Blackbird with a beakful of mealworms, perched on a washing line in garden

Breed your own mealworms

Mealworms are a great natural food for birds and can be used to feed them throughout the year.

How to culture mealworms

It can become quite expensive to constantly buy mealworms, so you might want to grow your own. 

For a constant supply of mealworms, prepare a large circular biscuit tin as follows: 

  • Punch small holes in the lid for ventilation, place a layer of old hessian sacking in the bottom and sprinkle fairly thickly with bran. Put a slice or two of bread and raw potato, followed by another two layers of sacking/bran/bread/potato, like a three-decker sandwich. You can put a raw cabbage leaf on top if you like. Keep the tin at room temperature, not in hot sun.
  • Introduce two or three hundred mealworms into the prepared tin. After a few weeks the mealworms will turn into creamy pupae, then into little black beetles. 
  • The beetles will lay eggs which hatch into mealworms and so on. Crop as necessary. Replace the bread, potato and cabbage as necessary. 
  • If you want to start new colonies, prepare another tin and transfer some bits of dry bread (these will carry beetle eggs) from the flourishing colony. 

It is very important that any mealworms fed to birds are fresh. Any dead or discoloured ones must not be used as they can cause problems such as salmonella poisoning. Always ensure you use an appropriate mealworm feeder



Rearing techniques

Place 20 adult beetles on a piece of moist blotting paper overnight. A drink in this form will increase egg production. Transfer the insects on to the above food mixture in a container which can be sealed by a muslin top or by a blotting paper lid waxed to prevent the entry of mites and other parasites

Adults of the next generation should appear after 130 days at 25°C, 70% R.H.

  • Some form of humidity is essential (range 55-80% R.H.)
  • For optimum conditions rear larvae at 25-30°C
  • Pupation is to some extent inhibited at 30°C
  • Do not overcrowd cultures 
Robin with a mealworm perched on a garden fork handle

Yellow mealworms (Tenebrio molitor)

  • Rearing: temperature, 25°C average; humidity, 70% relative humidity (R.H.).
  • Food: wheatfeed 10 ounces; rolled oats 10 ounces; yeasts 2 ounces.
  • This food mixture will produce about 350 adult mealworms in 200 days from 10 females (with 10 males). However, each female can lay about 100 eggs.
  • Incubation: 10-11 days at 20°C; 4-6 days at 30°C; larval period, from about 114 days (10-14 larval instars).
  • Pupal period: 30 days at 15°C; 9 days at 25°C; 6 days at 35°C.
Mealworm and suet gourmet mix on mesh tray on green pole Eurasian Nuthatch