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Larvicide Aerial Application

GCMCD is approximately 540 square miles of prime mosquito
habitat consisting of:



Crab Creek

Gloyd Seeps-North Columbia Basin State Wildlife Recreation Area

Winchester Wasteway

Frenchman Hills Wasteway

Potholes Reservoir

Moses Lake

Rocky Ford Creek

Royal Slope

Portions of the Columbia National Wildlife Refuge

Numerous smaller irrigation drainages


To cover this massive area, GCMCD has specific and specially modified loading and application equipment.  The primary application source is a Thrush 550 P aircraft located on site.  The aircraft can directly target and apply control agents to approximately 300 acres in an hour making it extremely cost effective and a superb contributor to the District’s arsenal.  The target application height is approximately 20-40 feet above the ground and a flight speed of 140 mph.  The aircraft is equipped with GPS guidance and application avionics used to precisely apply active agents to within tenths of a pound per acre.  While GCMCD tries to avoid flying during holidays and weekends, we do not have a set schedule for application due to changes in weather, water levels, and the countless other variables.


The primary goal of the aerial larvacide program is to target stagnant water in undeveloped non-agricultural waterways.  Application priority is in areas adjacent or within:


1) Inhabited resident and business areas regardless of the number of dwellings

2) Recreation areas where large numbers of people gather such as parks, campsites and lake shores

3) Major unconfined irrigation water ways such as Crab Creek and Frenchman Hills Wasteway

4) The lowest priority is on areas such as flood irrigated cropland and pastures where mosquito populations are self/human-propagated 


The primary control method is an application of dry larvacide granules.  The granules are applied directly to mosquito larvae habitat which mostly consists of stagnating water sources.  The majority of these active ingredients specifically target mosquito larvae, organic, and extremely safe.  The granules vary in density, but are about the size of lawn fertilizer. 


GCMCD utilizes several different active ingredients to include:


Bacillus thuringiensis israelensis (Bti)

Bacillus sphaericus (BS)



Larvicide aircraft
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