Mealworm Beetle
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Tenebrionidae
Genus: Tenebrio
Species: T. molitor
Binomial name
Tenebrio molitor
Linnaeus, 1758

Mealworms are the larval form of the mealworm beetle, Tenebrio molitor, a species of darkling beetle. Like all holometabolic insects, they go through four life stages: egg, larva, pupa, and adult. Larvae typically measure about 2.5 cm or more, whereas adults are generally between 1.25 and 1.8 cm in length.



Mealworms nestled in a bedding of bran within a jabari plastic container

Mealworms are typically used as a food source for reptile, fish, and avian pets. They are also provided to wild birds in bird feeders, particularly during the nesting season, when birds are raising their young and appreciate a ready food supply. Mealworms are high in protein, which makes them especially useful as a food source. They are also commonly used for fishing bait.

They can be purchased at most pet stores and bait shops, and are available via mail order or internet suppliers (by the thousand). Mealworms are typically sold in a container with bran or oatmeal for food.

When rearing mealworms, commercial growers incorporate a juvenile hormone into the feeding process to keep the mealworm in the larval stage and achieve an abnormal length of 2 cm or greater.

Tenebrio molitor is also used for biological research. Its relatively large size, ease of rearing and handling, and status as a nonmodel organism make it attractive for proof-of-principle study. Researchers worldwide, but particularly in Sheffield (UK) and Pusan (Korea), currently use this beetle as a model system for studies in biology, biochemistry, evolution, immunology and physiology.


Tenebrio molitor (flour beetle)

Mealworm beetles (darkling beetles) are prolific breeders. Mating is a three step process:

  1. The male gives chase until the female relents.
  2. The male then mounts the female and curls his genitals (aedeagus) underneath himself and inserts it into her genital tract.
  3. The male then injects a packet of semen into the female.

Dependent on incubation temperature, just days after mating, the female will burrow into soft ground and lay about 500 eggs.


After four to 19 days, the eggs will begin to hatch. These tiny mealworm eggs are food for their predators, such as reptiles.

Larval stage

During the larval stage, mealworms will undergo repeated molting between bouts of eating various vegetation or dead insects. This takes place 9-20 times (instars) as it gets too big for its current exoskeleton. During its last molt, it loses its carapace before curling into its pupal form.

Pupal stage

The mealworm remains in its pupal stage from three days to around 30 days (dependent on incubation temperature and overwintering). The pupa starts off a creamy white color, and changes slowly to brown during its pupation.

A mealworm pupa recently molted from the larva stage, the darker object is the discarded larva skin.

Typical life history:

  • Time spent as surviving egg: 10 to 12 days (Hill 2002)
  • Time spent as surviving larva: 12 to 54 days
  • Time spent as surviving pupa: 20 days (not available, Hill 2002)
  • Time spent as surviving adult: 80 days (60 to 90 days, Hill 2002)
  • Number of eggs per surviving adult: 80 (0 to 500 days, 1937, Hill 2002, Greenberg and Ar 1996)

Human consumption

A bowl of meal worms

Mealworms may be easily raised on fresh oats, whole wheat bran or grain, with sliced potato or carrots and little pieces of apple as a water source.

Mealworms have been incorporated into tequila-flavored novelty candies. However, mealworms are not traditionally served in tequila or mezcal drinks, the latter sometimes containing a larval moth (Hypopta agavis).

Rearing mealworms into adult beetles

Detail photo of a mealworm.

Mealworms are commonly used as feed for reptiles, fish, and birds, and are easily obtained from supply companies. They grow best in well-ventilated containers eight to ten inches deep with large surface areas, and smooth sides to prevent them from escaping. The mealworms are mostly nocturnal and prefer a dark environment. The food for the larvae can be flour or cereals. Moisture is provided by small amounts of fruit or vegetable matter that should be replaced before it goes moldy.

Adult beetles that arise from the larval population are moved to another container prepared with the same food mixture, to lay eggs for more young worms, which are transferred into the first tray, to provide a continuous supply of worms.

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • mealworm — [mēl′wʉrm΄] n. the wormlike larva of any of a genus (Tenebrio) of darkling beetles, which destroys flour, meal, etc …   English World dictionary

  • mealworm — noun Date: 1658 the larva of a darkling beetle (especially genus Tenebrio) that infests grain products but is often raised as food for insectivorous animals, for laboratory use, or as fishing bait …   New Collegiate Dictionary

  • mealworm — /meel werrm /, n. the larva of any of several darkling beetles of the genus Tenebrio, which infests granaries and is used as food for birds and animals. [1650 60; MEAL2 + WORM] * * * …   Universalium

  • mealworm — noun A larva of the darkling beetle Tenebrio molitor …   Wiktionary

  • mealworm — meal·worm (mēlґwərm) 1. the larva of any of various grain beetles of the genus Tenebrio, which eat and contaminate grain products such as flour and are also raised as food for insectivorous domestic animals such as birds. Spelled also… …   Medical dictionary

  • mealworm — mɪːlwÉœrm / wɜːm n. larva of various species of beetles (used as food for birds and animals) …   English contemporary dictionary

  • mealworm — noun the larva of the meal beetle, used as food for cage birds and other insectivorous animals …   English new terms dictionary

  • mealworm — meal•worm [[t]ˈmilˌwɜrm[/t]] n. ent the larva of any of several darkling beetles of the genus Tenebrio, that infests granaries and is used as food for birds and animals • Etymology: 1650–60 …   From formal English to slang

  • mealworm — /ˈmilwɜm/ (say meelwerm) noun the larva of the beetle Tenebrio molitor, which infests granaries, and is cultivated in great numbers as food for birds and animals …   Australian English dictionary

  • mealworm — noun the larva of beetles of the family Tenebrionidae • Hypernyms: ↑larva • Member Holonyms: ↑Tenebrionidae, ↑family Tenebrionidae …   Useful english dictionary