Sunday, September 26, 2021

Slaughter of Autumn

Very often, my fall images seem to be crime scene photos. I have not suddenly turned sadistic but I'm not apologetic either. It's how the cycle of arthropod life concludes. Nothing goes to waste. Most herbivorous insects do not live through the winter after they have reached adulthood. so they are now fair game to predators. Many predators are now in their prime, ready to continue the food chain that started with the abundance of plant growth after the summer rains.
A Calosoma sp. Carabid and a number of Pogonomyrmex sp. ants scavenge on a roadkilled Brachystola magna (Plains Lubber Grasshopper)
Misumenoides formosipes (Whitebanded Crab Spider feeding on Poecilanthrax sp (Bee Fly)
A female Peucetia viridans (Green Lynx) got herself a Sulphur. a welcome boost of proteine as she is ready to lay her big clutch of eggs
Zelus renardi, the small but fierce Leaf-hopper Assassin Bug. Probably the most common one around our backyard. It often tackles insects at least its own size. I have not seen any preference for leaf-hoppers.
Apiomerus flaviventris (Yellow-bellied Bee Assassin) lives closer to the sky islands. This assassin lives up to its common name and often grabs bees, but here it's shown with Pogonomyrmex sp., a Harvester ant. One of her sisters stung poor Kira in her right hind paw and she suffered greatly. Usually it's me.

Friday, September 17, 2021

Artfull Encounter

Tonight I went to a vernissage at the ASDM. A very nice exhibit of ‘Animal Impressions’. But eventually, I drifted away from the buildings to the trails. So lovely to have the park all to myself at sunset. So many butterflies still dancing in the fading light. But then I felt watched. No longer alone. A long-legged, long-tailed creature on the trail, quietly observing me. Joined then by two smaller shapes, much more impatient, curious. The small ones about the size of a cat. Hopping towards me, retreating, sitting secretively behind a cactus, sneaking forward again. All under the weary guard of the larger one. All of them – so graceful, so elegant! Yeah, cute too. My painting does not do them justice I’m afraid

Thursday, September 16, 2021

Population Explosion of the Ground Beetle Calosoma sp.

