The infestation problem is believed to have started when someone brought in contraband guava from another country without having them inspected and because they can multiply so quickly, modern science is trying to kill off the male flies.
Three trucks already have hit the streets doing very targeted spraying to kill off the fly. The technicians shoot a small amount of liquid from a nozzle at trees and telephone poles. The substance has a pheromone, or chemical, that attracts male fruit flies. It also contains the pesticide "Naled."
"The area will have this pheromone on it, attract the males, and they will consume some of the material and die. The females won't have anybody to mate with and the population will collapse," explained Santa Clara County Agricultural Commissioner Joseph Deviney.
They are about the size of house flies. It's believed they came into California as eggs or maggots in guava brought in from South America illegally and not intercepted during routine agriculture inspections.
Three guava fruit flies were found about two weeks ago. An area about 17 square miles will be targeted for spraying, east and south of downtown. "Yeah, I would consider it very safe," Jeffrey Honda said regarding the spray. He is a professor of entomology at San Jose State and he isn't worried about the use of the pesticide Naled.
"The insecticide breaks down very, very quickly. So if it's toxic at all, it's because it hits the skin or it's breathed in. But if it's mixed up with the bait, it sticks to, essentially the substrate, and allows the flies to come in and land on it, feed on it, and then die," he explained.
State and local agriculture officials worry the guava fruit fly will infest citrus and other fruit if not eradicated. "Even homeowners, we all have fruit trees in our backyards. We plant for our families. We can have our kids, we pick fruit off the tree to see where it comes from, open it up, you find maggots," Joe Deviney said.