Callibaetis nymphs in Rattlesnake Springs, Hanford Reservation, Washington, feed almost exclusively on fine particulate organic matter (FPOM) collected from the stream bottom.
Cushing, C. E. and Rader, R. T.
"A note on the food of Callibaetis (Ephemeroptera: Baetidae),"
Great Basin Naturalist: Vol. 41
, Article 7.
Available at: http://scholarsarchive.byu.edu/gbn/vol41/iss4/7