Tuesday, August 2, 2016

Cicadas emerge

In Arizona, we do not have any synchronized 17 year cicada shows of the eastern United States. Instead, our cicada emerge year after year, each of our many species according to its own schedule and in its special habitat. Among our multitude of species are desert species and some that live in riparian habitats or mountain forests.


Their songs also vary from species to species: some shriek, some buzz, some only bang their wings, others sing in big orchestras that overpower any human communication. But all appear in the heat of summer and their singing seems to be the sound of heat, sunshine, and the longest days ....

https://flic.kr/p/ypYpuK

All cicada develop from eggs that the females lay into the ground. Nymphs hatch and feed underground, sucking plant juices from tree roots.


At this age their front legs are specialized digging tools as can be seen in the exuvia above. Invisible to humans, but sometimes pursued by digging predators like moles or rooting pigs, the nymphs steadily grow, molt when their inflexible skin becomes too tight, and thus go through four or five stages of development (instars), typical for hemimetabolic species that lack a pupal stage.


Fully grown, they finally surface. Now the nymphs climb up on surfaces rough enough to securely anchor the claws of their tarsi. They need to hang perfectly still during the next act, their last molt leading from nymph to adulthood.


The exoskeleton bursts open in the back of the thorax. This slit widens, the insect pushes out until head  and upper body is free. Hydraulic pressure is generated and expands the body out of the old shell. Linings of the old tracheae that are also chitinous and are pulled out and turned inside out like the fingers of a glove. Those are the white strings hanging off the exuvia.


The young cicada hangs backwards out of its anchored old skin. Eventually gravity pulls it out even further and faster.

Teneral imago of an unidentified cicada species from Pena Blanca Canyon

 Below: Linings of the old tracheae that are also chitinous and are pulled out and turned inside out like the fingers of a glove. Those are the white strings hanging off the exuvia.


Neotibicen cultriformis (Grand Western Flood Plain Cicada) from Empire Gulch
Some photographers like to straighten up images of this stage for easier viewing. But for the animal, an upright position would simply not work and for any naturalist or biologist those images are obvious fakes.

Neotibicen cultriformis (Grand Western Flood Plain Cicada) teneral (fresh and soft) on the left, middle and right hardening and maturing
Eventually, hydraulic  pressure inflates the 4 little folded appendages on the back of the thorax into fully functional wings that are able to transport the heavy body as soon as they are hardened.

Another generation of cicadas is ready to join the chorus of summer.

Sunday, July 31, 2016

Arizona Spiders in July

To me, orbweavers with spiny abdomens seem exotic and tropical. But actually we have at least two in SE Arizona that I see occasionally.  
 
Acanthepeira close to stellata (Starbellied Orbweaver)

 When I found Acanthepeira stellata (Starbellied Orbweaver) in Sycamore Canyon, Santa Cruz County, and nearly mistook her for  a shriveled leaf. She typically rests during the day in the vegetation and occupies her web only at night, so this kind of cryptic shape and coloration seem certainly useful.


Micrathena funebris
Rather colorful and obvious, the day active Micrathena funebris hangs in her vertical orb web during the day. The spider occurs from southern Arizona and southern California south to Costa Rica. Until a couple of days ago, I had seen one specimen in Montosa Canyon (Santa Ritas). But when Heidie and Eric Eaton visited Sabino Canyon (Catalinas) on a balmy hot July morning Eric spotted many in the understory of the vegetation of the riparian-desert interface, and one day later, with a freshly honed search image, I saw them in the Athascosa Mountains (Santa Cruz Co) as well.

Cheiracanthium sp. (Longlegged Sac Spider)
Along highway 83, I collected two tightly woven retreats hoping they contained young Jumping Spiders. Instead, they turned out to be Prowling Spiders Miturgidae.  Eight eyes in two rows of four, claw tufts, conical spinnerets, and the habit of building silk retreats or sacs characterize the group.

Cheiracanthium retreat
 The spiders I found along AZ Highway 83 and again in the short vegetation along Montezuma Canyon Highway  belonged to genus Cheiracanthium (Longlegged Sac Spiders). They hunt, running quickly over the vegetation at night and build a new retreat every morning.


Diguetia sp
The space-filling, tangled web of the Desert Shrub Spider (Fam. Diguetidae) is suspended from the spiny pads of a prickly pear cactus. In the middle hangs her retreat, a dome that incorporates many old prey items.

Female Desert Shrub Spider weaving
Diguetidae possess only three pairs of eyes. Their bodies are usually covered in reflective setae, probably an adaptation to the radiation of the desert sun. At night, we found several females weaving  and repairing their webs.

