This is an interesting lens from Sigma. Most manufacturers make f/2.8 macro lenses in the 90-105mm range, and some make f/3.5 or f/4 macro lenses around 180-200mm, but this one is quite unusual. Sigma have apparently tried to offer a lens which combines the best of both worlds - a fastf/2.8 maximum aperture and a decently long reach.

And we'd say they've succeeded. This is a very well built lens and it's very, very sharp, even wide open at f/2.8. It allows a 20cm working distance which should be enough to avoid scaring the insects away. The only downside is that the autofocus isn't the fastest in the world, but then most serious macro photographers would probably prefer manual focus anyway.

Suggested extra: You might find the Manfrotto MN454 micropositioning sliding plate useful when mounting this lens on a tripod.