The state has had to do more spraying than it might otherwise. Ordinarily it augments spraying by releasing a swarm of sterile fruit flies, which dilute the population of flies capable of breeding. Normally an area would be sprayed once or twice before the release of sterile fruit flies to finish the job, but a shortage of sterile flies has led the state to continue spraying many areas every few weeks for several months.

State officials say there is no effective alternative, and they say they will continue the spraying despite the protests.

''None of this will change the protocol and procedures we use,'' said a spokeswoman for the State Agriculture Department, Veda Federighi.

'None of Your Business'

But the issue has provoked strong feelings among local residents. Although malathion is not known to cause any health problems, a coalition of environmental groups and grass-roots protesters say they believe further testing is necessary.

''There's a growing unease about the safety of long-term exposure to malathion,'' said Rick Cole, a Pasadena City Councilman.

''There's also a sense that the state has displayed an arrogant disregard for the right of citizens to informed consent,'' he said. ''The state is saying, 'We know what we're doing and it's none of your business.' And Pasadenans, like most Americans, don't like being pushed around.''

Pasadena officials sent their police helicopter up early this morning, knowing that the state planned to spray a section of the city. The helicopter was piloted by Lieut. Terry Blumenthal of the Pasadena police force, and also carried two other officers and Mr. Cole.