Will it be a bad summer for mosquitoes in Illinois? Here's what to know to stay safe

While periodical cicadas only occur in Illinois briefly, every 13 or 17 years — and don't sting or bite — another type of insect appears every year, all summer long, and most definitely bites. Some of them even spread diseases.

Are you ready for mosquitoes? Here's what to know about mosquito season this year.

What kinds of mosquitoes are in Illinois?

Two different kinds of mosquitoes bedevil the Prairie State, says the Illinois Department of Public Health:

Inland floodwater mosquitoes lay eggs in areas that will be flooded later and, in normal summer temperatures, emerge about two weeks after heavy rains. While "vicious" biters, floodwater mosquitoes have not been significant disease carriers in Illinois. The inland floodwater is the most common mosquito in Illinois.

Related: Cicadas broods map: Why are there so many cicadas in Illinois?

Vector mosquitoes, on the other hand, carry diseases. They lay their eggs in stagnant ditches, sewage treatment ponds, water in tree holes, discarded tires, clogged gutters and anything else that can hold water. Their eggs usually hatch within three days. Two common vector mosquitoes in Illinois are the Culex, or house mosquito, and the tree-hole mosquito.

Another disease-carrying mosquito is the Asian tiger mosquito, which arrived in the United States in 1985 in old tires. It is an aggressive day-biting mosquito that breeds in water-filled artificial containers, says the IDPH.

What diseases do mosquitoes carry?

While floodwater mosquitoes are not major transmitters of human disease, they do spread heartworm disease in dogs, according to the IDPH. The worms can severely weaken or kill a canine. The difficult-to-treat disease is easily prevented by medication prescribed by a veterinarian. Vector mosquitoes also transmit heartworm disease in dogs.

The most common human illness carried by mosquitoes is encephalitis, an inflammation of the brain, says IDPH. Severe cases sometimes result in death or permanent physical and mental disabilities. The last major nationwide epidemic of mosquito-borne encephalitis happened in 1975.

Culex mosquitoes, which bite from dusk to dawn, can carry St. Louis encephalitis and West Nile virus. Tree-hole mosquitoes, which bite during the day, are the main vector of California (LaCrosse) encephalitis in Illinois, says IDPH.

Related: How long is the cicada season in Illinois?

The IDPH recently announced the first two batches of mosquitoes to test positive in 2024 for West Nile virus in Illinois — one in Cook County and one in Morgan County. The confirmation follows a mild winter and spring and comes two weeks earlier than in 2023.

Most people infected with West Nile virus will not show any symptoms, but in rare cases, severe illness including meningitis, encephalitis, or even death can occur.

Last year, there were 119 human cases of West Nile virus and six deaths reported in Illinois, said the IDPH, citing provisional data.

What is the mosquito outlook for 2024?

Many published reports predict a bad season for mosquitoes in 2024.

Warm temperatures, plentiful rainfall and high humidity are all favorable to mosquito activity. In addition, a mild winter means more mosquitoes may survive the colder months.

The 2023-24 winter season in central Illinois saw well above normal temperatures overall, according to the National Weather Service.

When is mosquito season in Illinois?

Most sources list April and May as the beginning of "mosquito season" in Illinois. The average start is early to late April, according to the website Mosquitomagnet.com. Breeding season can last through September.

Related: What animals eat cicadas?

What can homeowners do to reduce the mosquito population?

The best defense against mosquitoes and the illnesses they may carry is to eliminate the places where they breed, says the IDPH. Among its suggestions:

• Empty water in old tires, tin cans, buckets, drums, bottles or other places where mosquitoes might breed. Check clogged gutters. Make sure cisterns, cesspools, septic tanks, fire barrels, rain barrels and trash containers are covered tightly.

• Empty plastic wading pools at least once a week and store indoors when not in use.

• Change the water in birdbaths at least once every week.

• Empty pets' water bowl daily.

• Level the ground around your home so water can run off and not collect in low spots. Fill in holes or depressions near your home that accumulate water.

• Fill in tree rot holes and hollow stumps that hold water.

• Keep weeds and tall grass cut short; adult mosquitoes look for these shady places to rest during the hot daylight hours.

• Use a flyswatter or household spray to kill mosquitoes, flies or other insects that get into buildings. Spray shrubbery and high weeds to kill adult insects. (Check the insecticide label to make the sure the spray will not damage flowers or ornamental plants.)

How can people protect themselves from mosquito bites?

IDPH offers the following advice to avoid the insects that "plague Illinoisans."

• Avoid places and times when mosquitoes bite. Peak biting periods usually occur just before and after sunset and again just before dawn. But each species has its own peak period. Tree-hole and Asian tiger mosquitoes feed during daylight hours in or near shaded or wooded areas.

• Ensure door and window screens are tight-fitting.

• Wear appropriate clothing. "Long-sleeved tops and long pants made of tightly woven materials keep mosquitoes away from the skin. Be sure, too, that your clothing is light colored. Keep trouser legs tucked into boots or socks."

• When outdoors, apply insect repellent as indicated on the product label. The more DEET a product contains, the longer the repellant can protect against mosquito bites. However, concentrations higher than 50% do not increase the length of protection. For most situations, 10% to 25% DEET is adequate. Apply repellents to clothes whenever possible; apply sparingly to exposed skin if label permits. Consult a physician before using repellents on young children.

On the other hand, some mosquito control methods are not very effective, says IDPH.

• Insect light electrocutors ("bug zappers") or sound devices do little to reduce biting mosquitoes in an area.

• Spraying your backyard with an insecticidal fog or mist is effective only for a short time. Mosquitoes will return when the effect of the spray has ended.

Daily mosquito-risk updates by city

The AccuWeather website includes seven-day mosquito activity forecasts for various central Illinois cities, including Peoria.

Cicadas 2024: Trillions of cicadas set to emerge in U.S. When do the cicadas come out in Illinois?

This article originally appeared on Journal Star: Will it be a bad summer for mosquitoes in Peoria and Illinois?