lizard lures!

I would guess if you get it near a large mouth / small mouth nest in the Spring, they'd defend their nest against them.  The yellow one looks like a newt, not sure about the purple one.  I have seen stranger things catch fish though.  
 
I find that many lures that I make, catch fish when other lures are catching fish.  And usually don't catch fish when other lures aren't catching fish.  So, when you give these puppies a try, give them a fair shake.  I.e., don't only used when nothing else is working, then figure they don't work.  Although it is always hard to put down the hot lure when it is hot, try tossing one out then.  That said, with these guys, especially that purple one, you might scare the fish a little...
 
Good luck