I upgraded from a bridge camera to a D80 earlier this year, primarily for better quality macro photography.
I've been using Nikons 60mm f2.8 AFS lens which is absolutely superb for wild flower & fungi macro, but you have to get extremely close to the subject to get 1:1 image size ratio.
I'm in the very fortunate position of just having been given a present of a Sigma 180mm f3.5 macro lens, which has a lens to subject distance of something like 600mm for 1:1 image ratio, which will be absolutely superb for insect photography.
The slight disadvantage of this lens, is that it is quite heavy, in comparison with the 60mm Nikon, and will undoubtedly require tripod support for stability, given it's telephoto nature. (Or fast shutter speed and high ISO settings, with attendant possible quality loss.
).
The other thing to bear in mind is that with the D80 not having a full size sensor, these lenses give true focal lengths of approx 1.5 x the stated focal length.
Regards
Mike.