It is not uncommon to find two conjoined flies. In such a state, they are known as a "moter" and act as a single creature with the above statistics, except with 2 hit points . If it is attacked with a weapon, it can use its reaction to split into two attack flies, each moving up to 5 feet without provoking an opportunity attack . The attack misses unless a fly remained in its original location. Variant: Swarm [ edit ] For a swarm of attack flies, use the swarm of insects ( Monster Manual p.