Adult darkling beetles vary greatly in size and shape: from 2 to 35 mm ( inches) and from flat to.... darkl larva

Adult darkling beetles vary greatly in size and shape: from 2 to 35 mm ( inches) and from flat to cylindrical. The larvae are about 25 mm (1 inch) long, cylindrical, and wormlike. The larvae of a widely distributed darkling beetle known as the mealworm ( Tenebrio ) are used as food for such pets as birds and fish. APA style: darkling beetle.