Coke Smith Photography & Travelogue

Two Summers in Arizona's Sky Islands!

Plinthocoelium suaveolens plicatum, one of the more spectacular beetles I researched these summers. 


The summers of 1990-91 were spent doing research in the deserts of southeastern Arizona, in Madera Canyon and the surrounding areas.  My thesis research primarily dealt with plant insect relationships between various species of insects and a pretty amazing plant found commonly in the region, Baccharis sarothroides.  My first summer there was spent with Lien investigating the inordinate density of insects found associated with this plant.  We spent countless hours and days in the desert areas collecting insects and establishing viable study sites for the following summer/study season. We spent our nights in a small bungalow deep in to Madera Canyon called “Bahai Kubu”, which was owned by a lovely Filipina lady and her American husband.

Madera Canyon is a spectacular example of what is more commonly known as a “Sky Island”.  Surrounded by a sea of desert, the Sky Islands of the southeastern Arizona are literally islands of Hudsonian Temperate forests populated with various conifers and hardwoods.  The flora and fauna of these “islands” are very unique and include many endemic species that are only found in each respective mountain system.  Owing to their location, they are also home to an impressive assemblage of Neotropical species as well. 

After my first summer, I spent the academic year of 1990-91 working on proposing and defending my thesis and finally getting it approved so I could spend the entire summer of ’91 in the field.  What a great summer it was!  While Lien was not able to join me for the entire summer of ‘91, I did make good use of my time there and assembled a good data set that allowed me to successfully complete my thesis in record time. I had a fantastic time working and collecting in the deserts of Madera Canyon as well as Pena Blanca, Tombstone, Carr Canyon, Reef Town site, the Chiracahuas, Patagonia, Texas Canyon and many other locations in that neck of southeastern Arizona.

There are many entomologists who flock to this part of North America every year due to the diversity of insects found there.  That year, they all used my base camp at Bog Springs campground as a rendezvous point for their collecting expeditions.  I was intending to camp there alone for the entire summer but was blessed with visitors nearly every single day.  I had a great time getting to know the various entomologist who came by, sharing war stories and bugs.  Great fun!

My two summers in Madera Canyon, Arizona rank up with some of the best summers ever!


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My "pad" at Bog Springs!  "Base Camp Madera"!  I lived here for several months during the summers of '90 & '91.


Home away from home.


A mixed community of Baccharis sarothroides (Desert Broom) and Mesquite (Prosopis julifora) near Madera Canyon.  This was a perfect assemblage of species for my studies.


My various research sites throughout southeastern Arizona.


My experimental plots in Madera Canyon.


One of my study plots.  I selected this one as it was near an arroyo and would more than likely have a good pulse of water when the summer monsoons started.  With more water, my theory was that more plant exudate would flow in the Baccharis plants and therefore there would be more insects attracted to the plants thereby proving my overall thesis.


Baccharis sarothroides, my study plant.  For reasons that I proved in my research, this plant attracts a statistically significant number of insects compared to any other plant in the region.  And the striking number of insects is not due to flowers.  This species produces an attractive, and even narcotic, exudate that attracts hundreds of species of insects.  I called it the "local pub".  During my studies, I proved beyond a statistical doubt that Baccharis does in fact attract more species than any other plant and this atraction was due to the exudate.  I was able to actually increase exudate flows with various techniques and increase insect populations accordingly in my experimental parts of my research in the field.



 Another study plot with many Prosopis julifloris.


During my studies, I discovered that the long proboscis of this Coreid Bug was responsible for starting the exudate flows in Baccharis.  Once this insect species pierced the thin bark of the Baccharis, the flows would start in that area.  And in following days, the flows would attract large numbers of many species of insects.


I created a cubic-foot tool that allowed me to count insects in a specific volume of space in order to perform comparisons of insect densities between various plant species in the region.  The fascinating part of my contraption is that it has now been copied in a current addition of National Geographic, titled "One Cubic Foot"!


For quick field identification, I kept and traveled with an "ID collection" of the various insects I found on the plants.


Trends in insect populations showed dramatic increases when the rains came in the late summer.


More data!


Insect aggregations like this were commonly seen along the bark of Baccharis where exudate was flowing.


A male Plinthocoelium suaveolens plicatum feeding on Baccharis exudates in one of my study plots.


Crioprosopis magnificus is one of the more spectacular beetles in North America and can be found in the areas of my studies.


Chrysina (Plusiotis) beyeri is another species commonly found in this area.


Once the August monsoons came it finally started to get exciting! 


Mount Wrightson is the dominant feature in the area.  This is the classic "Sky Island" that is home to numerous endemic and rare species.  The Sonoran desert gives way to a mixed conifer-Quercus woodland and eventually to a pine-juniper woodland at the higher elevations.


The forest community of Madera Canyon is biodiverse and complex.


Madera Canyon sunsets are some of the best anywhere!





 Please take a look at our North America Image Galleries!