Mealworms, superworms and gut-loading: feeding your feeder insects well
Mealworms and superworms are the easiest feeder insects to keep, but their nutritional value depends on a step too often neglected: gut-loading — feeding the insect an enriched diet for 24 to 48 hours before offering it to the reptile. A tub of worms costs 3 to 5 €; a home colony, almost nothing.
Mealworms or superworms: what are the differences?
The mealworm (larva of Tenebrio molitor, 2-3 cm) suits geckos and small lizards. The superworm (Zophobas morio, 4-6 cm) is bigger, more active and fattier: reserve it for bearded dragons and large adult geckos. Both have thick chitin and an unfavourable calcium-to-phosphorus ratio: they must remain supplements, never the basis of a balanced diet.
How do you gut-load properly?
A starved insect provides almost nothing: its full digestive tract is precisely what nourishes the reptile. Place the worms 24 to 48 hours before feeding in a box with:
- Dry base: wheat bran, oat flakes, commercial gut-load feed (5-10 €);
- Fresh calcium-rich vegetables: carrot, courgette, cabbage leaves;
- No citrus or salty foods;
- Final dusting of calcium just before serving, with feeding tongs;
- Vitamins once or twice a week depending on species and age.
How do you store or breed mealworms and superworms?
Mealworms keep for several weeks in the refrigerator (8-10 °C) in dormancy; take them out 48 hours ahead for gut-loading. Superworms, on the other hand, cannot tolerate cold: keep them at room temperature in bran with vegetables. A full breeding cycle is easy: larvae, pupae, then breeding beetles in three separate tubs, on the same principle as the cricket bin.
How often should you feed them out?
Once or twice a week for an adult leopard gecko, alternating with crickets and roaches; fatty superworms should stay a weekly treat for a bearded dragon. Excess leads straight to obesity. All our nutrition guides are on the reptile hub.
Frequently asked questions
Can a superworm injure a reptile?
Its mandibles are powerful: crush the heads of the largest ones before feeding them to slow animals, and never leave loose superworms in the terrarium.
Dried worms or live ones?
Dried worms will do in a pinch, but they lose part of their nutritional value and do not trigger hunting behaviour. Live, gut-loaded insects remain the gold standard.
This guide is part of Planète Pets’s Reptiles universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.