Macro lenses tend to be rated excellent to fantastic for the close-up work. Other features that might come into consideration would be utility as a non-macro telephoto. If you like insects, you likely would go for a 100 mm or longer lens. You might also want to consider using flash. I like to shoot snakes and other herps - for the poisonous ones I am happy to have as much distance between me and it, so that it doesn't get nervous (then I am Outta There!). Do you expect to be shooting near/at 1:1 or at lower mag?
I started out using a 60D and 60mm f/2.8, a nice combo for flowers / general use short telephoto. 60 is also a good studio macro length - you don't want to be forced to park the camera in the next room. Sometimes at 1:1 the working distance was short enough that ambient lighting was somewhat of an issue. There's where supplemental flash comes in handy. You can pop the 60 in your pocket, it is light weight. Also, it balances well in the hand on a Rebel. I have been using one on a copy stand at work for about 6-7 years now. A do-it-all APS-C kit for nature photography could be 24mm f/2.8 for landscape, 60 for macro, and if you are into larger insects or birds, 300mm f/4 L IS (used) with option of 1.4x TC. 300 f/4 L IS is an old lens with hilariously loud IS, but it focuses to about 1:3, which is great for dragonflies, butterflies, etc. To some extent it has been overtaken by the 100-400 f/4-5.6L IS II which also focuses to 1:3 mag.
I got interested in insects and finally got the 180mm f/3.5L, very heavy hand-held, but you get used to it. I will say that it is now a somewhat outmoded lens, unless you get a great deal on a used lens. The new 150 and 180 Sigmas are very good. The 180 Sigma is a beast, comparable to the Canon 100-400 in size and weight. 150 balances well and is lighter.
There are some esoteric lenses out there that are fabulous for specialists but lack IS and autofocus (hence less useful for general telephoto). The Zeiss 50mm and 100mm and the Voigtlander 125mm come to mind. All are very expensive.
Don't get the MP-E 65 until you are quite experienced with macro and macro flash at 1:1 or less.
Macro lenses often come up on the used market. If you aren't sure this is for you, get the Canon 60mm f/2.8 at ~ $300.00 (used or less).