While many familiar fly species do not utilize water for reproduction, certain types of flies have life cycles that depend entirely on aquatic environments. This reflects the broad adaptations within the insect order Diptera.
Typical Fly Reproduction
Most common flies, such as house flies and fruit flies, reproduce in terrestrial environments. Female house flies prefer to lay their eggs in moist, decaying organic materials like garbage, animal waste, or compost heaps. These environments provide the necessary moisture and nutrient-rich food sources for the developing larvae. Fruit flies are attracted to overripe fruit, sugary liquids, and fermenting organic matter for egg-laying. The eggs of these species typically hatch into larvae, which then feed on the surrounding decaying material. Most flies encountered daily complete their entire life cycle on land, in or near sources of decomposition.
Flies That Reproduce in Water
Despite the terrestrial habits of many common species, several types of flies specifically require water for reproduction. Mosquitoes lay their eggs directly on the surface of standing water or in areas prone to flooding. Midges also deposit their eggs in aquatic habitats, with some species laying gelatinous egg masses that sink to the bottom. Black flies, often found near flowing water, lay their eggs on submerged objects or scatter them over the water’s surface in streams and rivers. Drain flies, or moth flies, prefer the slimy organic film that builds up in drains, pipes, and septic tanks for egg development.
The Aquatic Life Stage
The reason certain flies lay eggs in water is due to their aquatic larval and pupal stages. After hatching from eggs, the larvae of these flies live and develop underwater. Mosquito larvae, often called “wrigglers,” feed on algae, plankton, and other microorganisms in the water. They have specialized breathing tubes, called siphons, that they extend to the water’s surface to obtain oxygen. Black fly larvae anchor themselves to submerged rocks or vegetation in flowing water and filter organic matter for food.
Midge larvae can respire through their skin, allowing them to survive in low-oxygen conditions in bottom mud. Drain fly larvae feed on the bacterial and fungal film within drains. The pupal stage for many of these flies also occurs underwater, where they undergo metamorphosis before emerging as winged adults.
Preventing Water-Breeding Flies
Controlling flies that breed in water often involves eliminating their aquatic breeding sites.
Mosquitoes
For mosquitoes, this means regularly emptying and cleaning containers that collect standing water, such as buckets, flower pots, and bird baths. Storing items like tires and toys in covered areas or upside down prevents water accumulation. Maintaining proper drainage by unclogging gutters and leveling ground where water can pool also helps reduce breeding habitats.
Drain Flies
For drain flies, prevention focuses on cleaning drains and pipes to remove the organic film where they lay eggs and larvae develop. This can involve using boiling water, baking soda and vinegar, or microbial drain cleaners to break down the organic matter. Addressing plumbing leaks and ensuring good ventilation can also reduce moisture suitable for drain fly breeding.