Tenebrio Life Cycle

Tenebrio, or darkling beetles, is a terrestrial arthropod, or insect, that lives primarily in meadows and fields. The Tenebrio beetle is rarely seen in the wild, though most of us are familiar with them. The larvae of the Tenebrio beetle is known as a mealworm, which is the staple diet for exotic pets like lizards, fish and turtles. Mealworms can be found quite readily in barns or in grain-storage silos. Tenebrio beetles have discovered that humans provide a much better environment for their survival than can be found in nature.

  1. History

    • Tenebrio beetles' life cycle looks a lot like a butterfly's in the sense that it goes through a metamorphosis stage, changing from a mealworm to a beetle. A Tenebrio beetle's life cycle can be marked into four specific stages. At the earliest stage, the female beetle will lay a clutch of eggs in a shallow nest. Within three weeks, the eggs hatch, and the newly born mealworms will begin the process of eating and growing. Interestingly enough, mealworms are not worms, but more like caterpillars. The mealworms have 12 segmented body parts and six short legs that are all concentrated toward the front of the animal.

    Development

    • As the mealworm grows, it molts or sheds its hard outer layer several times to accommodate the larger animal. The larvae will expand immediately after the outer shell has been removed in the brief period of time before the new shell hardens. It takes the mealworms approximately three months to reach the metamorphosis stage and can molt six or more times during that period, based on the availability of food and the rate of growth.

    Reproduction

    • At the time of the final molt, the larva ceases to be a larva and becomes a pupa. It is at this stage where the animal forms a chrysalis around its body and begins to change. Pupae do not eat nor will they move unless disturbed. Metamorphosis takes about two weeks, and then the newly formed beetle emerges--white at first, then darkening to brown and then black. The beetles only have about a month to produce as many offspring as possible before death.

    Misconceptions

    • Neither mealworms nor Tenebrio beetles pose any major health threats to humans directly as they are not parasitic for either animals or humans. The major cause for concern is as a nuisance. Mealworm infestations can cause a loss for farmers due to the beetle's voracious appetite, and its ability to reproduce quickly allows a small population to explode.

    Uses

    • Since it is easy to obtain and raise Tenebrio beetles at home, reptile and bird enthusiasts will breed them as an inexpensive way to feed their pets. Also, Tenebrio beetles are used in classrooms to demonstrate metamorphosis life cycles since their life cycle is considerably shorter than that of a butterfly or moth.