Uh...I'd rethink anything that involves 8 yr olds and potentially fire or anything hot .
It depends how much time you have, but I'm with Brendhan and Mici on this one. It doesn't necessarily have to do directly with bees, and the more simple it is, the better.
With a big age range, you have a challenge, since the 14 y-os could care less about what the 6 y-olds are doing.
Depends how much time you have. If you have to fill more than 2 hours, then you have a handfull. If it is less than an hour, make it a little presentation about bees.
I do like the pipe cleaner idea, and the dough/modelling clay idea is good too. Something as simple as coloring a bee, cutting it out, and pasting it on anther paper (teachers know more about this stuff) You can always take samples for them to try, and make some honey-based snacks.