Mothraya

Robot Moth is a giant robotic moth, and is the boss of Cossack Stage 1 in Mega Man 4. The red flashing light is its weak point, and Drill Bomb or Ring Boomerang are the best weapons to use (though Dust Crusher is also a good option). It can thrust its spike-tipped "proboscis" into the floor, causing a part of the floor to be destroyed.

Fun Facts
Robot Moth's Japanese name "Mothraya" is a nod to the Japanese movie giant moth monster, Mothra.