My father drives a truck and he saw a bee truck in Needles Ca. that was pulled over and they had the hives on the ground with smokers going and it looked like they were washing or spraying the beehives. What do you think was going on?
Inspecting and pest treating bees being brought into California for pollenation. California has bees to frame ratio and treatment requirements for all bees being brought into the state. Bees that don't meet those standards are refused entry. As a consequence beekeepers going into California for the 1st time often have to pull off and go through their bees combining hives and treating with Bt, checkmite+, Apistan, etc, in order to meet the standards.
Maybe trying to get rid of fire ants?