Mealworms are some of the most popular feeder insects for reptiles and amphibians, and among the easiest to raise and care for. These little critters are highly nutritious for pets such as lizards and frogs – and if you so desire, you can munch on a few as well! If you’re searching for a great feeder insect, read on to learn how to raise mealworms.

What Is a Mealworm?

If you're interested in raising mealworms, it pays to know a little about them first. An interesting fact right off the bat is that a mealworm is not actually a worm at all! It is just one of the four life stages of the darkling beetle, otherwise known by its scientific name, Tenebrio molitor. There are over 20,000 types of darkling beetles currently known, so you may have run into a few variations in your search for the best food for your reptile.

Many of the larvae tend to look quite similar in appearance, but there are aspects of the mealworm's life cycle and behavior that can help you distinguish between the common feeder species. For instance, the T. molitor mealworm is a cream to light-brown color in its early days as a larva, with a segmented body – each portion distinguished by a dark brown line. As it ages and approaches adulthood, its body darkens.

The Life Cycle of a Mealworm

The mealworm has four total life stages:

Egg

You can recognize a mealworm egg (or darkling beetle egg, to be more exact) by its shape, appearing as a small, white, bean-shaped bit of dust. It will be difficult to spot if found in the mealworm's natural habitat, as it is normally concealed by wheat bran and other substrates. The mealworm will remain in this substrate between 1-4 weeks.

Larva

This stage, known to many as the “mealworm stage” of the beetle’s life cycle, lasts for an average of 8-10 weeks. The mealworm starts relatively small but quickly grows to its maximum length of 1 inch. As it grows, the mealworm needs to molt, or shed its exoskeleton. Molting can occur up to 20 times during the larval stage. During this portion of the mealworm's life cycle, the larva eats and saves energy for growth into adulthood. This is why it is so nutritious!

Pupa

This is perhaps the strangest-looking stage in the life cycle of a mealworm. During the final molt of the larval stage, the mealworm metamorphosizes into a curled-up pupa. At this time, it no longer has a mouth or anus, and therefore cannot eat. Although it does have legs and little buds as the beginnings of wings, it cannot move these body parts, and is instead completely still. This lasts for about 3 weeks as the organs develop for adulthood.

Adult

Lasting for about 1-3 months, the darkling beetle adult is initially white with a soft exoskeleton that hardens over time. While the shell hardens, it becomes darker in color, first turning brown, and then black. Despite having wings, the beetle cannot fly. It begins to reproduce only days into adulthood, giving you plenty of time to continue raising mealworms.

Where Are Mealworms Found?

Mealworms are native to several countries of Africa, however, humans have distributed them throughout the world, and they have become a naturalized species of North America. They can be found happily burrowing in dark, moist soil, where they feed on decaying organic matter such as rotting wood and leaves. They can be found sneaking a bit of space in animal dens as well.

In captivity – or in cities and human-centered landscapes – mealworms will take refuge in similar habitats but will feed on grains, spoiled and rotting food, and natural vegetation. Anywhere they live, they are an incredibly important part of the ecosystem, as they clean up organic matter that may otherwise be left out and become unsightly or give off foul odors.

You are most likely to find mealworms in human environments than in the wild, though. Because food waste is so abundant, it’s easier for them to find nutrition in such landscapes, especially in home kitchens, grocery stores, warehouses and farms.

Which Pets Eat Mealworms?

Mealworms are packed full of nutrients for your pet. Compared to other species of darkling beetle larvae, the mealworm has more “meat” on its body and therefore offers more protein. The most common animals that eat mealworms include:

  • Birds
  • Geckos
  • Turtles

Raising Mealworms

Raising mealworms is surprisingly easy and one of the best ways to save money when caring for a reptile. If money is not your concern, raising mealworms is also just a fun hobby that many people share since they make simple pets that demand very little from their keeper. They are extremely prolific breeders and resistant to harsh environmental conditions, so you can grow a lifetime supply of this nutritious snack for your reptile (and yourself!) with little effort.

To learn how to raise mealworms, follow the instructions below:

1. Set Up the Container

Mealworms are not too picky about the material or size of their container. Although they will need a container about 5 inches deep minimum, they can be packed in there with over 100 individuals. The ideal mealworm containers are aquariums, terrariums or Tupperware that have a large surface area.

To prevent the mealworms from escaping while still providing airflow, you’ll need a screened lid – poking holes in a plastic lid may not be the best option, as you need to make sure that other creatures do not get into the container and wreak havoc in the colony. Ventilation is also essential to preventing mold and harmful bacterial growth. If you only have a plastic lid available, you can cut away its center and attach a section of window screen or similar material.

2. Add Food as Substrate

The substrate will serve a dual purpose: functioning as a “soil” into which the worms can burrow and take refuge in the darkness they naturally prefer, while simultaneously providing them the necessary nutrition they need to grow. The perfect foods to provide include:

  • Wheat bran
  • Oatmeal
  • Cornmeal
  • Wheat flour

To raise mealworms properly, layer your substrate until it is about 2 inches deep. You can choose to mix the food with commercial mealworm substrate, although it is not required and will not make a significant difference to the health of your colony. No matter how you prefer to set it up, you will have to regularly check the container to replenish it as the mealworms chip away at their snacks.

For hydration, avoid adding a bowl of water since mealworms will simply crawl in and drown. Instead, give them foods such as apples, potatoes and carrots to quench their thirst. Potatoes are the best since they can last long in the container without molding.

3. Maintenance of the Container

Keep your container at 77 degrees Fahrenheit – this is the best temperature for the worms and most accurately replicates their natural habitat. You may need to provide a heat lamp or other constant source of warmth, while ensuring the mealworms are not placed next to a window or other area where too much sunlight may come through.

It is not necessary to give the colony light, however, if you do, keep them on a regular day/night schedule. Your colony will reproduce at higher rates if their container is humid, but this needs to be monitored closely to avoid the growth of mold or fungus.

Lastly, remove any dead larvae, pupae or adults or the worms will become cannibalistic and no longer feed on the substrate you’ve provided. Females can lay hundreds of eggs at a time, so you’ll need to pay regular attention to both death and birth rates in your colony.

Mealworms are some of the most nutritional insects you can feed your pet. They are rich in protein, and depending on how you choose to feed, can provide your pet with lots of water as well. The species can survive for quite a while in this larval stage, so if you prefer, you can simply store them in the fridge with intermittent feedings after purchase (if live) or learn how to raise mealworms to start your own colony instead. Either way, they will provide your reptile with a great addition to a rich, well-balanced diet.

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Mealworms For Sale