What insects are affecting crops in California?

There are dozens. One of the pests that has been getting a lot of press lately is the glassy-winged sharpshooter, which can spread a virus that blights grape vines. With Napa being such a big wine growing area, this could have a major impact.

Another that has caused intermittent panics for the last 20 years or so is the Mediterranean fruit fly, which can infect most types of tree fruit, such as Apples and Pears.