Yes, the main ingredient in Drano is Lye, a powerful chemical that can dissolve tissue. Short-term exposure can certainly kill drain flies and larva. However, if the source of the fly infestation is not completely removed, they will return.

Will drain cleaner get rid of drain flies?

In most cases, Drano will kill drain flies, especially if it is a Drano variety that expands within the pipes. For long-term treatment, however, you will also need to take precautionary steps to keep the drain flies from returning.

Does Dish Soap Kill drain flies?

Dish Soap and Warm Water Kill drain flies in the sink basin, wall, or ceiling using a dish liquid and water mixture inside a spray bottle. Add two cups of warm water and 7 drops of dish liquid and shake. When you spot a drain fly, spray the fly with the mixture.