The Great Diving Beetle (Dytiscus marginalis) is a fascinating aquatic insect that is native to Europe and northern Asia. It is commonly found in Wales, much of England, and southern Scotland, but is less common on chalk and in the far north. As its name suggests, this beetle is rather large, with adults ranging from 27-35 millimeters (1.1-1.4 inches) in length and larvae growing up to 60 millimeters (2.4 inches) in length.
Appearance
The Great Diving Beetle has a distinctive appearance that sets it apart from other aquatic insects. Its body is oval-shaped and flattened, with a shiny black or dark brown exoskeleton that is covered in fine hairs. It has two large, powerful legs that are used for swimming, as well as two smaller legs that are used for walking on land. Its eyes are large and round, providing excellent vision both above and below the water's surface.
Behavior and Habitat
The Great Diving Beetle is an impressive underwater hunter, using its powerful legs to swim and its sharp mandibles to capture prey. It feeds on a variety of aquatic invertebrates, including insects, mollusks, and crustaceans. It is also known to prey on small fish and tadpoles, making it a fearsome predator in its aquatic habitat.
The Great Diving Beetle is found in a variety of freshwater habitats, including ponds, lakes, and slow-moving rivers and streams. It is particularly fond of still, shallow water with plenty of vegetation, which provides cover and a source of food.
Life Cycle
The Great Diving Beetle undergoes a complete metamorphosis, with four distinct life stages: egg, larva, pupa, and adult. After mating, females lay their eggs on submerged vegetation, where they hatch into larvae after a few weeks. The larvae live in the water and feed voraciously, growing rapidly and shedding their exoskeletons several times before reaching maturity.
After a year or two, the larvae pupate and transform into adults. The adults are strong flyers and are attracted to lights at night, making them easy to spot near bodies of water. They mate and lay eggs, completing the life cycle.
Conclusion
The Great Diving Beetle is a remarkable aquatic insect that is well adapted to life in freshwater habitats. With its impressive size, powerful legs, and sharp mandibles, it is a formidable predator that feeds on a variety of aquatic invertebrates and even small fish and tadpoles. Its distinctive appearance and fascinating behavior make it a favorite of insect enthusiasts and nature lovers alike.