Mayflies, ancient insects, are known for their short adult lives. While the winged adult stage is brief, their aquatic larval stage, called a nymph, can last for months or even years. This extended aquatic phase is where most of their feeding and growth occurs, supporting their entire life cycle.
Nymph Diet
Mayfly nymphs exhibit a variety of feeding strategies within aquatic environments, primarily consuming plant matter and decaying organic material. Most species function as herbivores or detritivores, acquiring nutrients from algae, diatoms, or detritus found in the water.
Many mayfly nymphs are scrapers or grazers, moving across submerged surfaces like rocks and plants to consume films of algae and microscopic diatoms. Their mouthparts are adapted to effectively remove these attached food sources. Water quality influences the availability of these food sources, as nymphs generally thrive in clean, unpolluted waters.
Other nymph species are collectors or gatherers, filtering fine particulate organic matter and microorganisms from the water column or substrate. Some are shredders, feeding on decaying plant material like leaf litter. A smaller number of species are predatory, consuming small insect larvae.
Adult Feeding Habits
Adult mayflies generally do not feed. Their mouthparts are vestigial, meaning they are undeveloped and non-functional for consuming food. This adaptation reflects their focus during this brief winged stage.
The primary purpose of the adult mayfly is reproduction. Energy for flight, mating, and egg-laying is derived from reserves accumulated during their nymphal stage. Adult mayflies live for a short period, from a few hours to a few days, dedicating this time to ensuring the next generation.
Mayflies in the Food Web
Mayflies occupy a foundational position within aquatic food webs due to their feeding habits as nymphs. As primary consumers, they convert plant material and detritus into their own biomass, making this energy available to higher trophic levels. Their presence indicates a healthy aquatic ecosystem, as most species require clean water to thrive.
Throughout their life cycle, mayflies serve as a significant food source for a wide array of predators. Nymphs are consumed by various aquatic organisms, including fish such as trout and salmonids, as well as other insect larvae like stoneflies, caddisflies, alderflies, and dragonflies. Frogs, aquatic beetles, leeches, and crayfish also prey on mayfly nymphs.
Upon emerging as winged adults, mayflies become a readily available food source for terrestrial and aerial predators. Birds, bats, and other insects like dragonflies feed on adult mayflies, especially during large emergence events. The transfer of energy from aquatic to terrestrial environments through emerging mayflies highlights their ecological impact. Their eggs also contribute to the food web, consumed by organisms such as freshwater snails and caddisfly larvae.