Sacramento, Calif. (AP) -- California officials have released thousands of insects in the San Joaquin-Sacramento River Delta to combat an invasive weed that has clogged the waterway. The state Department of Food and Agriculture let more than 5,000 water hyacinth plant hoppers go at several locations in San Joaquin and Sacramento counties this month. Officials hope the insects, which are native to South America, will establish self-sustaining colonies and begin chomping down on water hyacinth. The invasive plant forms a dense carpet on the surface of waterways, impeding boat access and clogging water intake systems.