Feeding mealworms (Tenebrio molitor) to Bearded dragons

Mealworms, or more specifically Yellow mealworms, are the larval stage of the Darkling beetle (Tenebrio molitor). They are known to be tasty to Bearded dragons, but contain high levels of fat, making them better for offering as snacks.

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. They are quiet, slow-moving, fairly odourless, need little maintenance and relatively small amount of space. Because of their popularity, Mealworms are fairly easy to culture on a small scale at home, but commonly available from specialised pet shops and online retailers (Buy live mealworms from Amazon.com ).

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:

* Values are averages calculated from sources. Expressed as %DM except moisture.

When comparing mealworms with other crawling food such as Superworms (Z. morio) and butterworms (C. moorei), they have more or less the same amount of protein (ca. 54% (1) (2) (4) (5) (6) (8) (9) (14) vs. 49% (4) (5) (8) (9) (14) (18) & 39% (8) (18) (19) ), less fat (ca. 30% (1) (2) (5) (6) (7) (8) (9) (14) vs. 36% (5) (7) (9) (14) (18) & 74% (9) (18) (19) ), are 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. 1:9 (8) (9) (14) (18) & 1:18 (18) (19) ). When compared to 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. 36% (5) (7) (9) (14) (18) ).

Feeding mealworms to Bearded dragons

Mature mealworm larvae are typically light yellow-brown in colour and 20 to 32 mm long. Their high fat content makes them a poor choice as a staple for Bearded dragon food and will lead to obesity and poor growth, especially in growing Bearded dragons.

If the occasional mealworm is fed, they should be fresh. Mealworms can be fed in a shallow, escape-proof dish with calcium supplementation to stimulate its intake. Uneaten mealworms should be removed immediately after feeding is over. Other higher protein feeder insects such as cricketssilkworms, and/or Dubia roaches should make out the bulk of a Bearded dragon’s food.

Additional mealworm larvae can be offered to breeding female Bearded dragons on a daily basis to improve the body condition between egg batches.

Mealworm life cycle

Like all holometabolic insects, 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 to 12 days and become mature after going through 8 to 20 molting stages – typically taking 3 to 4 months (but as long as 18 months). The pupal stage typically lasts 7 to  9 days (but up to 20 days at lower temperatures). As beetles, they live for 2 to 3 months. The total life cycle of mealworms range from 280 to 630 days.

Giant mealworms

Commercial mealworm producers sometimes include a juvenile hormone/steroids into the feed to prevent larvae from molting into adults, resulting in ‘giant’ mealworms. These mealworms can achieve a length of 2 cm or more. Avoid feeding these to Bearded dragons.