, especially near standing water. Even something as small as a bottle cap can support the development of hundreds of biting mosquitoes.

Prevention Tip: Conduct weekly inspections around the property and empty any containers of standing water, as mosquitoes only need half an inch of water to breed.


Ticks such as the blacklegged tick are able to transmit Lyme disease, anaplasmosis and babesiosis. Other tick species such as the American dog tick, Rocky Mountain wood tick and brown dog tick are able to transmit Rocky Mountain spotted fever, which is fatal in 20 percent of cases if not caught early enough.

Where they’re found: Overgrown vegetation at tree lines and foot trails through high grass.

Prevention Tip: Keep grass cut low, including around fence lines, sheds, trees, shrubs, swing sets and other difficult-to-cut locations.


Rodents such as the common house mouse are able to spread Salmonella, while Norway rats and roof rats are also able to transmit plague, typhus, leptospirosis, rat-bite fever, trichinosis and more. Inhaling dust that contains mouse droppings or urine can exacerbate asthma and allergy symptoms as well, especially in children.

Where they’re found: In homes and businesses, rodents are well adapted to live in close association with human activity.

Prevention Tip: Seal all holes larger than a dime and gaps wider than the diameter of a pencil (1/4 inch) to prevent rodents from getting indoors, as mice can fit through holes the size of a dime and rats the size of a quarter.

*Online engagement findings are a result of research conducted by Advanced Symbolics Inc.

Bug Barometer

As temperatures and precipitation levels increase, so, too, do pest populations. Despite this unwelcome fact, especially in the midst of collective concerns around the growing COVID-19 pandemic here in the US, NPMA says it remains steadfast in its mission to protect public health from the threats posed by pests. The organization’s bi-annual Bug Barometer is a seasonal projection of the pest pressure Americans can expect to see in their respective regions. This information is designed to encourage proper pest prevention and protection measures to reduce pest encounters that can pose a risk to health, homes and businesses.

Cindy Mannes, vice president of public affairs at NPMA, pointed out:

It goes without saying that this is a sensitive and uncertain time not only across our country, but across the globe. With people spending more time in their homes and yards, they may be surprised at how much pest activity they begin to notice. Unfortunately, pest pressure and populations won’t slow down this time of year and it’s important to stay vigilant against insects and rodents, which can contaminate food, inflict harmful bites and stings, transmit disease and damage property.

According to the group’s team of entomologists, ongoing warm, wet weather has allowed pest populations to spike early and will enable them to thrive throughout spring and summer across most of the US.

Fredericks explained:

Coast to coast, our country experienced unseasonably warm and wet conditions this winter, allowing certain pest populations not usually seen during this time of year to surge in population. These conditions allowed vector pests such as ticks, responsible for the spread of Lyme disease, and mosquitoes, common vectors of West Nile virus, Zika virus and eastern equine encephalitis to get a jumpstart on activity, and with more warm and wet weather predicted for summer across most of the US, we’ll likely see these populations, and others, rapidly expand.

Property owners should also be prepared for increased pressure from structural pests as well.

Fredericks added:

Damp conditions predicted for the Northeast, Southeast and South Central regions this spring and summer will enable termite, cockroach and ant populations to take hold and thrive. In areas expecting less moisture this season, stinging insects will also pose a significant threat, as families will be spending more time outdoors, increasing their likelihood of exposure to these dangerous pests, which send over 500,000 people to the emergency room every year.

Based on this analysis, the National Pest Management Association’s Spring/Summer Bug Barometer is forecasting a spike in moisture-loving pest populations across most of the US this season:

Northeast and New England

A warm, dry spring followed by a warm and wet summer will contribute to an increase in tick activity. Damp conditions throughout the summer will also provide ideal conditions for ants, specifically carpenter ants, and termites to thrive.


A mild and rainy spring will create conducive conditions that allow mosquito and termite populations to thrive. Summer conditions in southern Florida may also cause a spike in cockroach and ant pressure.

Great Lakes, Ohio Valley and Midwest

Warm and wet conditions throughout spring and summer across the entire region will contribute to an increase in tick pressure, and may result in greater ant populations.

North Central US

Warm, dry summer conditions in the southern part of the region will help ant populations thrive, and could mean more exposure to stinging insects. While cool conditions in the northern part may delay in tick activity, increased precipitation will create ideal conditions for mosquito populations to grow.

South Central US

A warm spring followed by a warm and wet summer across the entire region is expected to result in an increase in pest pressure, specifically for termites, ticks and cockroaches.

Southwest US

Cooler, wetter conditions throughout spring and summer are expected to drive ants indoors. Expect an increase in cockroach and stinging insect populations throughout the region.

Northwest US

Humid conditions throughout spring and summer in the eastern part of this region will allow stinging insect and tick populations to flourish. Warm and wet conditions in the western part of this region may also contribute to increased mosquito populations.

For more information on pests and pest management, visit NPMA’s website.