Natural History Wanderings

The Anza- Borrego Desert Natural History Association has the following report on the explosion of Spinx Moth Caterpillars. The months are devouring wildflowers in areas, but the Swainson’s Hawks and other birds are feasting on the caterpillars.

The wildflowers that are bringing visitors to the desert right now are mostly desert annual plants.  They have evolved over time to germinate only when there is enough moisture in the soil so they can quickly grow, flower, and produce seeds.  Those seeds will then wait in the ground, perhaps for years, until there is enough moisture once again for them to start the cycle all over again. This adaptation leads to a very short lifespan for an individual plant, a couple of weeks perhaps,  but tens of thousands of years of existence for the species.

But in nature, it does not go unnoticed that all of those springtime plants are also a good source of food.  The creatures that can rapidly swing into action to take advantage of that food are the creatures that will prosper over time.  Enter the Sphinx Moth.  Sphinx moths emerge from the ground and lay their eggs, thousands of them, on the leaves of the emerging plants.  When the food is there, as it is right now, the sphinx moth caterpillars eat constantly and grow fast, and it is incredible to see how many caterpillars can quickly mobilize to take advantage of the food source.  They are an army on the move.  Thousands of brightly colored Sphinx moth larvae can now be found in certain areas, devouring plants as rapidly as they can.  Their goal is to eat, grow fast, burrow into the ground where they pupate and emerge as moths, and then lay their eggs on the leaves of plants, to start the cycle all over again.

So the race is on right now.  It is the plants vs the caterpillars.  The people who love the wildflowers are cheering for the plants but to the caterpillars it is just one big feast out there!

To the birds, of course, the caterpillars look like lunch.