That's thanks to spring rain leaving standing water and neglected swimming pools for breeding. Even flower pots with residual rain water can be culprits.
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Santa Clara County's vector control district is busy breeding mosquito fish in special tanks to aid in the fight against the biting pests.
Russ Parman, the district's assistant manager, says mosquito control is important, not just to control a nuisance, but also to keep Zika and West Nile viruses from spreading.
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He says one female can produce 150 to 200 eggs at a time after getting some human blood from a bite. In a span of 40 days, a female can produce 500,000 surviving mosquitoes from four generations of offspring.
Mosquito fish are being raised by the district for distribution to pool owners to eat larvae.
A recent aerial survey discovered 719 neglected pools that Parman says goes beyond an inventory of 1,455 pools already identified.
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Staff will go out to work with the pool owners to abate the problem and offer the mosquito fish.
For the latest on this developing story watch ABC7 News at 5 p.m. and click here to follow David Louie for the latest updates.
Click here for full coverage on the Zika virus.