The genus Tegeticula is comprised of several types of moth. These moths are specialists in using the yucca plant as part of their life cycle. Rather than parasitic, the relationship is symbiotic in nature with both the yucca moths and the yucca gaining benefit. While many plants benefit from being pollinated by insects, The relationship between yucca moths and yucca plants is more complex than a haphazard visit from other insects.
There are around 40 different species of yucca plants. They are native to the United States and Mexico, preferring warmer regions. Yuccas are perennials that form large heads of spike-like leaves emanating from the base of the plant. Many cream-colored flowers form in a large, showy display on a tall spike that grows from the center of the plant in spring. The pollen within each flower is not loose, but is formed in small, sticky packets called pollinia.
While many insects visit yucca plants, including several species of moth, only those in the genus Tegeticula are capable of using the plant for reproduction. The wings of yucca moths are generally folded back against the body. They are quite small generally averaging from 5 to 10mm in length.
The wing patterns vary with the species. Many are all black, while others have brown and white stripes or speckles. Still others are pure white. All of these moths have one thing in common. The females have mouth appendages, known as maxillary palpi, that they use to gather pollen in a yucca blossom, then intentionally pollinate another blossom, using the palpi.
Yucca moths are the extreme specialists of the insect world. Each species of moth focuses on a particular species of yucca plant and will ignore all others. Both the moth's and the yucca plant's life cycle are inextricably linked. One cannot survive without the other. In fact, if yucca plants are cultivated where yucca moths are absent, no seeds will be produced by the plants unless they are pollinated by hand.
In the spring, yucca moths come out of cocoons buried beneath the earth. Both males and females immediately fly to the nearest yucca plant. The moths then mate. The yucca plant will have already sent up a tall spike of flowers by then. Once mating is completed, the female moth will make its way to a yucca blossom. The moth will then collect several of the pollinia together to form a small pollen ball.
The moth will then fly to another yucca plant to lay her eggs, carrying the pollen ball with her. She will locate another blossom on the new plant and lay a single egg within the ovary of the flower. Once accomplished, she will then carry the pollen ball to the top of the yucca blossom ovary, where the stigma is located. The moth will then place the pollen ball into the stigma, where it will pollinate the flower.
This intentional pollination process that the moth executes ensures that the ovary will form seeds. Some of the maturing seeds will, in turn, serve as a food source for the larvae of the moth when it hatches from its egg. The seed pod has three chambers, one of which contains the feeding larva, with the others producing seeds that will be untouched.
In late fall, the seed pod will dry out and split open to release its seeds. When the rains of Autumn begin , the larva will drop out of the seed pod to the ground. The larva will then burrow into the soil and form a silken cocoon, where it will spend the winter, changing into an adult moth, which will emerge in the spring to start the life cycle over again.