What is a litter of flies called?

What is a litter of flies called? A group of flies is not typically called litter, litter is usually for mammals like puppies or kittens. For flies, collective nouns include swarm, cloud, business, or cluster of flies. A swarm of flies is most common term for many flies together in air. A cloud of flies also used when large number. A business of flies is historical collective noun from old English, like business of flies or business of ferrets. So litter of flies is not standard, but if referring to eggs or larvae, you might say batch of eggs or batch of maggots. Flies lay batches of eggs, not litter. So correct terms are swarm, cloud, or business of flies, not litter. Litter usually refers to group of offspring born at same time to mammal, not insects. So answer is flies are called swarm or business, not litter, but batch for eggs.