I've lived in Wyoming my entire life, and can assure you these lighter colored 'dots' are indeed ant colonies. If you like, i could arrange an actuall photo sometime in the near future (as soon as today's snow melts off...lol). I agree its odd, but they do indeed end up showing in a grid pattern now and then. What strikes me as really odd is mans' difficulty in accepting that nature is capable of creating patterns from randomness. It's easier for me to visualize a grid pattern emerging from the ants in the area you have chosen to veiw simply because of the near constant winds in that area (the new queens are subject to the prevailing wind at the time of emergance). If you look again, you'll realize there is more randomness in the patterns than you first noticed. The variance in sizes you mentioned is subject to the size of the specific colonies. You'll find these things statewide, 'specially in the more barren, wide open spaces. Prairie dog colonies are much more messy and random than the overly organized ants, and you'll be able to just make out little trails between the colonies (if the resolution is high enough....)

Jesse
Powell, Wyoming