The Flea Rider is an enemy in the Castlevania series. They are Flea Men riding on specially trained Eagles (described in English translations as "war-geese").
Flea Riders are Flea Men who ride on specially trained war-geese. When controlled by a Flea Man, the goose flies in erratic patterns rather than the straightforward path it would otherwise take. The goose and Flea Man tend to be destroyed together.
Flea Riders are encountered all along the deck of the Ghost Ship. They soar in from the sky in endless numbers (although there are usually no more than two on the screen at a time) and fly around the hero in a somewhat erratic manner, albeit still on their trail. They can become a real nuisance while dealing with the many Heavy Armors that are also found in that area.
Flea Riders are encountered in the Castle Keep. They swoop in and start hunting the player. They are initially found stationary on their spawning spots in midair and will begin their chase when approached, indicated by the noise of their birds flapping their wings. Since some of them are found in precarious areas that are difficult to traverse by normal means, it's advisable to lure them down to ground level first, where fighting them is easier.
The goose is a slightly modified sprite of the Eagle seen in Castlevania Chronicles. This is referenced more directly in the Japanese version of Symphony of the Night, where they are explicitly referred to as eagles.