Metepeira labyrinthea (Labyrinth Orbweaver):
The typical cactus spider in our own backyard west of the Tucson Mountains is Metepeira labyrinthea (Labyrinth Orbweaver). Her web is an orb surrounded by tangled labyrinth lines. Egg cases are incorporated into the tubular retreat that is covered in detritus. Spiderlings often stay within the mother's labyrinth.

Metepeira labyrinthea (Labyrinth Orbweaver)
.

Close b to the ground, also protected by the cactus spines, a Agelenid spider (Funnel Weaver) lurked in her funnel entrance. Her web is not sticky, the fast spider rushes out to run down  prey that comes close. Eight eyes in two procurved rows and a pair of dark longitudinal stripes on cephalothorax and abdomen are characteristic.

Sosippus (Funnel Web Wolf Spiders)
 In similar locations the funnel web wolf spider can also be expected. So look them deeply into the eyes: all wolf spiders share a typical eye arrangement: a row of four in front plus a trapezoid of four further back.

Neoscona oaxacensis (Western Spotted Orbweaver)
 In the prickly pear at the Canoa I 19 rest stop we also found Western Spotted Orbweavers that already looked surprisingly grown up. That's a clear sign of the waning of another Arizona summer.

Wednesday, July 20, 2016

A magnificent Longhorn Beetle

About every three years the beetle collecting community - that does not include me, as a mere photographer - buzzes with new about the emergence of the spectacular longhorn beetle Megapurpuricenus magnificus   (Texas Canyon Longhorn). It's the beetle that used to be called  Crioprosopus magnificus, but when I had just learned that name, it was changed.


Many big beetles go through several years of larval development. But members of most species still emerge every year. But like the 17 year cicadas, the Texas Canyon Longhorns emergences appear to be rather synchronized. The beetles are very rare for a couple of years, then they appear in numbers, then again only a few individuals show up. Despite their common name, they do not only occur in Texas Canyon but in several sky island areas of Arizona and Mexico. The three year rhythm seems consistent everywhere, but the different populations all seem to be on their own clocks, so in a particular year they may fly in one mountain range, but not in the other.


Their host trees are several of the local live oaks, Arizona white oak, Emory oak, Silverleaf oak (Hovore 1983). In Arizona, the beetles seem to like smaller trees (or the host trees are stunted due to the beetles activity?) - the diameter of the stem  between knee and hip height is usually only about 10 inches. From Mexico there are damages reported, and those mostly occurred in pure Quercus potosina stands at 2500-2642 m elevations.  Under trees with fresh emergence holes you can often find piles of old saw dust that former generations of beetles pushed out when they emerged.


From Fred Skillman I learned a little about the beetle's biology. I'm not sure in which layers of the tree trunk the wood boring larvae feed, but when they are ready to pupate, they chew and exit hole to the outside. This is important because the adult beetle lacks the mouth-parts to chew its own way out. The hole is closed with a double plug of  wood pulp, then the larva pupates. When the imago (adult beetle) sheds the pupal skin in early summer it removes the first plug, but leaves the second in place. Behind it, the beetle is ready for the first heave rain of the monsoon.  At that time it emerges, neatly timed with its neighbors. Now males and females will be active for a short time, usually on warm mornings between 9 and 11 am and preferably after rainy days or nights, so they can find each other to start a new generation which will take flight after another three years.

If they don't get caught by collectors first. Luckily, the beetles behavior protects them to a degree: to find each other, they climb to the top of the tree canopy. The females may just sit up there and send out their pheromone signals, but the males can be seen cruising from tree top to tree top. In Texas Canyon, the oaks are fairly low and loosely spaced, so the beetles are quite visible once you develop a search image for them. Flying up there, the beetles are out of reach of most butterfly nets.

But there are other ways. Once I came upon a group of collectors on a friend's private property who were lounging on the soft carpet of leaves, leisurely watching the top of an oak.  In the morning they had found a female emerging from her pupal chamber in a nearby tree trunk.


They put her into a little cage and with a rope pulled her up into the tree canopy.  There she obviously did her chemical calling, because eventually we saw a male flying in.



 He circled, found the cage, landed on it. The collectors lowered it, reached impatiently with their nets, lost him. Warned, he disappeared. But soon another one showed up, and this one was caught.

 It took a lot of convincing to make the guys set him on a tree trunk for  me to take pictures. Believe me, their nets hovered right out of sight. They got three or four males that day, no harm was done to the population.


The female was eventually released, and after my photo shoot, she made her way up to the tree tops, this time without a lift and free to seriously enter the mating game.

