Hate to say it, but it's a good job that there are newts and assorted critters chomping on the tadpoles, or we'd be hip-deep in frogs!

I recall reading in a novel once where one character asked a wizard if he could turn people into frogs. The wizard said he could but it wasn't worth the bother because "Frogs multiply at a ferocious rate. I'd rather have one person that annoyed me than several hundred aggravating frogs!"