I reckon that one may be OK for butterflies and whole flower shots but you will not be able to get really close up head shots of bees etc. Depends what what you want to do really.
Most people start off wanting to see the pimples on bee's nose
That lens would get you started. You could buy extension tubes for not a lot of money - that would mean you could shoot even closer.
Edit: This guy really understands bug shooting in the wild - which is different to indoor macro shooting of small objects. Worth a read and he has the answers to just about every question. He mentions zoom lenses with a macro setting a little way down. ON THE HARDWARE BASICS MENU
http://macroshooting.com/Macro_Flash_Brackets.htm