Protein is one of the three vital parts of an ant colony's diet. Without it, the brood wouldn't develop and the queen wouldn't lay eggs. There are lots of sources of protein out there, so this guide is here to help you!
Feeder insects are one of the best, if not the best, source of protein for ants. In the wild, ants eat insects so it seems obvious to mimic this when keeping them. There are lots of types of feeder insects, so here's a quick overview.
Fruit flies are a great feeder insect for small colonies and semi claustral queens. They are small, packed full of protein and are easy to consume. The ants can feed the whole fruit fly to the brood unlike mealworms, which have a hard exoskeleton which is too hard to consume. If I could, I would only feed fruit flies, however they aren't viable for large colonies.
These are like mealworms, just smaller. They are a hit with small colonies. Buffalo worms are ideal to feed when your colony is in the stage where fruit flies don't really suffice, but crickets and mealworms are too much. They have a good amount of protein in them but like mealworms, suffer from a hard exoskeleton.
Mealworms are a good source of protein for ants as the colony grows. Due to their exoskeleton being hard, it is worth cutting up the mealworm into chunks. This means the ants can access the protein
inside easier. As the protein mealworms have contains more fat than other feeder insects, it is worth alternating this feeder, or not making it the colony's only protein source. If you coupled mealworms with the occasional fly or moth you found around your house (make sure to boil them), it would be better for the ants.
Crickets are an amazing feeder for more established colonies. You can buy micro crickets, which are also very good for small colonies. However, the bigger crickets are much better for larger colonies. Depending on the species of ant, you can either feed them with just the head taken off, or cut up. An example of this, for example is with Pheidole species, who have majors. The presence of these majors means that they can cut up and access the cricket themselves. For other species though, you may be better feeding them cut up.
Cockroaches are a great source of protein for large colonies. You can get different size cockroaches, from the massive Madagascarn cockroaches, to the tiny dubia nymphs, which means that you can find a cockroach type to suit your colony. The most commonly sold types are Dubia and Redrunners. Both are good for large colonies and have plenty of protein in them. I only recommend getting these if you have a big colony that can eat cockroaches, or lots will go to waste.