The thing that stands out to me here that could use fixing/improvement is the blurry object in the middle at the bottom of the shot. I find that because it is a brighter color than the rest, and quite blurry due to DOF, that it jumps right out of the photo and is the first thing I'm noticing here.
You have really nice DOF to get the ants in focus and the plant blurred slightly. I like the detail that we see in the ants. Really nice macro shot.
The lighting appears to have been very good as well. Natural lighting, which it looks like, isnt always reliable, and I think you took advantage of a good situation here.
The shot is green, and qualifies for the challenge, but I do think that the MAIN subject isn't the color, but the ants. Still a really good shot though.
I like the angle and framing/cropping as well. I think that anything farther away would take away the good detail which is appealing the most to me here.