Caenidae, or the Small Squaregill Mayflies, is a family of insects consisting of 4 genera comprising 26 individual species. They are found throughout North America in lotic, depostional environments, and they are sprawlers. Caenids occur in quiet and even stagnant water and are often overlooked because they are so small. They like to live in silty bottoms, and their gills are specially adapted for such environments. Adults usually emerge from May to September, but they emerge all year in Florida. Unlike other mayflies, squaregills can be found in degraded conditions and are not reliable markers for undisturbed conditions.