Mealworm Beetle

Adult mealworm beetles lay their tiny eggs in grain and grain containers, making it difficult for most homeowners to spot them. However, once they develop into larvae, they are easily seen as they are around an inch long. They adapt well to various habitats and occur in decaying animals, grains, grain products, and various plant species.

Mealworm larvae are readily accessible as they are sold at most pet stores for bait and to feed to lizards, turtles, and reptiles.

Fun Facts About Mealworm Beetles

• Mealworms can ingest and digest around 30 to 39mg of polystyrene daily.
• In 1968, the mealworm beetle traveled to space and circled the moon on the Soviet mission Zond 5.
• They belong to the darkling beetle family and are mainly used for feeding pets like birds and reptiles. However, some Asian and African cultures consume them as well because of their high protein content.

Mealworm Beetle Species, Types, and Scientific Name

Two species of darkling beetle produce mealworm larvae: the yellow mealworm beetle (Tenebrio molitor Linnaeus) and the mini or dark mealworm beetle (Tenebrio obscurus Fabricius), which is less common. The mealworm beetle is native to Europe but occurs all over the world now, except in Antarctica.

Mealworm beetles belong to the order Coleoptera, derived from the Greek words “koleos,” meaning sheath, and “ptera,” meaning wings. This refers to their forewings that act like a shield for their membranous hind wings.

This order, which consists of beetles and weevils, is the largest in the Insecta class. Most adult species in this order have tough, dense exoskeletons that protect the majority of their body’s surface.

Their forewings are called elytra and are just as strong as the beetle’s exoskeleton. They fold over the entire abdomen and act as protective shields for their big, membranous hind wings.

Their most distinctive characteristic is the appearance of their elytra which meet along the center of their backs, forming a straight line.

Mealworm beetles belong to the family Tenebrionidae, the 5^th largest family of the order Coleoptera. There are over 14,000 species in this family, with 1,345 species occurring in the United States alone.

However, these figures are relatively low since, in the past 3 decades, the classification of the family has changed, with many new taxa discovered each year.

Appearance: How To Identify the Mealworm Beetle

The mealworm beetle is generally dark brown or black in color and is often misidentified as the predaceous ground beetle, but mealworm beetles typically have clubbed antennae. However, both beetles are nocturnal and generally flightless.

Due to the sheer number of species in this family, there are considerable variations in size and appearance. However, most of them have elongated oval shapes and flattened bodies. Mealworm beetles can measure up to 1.5 inches long in North America.

These beetles are divided into 3 segments: head, thorax, and abdomen. They have abdominal defensive glandular reservoirs that secrete an extremely foul-smelling fluid, which is their chemical defense against predators.

Habitat: Where to Find the Mealworm Beetle

Adult mealworm beetles and their larvae are often found near the soil’s surface. However, they prefer living in weed-filled habitats, under stones or rocks, in leaf litter, or on decomposing logs.

In addition, several species can adapt to living in arid dunes or caves. Some species even take over other animals’ homes, like birds, rodents, and termites.

Mealworms are often found in grains and are a common pest in chicken coops and grain storage containers. In addition, they occur in peoples’ homes where there is grain with high moisture content. However, they are not common pests in homes, and many people start small businesses by raising them in their homes and selling the larvae as pet food or bait.

Diet: What Do Mealworm Beetles Eat?

Mealworm beetles are natural decomposers who eat feces, dead insects, and stored grains. They live in habitats where they are surrounded by their primary food source, typically under rocks, animal burrows, logs, or stored grains.

Life Cycle of the Mealworm Beetle

These beetles go through four stages of development:

• Egg
• Larvae
• Pupa
• Adult

The total duration of their life cycle depends on factors like temperature and food availability. However, the mealworm beetle’s average life cycle ranges from 4 to 12 months.

Egg Phase

The females start seeking dark, secluded areas to lay their eggs in the late spring or early summer. If they are in buildings during this time, they will lay their eggs in meal, flour containers, or grain. Females can lay up to 300 white, bean-shaped eggs at a time.

Larva Phase

When the larvae hatch, they are referred to as mealworms and are milky white with slim, segmented bodies. As they grow, they start to turn yellowish-brown within a few days.

They feed on whatever surrounds them and grow to about an inch long while shedding several times in the process, which contaminates food supplies.

Pupa Phase

They remain in their larvae stage until Fall and then morph into pupae to hibernate. The pupae are C-shaped, stout, and light yellow in color, but as they enter adulthood, they become darker.

Adult Phase

Once winter is over and the temperature rises, adult mealworm beetles will start to emerge. At first, they are white and orange but eventually turn dark yellow or black within a few days. These beetles are relatively slow but can fly, making it easier to travel and infest new territory. The adults can live up to 3 to 12 months.

Prevention: How to Get Rid of the Mealworm Beetle

Mealworm beetles don’t cause much damage but carry various diseases that may negatively impact their host plant. They are also major pests when raising poultry because they are carriers of avian diseases and Salmonella.

Seedlings are the most susceptible plants in gardens, so be sure to inspect the younger plants often. Look for any damage and check the soil for the source if you do find anything.

Damage is generally caused by darkling beetles and other insects like cutworms. As a preventative measure, you can install a floating row cover overtop, which should keep them out.

If an infestation occurs, you must remove the source by locating the infested material and placing it in an airtight container before disposing of it. In addition, you can freeze this container for five days, killing the adults and eggs.

To prevent further infestation, store pantry items like cereal, grain, pet food, bird seed, and flour in tight containers.

They are also attracted to animal feces, so if you have dogs and cats, remove any excrement from the property so as not to create a breeding ground for them.

Up Next

• Dung Beetle Facts
• What is the Big Black Beetle in my House?
• 10 Red Beetles and Bugs You Should Know

1. Epic Gardening, Available here: https://www.epicgardening.com/darkling-beetle/
2. Beetle Identifications, Available here: https://beetleidentifications.com/mealworm-beetle/
3. Orkin, Available here: https://www.orkin.com/pests/yellow-mealworms/mealworm-beetle-life-cycle
4. Wikipedia, Available here: https://en.wikipedia.org/wiki/Mealworm