Urban Refuge

Male monarch resting in a mesquite tree       photo by Richard Halliburton

One of the greatest wonders of the natural world is the annual migration of millions of monarch butterflies from eastern North America to fir forests deep in southern Mexico each winter. But Michoacan, Mexico is not the only place that monarchs overwinter. Right here in central Phoenix, teams of butterfly scientists, or lepidopterists, have been tracking monarchs that overwinter along the Salt River, as well as along the Colorado River near Yuma and Parker, Arizona. Numerous "hot spots" around the state of Arizona, from Grand Canyon in the north to Patagonia in the south, also attract monarchs to feed and breed at various times of the year.

Monarchs are very selective about what species of plant they will lay eggs on, since the caterpillars are adapted to feed almost exclusively on milkweeds. However, the adults will gather nectar from a wide variety of flowers. Even though they are endemic to North America, monarchs are happy to feed on plants imported from the Mediterranean, such as lantana and rosemary, or Australia, such as eucalyptus and wattle trees.

Female monarch nectaring on a wattle tree

For roosting, though, they need just the right kind of canopy and just the right kind of leaves to hang onto with their tiny feet, says Gail Morris, director of the Southwest Monarch Study.  Gooding's willows, large trees native to Arizona, are their favorite at the riverside location in central Phoenix. At least that is where they have been noticed by people who pay attention to these sorts of things. It is quite possible that they are hanging out in the eucalyptus trees in your neighborhood, as they do along the coast of California. If you see monarch butterflies floating around your neighborhood this winter, people want to know, especially if you can see a tiny round tag with numbers on its wing. These tags are one way scientists are keeping track of butterflies that roam through Phoenix. You can report your sightings, with or without tags, to swmonarchs@yahoo.com.

Photos are excellent documentation too, since it is easy to confuse a monarch with the more abundant and closely related queen and occasional viceroy butterflies that also flutter around these parts. Learn the differences here: Identifying Monarch Butterflies.

Stalked Puffball

My greatest excitement today was finding this stalked puffball, Battarrea diguettii, on my morning walk. This is a new species for my "life list," and the second type of stalked puffball I've seen growing around Phoenix. It's a wonder that the neighborhood isn't covered with these strange fungi, as the spores must number in the billions from just this one specimen. This and other members of the genus Battarrea have lots of folk names: sandy stiltball, desert drumstick and donkey fungus are the most common. A close relative of this species, Battarrea phalloides, has been found all over the world, from Africa and Oahu to Uruguay, where none other than Charles Darwin collected specimens in 1833. Diguettii is distinguished by the pores on the cap that release the powdery spores, and is endemic to the Mojave and Sonoran deserts of North America.

Life and Death

Around here, if a scorpion doesn't get you, the ants will. This Arizona desert scorpion (Hadrurus arizonensis) I found on the sidewalk probably met its death by a crushing foot, but it did not take long for tiny Southern fire ants (Solenopsis xyloni) to swarm in for a feast.  At least the scorpions usually hunt solo. 

Also known as the Giant Hairy Scorpions for short stiff hairs along the sides of their legs, this species is reputed to be the largest in the U.S., measuring up to six inches long from the tip of their stinger to the small, sharp jaws or chelicerae. Add on all those legs plus the formidible claws, or pedipalps, and they are quite impressive. This one was about four inches long based on my calculations as sized up to my pen. (I need to add a small ruler to my pack for observations like this.) The ants are just a teensy fraction-maybe a sixteenth of an inch-or a couple of millimeters apiece if you prefer metric. Although scorpions can deliver a painful sting, they rarely cause a serious reaction in humans, and this one is actually one of the least toxic, despite its size. The dark back and pale legs also distinguish this species from the smaller, more dangerous and much more common bark scorpion (Centruroides exilicauda) that haunts the SW deserts. 

As gruesome as a scene like this may be, it is a reminder that all life thrives on death, humans included...unless you like your meat very fresh!

Exoskeletons

After a month or two spent mucking about in a pond for food, the aquatic larvae, or nymphs, of dragonflies crawl out of the water, crack open the skin on their back, and begin new lives as aerobatic adults. I found these exoskeletons, or exuvia, of roseate skimmers (Orthemis ferruginea) clinging to a cement wall along the Central Arizona Project canal, where a trough of still water serves as a year round breeding ground for dragonflies, as well as dozens of other insects. The exuvia are perfect casts of the fearsome jaws and giant eyes that make the larvae successful predators. I would like to have witnessed the magical hour when dragonflies emerged from these chitonous skins. Even more, I would like to be able to shed my own skin and fly! 

