The great diving beetle (Dytiscus marginalis) is a large aquatic diving beetle native to Europe and northern Asia, and is particularly common in England.The great diving beetle, true to its name, is a rather sizable insect. The larvae can grow up to 60 millimetres (2.4 in) in length, while the adults are generally 27–35 millimetres (1.1–1.4 in). They are able fliers, and fly usually at night. They use the reflection of moonlight to locate new water sources. This location method can sometimes cause them to land on wet roads or other hard wet surfaces.