TNPondBoss,

There are widespread small varieties (talking like size 26) that will very likely populate your pond. These are important especially to juvenile fish. There are also some very large varieties (e.g. hexagenia) that probably will not populate your pond on their own. These are notable sources of food for adult panfish and even some predators like SMB.

As RAH mentioned, mayflies require specific habitat and so the diversity of mayflies your pond will support depends of the diversity of habitat. To get hex's established you must have some clear bottom that will allow the nymphs to build stable burrows. They feed on the detritrus of organic matter that "rains" through the water column. In lakes, most frequently they occur in low light depths where plants do not get established. Most ponds can provide this habitat for only a short period of time in their early life. Deeper ponds are a better bet on getting them established for a longer period of time. A silty bottom is what they prefer.

If you want to try to establish hexagenia, the eggs are relatively easy to collect. When they are hatching, after dark ... park your vehicle near the shore and shine the headlights over the water. The day old mayflies that are mated will be drawn to the light. Below the headlights place a large tub of water. What mayflies don't end up on the surface of the tub's water you can easily grip by their closed wings and place them there. They will deposit eggs in the tub and after 2 to 4 hours you would have a sufficient number of eggs to have a hatch the following year in your pond. If you have good habitat the hatch will be good and probably improve until they are fully established. They are organisms that can improve water quality while also providing food to your fish. If you think you have good habitat for them I would encourage you to try to establish them.