This trough on top of the CAP canal collects debris and mud,
creating a year-round pond that is brimming with aquatic life.

An adult Roseate Skimmer rests on a blade of grass.

Dragonfly larvae blend in with muck at the bottom of the pond.

Mussels and Clams

Quagga mussels (Dreissena rostriformis ssp. bugensis) and Asian clams (Corbicula fluminea) have claimed some territory along the Central Arizona Project canal, far from their native habitats in Ukraine and southeast Asia respectively. A small pile of shells is spread out across the trail after being scraped out of pipes in a water treatment plant in north Glendale, looking quite out of place in this arid scene.

Hitching rides on ships and then on smaller boats, both species have become naturalized in many freshwater systems in North America including the Colorado River and its system of reservoirs and canals. The clams are considered to be symbols of prosperity in Asia and have also been intentionally introduced through the aquarium trade and as a source of food.

Katydid

This Elegant Bush Katydid (Insara elegans) appeared on my window screen recently. Also called a Mesquite Katydid, they are distinguished from other katydids by the long narrow wings marked with white stripes. Katydids are nocturnal, so this one seemed content to let me photograph it mid-day as it rested. The males are the source of some of the rasping night sounds coming from high in the trees during the summer around here.  The name "katydid" is supposedly and onomatopoeia for this sound, but that's a real stretch, at least for this species.  Elegant, yes, for the slim wings and extraordinarily long  antennae. This was the first year in twelve that I've seen this species in our neighborhood, which makes me wonder: Have they always been around, and I just haven't noticed, or are they having an especially good year, so more abundant? 

Desert Shaggy Mane

The desert shaggy mane mushroom (Podaxis pistillaris) or "black powderpuff" is actually a type of puffball. Open it up and, depending on the ripeness, it will either be filled with thick white goo or erupt in a cloud of dark spores. These began popping up in gravel along Highway 17 after monsoon rains at the end of July this year. Sadly, they are reported as being inedible not due to toxins, but because they are just plain foul-tasting, as well as tough and woody. However, if you are truly desperate, or just curious, munching on an immature stalked puffball won't kill you.  This species is common in desert regions around the world. Australian aborigines have used the spores mixed with water for body paint and the dry spores for hair dye.

Tailless Whip Scorpion

Last night we had an unusual visitor on our front patio: a tailless whip scorpion (Paraphrynus mexicanus). These long-legged relatives of spiders and scorpions are actually quite common in the Sonoran Desert, but they are normally very secretive nocturnal creatures. At rest it will fold up all of its legs and become an innocuous looking black blob about the size of a quarter. But when it extends all of its appendages, the whip scorpion expands to the diameter of a dessert plate. Crawling sideways like a crab, it rivals any sci-fi creation ever imagined by Hollywood.

Two serrated claws, or pedipalps, are curled up in front of the face, which is beaded with five shining eyes. A pair of forelegs serve as long thin antennae that it waves around to feel for potential prey.
They are members a group of arachnids called Amblypygids, which means "blunt rump," because they lack the curved tail that their cousins, the scorpions, wield for weapons. They have no venom or stinger, so are reportedly harmless to humans. Amblypygid moms carry their newly hatched young on their backs, a trait shared by scorpions; I like that these scary looking animals exhibit nurturing behavior.

Our visitor was very patient with us, posing for photographs and demonstrating its graceful movements without dashing away. Perhaps we'll be lucky enough to have a family of Amblypygids take up residence in our yard to help control the cricket population that has been keeping me awake at night. Or maybe they already have; it's been a little quiet around here lately.

Toad-ally!

On warm summer nights, some central Arizona neighborhoods are visited by these princes (and princesses) in disguise, Sonoran Desert Toads (Incilius alvarius). The New River corridor is a popular stretch of habitat for these wide-mouthed, warty amphibians. Although the adults are terrestrial, and content to spend most of the year in burrows that may be miles from any water, permanent or temporary ponds are necessary for reproduction. 

