I like how the pewter bug's tones match so well the tones of the leaves around it. Had you used the rule of thirds here, it would have gone far in implying the world around the bug, and enhance the illusion that this bug actually belongs here.
This obviously fits the challenge in your mind, otherwise you wouldn't have submitted it. However, it doesn't fit in my mind, sorry. I think the intent was to deal with life critters. But of course that's just my interpretation.
As for the photo, you got nice lighting and nice detail in the bug. Looks kind of weird rotated because I know that a pewter bug can't hang on. I would probably crop just a bit off the bottom to get rid of that swirly intrusion in the leaf in the bottome left.