But with a picture in hand, I finally called Cooperative Extension to see if I could identify the little critters. Because they liked the fruit he thought they might be fruit flies, but when he saw the picture he called to say they were Fungus Gnats.
He sent me a link to the Colorado State Extension site where I learned:
Fungus gnats (Bradysia species) – also known as dark-winged fungus gnats, are small, mosquito-like insects often found in homes and offices, usually in the vicinity of houseplants. They are considered a nuisance when present in noticeable numbers, but the adults are harmless insects that do not bite. Fungus gnat larvae develop in the growing medium of houseplants and are considered minor pests of houseplants. . .
The most important strategy to minimize fungus gnat problems associated with houseplants is to allow the growing medium to dry between watering, especially the top 1 to 2 inches. The dry-growing medium will decrease survival of any eggs laid and/or larvae that hatch from the eggs as well as reduce the attractiveness of the growing medium to egg-laying adult females. In addition, it is recommended to re-pot every so often, particularly when the growing medium has “broken down” and is retaining too much moisture. Furthermore, be sure to remove any containers with an abundance of decaying plant matter such as decayed bulbs and roots, which provide an excellent food source for fungus gnat larvae. . .
And the fruit fly? That looks totally different. Picture and text are from an Oklahoma State webpage
"An effective means of detecting the presence of fungus gnat larvae is to insert 1/4 inch slices or wedges of potato into the growing medium. Larvae will migrate to the potato and start feeding within a few days. The potato slices should be turned over to look for larvae present on the underside."
There's a lot more on the links if you want to know more.