They will take advantage of nearly any water source we provide for them, intentionally or unintentionally, to re-hydrate. Dog dishes, bird baths and shallow steps of swimming pools are perfect places to sit for a while and fatten up after a long winter below ground. Toads imbibe water through their skin, especially through a special "drinking patch" on their belly and hind legs. A few hours sitting in a mud puddle can make the difference between a "full" toad and a skinny toad. Although many folks regard them as pests, because they are also quite toxic, especially to dogs that harass them, having a few toads around can serve as effective pest management, since they will eat huge quantities of insects. 

Toad scat is dry and ashy, essentially the keratinous remains of the insects they have eaten. This large sample of toad  scat is compared to my ring; it's as thick as my finger, but not gooey at all. If you step on it, the turd turns to dust and blows away on the wind. Just another fun little nature tidbit for you!

Female Instincts

This elegant and docile looking nectivorous wasp is also a vicious predator who will slay spiders more than twice her size in order to insure the success of her children.  Also known as a tarantula hawk or spider wasp (Pepsis thisbe), these huge wasps grow up to two inches (5 cm) long from the powerful jaws to the tip of their glossy black abdomen.  Females can be identified by the curled tips of their antennae, while male antennae are straight. Both are commonly seen sipping nectar from a variety of flowers, and are especially fond of milkweeds. But only the female possesses a sharp stinger and the instinct to use it to deliver powerful neurotoxins to stun food for her offspring. Unless you harass her, there is very little chance that a tarantula hawk would attack a human. But if you are a tarantula, she will chase you down.

We were fortunate to witness the aftermath of such a biochemical attack along the Upper Salt River  last weekend. While walking along the road to our camp, we noticed a tarantula splayed out in the dirt. I poked it with my toe, but it didn't move. Within moments, a tarantula hawk started circling the spider, so I stepped away, and she landed on top of it and began to drag it up the hillside. We think she must have already delivered the neurotoxin that effectively paralyzes the prey, and was returning to retrieve it  once it was completely immobilized. Unperturbed by our presence, we watched as she pulled the spider up beneath a rock. A single egg will be buried with the zombified spider, providing nutrition for wasp larvae as it develops into a two inch long grub, eating the spider alive as it grows. After the larvae has had its fill, it will pupate and remain in a resting stage underground for several months before emerging as an adult wasp. 

I like knowing that for every tarantula wasp, there was once a big hairy tarantula walking the earth. We see a lot of wasps around, so that must mean that there are is an equally healthy population of tarantulas in the neighborhood.  

Moth Night

Moth Night at the Boyce Thompson Arboretum in Queen Creek last Saturday night attracted not only thousands of insects, but a few dozen naturalists and photographers ranging in age from 4 to 80. Using a pair of mercury vapor lamps mounted in front of a white sheet, entomologists from the Central Arizona Butterfly Association led the crowd in a frenzy of bug identification and admiration. 

The star of the show was a single patient Western poplar sphinx, with its nearly six inch wingspan and thick furry body. Surrounding this moth were dozens of white-lined sphinx, cholla moths, silk moths, five-spotted hawkmoths, tiny variegated tiger moths, and a handsome rustic sphinx, all fluttering in the bright lights. 

Western Poplar Sphinx (Pachysphinx occidentalis)

Beetles clamored to the scene by the dozens, including june beetles, blister beetles, mesquite beetles and click beetles. Cicadas, grasshoppers and bright green katydids also showed up. My favorite were the ant lion adults, elegant beasts with long lacy gray wings, and a pair of gracefully curved, thick, glossy antennae. Close encounters with three species of snakes and dozens of bark scorpions shining under black lights made this a 5-star event worth repeating in our own back yard. Next frivolous purchase: a mercury vapor lamp.

Ant Lion Lacewing 

Crack Climbing

It might seem like life is over once a pond dries up, but mud cracks are moist shady refuges for all kinds of life. Seeds take root, mosses grow and new toads explore these tiny canyons. 

Water Tigers

Water tigers live in ephemeral pools, devouring tadpoles, fairy shrimp, mosquito larvae and anything else it can grab with its jaws. These 2-3 inch long larvae of predaceous diving beetles are some of the most vicious predators in the desert suburbs, sucking the guts out of their prey and then disposing of the empty carcass. There are about a dozen species of predaceous diving beetles in North America, named Dytiscus in Latin, which means "great diver." 

My first encounter with a water tiger was here at a pond in Skunk Creek, just east of I-17 near the pedestrian bridge north of Jomax. Monsoon storms in late July this year revived myriads of critters that wait patiently in a dormant phase for water to return to the desert. When I first saw the dim outline of the larvae swimming in the murky water, I thought it was a small fish...but there are no fish in this usually dry wash. We captured one with a net and found that it had six jointed legs near its fearsome jaws, tipping us off to its identity as an insect. 

