Note: this page is inchoate. Our own knowledge of the moths of Saguaro Juniper lands is at that stage as well (aside from our paucity of images so far). But there is an excellent web source from the Biosciences University of Arizona: Moth list for SE Arizona -- this link will take you to as full a listing as is available. A related link is that for the Sphingidae and Saturniidae of Northern Sonora, which provides beautifully detailed images of these moths. For a remarkable association of some of our moths with archaeological finds of the Anasazi, see Datura.
In September of 2000, we experienced the "Fall of the Burn Worms", a sudden explosion of the caterpillars of the Buck Moth (genus Hemileuca). Although at that time we captured only one poor image -- (Click on the image to enlarge it.) --
a number of us had the decidedly unpleasant experience of brushing our bare skin against one of these mesquite- and Palo Verde-eating monsters, and being literally (and painfully) burned, producing skin-scab formations that lasted some time. These caterpillars possess defensive "urticating hairs" -- pointed, dart-like hairs that produce venom and are readily shed by the larva onto a predator's skin when the caterpillar is touched. The adult moths are blackish with white wing-bars. We're not sure of the species, though it may have been Hemileuca tricolor, since it was feeding on Palo Verdes as well as Mesquite trees. See Werner, Floyd & Carl Olson, 1994, Insects of the Southwest, Tucson: Fisher Books, p. 84 for further discussion, and see Saturniidae for images of adults.
In the Fall of 2007, the Burn Worms returned, again in quite considerable numbers. We can now get better images of the caterpillars, and also of the (very few) adult moths that resulted, but some kind of disease appears to have severely decimated the 2007 caterpillar population. In the image below (taken in November), you see a small piece of the outcome:
In the photo above, several now-shrunken corpses are strung out over a small section of one branch near the top of this mesquite tree. This pattern was repeated not only all over the upper reaches of this particular tree (suggesting the larvae had all crawled as high as they could before dying), but on a number of other trees in the vicinity. Tom Orum suggests a possible virus epidemic may have struck in our area.
Below, three images of the beast: at left, a burn worm encountered on a man's shirt in September 2006; center, closeup of one burnworm corpse from the observed November 2007 charnel-house mesquite tree; at right, one of the few adult buck moths we encountered in the vicinity that November. (Click on each image to enlarge it.)
These moths were photographed in March of 2004 (below left) and 2005 (center & right), feeding on Desert Marigold and Chicory respectively. (Click on each image to enlarge it.)
Two views of a White-lined sphinx (Hyles lineata) caterpillar. These are very common in our desert. These below were two of many seen on August 19, 2004, eating the leaves of low-lying plants in the vicinity of the saguaros near the Airport above Hot Springs Canyon. (Click on each image to enlarge it.)
For an image of the adult White-lined Sphinx Moth, see this link: : Biosciences UA: H.lineata image.
Here is another kind of caterpillar, working on a Mesquite tree on August 20, 2004. This one, in contrast to the Sphinx and Buck Moth caterpillars above, emphasizes camouflage (Click on the image to enlarge it):