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Green Drake Mayfly Epherema danica

Reaching a length of 15 to 25 mm the Green Drake Mayfly is the biggest species in both Britain and Ireland. The species does look a lot like the Drake Mackerel Mayfly, but the markings on the body are much smaller. When it comes out of the water it first becomes a sub-adult. The subadult has fully developed wings, but can not mate. The subadult has milky wings (transparent in the true imago) and much shorter forelegs and tails. The subadult is usually found in the vegetation close to the place they left the water. They don't fly much, but usually crawl around, looking for a good place to moult into the true adult. The adults do fly regularly and may even be seen dancing over the water in groups. Adults are as always in May Flies short lived: some 2 to 4 days. After depositing the eggs, the females just drop dead on the surface of the water.

The larvae do not build a home for themselves, for they are diggers. They dig themselves into the sandy soil. While doing so, they eat whatever materials they find in the sand. They may also filter edible particals from the water by sticking their head out of the just dug tunnel. It usually takes them two years to complete the larval stage. Fish and amphibians are fond of the emerging and dying adults. The adults are imitated for fly fishing, attracting trout mainly.

The Green Drake Mayfly prefers (slowly) moving waters with a clean, sandy soil. They will avoid all waters with a layer of debris on the sand. Adults are on the wing from April till June, but most numerous in May. This is one of the most common Mayflies in Britain and Ireland.