Sunburst Diving Beetle Thermonectus marmoratus

The Sunburst Diving Beetle, also called Spotted Diving Beetle, is native to freshwater pools and slow-moving streams of southern USA (California to Texas) and northern Mexico. If pools dry up they fly to a new one.

The adult beetle grows to 1.5cm. They pupate on land. Both larvae and beetle are predators of other aquatic larvae, particularly mosquito larvae. The beetle carries its own bubble of air supply as it dives.

The yellow-spotted colouring warns potential predators that they produce a toxic chemical for defence.

The larvae start out as tiny, krill-like, clear worms and grow to an aquatic caterpillar-like worm.

The larvae are the only known animal to have natural bifocal capability, it having recently been discovered that each eye has 2 retinas and focal planes - one for close focusing and one for distant.