Knowing what is hatching out on the river can be complicated, along with knowing what stage they're in in regards to their life cycle. In this blog, I will be talking briefly about the different aquatic insects that you are likely to find out on the river along with a look into what their life cycle is.
The full life cycles of aquatic insects typically involve four stages: egg, larva (or nymph), pupa, and adult. The eggs are usually laid in or near water, and the larvae or nymphs live in the water and feed on aquatic plants and animals. As they grow, they molt and shed their exoskeletons. When they reach the pupa stage, they undergo metamorphosis and transform into their adult form. Finally, they emerge from the water and live as adults on land, where they mate and lay eggs to start the cycle again.
Mayflies
The life cycle of a mayfly typically includes the following stages: egg, nymph, subimago (or dun), and imago (or spinner). After hatching from the egg, the mayfly nymph lives in water for several months or even years, feeding on algae and other aquatic organisms. When it is ready to transform into an adult, it emerges from the water and molts into a subimago, which is a winged but immature form. The subimago then molts again into the fully mature imago, which mates, lays eggs, and dies within a few days to a few weeks.
Caddisflies
The life cycle of a caddisfly starts with an egg that hatches into a larva. The larva then builds a protective case around itself using materials such as stones, twigs, or sand. A great presentation of this stage is the 'Peeping Caddis' nymph on my website. The larva feeds on aquatic plants and animals and grows through a series of molts. When the larva is fully grown, it pupates inside its case. After a period of time, the adult caddisfly emerges from the case and flies away to mate and lay eggs, completing the life cycle. A great imitation of this stage is the 'Elk Hair Caddis' fly.
Stonefly
The life cycle of a stonefly begins with an egg which hatches into a nymph. The nymph then goes through several stages of development, molting its exoskeleton each time, until it reaches adulthood. Once it has reached adulthood, the stonefly will mate and lay eggs, completing the life cycle. The length of the life cycle varies depending on the species of stonefly, but can take anywhere from several months to several years.
Midge
The life cycle of a midge typically includes four stages: egg, larva, pupa, and adult. The midge lays eggs in water, which hatch into larvae that feed on organic matter. The larvae then go through several molts before entering the pupal stage, in which they metamorphose into adults. The adult midges emerge from the water and mate, with females laying eggs to start the cycle anew.
Baetis
The full life cycle of a baetis, also known as a blue-winged olive, begins as an egg laid in water. The egg hatches into a nymph, which lives underwater and molts several times before emerging as a dun, or subimago, that flies to nearby vegetation. The dun molts one last time and becomes an adult, or imago, which then mates and lays eggs back in the water to complete the cycle.
Damselfly
The life cycle of a damselfly typically includes the following stages: egg, nymph, and adult. The eggs are laid in water, and once hatched, the aquatic nymphs undergo several molts before emerging as winged adults. The adult damselflies mate and lay eggs in water, completing the life cycle.
Chironomid
The life cycle of a chironomid, also known as a non-biting midge, includes four stages: egg, larva, pupa, and adult. The eggs are laid in water and hatch into larvae that live in the water and feed on organic matter. After several molts, the larvae enter the pupal stage, where they transform into the adult form. The adult chironomids emerge from the water and mate, and the females lay eggs to complete the life cycle.
Thank you so much for reading through this months blog, I hope you learned a lot from it. Tight lines!
If you would like to purchase any custom variations or flies that are not on my website to match the hatches on your river, send me a message through my Contact Form or email me at Thomasflyandtackle@gmail.com.