It is not easy to harm insect species by collecting. The number of eggs that each female produces is enormous. So gaps left by the ones collected should normally be closed by the offspring of those that remain. None-the-less,  older collectors tell me that this particular species used to be much more numerous, if never common. Due to its popularity and its insular distribution, it may have been over-collected. But Fred Skillman also tells of occasional floods in Texas Canyon that may have drowned big numbers of beetles waiting to emerge - remember, most of their holes are only knee-high in the trees. And besides such local catastrophic events, there seems to be an ongoing decline of insect numbers not only in the Southwest, but all over the world may it be due to habit loss, insecticides or climate change. 

References:
Hovore F.T. (1983) 1984. Taxonomic and biological observations on southwestern Cerambycidae (Coleoptera). Col. Bull. 37: 379–387 (Full text)
Sánchez-Martínez G., Moreno-Rico O., Siqueiros-Delgado M.E. (2010) Crioprosopus magnificus LeConte (Coleoptera: Cerambycidae) in Aguascalientes, Mexico: Biological observations and geographical distribution. Col. Bull. 64: 319-328 (Full text)

Saturday, July 16, 2016

Interesting but repulsive study sites


When you walk long enough through lonely stretches of desert, you'll eventually find a carcass. It's a valuable source of nutrients for many insects from Honey Bees (!) to Blow Flies, Dermestid Beetles and many more.

Dr. Art Evans checking for beetles on a dead deer Photo Robyn Waayers
 True entomologists would study a sight like this closely, to find interesting specimens. With experience and  comparative data, it is possible to deduct a timeline for the process of decay determining the kind of insects present as well as their state of development. This is used in forensic science.

Calliphoridae (Blow Flies) and Silphidae (Carrion Beetles) are among the earliest arrivals. This deer was killed the night before I found it in the very early morning
"During this decomposition, the remains go through rapid physical, biological and chemical changes, and different stages of the decomposition are attractive to different species of insects." Gail S. Anderson, American Board of Forensic Entomology, School of Criminology, Simon Fraser University

Insect species arrive, lay eggs, larvae feed, walk off to pupate all in a rather strict and timely pattern that gives reliable clues about the time of death. So both species identification and knowledge of the ontogeny of the insect in question are important for the evaluation.

Dermestes Beetles arrive later. Their  larvae clean the skeleton and are often put to that use in forensic labs and biological collectionss

Dermestes marmoratus, one of several species that are usually attracted to dead things in the desert, but also to dog food that's left unattended

 I was once asked to work for the LAPD on desert sites because of course desert cases progress under conditions different from cases in other climates and we also have our own specific set of  insects here. I declined, and I also did not check out the cow I found in a wash behind 'The Thing' on interstate 10 in SE AZ too closely (July 10, 2016).
 
Necrobia rufipes (Red-legged Ham Beetle) and Creophilus maxillosus (Hairy Rove Beetle)

 But on one of my first excursions to Madera Canyon with Eric Eaton, he pulled out his long forceps and lifted an older cow hide, so I got to see many of the clean-up crew scurrying quickly into hiding. The two above were among those very late visitors. The rove beetle was probably not scavenging but actively hunting, preying on the scavengers and their larvae.


 One of the last beetles on a very mummified and desiccated carcass is often a scarab relative of the family Trogidae (Hide Beetles). They show up when only bones and the hide are left - hence the common name Hide Beetles. You can also find them close to Coyote scat that contains a lot of hair. We have a number of Trox and Omorgus in AZ and all are quite similar. Bill Warner identified this group of Omorgus from AZ

Sunday, July 3, 2016

Midsummer week in a NW German forest


At low magnification, the old slide photos still look nice enough. Kurler Busch 1983
After growing up with camera in hand since I was 4 years old, I discovered insect photography while I was still in high school in Dortmund, Germany. I bought what was then professional quality equipment: A nice Canon A1 SLR and the 100 mm dedicated Canon macro lens. Then I spent most of my money from allowance and working at a book store on slide film. I sold some images to nature magazines and gave slide talks at the zoo and our birding group. So I thought a lot of my slides.

Another set from back then
But I brought only a fraction of my slides with me to America and began digitizing them some years ago. To my great disappointment, the quality was far inferior to my newer digital photos. I put the blame on my inexperience at the time  and the lack of direct feedback while shooting slide film. While I still get rather impatient with friends who slow down our excursions by critically reviewing each shot on their digital cameras in the field, I am grateful that I, too, can see and fix some problems right away.  Being free of the limitations of expensive slide film, I also definitely take more shots, so I can bracket the settings to hopefully end up with a good shot among several choices.


