Two winters ago we had a few aphids on some of our indoor houseplants. Then one day we just spotted this tiny little creature on one of the leaves of our plants. I watched him for awhile, and saw him go up to an aphid, sting it, then go in search of another. The little bug was about the size of a head of a pin, hardly noticeable, especially if you weren't looking for him.
We found out later that this guy was a tiny parasitic wasp. Sounds scary, but these little guys are actually amazing beneficial insects. Greenhouses order millions of these in packages through the mail and release them in their greenhouses to take care of small soft-bodied pests like aphids and whiteflies. They have no ill effect on humans and the populations simply die down if there are no more pests to support them.
We thought ourselves very lucky to get this picture and to have a beneficial ally fighting for our plants' health and survival alongside us. An ally is an ally, no matter how small!