Bite

Melee Weapon Attack: +4 to hit, 5 ft., one creature,. 4 (1d4+2) piercing damage and the flea attaches to the target. While attached the flea doesn't attack. Instead at the start of each of the flea's turns the target loses 4 (1d4+2) hp due to blood loss. The flea can detach itself by spending 5 ft. of movement. It does so after draining 12 hp of blood from the target or the target dies. A creature including the target can take its action to detach the flea by succeeding on a DC 11 Str check.