There are over 300 species of diving beetles (Dytiscus sp.) in North America, making it the largest American family of water bugs. They are found in habitats of standing water of ponds and streams, especially with a muddy bottom.
Diving beetles are usually black or brown and oval-shaped. Adults average one-sixteenth to two-inches long, with a piercing-sucking mouth type. Their hind legs are made for swimming. Diving beetles get their name from their ability to grab and carry air bubbles at the end of their abdomen, enabling them to breath from the bubbles while swimming under water.
In some American Indian cultures, there are stories that credit the diving beetle in bringing up the first earth (soil) when the world was covered with water.
The diving beetle is also known as the predacious diving beetle. This name reveals this insect’s identity as a predator. Even the larvae are hunters whose nickname is the water tiger. Both the larvae and the adults will attack and kill a variety of prey, including mosquitoes and their larvae, making them a beneficial insect. Adults will also eat animal matter, larvae, water insects and fish, young or old. It is because of this fondness for fish that they are considered a pest in fish hatcheries.
They are attracted to lights and may even leave the water in the evening to fly toward them. For this reason, Ohioans have sometimes nicknamed them the electric light bug.