The Euphoria species of Arizona, USA

Overall, in 2010 the numbers of insects in Arizona seemed rather low compared to for example 2007-2008. The extremely dry summer of 2009 and a general increase in temperatures may be the reasons. Small, short-lived and heterotherm, insects are likely to be sensitive to climatic changes. Many species may also reach the limits of their tolerance in hot and arid Arizona. If it gets any hotter and drier here, they may not survive. But so far we are still hoping that this was a temporary decline in numbers and that many species will rebound. Others may be replaced by even more heat adapted species from Mexico.

But even though collection numbers in terms of species as well as individuals were low, I did succeed to complete my virtual collection of the genus Euphoria in the subfamily of  the Flower Chafers, Cetoniinae this year. These are day-active scarabs that fly extremely well with their hard wing covers (first wing pair) closed. A sneak preview of Bill Warner's yet unpublished Checklist of Arizona Scarabaeoidea confirmed that the ten species below are the ones that I can hope to find.

Euphoria Species of Arizona

 

Since I prepared this table, there has been a revision of the genus Euphoria and some names have been changed: E. fulgida holochloris is now E. monticola .  E. fascifera trapezium is now simply E. fascifera, E. kernii was always spelled like this, E. histrionica is now  E. sonorae

Usually I try to photograph living beetles, but I was also delighted to have access to the beautiful and rather complete collection of Patrick Sullivan in Sierra Vista. The specimens of Euphoria devulsa and E. canescens were photographed in this collection. Even Pat's representative for E. canescens came from Mexico, but Barney Streit told me that E. canescens can be found on Sunflowers along  Duquesne Road,Cochise County, Arizona.


E. kernii, which is so common on Opuntia and Prickly Pear flowers further east (Texas), is found in Arizona in a light and a nearly black morph and seems fairly rare.

E. quadricollis (E. arizonica) female and male

E. quadricollis, synonym E. arizonica, 'is sexually dimorphic, with the females tending to be shiny, broader and much darker than the more gracile, tomentose males. The amount of dark spotting on both sexes is variable, but usually much less in males' (Bill Warner via email). Females seem to be less represented in collections which led to some questions about the identification of the female that I found on a tree stump at Copper Canyon, Cochise Co.The image of the male is of a specimen curated at the collection of the University of Arizona.

Euphoria verticalis

E. verticalis, which used to be in the genus Stephanucha when I collected my first specimen in 2007, apparently flies after both rainy seasons: Eric Eaton caught the first one this year in early April when it was buzzing knee-high along stands of wild flowers in Sabino Canyon. In late September I usually find dozens around Annual Sunflowers at the Santa Cruz River and on Desert  Broom bushes in Molino Basin.

  Euphoria leucographa (sepulcralis rufina)

Every year in late summer,  Desert Broom is also the best place to find Euphoria leucographa, our most common Euphoria. With many other insects, the beetles enjoy the sweet juices oozing from the bark of this bush after generous monsoon rains. In October they also frequent the Desert broom flowers.

Euphoria sonorae (histrionica)

 I collected the similarly patterned, smaller E. sonorae in the Huachucas, from lower Carr Canyon to the very top of Miller Canyon. These beetles bury deeply into the flower disc of Sunflowers. This is so typical for them that they can be recognized immediately by their protruding hind ends.

Euphoria inda

I have encountered E. inda only once, at the research Station in Portal buried in flowers of milk weed and then flying off to the mesquite where I photographed it. B. Streit found it west of Portal in thistle flowers.
About this species, Art Evans has an interesting story to tell in his blog - how a specimen made it all the way to Africa to be described there as a newly discovered genus, until Art found it in the South African Museum in Cape town  and dismantled its cover.

 E. monticola (fulgida holochloris) is a great imitator of Carpenter Bees. Like the bees, it spends a lot of time on the wing without landing. when the beetle is buzzing by at high speed the closed shiny fore-wings give a perfect impression of the bee's heavy, dark body.

