The life of a mealworm...

Mealworms at every stage of their life-cycle

Description
The mature form is a black beetle, the Darkling Beetle, but we are more interested in the caterpillar-like larval stage.

In the wild, the beetles can be found in warm and dark environments such as beneath logs. Its genus name, 'Tenebrio' means 'one who likes darkness'.

Darkling Beetles are scavengers who feed on decomposing plant or animal material. In man made environments, they can be a pest, living where we store grains and grain which they'll happily eat (and they eat a lot).

Life Cycle:
The Darkling Beetle is an holometabolic insect (yes, I had to look that one up) meaning that has distinct forms during each stage of its lifetime. Tenebrio molitor has an egg, a larval, a pupal and an adult (beetle) form.

The Egg Stage-
I couldn't take any decent photos of mealworm eggs. They're tiny and white and sticky, forming little clumps. The eggs can take on some of the coloration of the material in which they were laid.

The female beetle lays 100 to 200 eggs at a time and up to 500 over her lifetime. The eggs then take from 4 to 19 days to hatch. In the conditions found in most homes, it will take about a week for them to hatch, into larvae.

Mealworm larvae

The Larval Stage-
This stage is what most folks are familar with and call a 'mealworm'.

Mealworms start off very light brown or creamy color and darken as they age. This stage takes 3 - 10 weeks. Mealworms are very active and feed on a variety of foods. They molt up to 20 times as their innards outgrow their exoskeletons. storing up energy for the next stage. After the last molt, the larvae normally darken, curl up and change form, becoming pupae.

Alien looking pupae.

The Pupal Stage-
This stage of the lifecycle lasts for a period of 2 - 3 weeks but it may be longer in cold conditions.
During this stage, the pupae seem inactive but inside their hard shell, all of the complex structures of the adult beetle are forming.

Adult beetles. They start light, but darken with age.

The Adult Stage-

The adults emerge from their pupal case as cream and light brown beetles. They are quite soft at this stage too. With time, they darken, eventuslly becoming black.

They can mate and lay eggs within two weeks and live for a couple of months.

Each stage except the pupal stage will eat bran and 'drink' from moist vegetable matter.

There you go, a brief overview of the life cycle of a mealworm. Don't forget to look at my other mealworm article on building a mealworm palace

Dont just take my word for it, here's a link to a page chock full of Darkling Beetle Fun Facts

All the pics were taken but yours truly. Only a couple of mealworms were harmed during the making of this post (and they were delicious).

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