Mealworm larvae are popularly fed to pet animals. Because of their high protein and fat content, mealworms are frequently fed pet Leopard geckos.
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Mealworms, or more specifically yellow mealworms, are the larval stage of the mealworm beetle (Tenebrio molitor). The mealworm beetle is a type of darkling beetle.
Like all holometabolic insects, the darkling beetle goes through four life stages — egg, larva, pupa and adult. Although all these stages can be fed to pet Leopard geckos, it is the larval stage — i.e. ‘mealworms’ itself — that is most frequently used as food for Leopard geckos.
Mealworms are known to be high in fat and high in protein. Because of their fat tails, Leopard geckos benefit from eating mealworms when they need to gain weight.
Mealworms (Tenebrio molitor)
Tenebrio molitor goes through four life stages — egg, larva, pupa and adult.
- After eggs have been laid by adult beetles, mealworm larvae will hatch within 10-12 days and become mature after going through 8 to 20 moulting stages — typically taking 3-4 months (but as long as 18 months).
- The pupal stage typically lasts 7-9 days (but can take up to 20 days at lower temperatures).
- Adult beetles are typically 12 to 18 mm / 1/2 to 3/4 ″ and live for about 2-3 months.
The total life cycle of mealworms ranges from 280 to 630 days.
Mealworms are omnivorous and can eat all kinds of plant material as well as animal products such as meat and feathers. They are typically fed on cereal bran or flour (wheat, oats and/or maize) supplemented with fresh fruits and vegetables (carrots, potatoes, lettuce) for moisture together with protein sources such as soybean flour, skimmed milk powder or yeast.
Mealworms are quiet, slow-moving, fairly odourless, need little maintenance and a relatively small amount of space. Because of their popularity, mealworms are commonly cultured by Leopard gecko keepers at home.
Mealworm nutritional values*
As a food, mealworm larvae contain high amounts of protein, but also high amounts of fat and has a low calcium availability:
- Moisture 62%(2)(8)(10)(14)(18)
- Total protein 54%(1)(2)(4)(5)(6)(8)(9)(14)
- Total fat 30%(1)(2)(5)(6)(7)(8)(9)(14)
- Calcium:Phosphorus ratio 1:14(5)(6)(8)(9)(11)(14)(18)
* Values are averages calculated from sources. Expressed as %DM except moisture.
When comparing mealworms with other crawling food such as butterworms (C. moorei), they have more or less the same amount of protein (ca. 54%(1)(2)(4)(5)(6)(8)(9)(14) vs. 39% (8)(18)(19)), less fat (ca. 30%(1)(2)(5)(6)(7)(8)(9)(14) vs. 74% (9)(18)(19)), are considered just as tasty and has more or less the same amount of available calcium levels (Ca:P ratio of 1:14(5)(6)(8)(9)(11)(14)(18) vs. 1:18 (18)(19)).
When compared with crickets (A. domestica), mealworms have less available calcium (Ca:P ratio of 1:5(6)(8)(18) vs. 1:14(5)(6)(8)(9)(11)(14)(18)), less protein (ca. 64%(3)(5)(6)(8) vs. 54%(1)(2)(4)(5)(6)(8)(9)(14)) and more fat (ca. 21%(3)(5)(6)(8) vs. 30%(1)(2)(5)(6)(7)(8)(9)(14)).
Feeding mealworms to Leopard geckos
Mealworms are popularly fed to Leopard geckos(62). Larvae are typically light yellow-brown in colour and 20-32 mm / 13/16-1 1/2 ″ in length. Nutritionally they contain high amounts of fat, relatively high amounts of protein and a low Ca:P ratio.
Because of their fats tails, Leopard geckos can eat high volumes of mealworms without problems. Whereas the high fat levels cause obesity and other problems in many other pet lizards, Leopard geckos tend to store this fat in their tails, mainly utilising the proteins for growth and body function.
Mealworms can be fed in a shallow, escape-proof dish with calcium supplementation to stimulate its intake. The mealworms should always be fresh. Uneaten mealworms should be removed and replaced every day.
Although mealworms are a relatively good food source for Leopard geckos, it is important not to feed them as the only protein source. Other higher protein feeder insects such as crickets, silkworms and/or Dubia roaches should make out the bulk of a pet Leopard gecko’s food.
The body condition of female Leopard geckos during the breeding season can be improved by adding more mealworms to their diet.
Commercial mealworm producers sometimes include a juvenile hormone/steroids into the feed of mealworms to prevent larvae from moulting into adults — resulting in ‘giant mealworms’. They should not be confused with superworms (Zophobas morio). Giant mealworms can achieve a length of 2 cm / 13/16 ″ or more.
Mealworms are popularly fed to Leopard geckos. Although they should not be used as the only food source, mealworms are a great choice for picky eaters, emaciated Leopard geckos and breeding females.
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