For weeks, the blacklight in my yard in the Creosote/Saguaro flats of Picture Rocks, Pima Co, Arizona has been overrun by huge numbers big, black beetles. They densely cover over 30 square feet of wall and desert floor around my light. The longer my lighting session goes on, the more arrive.
This is a real population explosion of Calosoma probably Calosoma peregrinator. We have a number of very similar Calosoma species here, so I will just use the genus name from here on.
Fast on its strong legs and equipped with big prognath mandibles, Calosoma is a potent predator that grabs whatever other insect they can catch. Moths, desert roaches, ant lions, other beetles, carcasses – Calosoma is not selective at all. I am actually giving up black lighting until the curve of this population explosion is on the down-slope. That may take a while, because the individual beetles can live for several years.
Of course other people in Arizona also find the beetles around their porch lights and swimming pool illumination. Lighted storefronts attract them at night, store owners spray against ‘this pest’ and dead beetles litter the walkways in the morning. So even though the beetles are mostly night-active or crepuscular (dawn and dusk-active) and during the day only single individuals are visible running through the cinch-weed, people are aware of them and are getting annoyed. Thanks to social media, speculations as to what they are and what to do about them abound.
This is what they are not: Many Arizonans want to call them Stink Bugs. But Stink Bug is a folksy name for the Desert Stink-beetle or Pinacate Beetle. Similar in size and some behavior to Calosoma, Stink-beetles are darkling beetles in the genus Eleodes. They got their popular name for a good reason: Eleodes has 2 scent glands that open to the very tip of the beetle’s abdomen. When threatened, Eleodes releases the smelly, staining fluid (containing a potent mix of benzoquinones and caprylic acid) – either directing the chemical spray directly at its attacker, or just pouring it all over itself by standing on its head, ejecting the chemical and letting gravity do the rest, rendering the beetle distasteful to many attackers. This ability gave the Stink-beetle its name, and its headstand is a very well-recognized warning that many predators understand. It also gave the Stink-beetle the confidence to stay out in the open at dusk where people saw it and noticed it. So It got not only one, but several common names that are well-known all over the southwest. The Desert Stink-beetle is a peaceful, slow moving feeder on starchy seeds and fungal matter. I often see many coming together where Creosote bushes drop their fuzzy fruit. Eleodes have fused elytra that give them a hard shell and protection from evaporation. But they have lost the ability to fly.
There is another flightless beetle walking the desert, also black and of similar size, and even shape: the Cactus Longhorn Moneleima. When these longhorns move between cacti across a stretch of bare sand, you may sometimes see them stop and point their hind end upwards. They do this very much in the manner of Eleodes, though in fact, they lack stink glands. They are mimics of the Desert Stink-beetle. The existence of mimics that not only look like Eleodes, but even imitate its behavior, demonstrates how effective the protection is that Eleodes gains from its chemical warfare. Cactus Longhorns and Desert Stink-beetles are often confused even by human observers.
But back to Calosoma, the predatory Carabid whose population explosion bothers so many people. Even though it also has a distinctive smell (Hydroquinone) it is actually quite different from the Stink-beetle, being a fast runner and able to fly very well. And while the Stink-beetle larvae could be compared to big meal worms (they are in the same family) that feed on starchy stuff, Calosoma larvae are already potent predators, that go after all kinds of soft-bodied arthropods and also, opportunistically, carcasses.
I think it is this high protein diet that makes the larvae of Calosoma to grow up quickly (a few weeks) and prepares the species to take advantage of sudden abundance of prey species as we are seeing after this monsoon season. When hundreds of White-lined Sphinx caterpillars were appearing in the desert, feeding on herbs that were sprouting everywhere, Calosoma armies were ready to attack them, together with tarantulas, tortoises, lizards, kestrels, coyotes – you name it. Of all of these, only Calosoma has a generation sequence short enough to result in visible, sudden population increases. I am sure that other insect predators and parasites might have reached similar population peaks, but little braconid wasps and even tachinid flies would be much less obvious to humans.
Contributing is the fact that Calosoma is a night active, flying insect that uses light sources (the moon in nature) for orientation. Artificial lights, especially those with a high UV component, are irresistible to those big black beetles, so they can quickly congregate by the hundreds.
So at your porch lights running to invade your doors is Calosoma, the Caterpillar-hunter. It’s that predatory Carabid that everybody sees and gets upset about. Not the slow Desert Stink-beetle Eleodes, a Darkling Beetle, and also not the Cactus Longhorn Moneleima, though single individuals of both genera can be seen stalking (not running!) over the desert sand at dusk and dawn. Ironically, the role of Calosoma as a predator that very quickly reacts to sudden abundances of ‘destructive’ caterpillars has been well known by many forestry experts for a long time. Calosoma inquisitor, a European Species, was actually introduced to the US for biocontrol of certain periodic caterpillars. How strange that avid gardeners here in Arizona are now the ones that spray and kill an endemic Calosoma because they are ‘grossed out’ by the usually mis-identified beetles.
There is a very close relative to our black Calosoma species, Calosoms scrutator. This one doesn't like the hot dry desert as much as its dark relatives. You can find this one in the medium elevation of the sky islands of the Southwest.

Tuesday, September 7, 2021

September Morning

Sugar-water bat pee pattern on the garage door. Shrike screaming from the old Ironwood, Snake tracks crossing the path, straight ones from rattlers, undulating ones from constrictors. Weaving lizard lines with little footprints. Much straighter and more deeply engraved iguana grooves. Then, following my trail instead of crossing it, a sidewinder's diagonal hatching, first of this year. Observations while jogging after my dogs. Sweat in my eyes, mosquitoes buzzing.

Friday, September 3, 2021

Wolfberry bugs

Yesterday I cruised through Saguaro National Park West on the open part of Golden Gate loop. We got record monsoon rains in July and August, so every leafy plant, including Ocotillos has greened up. The Saguaros must have doubled their circumference. In the park, flowers are relatively rare at this time.
Thousands of nectaring butterflies are clinging to a few yellow Asteraceae. Some bushes, noticeably Sweet Acacias and Wolfberry (Lycium), are already heavy with fruit.
After snacking on sweet berries for a while, I remembered one of my missions: to check Lycium sp.bushes for Echenopa permutate, nymphs or adults. One of my clients is working on their audible communication and I have a standing order for life specimens.
Lycium pallidum from Gardner Canyon
Lycium brevipes from Mexico, a common plant in Nurseries in AZ
Lycium andersonii, probably our most common desert species with nearly succulent small leaves and small whiteish flowers While not finding any treehoppers this year - the Lycium plants were obviously drought-deciduous and this year put out leaves only after the first monsoon rains - I did learn something about the available Lycium species in Arizona. And since google brings up the popular Goji Berries with any Wolfberry search, but then proclaims that they (all?) stem from China, let me clarify here: Goji berry is a Wolfberry (genus Lycium) from China, but we have quite a number of endemic Lycium species in the US and especially in Arizona. With edible, probably healthy berries.
The first bushes I checked looked extremely healthy. