Firefighters said they're starting to feel under attack. They have been wearing their long-sleeved yellow jackets most of the time to keep the mosquitoes off of them.
They're also warning people who live in the city about the problem and advising them to get rid of all standing water around their homes or in gutters to help aid in the issue of decreasing the mosquito problem.
In addition to clearing standing water, you can also use mosquito fish and frogs in water features at home to act as a natural defense against mosquitoes.
The first human West Nile virus case of the year in California was reported last week, in Kings County.