At rest, the water tiger will lift its rear end to the water surface to breathe through a pore or spiracle at the tip of its abdomen. Like their adult form, a large flat beetle, they are elegant and rapid swimmers. The larvae will pupate in the mud once the pond begins to dry, emerging as an adult when the next storm cycle revives the ponds it lives in. We never saw any adult diving beetles, but did witness plenty of water tigers prowling in the pools. 

Mexican Bird of Paradise

Mexican Bird of Paradise (Caesalpinia pulcherrima) lights up the Valley in mid-summer with flaming orange flowers. These plants in the Bean family (Fabaceae) have been part of world wide horticultural trade for so long that no one knows exactly where the first wild populations were discovered. Medicine men in Suriname have been using the plant for centuries, so this may be a clue to its origins.   It is also the national flower of Barbados, and displayed on the royal flag there, another clue to its native roots.

In the Phoenix area, Mexican Bird of Paradise provides welcome relief in the sometimes drab urban landscape, thriving along highways and industrial areas wherever there is a reliable drip system. Hummingbirds, carpenter bees and honeybees are frequent visitors to the flowers, serving as pollinators. The resulting bean pods produce hard seeds that are toxic enough to induce abortion in early term pregnancy, which was sometimes advised by the aforementioned South American medicine men. 

Beetlemania

The Iron Cross Blister Beetle (Tegrodera aloga) is a handsome beast, emerging in late spring in Sonoran Desert wherever there are soft sandy soils that support healthy colonies of ground-dwelling digger bees (Centris pallida). Yesterday evening we found a newly emerged swarm of beetles along the Central Arizona Project canal road north of Deem Hills Recreation Area. Thousands of beetles were feeding on fresh foliage of wheelscale saltbush (Atriplex elegans) at the edge of the road.

According to Carl Olson's guide to "50 Common Insects of the Southwest," these beetles have a complicated life cycle that depends on the bees and a healthy crop of palo verde flowers. Here is how Olson describes the scene:

"After mating, females seek palo verde trees in bud stage, lay eggs at the base of the buds, and then die. The eggs and buds develop together, eggs hatching when the flower opens. Larvae wait in flowers for native bees to arrive, hitch a ride back to the nest, where they stay, feeding on the juvenile bee and its provisions. They pupate in the nest and wait for next spring to emerge as adults."

This is just one more example of how everything is connected to everything else somehow.

Mingled in this little web of life, we also found a few Red-eared Blister Beetles wrestling with the Iron Cross Beetles. It was tough to tell if they were trying to mate with them, or having some kind of aggressive issue with their cousins. Red-ears have their own swarms earlier in the spring when brittle bush is in full bloom, so these few seemed to have missed the high season for mating with their own.  I suspect that this perennial urge is what got this one to pursue and mount a beetle of a different species, but probably with no success, since beetle mating paraphernalia, as with most insects, is highly specialized.

Spider Home

The leafy retreat of a female desert shrub spider (Diguetia canities) resembles a cocoon strung up by strands of web. Where these small spiders are abundant, you'll find their homes on nearly every shrub, especially bursage (Ambrosia spp.) and saltbush (Atriplex spp.). I found this one at Spur Cross Conservation Area attached to bursage, hanging over a  desert anemone (Anemone tuberosa). Perhaps the pollinators attracted to the anemone were her prey. Very clever, those spiders!

Yield to Brittlebush

If suburban sprawl has you worried that central Arizona may one day be completely overtaken by pavement, just remember that the life contained in Brittlebush (Encelia farinosa) seeds is far mightier than the Arizona Department of Transportation.  Able to sink roots into any gap in sidewalk, oblivious to vehicle exhaust and blossoming in the driest locations, Brittlebush will surely pioneer the restoration of this desert after the last drop of oil has been burned.

I joined this specimen thriving on an island in the middle of a round-about at Happy Valley Road and the I-17 yesterday, to document its life amidst the chaos of evening commuter traffic. I've been watching this plant grow for months, relieved each time I passed by that some ADOT crew hadn't doused it with herbicide or snatched it up by the roots. Now she is on her way to producing seed, and if all goes well, the island will be well populated by her progeny next spring!