Tenebrio obscurus is a species of darkling beetle, whose larvae, when used as feeder insects for reptile and amphibian pets, are known as mini mealworms. These insects should not be confused with younger mealworms (Tenebrio molitor) or with the confused flour beetle (Tribolium confusum), which is also occasionally used as a reptile feeder insect. The larvae resemble very small mealworms, about ½ to ¾ inch (12 to 19 mm) in size. Once they reach adult size, the larvae pupate, and later emerge as small, black beetles.