mealworm n : the larva of beetles of the family Tenebrionidae
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 2.5cm or more, whereas adults are generally between 1.25 and 1.8cm in length.
UsesMealworms are typically used as a food source for reptile 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. They are commonly used for fishing bait.
They can be purchased at most pet stores and are also available via mail order and the internet. 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.
ReproductionMealworm 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 (aedagus) underneath himself and inserting it into her genital tract. 3) The male then injects the female with a packet of semen. Dependent on incubation temperature, just days after mating the female will burrow into soft ground and lay between 70 and 100 eggs.
GestationAfter 1 week the eggs hatch and larvae emerge.
Larva StageDuring the larva stage "mealworms" will undergo repeated molting between bouts of eating various vegetation or dead insects. This takes place 10-14 times (instars) as it gets too big for its exoskeleton. During its last molt, it loses its carapace before curling into its pupal form.
Pupal StageThe mealworm remains in its pupal stage from 6 days to around 30 days (dependent on incubation temperature and overwintering). The pupa starts a creamy white colour and changes slowly to brown during its pupation stage.
AdulthoodThe newly emerged mealworm beetle will sit still as its wings unfold and dry. It will appear a creamy color, stop moving, and will slowly brown over a period of 2-7 days. Once the mealworm beetle has browned they will become sexually mature and begin to look for a mate.
- Incubation: 10-11 days at 20°C; 4-6 days at 30°C
- Larval period: 90-114 days (10-14 larval instars).
- Pupal period: 30 days at 15°C; 9 days at 25°C; 6 days at 35°C.
- Adult Stage 1 - 2 Weeks
Human consumptionMealworms can be easily raised on fresh oats or grain, with sliced potato or carrots and little pieces of apple as a water source.
Mealworms can be dried and crushed and used as a protein rich flour. They are also used whole in recipes: in sautees, or spaghetti dishes.
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).
Pest controlUsually a mealworm infestation within premises of any kind is generally attributed to poor housekeeping practices in regards to cleaning away scraps of food and ensuring stored food can’t easily be got at by pests.
If an outbreak has occurred then any tainted food should be disposed of in an outside bin with a tight fitting lid. If the contaminated food is placed in an inside bin the infestation will continue.
In addition an effective insecticide spray can be used to eradicate the problem. This is generally applied to the area in and around the outbreak and will be administered for at least three weeks post-infestation, as the larvae have such a long life span.
mealworm in German: Mehlkäfer
mealworm in Spanish: Tenebrio molitor
mealworm in French: Ténébrion meunier
mealworm in Dutch: Meeltor
mealworm in Japanese: ミールワーム
mealworm in Polish: Mącznik młynarek
mealworm in Portuguese: Bicho-da-farinha
mealworm in Finnish: Jauhopukki
mealworm in Turkish: Un kurdu
mealworm in Ukrainian: Хрущак борошняний