The properties of Buzzy Beetles are very similar to that of the Green Koopa Troopas in that they curl up into their shell when jumped on, and can then be kicked. The main difference between the Buzzy Beetles and the Green Koopa Troopas, other than their look, is the fact that they are impervious to Fire Mario's fireballs.
Super Mario Bros.
Buzzy Beetles first appeared in World 4-2 of the game Super Mario Bros. The same underground level in which the warp zones to worlds 6, 7, and 8 are located. Also, once the game is completed, all the Goombas are replaced with Buzzy Beetles in the "Second Quest".
Super Mario Bros. 3
All of the original characteristics of the Buzzy Beetle were kept in tact for Super Mario Bros. 3, but their use and abilites were expanded. Buzzy Beetles now have the ability to walk on walls and ceilings, and when Mario gets close enough they will drop down and try to attack Mario by spinning on their backs in his direction.