The elongate larvae live in accumulations of stagnant water such as drain traps, wet manure, dirty garbage containers, septic tanks, and wet leaves. They have a grey body, a series of distinct dark bands across the back and a breathing tube at the end of the body. Development from egg to adult takes about 2 to 3 weeks. The adults can be killed by residual or pyrethrin space sprays that are used to control adult house flies. Solution of the problem requires that the breeding site be found and cleaned up or eliminated.
Floor drains are a good starting place.
Remove accumulations of muck in the drain and flush with scalding water. The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.