A mealworm’s life (Tenebrio molitor)


Mealworms are great for chooks, fish or reptiles (and blog authors…) to snack on. They’re easy to breed and take little care.

I was turned on to mealworms by our friend, Vicky who has bred them for a while.

Doing a little research online, I discovered that there is a semi-automated system that you can make at home to breed them up  conveniently.

But now, what are we dealing with?

The mature form is a black beetle, the Darkling Beetle, Tenebrio molitor 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.

imageMealworm 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.

imageAlien 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.

imageAdult 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, eventually becoming black.

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

imageEach 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

A family with a garden near Gawler where we experiment with sustainability.

4 thoughts on “A mealworm’s life (Tenebrio molitor)

    • Thank you. I just found your two comments in our spam folder. Sorry for not replying earlier but I didn’t know it was there!
      Please keep following our blog and I think that now your comments will not go to spam.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s