Megaloptera
Your insect is probably an alderfly or snakefly
Fact file
Order: Megaloptera
Body length: 0.5 - 15mm
Species: World - 4500, UK - 159
Adult alderflies are often found resting on alder trees near ponds and lakes. Their larvae are aquatic and live in water for up to two years before pupating and emerging as an adult.
Snakeflies have very long 'necks' giving them their common name. They eat aphids and are commonly found in thickly wooded areas.
