The regular spraying of insecticide into gully traps at the void decks of Housing Board apartment blocks, an ongoing effort of the National Environment Agency (NEA) in the prevention of dengue fever and malaria, is laudable.

But I have seen workers spraying the insecticide on the trap cover instead of into the gully trap.

Only about half the insecticide drips into the gully traps while the rest stays on the trap covers, leaving ugly brownish stains on them.

Workers should open the trap covers with a hook and dispense the full dose of insecticide into the gully traps, closing them afterwards.

The NEA needs to educate the contractor who tendered for the job on how to do it right.

Chin Kee Thou