In the washing machine room, there is this floor drain, which drain out water from the washing machine. But, the place has alot of cockroach, especially my first wash at that place. I put ridsect and eventually cockroach is less seen. Nevertheless, there is still this cockroach smell whenever I open the door. I have tried placing charcoal to absorb the smell, don't seem working.

Anyone has any idea how to reduce the smell of cockroach? Thanks