Mealworms vs Calci Worms: Which Is Better for Garden Birds?

Both mealworms and calci worms are excellent for garden birds, but they do different jobs. Here is an honest comparison to help you decide what to put in your feeder.

If you have shopped for bird food recently, you will have noticed that mealworms are no longer the only larvae on the shelf. Calci worms, sometimes listed as calciworms or black soldier fly larvae, have become far more common, and the question we are asked more than almost any other is simple: which one should I be buying?

The honest answer is that they work best together rather than in competition. But understanding what each one does will help you feed your garden birds more thoughtfully, particularly through the key times of year: breeding season, the winter cold and the summer moult.

What are mealworms?

Mealworms are the dried larvae of the mealworm beetle, and they are one of the most protein rich foods you can offer garden birds. Premium dried mealworms contain up to around 53 percent protein, which makes them a dense, energy giving food that birds instinctively recognise. They are higher in fat than calci worms too, which is exactly what birds need to stay warm through the colder months. Robins, wrens, blackbirds, thrushes, tits and many more will take them readily from a feeder or an open dish.

What are calci worms?

Calci worms are the dried larvae of the black soldier fly. They are still high in protein, but their stand out quality is calcium. They contain far more of it than mealworms, which matters most during the breeding season, when female birds need calcium for healthy eggshells and growing chicks need it for bone development. They are also softer and smaller than mealworms, which makes them easier for young, newly fledged birds to manage. If you have nesting birds nearby, or you can hear hungry chicks, calci worms are a brilliant thing to have on the feeder.

So which should you buy?

Both, ideally, and that is not simply us trying to sell more. Mixing dried mealworms and calci worms in the same feeder gives visiting birds access to high quality protein and the calcium they need in one place. It is a more balanced offering than either on its own.

If you can only choose one, think about what you are trying to support. Feeding mainly through winter, when birds need dense calories? Lean towards mealworms. Heading into spring with nesting birds nearby, or seeing lots of fledglings in the garden? Calci worms are the priority.

One thing worth remembering: neither should be the only food on your feeders. They are excellent supplements, but birds also need seeds, fat based foods and fresh water every day. Think of them as the protein course in a balanced garden menu.