Hidden Hoppers

HIDDEN WILDLIFE abounds in Arizona, animals so beautifully concealed that most of us never notice them. I am not talking about an elk standing motionless in a dense stand of ponderosa pine trees or a coyote crouched behind an ironwood tree. The creatures I have in mind are grasshoppers, masters of disguise. A challenge to see, grasshoppers can entertain and amaze a walker almost anywhere in Arizona. If we take a grasshopper hike through the foothills of the Huachuca Mountains in southern Arizona, we might pause for a moment, and sit on some rocks to catch our breath and admire the landscape. While extracting sandwiches from our daypacks, we detect a hint of movement in a clump of grasses next to a nearby rock. The little movement that catches our eye leads us to a wonderful insect, one of the toothpick grasshoppers, long and ridiculously thin, a nearly perfect imitation of a grass stem. The hopper freezes, follow-ing the long-established strategy of its species, which is to rely on camouflage rather than flee a potential predator, such as the Mexican jay we saw earlier. And what camouflage it is, for the insect aligns its body parallel to its perch so as to merge seamlessly with its surroundings. Moreover, the grasshopper's anten-nae are flattened and grasslike, much wider, shorter and more compressed than the antennae of its cousins. We forget about lunch (for a minute or two) while oohing and aahing over this stunning insect. After admiring our grasshopper companion (and enjoying our lunch), we resume walking while keeping our eyes peeled for more beautifully camouflaged hop-pers, knowing that Arizona boasts one of the most diverse grasshopper faunas in North America. Unfortunately, unlike the mammals, birds and even butterflies of the West, grasshopers have not inspired field guides lavishly endowed with color illustrations. It will probably be awhile before watching grasshoppers is as popular as bird-watching. But we don't mind being

Hidden Hoppers Grasshoppers have mastered the art of camouflage

Going Undercover A toothpick grasshopper (right) mimics a slender green stem blending into the foliage to hide from predators such as wasps, ants, snakes and birds. The pallid-winged grasshopper (below) lives mainly in desert and semidesert areas from southwestern Canada to Argentina, making it one of the most widely dispersed grasshoppers in the world.

Pioneers. The key lies in walking along with our eyes on the ground, waiting for something to move. Most grasshoppers trust their expertly camouflaged color pattern rather than leaping wildly all over the place. Here's another one. It jumps only a foot or so, waiting until the last possible minute to avoid being flattened by my hiking boot. We keep our eyes fixed on the spot where the insect lands, but even so, it is hard to believe that we are looking at a grasshopper, not a fallen oak leaf. Just like the grass mimic, this leaf-imitating grasshopper pulls off its deception by using a combination of tricks. Its rich tan color exactly matches an old oak leaf and its thin, laterally compressed body and ridged thorax has "oak leaf" written all over it. Moreover, the insect lies on its side in the leaf litter to foster the illusion of a fallen leaf, enhanced by antennae shaped like an oak leaf petiole. I have stumbled across many such marvelous grasshoppers, this one resembling a stem, that one a fallen leaf, these, mere stones. The Huachucas harbor a lovely, deep-orange-red-and-black species with a real fondness for orange-red, black-dotted rocks. A solid gray grasshopper hangs out on the somber, gray limestone outcrops of the Chiricahua Mountains. A grasshopper found in the desert areas around Phoenix sports a pointillist coat to match the highly weathered granite boulders on which it rests. And let's not forget the pebble mimics. One of my favorites sits quietly in the fine gravel of desert washes in central Arizona, with blotches and patches that break up the outline of its body and subdivide it into a collection of pebble-sized segments. The different "pebbles" are white or pale gray or pale pink, and create the illusion of being part of the desert floor. Take your eyes off the hopper for even a moment, and it will magically disappear into its surroundings.

Why do so many grasshoppers try to blend into the woodwork, leafwork or stonework? The answer comes in the form of jays, loggerhead shrikes and a host of other birds that like nothing better than a beakful of grasshopper. For millennia, insect-eating birds have been scanning their environment with keen eyes. In this bird-eat-bug world, any edible grasshopper whose color pattern happens to make it harder to find has a better chance of living long enough to mate and leave descendants that will inherit its life-preserving camouflage. The spread of camouflaged grasshoppers in the past created pressures on the grasshopper hunters, favoring any jay or shrike or sparrow that inherited vision superior to its compatriots, the better to pinpoint hard-to-find prey. As these eagle-eyed predators became more common, their presence gave an edge to any grasshopper that happened to look even slightly more convincingly like a few pebbles or a green grass stem. The never-ending arms race between the eaters and the eaten has resulted in today's visually gifted birds and their all-but-invisible prey. If this explanation is on target, then the noxious, bad-tasting grasshoppers should lack the camouflage of their delectable cousins because they have nothing to gain by hiding from birds that quickly frequently eat their own dead. Learn to avoid these nasty-tasting species. We can test this proposition by taking another grasshopper walk in the scrubby mesquite range in the San Simon Valley of southeastern Arizona after summer monsoon thunder-storms have generated fresh grasshopper food. The hoppers are everywhere, some superbly camouflaged, some not. Among those that stand out is the huge horse lubber grasshopper, a study in jet black, fluorescent green and cadmium yellow. It makes no effort to evade me, but when I touch the creature it raises its green wings to flash previously hidden, bright-red hind wings while also hissing at me and spraying a stinking chemical mist from openings in its tho-rax. I withdraw my hand. I'm not the only one to give the horse lubber a wide berth. Entomologist Douglas Whitman has offered some horse lubbers to hungry captive birds, most of which said in effect, thanks but no thanks. Those willing to down a couple of immature lubbers vomited and thereafter wisely refused to touch the things. The horse lubber is repre-sentative of most billboard grasshoppers in combining a memorable color pattern, a lack of evasive behavior and an evil taste. The robustness of this relationship shows that when an insect is chemi-cally protected, it can afford to be conspicuous, and even advertise its unpalatability. But edible grasshoppers must rely on wonderfully detailed cam-ouflage to keep out of view of hungry enemies. The amazing grass-, rock-,leafand pebble-mimicking grasshoppers are the legacy of this process. If you can find them, congratulate yourself for having detected some of the most beautifully concealed creatures of the desert. Al John Alcock of Tempe is Regents' Professor of Biology at Arizona State University. He has written about the biology of desert animals, large and small, in a number of books including Sonoran Desert Summer and In a Desert Garden, both published by the University of Arizona Press.

Formerly a wildlife biologist for the Bureau of Land Management, photographer Marty Cordano recently relocated to Alaska where his work focuses on nature and environmental issues. He likes grasshoppers so much that he doesn't mind if people refer to him as a grasshopper "lubber."