|Alderfly (Sialis lutaria)|
So I did some research and here's what I found:
- They are a primitive insect and apparently one of the first to have developed a pupal stage to their lifecycle.
- They are not very good at flying so they are mainly found around the ponds and streams that they emerge from and explains why the one I saw looked like it was struggling.
- Adults only live for a few days. They emerge to mate and may not eat in this time just existing on reserves from the larval stage.
- Once mating has taken place, which is often at night, the female will lay up to 200 eggs on vegetation over hanging the water. This isn't always on Alder trees
- They live in the silt of the bottom of lakes or slow flowing rivers where they crawl around feeding on smaller organisms and insects. They hide amongst weed and under stones.
- After a year or sometimes two they go to the pupal stage. They bury into the silt and pupate and after a couple of weeks emerge as adults.
- They are part of the order of insects called Megaloptera which also has Dobsonflies and Fishflies in it. This order of insects has some of the largest aquatic insect larvae.
- As larvae the eat a lot of insects but are themselves eaten by fish. Watching the lake while eating my sandwiches I bet the adults are good Swallow food too!
So, I hope you enjoyed this, here's a few links to more information -
Hope you enjoyed,