It often seems like fruit flies just appear out of nowhere, they can be a problem all year round, but are especially common during summer/fall. You see, when a fruit is overripe or starts to go bad it begins to ferment, producing alcohol, which attracts fruit flies. They continue to gobble up the fermenting fruit, and in the process, lay hundreds of eggs which hatch into larvae in mere hours. Fruit flies are common in homes, restaurants, supermarkets and wherever else food is allowed to rot and ferment. Adults are about 1/8 inch long and usually have red eyes. The front portion of the body is tan and the rear portion is black. Fruit flies lay their eggs near the surface of fermenting foods or other moist, organic materials. Upon emerging, the tiny larvae continue to feed near the surface of the fermenting mass. This surface-feeding characteristic of the larvae is significant in that damaged or over-ripened portions of fruits and vegetables can be cut away without having to discard the remainder for fear of retaining any developing larvae. The reproductive potential of fruit flies is enormous; given the opportunity, they will lay about 500 eggs. The entire lifecycle from egg to adult can be completed in about a week. The best way to avoid problems with fruit flies is to eliminate sources of attraction. Produce which has ripened should be eaten, discarded or refrigerated. Cracked or damaged portions of fruits and vegetables should be cut away and discarded in the event that eggs or larvae are present in the wounded area. A single rotting potato or onion forgotten at the back of a closet, or fruit juice spillage under a refrigerator can breed thousands of fruit flies. So can a recycling bin stored in the basement which is never emptied or cleaned.
People who can their own fruits and vegetables, or make wine, cider or beer should ensure that the containers are well sealed; otherwise, fruit flies will lay their eggs under the lid and the tiny larvae will enter the container upon hatching.
Drain flies are small, dark-winged, non-biting gnats. Their wings are covered with scales so they disappear in a cloud of fine dust when swatted or mashed. These nuisance gnats can be found resting on walls or ceilings, and make short hopping flights if disturbed. Drain flies breed in polluted, shallow water or highly moist organic solids. You will find the eggs, larvae and pupae in the muck, slime, or gelatinous film often accumulating on the sides of drains. Other breeding sites include dirty garbage containers, rain barrels, tree holes or in low lying areas adjacent to buildings where water collects and algae or mould grows. The female flies deposit laid eggs in irregular masses of 10 to 200 directly in / on moist organic debris. These eggs usually hatch in less than two days and the larvae feed on the decaying organic matter, microorganisms, algae and sediment in the debris and mature in 9 to 15 days. Larvae pupate in / on the surface of this material and new adults emerge in 1-2 days. Controlling drain flies should be aimed at elimination of breeding sites. The most effective control method is to clean pipes and traps thoroughly to remove accumulated slime. Pouring hot water down the drain may provide short-term control. Drain fly larvae are difficult to drown because they are able to trap air bubbles and remain submerged for a day or more. Do not pour insecticides down drains to kill drain flies.