I have tried to do similar with spiders but for some reason she is freaked out by them! maybe its just instinct, my mum was a screaming mess everytime she saw a spider and i didnt want to put that on DD....even though i want to scream....i even held a bloody daddy long legs that was hidding behind the loo but she wasnt keen on it atall!
That is so true. My mum was the same and made a huge deals out of all things yuck, so even though on the inside it's awful, I am really aware of the kids watching me. It has paid off. DD used to be pertified of everything that moved, and now through positive exposure she's pretty good. If she sees a spider/lizard/bug of any description/mouse she'll tell her father it's there, but 'don't worry dad mum will take it outside'.
I totally agree with Inanna about the positive exposure to snakes too. We've taken the kids to a few and DD is quite proud about her knowledge.

The thing we've had to scare her about though is crocs and the waterways up here....healthy respect just doesn't cut it with them.