What is the name of those large, flying, yellow insects that literally look like a ball of fluff

Question

I saw one of these a few years ago hovering [not flying] slowly around a citrus tree, at dusk. I believe the wings were transparent. It definitely was not a bee, or a bird, more like a orange-yellow flying tribble.

What was it? Thank you. Dave.

Answer 1

I think i was a luna Moth or a io moth.

Answer 2

Learn to Id them, here -

http://bugguide.net/node/view/15740

http://www.butterfliesandmoths.org/