500D Close-up Filter
If you don't have a macro lens, or it's beyond your budget, consider purchasing a two-element close-up filter, sometimes called a diopter or lens. This screws on to the front of a telephoto zoom lens (or macro lens) and allows the lens to focus closer than it normally does. These filters are sharp, very portable, and much less expensive than a dedicated macro lens.
I used the Canon 500D filter on a 70-200mm lens for this shot. The filter is available in a limited number of filter sizes. So if there isn't an exact match to your lens's filter size, purchase a larger diameter filter and add a step-up ring to fit the lens to the filter.