Standing Water Not Always A Mosquito Breeding Pool

Armen Hareyan's picture

Recent monsoon rains have filled washes, rivers and even some streets with running water. In most cases, the water moves on and things dry out until the next rain.

Pima County's topography influences where water flows, soaks in, or remains standing. Some water may stand for an hour, a day, or longer. Mosquitoes need approximately three days of standing, calm water to breed their larva.


"Most pools of standing water evaporate or soak into the ground, which does not allow time for mosquito eggs to hatch" said Patti Woodcock, Community Relations Manager for the Pima County Health Department. "Water in motion does not allow breeding either. Think of puddles in the road when vehicles drive through. Any eggs that might have been laid there would be dispersed and destroyed."

In addition, residents should be aware that while monsoon rains cause brief, rapid growth of weeds and grasses, mosquitoes do not lay eggs there. City and County staff, however, will continue to clear excessive brush on public right-of-ways and in wash channels.

Residents should call the West Nile Virus hot line at 243-7999 to report water that has been standing for three or more days on public property, as well as continue to monitor their own properties for standing water. Public sites that have been treated are marked with non-toxic, biodegradable blue or orange paint that includes date of treatment, initials of responding agency (PC or COT), and L for larvicide.


Please, click to subscribe to our Youtube Channel to be notified about upcoming health and food tips.