Mosquito numbers are down “seven fold” after three consecutive nights of fogging in and around the wetlands on the western side of Moab with Biomist 4+4, according to Moab Mosquito Abatement Manager Libby Nance, and further efforts to combat the mosquitoes are ramping up.

Grand County Clerk/Auditor Chris Baird announced on Tuesday, July 9, that Vector Disease Control International, Grand County, and the Moab Mosquito Abatement District have scheduled an aerial operation to apply a granular larvicide, Altosid P35, over approximately 300 acres within the Scott M. Matheson Wetlands Preserve to reduce the number of mosquitoes before they hatch.

In a press release, Baird stated the aerial application will be performed Sunday, July 14, weather permitting; the backup application date is Monday, July 15. The Scott M. Matheson Wetlands Preserve will be closed for the duration of the treatment.

Baird said Altosid P35 is effective against almost all species of major nuisance and vector mosquito species and is one of the principle insecticides used for larval mosquito control in the United States. The active ingredient is (S)-methoprene.

“The insect growth regulator is immediately activated when wet and released to start controlling adult mosquito emergence,” Baird said. “Altosid provides up to 35 days of residual control in continuously wet conditions and offers pre-treatment capabilities 15 days…pre-hatch. (S)-methoprene degrades rapidly in the sunlight, both in water and on inert surfaces, meaning that it should not persist in soil or contaminate ground water.”

Nance said the larvicide has no effect on non-target species such as bees, frogs, fish or aquatic invertebrates.

The chemical’s safety data sheet also says that it is not classified as a carcinogen nor a reproductive toxin.

Vector Disease Control International (VDCI), a mosquito control company operating out of Ogden, Utah, will be using a single-engine aircraft flying at an altitude of approximately 300 feet to conduct the aerial application. Baird said the aircraft is equipped with an aerial spray guidance system specifically engineered for mosquito control operations, and this method of application will allow them to treat in areas with limited road accessibility. Fogging with Biomist 4+4 is also planned to continue until mosquito numbers are down to target levels.

Aerial treatment of larvicide, continued fogging planned