Our big lush stand of fava beans at our elementary school garden became a perfect example of the balance that plant and animal communities achieve when left to work their magic. In early spring, the tender fava bean tops became food for the aphids. The ants probably brought them as there were many ant colonies living in the loose soil in our wooden boxes which stayed well above the rainy season water level. I assume that the ants had sheltered the aphids in their nests and brought the ants to the bean plants to serve as their "cows". The ants don't have mothparts for sucking plant juices and depend on aphids for a nice sugary drink of plant juice.
Soon after the aphids began to multiply, the lady bug beetles appeared. By May, there were many lady bug larva and eggs as well as adult beetles. In fact, there is a whole colony of lady bugs at various life stages reproducing in this stand of fava beans.
We did not try to kill the aphids or wash them off with blasts of water. We just waited. Now their numbers are being brought into balance by a healthy population of lady bugs.
Many of our plantings include something for the insects; plants like alyssum, Verbena bonarensis, Matricaria, sunflowers, and salvias. We are planning a garden that supports a variety of life so our vegetables will be healthy.
