Found in the parched Sonoran desert of southern Arizona and northern Mexico, the senita moth depends on a single plant species — the senita cactus — both for its food and for a place to lay eggs. The senita cactus is equally dependent upon the moth, the only species that pollinates its flowers. Senita cacti and senita moths have a rare, mutually dependent relationship, one of only three known dependencies in which an insect actively pollinates flowers for the purpose of assuring a food resource for its offspring.. . .
The problem is that the moths lay their eggs inside the cacti’s flowers immediately after pollination, and when the eggs hatch the moth larvae eat the fruit, destroying the flowers’ chances to produce seeds. Historic theory predicts extreme ecological instability for this relationship; as moth populations increase, more flowers are destroyed, fewer new cacti appear, and the spiral continues until both species disappear.
Yet that hasn’t happened, and Holland, assistant professor of ecology and evolutionary biology, spends several months each year observing moths and cacti in the Mexican desert to document why.
Many orchids have also developed relationships like this. Most orchid flowers have evolved to attract a very specific insect. I hadn’t realized some cactus did this as well.