Larvae - 5/16" long. Slender, segmented and worm-like with three pairs of tiny legs on the thorax and one abdominal proleg at the rear.
Females can lay up to at least 110 eggs a month and eggs hatch in 4-7 days.
Larval development takes up to 7 weeks. Mature larvae seek a sheltered place to pupate for between 7 and 11 days.
An adult beetle may live up to two years.
The beetles are attracted to poultry operations, which have ideal conditions for their development. The damage to insulation is carried out by lesser mealworms seeking a safe place to pupate because the darkling beetles prey on the lesser mealworms.