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March 24 2015 – Coyote Hills Regional Park Trail Closure for Larval Mosquito Treatment

HAYWARD – The Alameda County Mosquito Abatement District will be conducting a helicopter treatment for larval mosquitoes which will require the closure of park trails.  All Coyote Hills Regional Park trails will be closed on Thursday, March 26th until operations are completed.  Trails will reopen in the afternoon.

Unseasonably high temperatures have created large numbers of marsh mosquitoes, primarily Culiseta inornata (the winter marsh mosquito) and Culex tarsalis (the encephalitis mosquito).  Culex tarsalis is an important vector of West Nile virus.  Access throughout the marsh is very difficult making an aerial application necessary.

Larval mosquitoes will be treated with two bacterial products, Bacillus sphaericus (Bs) and Bacillus thuringiensis israelensis (Bti).  Both Bs and Bti are extremely mosquito specific and do not affect other aquatic life.  Products will be applied in granular form.

“Our mosquito control program focuses on treating mosquito larvae in the water where they are developing,” says District Environmental Specialist Erika Castillo.  “With this helicopter treatment, we will be able to treat a large amount of water quickly, greatly reducing the number of adult mosquitoes coming from the marshes.”

The Alameda County Mosquito Abatement District is also asking the public to rid their property of any standing water and report any dead wild birds (especially crows, ravens, jays, magpies and birds of prey).  Dead bird reports can be done online through the California Department of Public Health website at

The public can access information about the planned helicopter treatment, mosquitoes, West Nile virus, and mosquitofish on our website:  Residents can also pick up FREE mosquitofish at our District office from 7:30-4:30pm for their ornamental ponds, horse troughs, or neglected swimming pools.  We are located in Hayward at 23187 Connecticut St.  Our phone number is (510)783-7744.