Hillsborough expanded mosquito control as traps showed dengue virus activity

The county said daytime helicopter flights mainly target mosquito larvae. The helicopters apply a liquid larvicide called Bacillus thuringiensis israelensis, or BTI. BTI is a naturally occurring bacterium, the county said. When used appropriately, BTI is not harmful to people, pets, fish, birds or beneficial insects.

Pilots fly low to treat coastal areas. Helicopters can drop to just a few feet off the ground. The low flights can be louder than residents are used to.

Nighttime flights

Nighttime flights target adult mosquitoes. These treatments generally start after sunset and end before sunrise. The county uses Dibrom, an EPA-registered insecticide, for these flights. Ultra-low volume equipment applies it in extremely small droplets. Residents may notice an odor. The county said the treatment does not pose a health threat to people or pets.

What residents can do

The county recommends the 3 Ds:

• Dress: Wear light-colored, long-sleeved clothing and closed-toed shoes.
• Defend: Use a repellent with a CDC-recommended ingredient, such as DEET or Picaridin.
• Dump: Dump or cover standing water around your home.

Residents can sign up for alerts about localized aerial treatments at the county's mosquito operations hub.