This  year (2016), I had the opportunity to spend the second week of June  in my family home close to forest and meadows where in the early eighties I worked on the arthropod part of a very inclusive inventory of fauna and flora of the Kurler Busch. I am proud to say that much of the area has now the designation Naturschtzgebiet Kurler Busch, so it has become a nature preserve.
Our house in 1978 and in 2016. It is now completely overgrown by trees and invisible from the road. Between nightmare and enchantment
 But his time I was in Kurl to sell our house and liquidate my mother's estate. That was a sad duty and I escaped into the forest whenever I could. With me was only my trusted little workhorse of a digital camera, my old Olympus SP-800UZ, the DSLR and its lenses being too bulky to take.


Very soon, I found out that the lack of quality of my old German images had only little to do with the factors mentioned above. It's all in the light! Now, like then, I did not have the use of balanced double flashes with diffusors. But I am also quite fond of natural light photography and see it as a worthwhile challenge.


 North Rhine Westphalia is part of the Dutch/NW German bay and has a rather oceanic climate, with  lots of clouds and fog. The light has a very different quality from the harsh glare in Arizona. Under the forest canopy, the diffuse light is filtered into all shades of green and blue that at first seemed to overwhelm everything else.

 Pyrochroa coccinea, a Feuerkaefer
But as I adjusted, I soon appreciated again the intensity of local color and the lack of hard cast shadows. Also, at 51.5570° N so close to midsummer, daylight lasted endlessly, even if the entrance angle of the light stayed rather low most of the time.

This photo was taken around 10 am.
Anyway, I decided rather than to invest too much time effort and luggage pounds into old slides  to try and reshoot as many insect species as possible within a week. It turned out that I still knew where to find most insects because over nearly 4 decades, very little had changed in the mature forest, or at least not for the worse. Germany has been protective of its remaining forests for decades. Development of those areas is avoided, and wood harvesting is done selectively and without clear-cuts. reforestation usually progresses very quickly. A lasting threat: Building new roads still seems to take priority and may condemn big stretches of natural land and isolate others.

The Koernebach in Kurl/Husen 2008 and 2016. Too bad I cannot find a photo of the unappealing industrial canal that was there before
Positive changes were obvious in the management of creeks and rivers. In the seventies, I still experienced the last years of mandatory 'canalisation' of all untamed creeks, and activity that transformed them into nothing but industrial wastewater ways. Since then the political attitude has completely changed. Even old industrial wastewater canals, which in my childhood emitted foul odors an ran inaccessibly between steep concrete banks, are now meandering clear brooks again. The Emscher Project is the most famous renaturation. The smaller tributary Koernebach, that runs through Kurl, has shared the fate of the Emscher.  So, about one decade ago I found the revived  Koernebach meandering happily through lush meadows, but now in 2016 it was already shielded by a mature riparian forest of huge willows and alders.

Landstroper See, another bergsenkungsgebiet turned nature preserve
For centuries, coal from the Ruhr Valley had been driving the German economy. But for the last 50 years or so, the dense network of old coal mining tunnels has been collapsing under the area.  This created many problems but also interesting opportunities. Where the ground sinks, water back-flows against the direction of the natural water sheds and accumulates in swamps and even ponds. Ice-skating on the Lanstroper See was a great treat for us during winters that were cold enough, and for birds and birders such 'Senkungsgebiete' were always paradise (See also the Hallerey in west Dortmund).  But this process would drown half the Ruhr Valley if left alone. So industry-sized pumps are running constantly to control the expansion of these wetlands, and tempers often flare when proponents of forest trees and agriculture clash with those who want more swampy birding areas.

The Kurler Busch has its own version of a Senkungsgebiet: The Ramsloher Bach. It was originally the core of the nature preserve I helped to create. By now it is so overgrown that I could only peak in by climbing on a hunter's high seat. I was disappointed, but the herons and egrets living there were not.


Cool overcast mornings are not great for insect observations. On the first days, due to jet lag and early sunrise I got up before 4 am and walked into the forest. I got the impression that I would not find anything but snails and slugs that seemed to have proliferated enormously since my last visit.


Even around 10 am on those cool cloudy mornings, the white umbels along the forest paths attracted much fewer bugs than I had hoped. But actually, by comparison, the German bugs proved tougher than AZ insects at the same temperatures.  Flower-longhorns and one of my favorite scarabs soon gorged themselves on pollen, together with bumblebees and flies. Surprisingly, Honey bees were missing.

