The Life cycle of the tenebrio beetle By:Rob Salem www.javafinch.co.uk
  Lets start with a bit about the Tenebrio beetle.
The Tenebrio beetles are shiny black beetles, about 15 to 20 millimetres long. The beetle passes through four life-stages (metamorphosis): egg, larva, pupa and adult They have concealed beneath their hard shell, well developed wings, also they are well-accomplished flyers and are attracted to lights at night. Their larva's, which are 30 to 35 millimetres long, hard bodied and are yellowish brown in colour.
They are seldom a pest in homes, they are, however, major pests in storage facilities, in dark undisturbed locations. The female adult beetle can lay around 200 to 500 eggs singly or in clusters.
The Egg
Egg
Sorry I could not
find an egg to show you.
Larvae
Pupa
Day old beetle
 
EGG'S: The eggs of the Tenebrio beetle are laid directly onto the food source, in our case wheat bran flakes. Once mated with the male, the female can lay up to five hundred eggs, either singly or in clusters, These eggs are oval shaped and are very hard to see, they measure one millimetre long. And will hatch in about 20 to 40 days time.
  
 
LARVAE: The larvae stage of the Tenebrio beetle, is known to a lot of people as the mealworm, this is when it's most useful to us bird keepers and fishermen, also they can be fried and sprinkled on to a salad, (not for me thanks). The larvae has 13 to 15 yellowish brown segments that makes up its body, apart from the segments it has three pairs of legs at the head end. As the larvae grows it will need to shred its skin so it can get bigger, this will happen several times over the larvae stage. The larvae stage can last for weeks or months depending on the environment in which it's kept, according to some literature the larvae has been know to last up to two years.
 
PUPA: The pupa stage of the Tenebrio beetle is when the beetle does the most metamorphosis. The pupa measures about, 20 millimetres long. At this point the pupa looks like something from outer space. The pupa doesn't move but when picked up it will riddle. Inside this pupa the mealworm is changing into a beetle. The pupa cracks open between 18 to 24 days and the final stage begins, the new beetle emerges.  
 
THE BEETLE: When the beetle emerge from the pupa, it's soft and white in colour, after an hour or so the beetle starts going orange and hardening up its body shell, after a week or so the beetle will be black, a young adult. The life span of the beetle is only 2 to 4 weeks.
From egg to beetle takes approximately three months depending on moisture and warmth.



The two photos here are showing the beetle just three hours after emerging from the pupa.		  
 
Larvae Shredded skin
 
 
 
Setting-up A Mealworm Culture in easy to follow step by step instructions
Things needed:
1. Plastic containers with good lids.
2. Bran flakes
3. Crust of bread or card and fruit
4. 30 to 50 larger not small Mealworms or 10 Tenebrio beetle's
5. A warm dark place
 
First:
Take the plastic container and pour the wheat bran all over the bottom of the container until you have a depth of around an inch or two of bran, now add the mealworms in the container, O.K. that was pretty simple.
We need to put some moisture in with them to keep them alive, now either use a crust of bread laid on top then change it, when it starts to dry out.
Or place a piece of cardboard on top of the bran and put half of apple or potato on it, this way the damp fruit does not make the bran go mouldy.
Another way is to lay a piece of hessian sack over the bran and spray water on top with a spray bottle, just be very careful not to wet the sack to much or the whole culture will go off.
The mealworms will keep shredding their skins, until they pupate.
Keep this box in a dark and warm place.
Secondly:
When they have turned into pupae, I remove the pupae to a second plastic box, so they are undisturbed by the mealworms (lava).
This box is set up exactly the same as the first box and the moisture levels are maintained the same, no need to feed these.
After about 18 to 24 days the pupa start to crack open and the young adult beetle appears, watch out for the new beetle's and remove them as quickly as you can, so they don't start feeding on the other dormant pupae's.
Thirdly:
Take a third plastic box this will need to be smaller than the other boxes, so it can fit inside the boxes you have used for stages 1 & 2.
This smaller box will need holes drilled at the bottom, big enough for bran to pass through but small enough to keep the beetles in.
This smaller box will need to go inside a fourth empty plastic container.
This is the clever bit! Again put the same amount of bran in the small box as before, add the beetles as they hatch, and let them mate, the female will lay hundreds of eggs in the bran, the more beetles the more eggs you will have.
The adult beetles will eat their eggs if not removed.
So every second day for two weeks lift the smaller box up and shake it like a sieve so all the bran dust and eggs fall into the fourth container, after two weeks of doing this the fourth container will be quite full of bran and most importantly eggs! While all this is going on the beetles will need feeding and kept moist, place a small piece of cardboard on top of the bran lay apples or carrots on the cardboard and let the beetles feed of this, just remove it before you sieve out the bran.
The beetles will only live for two to four weeks.
When you have collected enough bran and eggs in the fourth container take it away and cover the bran with a piece of newspaper or a piece of hessian sack.
Then place the container somewhere dark and warm for 30 to 40 days, you must spray water on the paper or hessian every day to keep the whole culture moist.
After the time is up! It starts all over again.
 

Looking after a container full of small mealworms
The container should have bran replaced as necessary, this is the basic diet, in this culture add dry brewers yeast plus some scraps of meat, (don't over do the meat) some vegetables such as carrots and potatoes cut the into quarters. Put a layer of chicken mash over the entire box about ¼" thick. Spray the surface lightly with water and keep it damp with a daily sprinkling, do not soak. This way the mealworms will grow on to larger worms ready to start the next culture

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2002