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Insects and other arthropods

Raising yellow mealworms

Yellow mealworm
Photo: Espace pour la vie


Yellow mealworms – darkling beetle larvae – are excellent candidates for raising at home. They make no noise and easy to handle. All you need is about sixty larvae, easily obtained from a pet store, to start your own breeding operation.

You will also need:

• at least three plastic containers with lids. To make sure they are properly ventilated, make a hole in the lid and cover it with mosquito netting or cheesecloth (you can also buy special containers for this purpose in pet stores);

• various grains, mixed in the following proportions:

  • 10 parts whole oats or wheat
  • 10 parts rolled oats or whole wheat flour
  • one part wheat germ or powdered milk
  • one part yeast (important to prevent dietary deficiencies in insects)
  • cut up vegetables (cabbage, carrot, potato, lettuce) or fruit (preferably apple), to provide the insects with the water they need to grow

• if necessary, something to heat the vivarium (40 W light bulb or heating pad).

Caring for your vivarium

Place the vivarium in a dimly lit, dry, well-ventilated spot. In a clean container, place a layer of the mixed grains, about 2.5 cm thick, add the larvae and leave a few chunks of fruit and vegetables directly on the mixture.

The mealworms will grow to about 3 cm before turning into pupae. As soon as the first pupae appear in the container, transfer them into a second container so that they won’t be eaten by the mealworms. Since the pupae do not eat, you don’t need to add anything to the container.

When the adults emerge, they’ll look like little whitish beetles. They will soon turn black. They may also eat the pupae, so make sure to move them into a third container with a 2.5 cm layer of grain and some chunks of fruit and vegetables. Adult darkling beetles can begin mating two to five days after they emerge. Females can lay up to 40 eggs a day. The eggs hatch after about 12 days. The mealworms moult several times before reaching their maximum size. At temperatures ranging from 18 to 25°C, darkling beetles take six to ten months to complete their life cycle, under artificial conditions.

Replace the chunks of fruit and vegetables frequently, as soon as they dry out. Replace the mixture of grains, too, as soon as it starts looking sandy. You will first have to remove the insects by sifting the mixture or picking them out one at a time. Remove any dead insects regularly and take the opportunity to stir up the mixture and mix in the moulted skins, so the insects will also eat them. Whenever you harvest your mealworms, be sure to leave several larvae so they can reach adulthood – otherwise your mealworm “farm” won’t last very long!

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