bat guano is nature's most highly refined organic fertilizer. guano starts out as plant life. insects eat from the plants then fly into the air and are eaten by the bats. the bat droppings fall to the cave floor; then the guano beetles and decomposing microbes attack the bat droppings and use it as food. guano is the most distinguised natural fertilizer known to mankind. the Inca civilization of South America used guano so extensively that the penalty for harming the animals that produced it was death. it has been used effectively in agriculture for hundreds of years. pound for pound barn yard manure or commercial fertilizer do not compare to guano for balanced plant food nutrients.