We have yucca plants in abundance in our pastures and ditches. The yucca plants we have in our area seem to be the Yucca glauca or Small Soap Weed Yucca. You can distinguish this plant by it’s numerous, stiff, narrow, long leaves and it’s large white, bell-shaped flowers blooming in the spring.
If you happen to be out walking by the blooming yucca plants, you may not realize the beneficial circumstances taking place around you between a small moth and the yucca’s. If you stop to watch, you may see a small, pretty, white moth, called a Yucca moth, flying from plant to plant. This moth is only about 1/2 inch in length with front wings that are a silvery white with gray hind wings.
Though this moth may be small it has a very important job. There is a mutual dependence between the yucca plants and these small moths. The Yucca moth is the only pollinator of the Yucca plant and the Yucca moth feeds only on the Yucca’s seeds. So consequentially the two are dependent on one another for survival.
In the spring around May and June, the Yucca moths emerge from the ground to mate in the yucca blooms, mostly in the evening hours through midnight, when the blooms are fully open. The females then fly between the plants, collecting pollen from the flowers using her specially adapted mouthparts. She then forms the pollen into a ball carried between her tentacles and thorax. After she choses a yucca plant, she places her eggs in a specific area in the plant. She then deposits pollen in the stigma of the plant, fertilizing the flower, which in turn produces the fruit and seeds necessary to feed her offspring.
When the larvae hatch they feed on the seeds of the yucca. Later they will emerge from the plant pods where they have been feeding to drop down to the ground to burrow into the soil where they wait to emerge once again in the spring to continue the cycle.
In late June the blooms on the yucca plants have dropped off. If you see green pods on the yucca plants throughout the summer you will know that the moths were there pollenating the plants.
So this spring as you see the yucca plant’s flowers and pods bending in the Kansas wind, remember the age-old symbiosis between this hardy plant and a small white moth.