County helicopters will launch an aerial assault next week on a mosquito species that county officials say has been laying its eggs in the marshy soil of the Palo Alto Baylands and surrounding areas.
The Santa Clara County Vector Control District has announced that, weather permitting, it will be applying a biological control agent and insect-growth regulator in certain marshes of the county's coastal areas. These include the ITT Marsh and the Palo Alto flood basin in Palo Alto and the Zanker Marsh near Alviso, the district announced.
The aerial assault will target the winter salt marsh mosquito, which lays its eggs in late spring and early summer. Eggs can lay dormant for many years, according to the district, and can hatch as early as November. According to the vector district, which has been monitoring the mosquito larvae, current field conditions and mosquito growth trends "indicate a high probability that a significant number of salt marsh mosquitoes will become adults in early to mid-March if left untreated."
The goal of the operation is to "minimize the number of mosquitoes and reduce the risk of mosquito bites to residents in the surrounding communities."
"If left untreated, this species is known to bite viciously during the day and can fly over 15 miles from its breeding grounds to feed on humans and other mammals," the announcement states.
The range of the marsh mosquitoes -- also known as "aedes squamiger" -- means that they can affect residents from the north coastal areas, including Palo Alto, to the southermost part of San Jose and Milpitas in the east.
The operation will treat about 725 acres in Palo Alto and 90 in Alviso with methoprene, an insect-growth regulator, and a bacteria called bti. When consumed by mosquito larvae, bti produced an insecticidal protein that kills the larvae, according to the vector district. The announcement notes that these products are mosquito-specific and "short-lived in the environment." They are not harmful to birds, fish, other insects, wildlife or humans, the district said.
The operation is set to start in Palo Alto at about 7:30 a.m. on Feb. 16 and then proceed to Zanker Marsh. If needed, it may be extended to Feb. 17. The application of the larvicide is designed to produce large droplets, according to the district, that go "straight into the marsh with minimal drift to surrounding areas."
In Palo Alto, the helicopter may make low-altitude passes over trails surrounding the treatment area, the district said, and the public is advised to avoid areas where the helicopter is operating. The district will post signs and various locations where treatment will occur and staff will be available to notify visitors about the operation.
"Treatment in the coastal areas of the county is necessary to offset the hatching of aedes squamiger eggs, which has been facilitated by winter rains," said Assistant District Manager Russ Parman. "We hope to decrease mosquito numbers by 90 percent with the aerial operations, and significantly reduce the extreme nuisance caused by these mosquitoes well into the summer."
The district also encourages residents to report mosquito-breeding sources and take preventive measures such as wearing long-sleeved shirts and long pants and using repellent.
More information is available at 408-918-4770 or at SCCvector.org.
Comments
Greenmeadow
on Feb 10, 2017 at 10:52 pm
on Feb 10, 2017 at 10:52 pm
According to NPIC (jointly operated by Oregon State and US EPA):
"Methoprene is moderately toxic to some fish (rainbow trout), and highly toxic to others. In three studies on bluegill sunfish, the results were different in each case, ranging from moderate to very high toxicity. Methoprene can accumulate in fish tissues. It is moderately toxic to crustaceans such as shrimp, lobsters and crayfish, and very highly toxic to freshwater invertebrates."
These pesticides may not be that dangerous to humans, but it sounds like they mess up the food chain. On the East Coast, states are now restricting the use of Methoprene to protect lobster and fish populations. Researchers have also determined that methoprene applied at mosquito-control concentrations caused malformations among southern leopard frogs.
Do we really need to kill these mosquitos?
Registered user
Crescent Park
on Feb 10, 2017 at 11:11 pm
Registered user
on Feb 10, 2017 at 11:11 pm
"Do we really need to kill these mosquitos? "
Absolutely - remember a few summers ago, when the levees were leaking, and the marsh mosquitos were biting? It made it miserable to go outside. Large painful bites. They gotta go.
Another Palo Alto neighborhood
on Feb 11, 2017 at 3:58 pm
on Feb 11, 2017 at 3:58 pm
We are spoiled--the worst mosquito day in Palo Alto is far better than a typical day in the south.
Our superficial desire to mindlessly spew chemicals to create a bug-free paradise will someday have serious health consequences. Just as routine antibiotic use produced drug-resistant bacteria, our routine methoprene use is producing methoprene-resistant mosquitos. This isn’t just an issue about getting painful bites. Sooner or later, these methoprene-resistant mosquitos will be spreading diseases to humans.
Unfortunately, our county’s vector control has a 1950s spray-everything mindset. Our first line of defense should be using natural predators like birds and bats, saving the chemicals for disease outbreaks where lives are at stake.
The danger that drug-resistance bacteria pose today makes our past antibiotic overuse look rather reckless in hindsight. Today’s routine use of methoprene will someday look similarly cavalier.
Midtown
on Feb 12, 2017 at 3:33 pm
on Feb 12, 2017 at 3:33 pm
Chemistry for better living!
Ohlone School
on Feb 13, 2017 at 9:52 am
on Feb 13, 2017 at 9:52 am
Are the local mosquitoes known to spread specific diseases? Or is the spraying just to reduce itchy bites?
Professorville
on Feb 13, 2017 at 2:04 pm
on Feb 13, 2017 at 2:04 pm
There were one or two years during the Great Recession when the mosquitoes were under-controlled. I don't go to or live near anywhere marshy, but how else can it be explained that I caught a severe case of West Nile Virus, which kept me sick for three months??