Tuesday, July 20, 2010

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"  

Friday, July 9, 2010

Our Place at Night

In Arizona, the Monsoon season has begun. Temperatures have been hovering above the 100 mark for days and finally the humidity is also rising. Today, clouds are covering most of the sky. Although it hasn't actually rained yet, the fauna in our back yard is waking up from the stasis induced by the dry heat of June. But since it is still so hot during the day, one has to get a flash light and walk the night to see the animals.

At sunset, several species of bats flutter and zigzag like butterflies. Lesser Nighthawks Chordeiles acutipennis begin sailing across the sky.

The Nighthawk has spent the day immobile and nearly invisible, huddled down on a Palo Verde branch.

At dusk he flies at high speed sweeping insects into his wide, short beak that is surrounded by bristles that serve as sensory organs and as a catching basket.

Pack Rats rustle around their piled-up middens, Cactus Mice Peromyscus eremicus (picture) hide in the shadows, and we see Pocket Mice hopping around. These miniature versions of the Kangaroo-rat are too shy and fast for my camera, but I'll keep trying.

Another shy creature is the female Tarantula Aphonopelma sp. that excavated her burrow in our drive way. She opens the silk cover of the entrance every night to come out to hunt, but she stays close enough to her hole to slip back in as soon as my flashlight beam hits her.

The males are much less camera shy, and anyway, they don't have holes to hide in when they are wandering about hunting and looking for females.

Black Widows Latrodectus hesperus are hanging quite unafraid in their webs, presenting the red hour-glass of their under-bellies as a warning. Who would bother them? A bite can be devastating. But you won't find them during the day.

Lightning quick Sunspiders, also called Windscorpions, Solifugae rush by. Having no poison, they rely on the strength of their formidable mandibles to overpower their prey.

A female Scorpion is carrying her offspring on her back. Scorpions, like many other insectivores, are attracted to the bounty on my black-lighting sheet.

A real nuisance for the insect collector are the big Sonoran Desert Toads Bufo alvarius. They have learned to come to my black light and probably get more beetles than I. We've reached an uneasy coexistance with these amphibians that seem to emerge earlier every summer. Even our dog Cody has learned from his first nearly tragic encounter that sent him to the vet with a racing heartbeat and partial paralysis. For several years after that he was a bufotenin licking junkie: We could always tell from his swagger and fluffed-up fur when he had found the first toad of the season and was high again. But by now he leaves them alone, even when they use his water dish as a swimming pool. None of the other dogs ever bothered the toads.

As every bird bath has its toads, every porch light has its Mediterranean House Gecko Hemidactylus turcitus. This introduced species spends its life in the vertical plane of walls. Special toe pads give the Gecko a secure hold that allows him to shoot forward and snap up any moth that is drawn to the light.
I hope they also get some of the Kissing Bugs Triatoma rubida. These Reduviids grow up in Pack rat nests, but at night the adults hang around lights and are always ready for a meal of blood from our sleeping dogs.

Another Gecko hunts on the ground. The native Western Banded Gecko Coleonyx variegatus bogerti lacks the toe pads of its European cousin. His very thin, soft skin may make him more dependent on cooler, moister hide-outs. During the day I find this species under flower pots and bird baths in shady places.

With a dry rustling noise, huge Long-horned Beetles land close to lights: Palo Verde Root Borers Dreobrachus hovorei. At up to 4 inches, they are the longest, if not the heaviest Arizona Beetles.

I am expecting to find their relatives, the long-jawed Nothopleurus lobigenis any day now, too. I remember from last year that they seem to take their clue from the first actual downpour.

Sadly, this summer we are missing our Western Screech Owls Megascops kennicottii. Since we bought our house in the Tucson Mountains in 2002 we heard their dropped-ping-pong-ball call during summer nights and every year watched about four young ones emerge from a cavity in an old Ironwood tree. Last year's terrible drought seems to have been too much for them.

When the dogs start barking at night, we listen whether they are joining the choir of the coyotes, race around and bark angrily at Javelinas, or give the stationary, rhythmic bark that we have learned to associate with rattlers Crotalus atrox . These snakes become night active when the temperatures force them into shelter during the day.