Mealworms Tenebrio molitor 

Breeding Instructions Click images to enlarge

Difficulty Level - Easy

Time Table - 4-6 months from egg to beetle depending on temperature

Food - They eat the oat or bran substrate

Water - Provide apple, potato, or "orange cube"

Temperature - 70 - 80F works best. Lower temperatures slow down the cycle.

 Materials needed - Click to enlarge

Rearing Habitat Supplies


A plastic container with lid at least one pint size. The size will depend on your needs.

Rolled oats or bran about 2 inches deep for substrate and food.

A wadded up piece of paper for hiding and a piece of apple or potato, or "orange cubes" as a water source. Replace water source before it becomes moldy.

Holes in lid - Click to enlarge Rearing Habitat Assembly

Punch small air holes in the lid or cut out a section and glue on a piece of screen. This allows air in and keeps moisture from building up and causing mold. I used a push pin to puncture holes in this pint size container. Colony temperature should be maintained between 70 and 75 F.  the Adult larvae may be refrigerated to delay pupation and allow more time to use as feeders.

Assembled set-up - Click to enlarge Fill the bottom of your container with 1 to 2 inches of oats or bran. Add the wadded up piece of paper. I tore open a toilet tissue roll and pealed a layer off.  Add your moisture source. I like the Fluker's Orange Cubes. They are   gel cubes that contain nutritious kelp, spirulina, brewer's yeast, and more to gutload feeder insects and they are less susceptible to mold. If you use potato or apple, make sure to change it regularly.
Add Bugs - Click to enlarge Add bugs

Females Lay 100-200 eggs at a time and may lay 500 - 1000 total.  Eggs hatch in about a week.  Larvae (the stage used as feeder insects) shed their skin about 15 times during the larval stage and then morph into pupae. 


Separate pupae

When they morph into pupae you will want to separate them from the colony. The beetles will eat the defenseless pupae. Once the pupae morph into beetles (about 7-10 days) you may return them to the colony.

Frass and tiny meal worms - click to enlarge Refresh the moisture source frequently. After a few weeks, you will want to clean the container and refresh the substrate. A colander works well to sift through the substrate.

This picture shows frass or insect poop. Tenebrio molitor will extract and use all of the moisture in their food and leave behind dry, tiny droppings. If you look closely  you will see tiny meal worms in this frass. When you clean out the container pay close attention to what you discard.

Growth stages - click to enlarge This photo shows the life stages of the mealworm. Each stage begins with a "white" or light version of the stage. As it matures and completes the stage it darkens.  Dead mealworms are stiff and dark brown or black and should be removed from the container. Pupae should be removed as they are extremely vulnerable and susceptible to being eaten. 
Facts and Info
Nutritional Content
Protein 19%
Fat 14%
Carbohydrates 4%
Fiber 2%
Moisture 63%

For more see  Nutritional Values

Stage Time (affected by temperature, humidity and food)
Egg 4-19 days 
Larva 10 weeks. Can be seen in 7-10 days
Pupa 6-18 days


8-12 weeks



Mealworms can be purchased in nearly all pet stores or online.

They are very easy to breed.

Mealworms are not actually worms. They are the larval stage of the darkling beetle. Adult beetles can fly.

Mealworms will not bite.

Mealworms can be stored in a refrigerator for several weeks to delay pupation or to extend their life.

They can be "gut loaded" to enhance their nutritional value.

Threats include cannibalism, mice, ants, and mold.

Size of adult mealworm  (larval stage) is 1 to 1.25 inches.

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