SWARMS of bees have showered parts of southern Taiwan with their droppings, leading locals to believe plane toilets were being emptied over their homes, authorities said today.

"Bee droppings are harmless to human health but it's very difficult to wash off," Kaohsiung city's environmental protection bureau said.

"The bureau can't doing anything about the bees so we urge the public to be careful."

The bureau said it had received many calls complaining about strange yellow "flakes" left on cars and laundry, and angry requests that airline companies clean up their act.

However, a lab analysis found the flakes were in fact bee droppings while airlines explained that all in-flight toilets are only emptied on the ground, it added.