(Photograph = Yucca seed pod, Aiden Grey)

Introduction

Yuccas are pollinated by Yucca moths. All species of Yucca require the pollinator services of a moth in the genus Tegeticula. When they pollinate the yuccas, the moths also lay eggs. The eggs hatch and are entirely dependent upon Yucca seeds for food.

The Details

If you grow Yucca plants in an area without their specific Tegeticula moth, they will not make seeds. They need the moth to pollinate their flowers. The moth larvae grow entirely within the developing Yucca fruit and eat seeds as they grow. Thus, the moth provides a service to the plant, but at a cost.

This arrangement means that some seeds of the Yucca plant will be destroyed by the moth larvae. Thus, for the system to work, the percent of destroyed seeds should not be excessive so that the plants are still able to make some viable seeds and reproduce effectively. The moth cannot be too successful or it will kill off the Yucca population and there will be no food for the larvae.

In one species of Yucca that was studied, 0.5% to 3% of the seeds were destroyed. In another Yucca species, up to 45% of the seeds were destroyed.

Additional Reading: Yuccas and the Yucca-moth Symbiosis