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They only work one tile at a time (unless you can match up two gumdrop bees together), but every little bit helps.
The gumdrop bee thing will seek out tiles that need to be cleared for level completion.
Line-clearing power-ups go either horizontally or vertically, and will clear out a row or column depending. Try to remember what creates what and use that to your advantage whenever possible. Depending on the configuration of the matched tiles (a straight line, a 2x2 square, a 'L,' a 'T,' etc), you'll create different types of power-ups. Try to stick to matching more than three every chance you get. Matching four or more of the same tile will always create a power-up of some sort, which always comes in handy.