Mealworm beetles

Pronunciation

How to pronounce Tenebrio: /tɛˈnɛbrio/

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Summary

The genus Tenebrio, including species such as Tenebrio molitor (yellow mealworm beetle), is globally distributed primarily in temperate regions. Known for their larval forms, which are used as a food source and in biomedical research, these beetles can also be pests in stored foods.

Physical Characteristics

Adults are generally 1.25 to 1.8 centimetres (0.49 to 0.71 in) in length, dark brown or black in color. Larvae are lighter colored, typically measuring about 2.5 centimeters (0.98 in) or more in length.

Identification Tips

Differentiated from other beetles by linear grooves along the abdomen and having only four tarsal segments on hind legs. Adult black mealworm beetle (T. obscurus) has a more rounded abdomen ending in a pointed tip, while T. molitor has a rectangular, blunt-ended abdomen.

Habitat

Mainly found in buildings and storage areas; may also occur in hollow trees.

Distribution

Originally from the Mediterranean region but now cosmopolitan due to human trade. Present in many temperate regions worldwide.

Diet

Larvae feed on vegetation and dead insects; adults are commonly found in stored grains and grain products.

Life Cycle

Goes through four life stages: egg, larva (mealworm), pupa, and adult. Eggs hatch after 4 to 19 days; larvae can go through 9 to 20 instars; pupation occurs after the larval stage, with adults emerging after 3 to 30 days depending on environmental conditions.

Reproduction

Males release a sex pheromone to attract females. A female can lay about 500 eggs over her lifespan of 6-12 months.

Ecosystem Role

Considered pests primarily affecting stored grains but also beneficial as a source of food for animals and humans; can degrade plastic waste and polystyrene.

Economic Impact

Increasingly used as animal feed and in human nutrition; being promoted as a viable food source due to high protein content and potential for waste degradation.

Cultural Significance

Historically consumed in many Asian countries, particularly Southeast Asia; marketed as a healthy snack food and used in various food products.

Health Concerns

May pose health risks if consumed by humans or animals, with rare instances of larvae surviving in the alimentary tract.

Similar Taxa

• T. obscurus (black mealworm beetle)

Misconceptions

Often confused with black mealworm beetle, which can be distinguished by differences in abdomen shape and color.

Tags

• mealworm
• Tenebrio
• pest
• food source
• biomedical research