Along the borders of paths and agricultural fields, ideally herbicide and pesticide free zones give sanctuary to wild flora and fauna
As soon as the sun broke through a little bit, the weed and wildflower rich borders of agricultural fields and meadows became quite interesting. For years now, narrow stripes of land are spared any intensive use and kept free of herbicides. Where the fields are much smaller than in the US, these areas form a viable network. Here wild herbs are preserved, reproduce and provide seeds for birds, nurture  pollinators, and in general make living space and food for all sorts of small native wildlife.


 From flower visiting beetles of various families, to flies, bees and colorful spittle bugs - the wild flower diversity results in great insect diversity. 


Leaf beetles (Chrysomelidae) are mostly small but colorful, making me think that they are giving warnings of toxicity or noxious taste to predators. The shiny beauty of the Europeans keeps up well with that of their Arizona relatives. The ones above were all photographed within a few hundred feet of a path between a meadow and a barley field. The Alder Leaf Beetle must have flown over from the nearby riparian forest. 


Along paths deeper in the forest, where the light is dim and high groundwater levels are always ready to fill the trenches, burning nettles (Urtica sp.) abound. This usually is a sign of disturbance and high nitrate levels. But bugs like the burning nettles. My usual photo technique to support with my left hand the leaf with the subject as well as my camera-wielding right hand became a little tricky as I'm not too fond of nettle burns. But a firm, determined reach usually breaks all those little injection cannulae before they can penetrate the skin.  This year the nettles seemed richer in weevils than ever, but maybe my friendship with one of the world's best weevil specialists Charlie O'Brien, has sharpened my eyes. 


  Germany's favorite and most well-known beetle was always the Maikaefer, or Cock Chafer, Melolontha melolontha. Lucky charm to us kids, not so well liked by foresters, this scarab has a somewhat unpredictable rhythm of appearance (every seventh year was supposed to be a boom-year) and some people say it's now getting rare. I found one in my own overgrown backyard which every day seemed to become more and more of an enchanted garden.
Hoplia philanthus
In a Barley field I found a scarab that was completely new to me. I could only guess the genus from what I'd seen on Swiss mountain meadows.  But my internet connections to entomologists from all over the world payed of: I quickly got it identified with the help of two great scarab workers, Bill Warner and Carsten Zorn

Cepaea hortensis and Cornu aspersum
German friends and relatives visited and all had observations to share: of a booming invasion of the Gefleckte Weinbergschnecke, Cornu aspersum that might eventually displace my old friend the Banded Garden Snail Cepaea hortensis.


..of A hornet queens (Vespa Crabro) that tried to nest in a little bird house at my cousin's place main entrance door and was carefully relocated at night, with the birdhouse. In fact, I had never before seen so many hornet queens seeking nesting sites as this June. Endlessly probing for cavities they did not sit still for photos. So the image is from a visit at another season and shows a male.


... of unusual numbers of fat round blue-black beetles that turned out to be the dung beetle Geotrupes stercorarius.

Harmonia axyridis (Multicolored Asian Lady Beetle)
... of smelly ladybugs that in winter congregated in big masses around windows and doors ..... these  imported Asian Ladybugs that had not been part of the equation when I left in the eighties but now were everywhere.

Bee keeper close to our forest in 1984
 There were very few Honey Bees around. My biologist friends were unconcerned - they said that there was just no locale bee keeper around because the blooming season was just beginning. That may be true. The hives of the guy in the above photo had always been close to the forest, but his lot was now unused and overgrown with weeds. In Arizona, feral honey bees are so common that they are probably a serious threat to the native bee population. But in Germany feral bees are rare and probably do not survive the winter.  

Bombus terrestris and Bombus lapidarius enjoying garden flowers
 What I found instead were Bumblebees. There may have been smaller endemic bees like andrenids around as well, but I did not see any. The cool temperatures of those June days probably gave the bumblebees the advantage: they are efficient, if facultative thermo-regulators. They can let their body temps float with environmental temperatures to save energy, but they can also actively increase their temperature, if it's worth it. So where good nectar sources await them, they are out a 7 am, busily collecting.
During my short visit I found at least 5 species of Bumble Bees, many in gardens with decorative flowers. Thank you, Bernhard Jacobi for help with the identifications!
Male Bombus pratorum  nectaring on cherry leaf nectaries
One evening I found a male Bombus pratorum  buzzing around greenery where no flowers were obvious.It turned out that he was systematically visiting the extrafloral nectaries on the leaves of a bush of wild cherries.Of course, being male, he was just drinking by himself, not collecting.

This time, I had dreaded my visit to Germany very much. But by the time I drove to the airport to fly back to Arizona, I was thinking that this shouldn't be my last visit to the forest of my childhood. I'm pretty sure that I will be back one day.