"The blue-winged olive is one of the most prolific and biologically diverse mayfly families, known by biologists as 'Baetidae.' Did you know that there are over 130 species of Baetidae in United States and Canada alone? On a given day, there can be myriad different species emerging from the river. With such biodiversity, always make sure you're 'matching the hatch' exactly. The key is being cognizant of size, color and profile.