There are several ways to kill maggots in a bin, including:

1. Boiling water: Pouring boiling water over the maggots will kill them instantly.
2. Salt: Sprinkling salt around the rim of the bin, on top of the bin bags, or directly onto the maggots will dehydrate them and kill them.
3. Vinegar: A mixture of vinegar and hot water in a 1:2 ratio can be sprayed on the maggots and the inside walls of the bin. This solution will kill the maggots, sanitize, and deodorize the bin.
4. Insecticide: Bug sprays that are used for normal use can also be used to kill maggots in the bin. Spray the entire bin with the insecticide and wait for at least 30 minutes for it to kill the maggots.
5. Bleach: Pouring boiling water with a small amount of bleach over the maggots will kill them.
6. All-purpose cleaners: Mix one part of the cleaning solution with four parts of boiling water and pour it on the maggots.
7. Cinnamon powder: Mix cinnamon powder with water and pour the solution over the larvae to kill them.

Its important to identify what the maggots are feeding on and remove the food source to prevent them from growing or surviving. Regular cleaning, good hygiene, and vacuuming can also help control and prevent maggots from infesting the bin.