Controlling Insects After Flooding: How To Minimize Mosquito, Fly And Other Insect Problems

After a flood, mosquitoes, flies and other insects may be more abundant than usual, posing potential health problems. Filth and debris left by the storm create excellent breeding conditions for houseflies and mosquitoes, some of which may be capable of spreading typhoid, dysentery and encephalitis. The key to controlling insects is removal of their breeding places-any standing water, especially stagnant water. In warm weather this should be done immediately after you return to the premises.

  • Empty water from barrels, old tires, cans and other vessels. In addition to being a breeding place for insects, this water may be polluted by floodwaters. Check clogged gutters and flat roofs that have poor drainage. Make sure cisterns, cesspools, septic tanks, fire barrels and rain barrels are covered tightly.
  • Drain ponds, pools or any standing water in which mosquitoes may breed.
  • If drainage is impossible, treat water puddles still standing after a week with larvicide as recommended by a county Extension agent.
  • Dispose of refuse. Bury animal carcasses as soon as possible. Remove garbage at least once every week. Be sure garbage cans have tightly fitting lids. When using manure and garbage as a fertilizer, spread it thinly so it will dry quickly and not support fly development.

Patch screens and other places where mosquitoes may enter buildings.


Use a household spray or an aerosol bomb to kill mosquitoes, flies or other insects that get into buildings. Spray shrubbery and shaded areas of buildings to kill adult insects. Contact your county Extension agent for specific recommendations.

If possible, keep small children indoors, especially in the evening. If you must go outside at dusk, use a repellent on exposed parts of your body and clothing.

Additional resources:

Your county agricultural agent

Disclaimer and Reproduction Information: Information in NASD does not represent NIOSH policy. Information included in NASD appears by permission of the author and/or copyright holder. More