 Euphoria monticola (photos D. Danforth)

In July and August, I've seen them in the Chiricahuas and the Canelos in similar forested areas under oaks where the ground was covered in moist leaf litter. The male beetles seem to patrol certain paths and clearings, never flying more than a few feet high, probably in search of females on or in the ground. Females are hardly ever collected

 

Euphoria fascifera trapezium 

 E. fascifera trapezium, which I knew from California, is reported occasionally from our lower desert areas, supposedly associated with pack rat nests. This year it was observed in Tucson in early summer. It seemed to be feeding on fresh Mesquite pods that were bleeding after Mesquite Bug infestation. I finally got hold of one in October when Bruce Mitton collected it for me on blooming Rabbit Bush in his yard in North West Tucson where they regularly breed under his raised planters with lots of composted manure.

The life cycle of this genus is not well described. There seem to be one to two generations per year. The phytophagous larvae have been found in the ground under cow dung and in ant hills. Some adults are reportedly associated with gopher and pack rat nests. Adults feed on pollen, tree-sap, sweet fruit. They have been known to invade bee hives. Rarely, they become pests, damaging young corn or the flowers of roses or mango.

Beetle Parties

Every year Fred and Carol Skillman host their famous annual 'Beetle Bash' at Cochise Stronghold when the monsoon hits (or should hit) Cochise County. The party was delicious, interesting, inspiring, educational, and lots of fun. Thank you so much, Fred and Carol!



The following day, July 11, Eric Eaton and I headed for the Chiricahua Mountains. There was some indication that it had been raining there but the ground was rather dry.
Still, at at a lush creek crossing among ash and oak trees beautiful metallic green-blue Euphoria fulgida holochloris were buzzing around, looking very much like low-flying Carpenter bees.


We set up black lights at Onion Saddle, elevation 7600 ft, in an area with tall Alligator Junipers, Silverleaf Oaks and some Ponderosa Pines. Bill Warner and Aaron Smith stopped by and made us very envious with a beautiful specimen of the rare Carabus forreri. Collectors from as far away as Europe come searching for this beetle endemic to the Chiricahuas and the Huachucas of Arizona.




The sun had set but it was still too bright for the black light to attract anything when the humming and buzzing began. Big dark Scarabs that I later identified as the Dynastinae Coscinocephalus cribrifrons were zooming in on our location. They weren't headed for the black light. They ignored it and landed on a tree near by. More and more beetles appeared as it got darker. I soon found two more trees within a fifty meter radius where more of them were congregating. There must have been close to a hundred beetles per tree, running up and down the trunk, their elytra partly open, ready to take flight again and buzz around some more. The noise of all those feet on the bark sounded first like raindrops and then like a little waterfall.





Clumps of seven or eight beetles clinging together kept falling to the ground still madly scrambling after each other. It became clear that this was similar to a lekking situation where many females and even more pursuing males were coming together to mate. I have no clue how the first arrivals pick a particular tree to be their dancing ground - to me the three chosen trees had nothing to distinguish them from their neighbors. Two of them were junipers, the third one some kind of spruce. At the height of the party the trees were probably surrounded by a thick cloud of pheromones, attracting more and more beetles.



Interestingly, there were also numerous sarcophagid flies attending the dance. Nearly every beetle had a following that approached as soon as the beetle was busy with other beetles or momentarily incapacitated. Even though the flies weren't Tachnidae who are well-known Scarab brood-parasites, I think they were specifically targeting this pheromone-loaded situation, probably to attach eggs to the female beetles that would be transferred to the beetle brood as parasites. My theory is supported by the observation that the flies were all of just one species, their incredible persistence in following the beetles around, and that there were so many of them on the mating trees but none at the black light that had also attracted scarabs (of different species) by then.

The whole mad spectacle ended about an hour after sunset. Sinking temperatures may have curtailed the high activity level at that time.


Our patience at the black light was rewarded by a few more interesting beetle species and a three beautiful huge Oculea Silk Moths.
This chapter of my blog also appeared in  "Scarabs Newsletter # 57"