Mosquitoes, Hurricanes, and Flooding

What You Need to Know

• Adult mosquitoes do not generally survive high winds during a hurricane.
• Immediately following a hurricane, flooding occurs. Mosquito eggs laid in the soil by floodwater mosquitoes during previous floods hatch. This results in very large populations of floodwater mosquitoes. Most of these mosquitoes are considered nuisance mosquitoes.
• In general, nuisance mosquitoes do not spread viruses that make people sick. The types of mosquitoes that can spread viruses may increase 2 weeks after a hurricane, especially in areas that did not flood but received more rainfall than usual. However, it can take several more weeks before mosquitoes could start spreading viruses to people.
• Increased rainfall may result in increased hatching of mosquito eggs. In areas with ongoing spread of chikungunya, dengue, West Nile, or Zika viruses, you may be at increased risk of getting infected with a virus. Take steps to protect yourself and your family from mosquito bites.
• Because people spend more time outside cleaning up after a hurricane or flood, they are more likely to be bitten by nuisance mosquitoes. Though these mosquitoes generally don’t spread viruses, they can be aggressive biters. Some people may react more strongly to bites. Learn about mosquito bites and take steps to reduce swelling and itching. See a healthcare provider if symptoms worsen.
• Large numbers of floodwater mosquitoes can slow recovery efforts by making work outdoors difficult. Use of insecticides by mosquito control professionals can reduce numbers of mosquitoes in affected areas.
• Flooding caused by hurricanes can be severe, and an increase in nuisance or floodwater mosquito populations is expected in the weeks after flooding. However, because nuisance or floodwater mosquitoes don’t spread viruses to people, an increase in the number of people getting sick from diseases spread by mosquitoes is not expected after flooding.
• State and local health officials can request technical assistance from CDC to monitor the flooding situation.

Protect Yourself and Your Family from Mosquito Bites

• Wear long-sleeved shirts and long pants.
• Use Environmental Protection Agency (EPA)-registered insect repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone.
• Treat clothing and gear with 0.5% permethrin.
• Learn more about mosquito bites and how to protect yourself.

Take Steps to Control Mosquitoes Inside and Outside Your Home

After a hurricane or flood, the health department or mosquito control district will often take steps to reduce the mosquito population. Once flooding recedes, residents can take steps to help control mosquitoes in and around their homes to prevent mosquito bites.

• Remove standing water where mosquitoes could lay eggs. Once a week, empty and scrub, turn over, cover, or throw out any items that hold water like tires, tarps, buckets, planters, toys, pools, birdbaths, flowerpot saucers, or trash containers.
• Keep mosquitoes outside.
  • Install or repair and use window and door screens.
  • Do not leave doors, including garage doors, propped open.
  • Use air conditioning when possible.