Joshua tree & yucca moth mutualism

Can you imagine Joshua Tree National Park without any Joshua trees?


Can you imagine Joshua Tree National Park without any Joshua trees? The iconic Joshua Tree is under threat from climate change and may be extinct from its namesake park within a human lifetime. The places where they live could become too hot and dry for them or the species that they depend on to survive. Joshua trees have an intricate symbiotic relationship with a tiny moth pollinator who lays her eggs in the trees’ flowers and then pollinates them so her young can eat the resulting seeds. As the fruits grow, her developing moth larva consume a portion of the growing seeds, while the uneaten seeds have a shot at becoming the next generation of Joshua trees. The larva will then pupate in the soil, waiting until the following spring to break out from their underground cocoons as new moths and rise up out of the desert sand to find flowers and start the process again. The important timing of moth emergence and tree flowering could become mismatched as species’ biological clocks will probably respond in different ways to the changing climate. These moths live for just under a week and in that short time must find a mate, lay eggs, and then pollinate the tree for their species to continue (they don’t even eat!). When the tree flowers there are only a few days that they can be successfully pollinated and past that they won’t be able to make seeds - this means no future Joshua trees. My research looks at how the interaction between the trees and moths changes with climate and other environmental factors and considers how we can best manage for their future survival.

For more information, see Juniper's research at



By Juniper Harrower PhD candidate,

Environmental Studies and Art, University of California Santa Cruz