Answer: The real question is, are these creatures pests? Mites are minute, eight-legged creatures that prefer dry conditions. The crawling things you've seen may simply be soil organisms that enjoy the company of your lime tree. There are some houseplant soil pests, though they tend to be symptoms of a greater threat to plants: overwatering. The list of common houseplant soil-dwellers includes springtails, fungus gnats and symphylans. They aren't a problem unless there are a lot of them, and the soil usually has to be overly-moist for them to thrive in large numbers.
You wouldn't see fungus gnat larvae scurrying on the soil surface, but the other two would appear there. If you have a magnifying glass, you can probably identify them. Here are some images I found on the WWW to help you with i.d.:
springtails (collembola): http://www.geocities.com/~fransjanssens/
If you find either (or both) of them in your soil, allow the soil to dry out well on the surface between waterings. In winter, citrus usually need less water, and a deep drenching followed by a drying-out period is all that's necessary.
If the critters don't fit either description, then it's best to take a sample in a small bottle, and contact your county agricultural extension service (ph# 522-8567 ) to find out where to send them for identification. Once you know what they are, you'll know whether or not they are pests, and if necessary, how to control them. I'd love to hear what you find out! Good luck.
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