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The threat to mayflies applies also to their eggs. "Modest levels" of pollution in rivers in England are sufficient to kill 80% of mayfly eggs, which are as vulnerable to pollutants as other life-cycle stages; numbers of the blue-winged olive mayfly (Baetis) have fallen dramatically, almost to none in some rivers. The major pollutants thought ...
Description. Ephemera danica can reach an imago size of 15–20 mm (0.6–0.8 in) in males, while females are larger, reaching 16–25 mm (0.6–1.0 in). This mayfly, with its characteristic markings and three tails (Cerci), is the most commonly seen of British Ephemeridae. Imago wings are translucent with dark veining, while in subimago they ...
The eggs are laid by the female dipping her abdomen into the surface of the water. This mayfly usually has a two-year life cycle (one- and three-year cycles have also been recorded), [1] with the nymphal stage lasting for most of this period and the adult being on the wing briefly in summer.
Rhithrogena germanica is a European species of mayfly, and is "probably the most famous of all British mayflies", because of its use in fly fishing. It is known in the British Isles as the March brown mayfly, a name which is used in the United States for a different species, Rhithrogena morrisoni. [3] It emerges as a subimago at the end of ...
Cloeon dipterum is widespread across Europe and Asia. In the British Isles, C. dipterum is the commonest mayfly in ponds, with around 40% of all ponds containing C. dipterum, rising to 70% in the south. [9] In 1953, a single female Cloeon dipterum was discovered in Illinois, having not been previously recorded in North America, and was found ...
Hexagenia limbata. (Serville, 1829) [1] Hexagenia limbata, the giant mayfly, is a species of mayfly in the family Ephemeridae. It is native to North America where it is distributed widely near lakes and slow-moving rivers. [2] The larvae, known as nymphs, are aquatic and burrow in mud and the adult insects have brief lives.
Baetidae is a family of mayflies with about 1000 described species in 110 genera distributed worldwide. [1] These are among the smallest of mayflies, adults rarely exceeding 10 mm in length excluding the two long slender tails and sometimes much smaller, and members of the family are often referred to as small mayflies or small minnow mayflies.
Baetis sahoensis. Baetis is a genus of mayflies of the family Baetidae, known as the blue-winged olive to anglers. There are at least 150 described species in Baetis. [1][2][3][4] They are distributed worldwide, with the most variety in North America and northern Europe. [5]