I was asked a question last week about what white-lined sphinx moth caterpillars eat. I had read that they eat wild relatives of the four-o’clock, a garden plant. A few weeks ago we visited Boyce Thompson Arboretum State Park and I got some great first-hand information about what kind of plants the caterpillars feed on.
At the arboretum we found caterpillars on a native plant that is being used as a landscape perennial called pink guara (Guara lindeimeri). I noticed, however, the caterpillars were only eating the flowers. Often the flowers lack toxins or feeding deterrents found in the leaves or stems, although I don’t know for sure this is the case here.
![whitelined sphinx moth](https://i0.wp.com/growingwithscience.com/catguara.jpg?resize=320%2C215)
Some of the caterpillars were working on a plant called white ratany (Krameria grayi).
![whitelined sphinx moth](https://i0.wp.com/growingwithscience.com/catratany.jpg?resize=320%2C215)
![whitelined sphinx moth](https://i0.wp.com/growingwithscience.com/catratany2.jpg?resize=320%2C215)
I needed a friend’s help to identify that one. The plant has pretty purplish-pink flowers, but they are inconspicuous. She said the plant is a partial parasite that takes food from the roots of fellow desert plants like bursage or creosote bush. I also found out that the flowers produce an oily substance rather than nectar (weird!), but that some native bees will take it to mix with pollen.
![whitelined sphinx moth](https://i0.wp.com/growingwithscience.com/catspurge.jpg?resize=320%2C215)
Finally, we cheered the caterpillars when we found this batch eating the noxious weed, spotted spurge. Go white-lined caterpillars, go! (Sorry, the photo isn’t all that great).
For more information about white-lined sphinx moths and their caterpillars, check these previous posts:
Raising Caterpillars, which also has a photo of the adult
More About White-lined Sphinx Moth Caterpillars
Bug of the Week:Â White-lined Sphinx Caterpillars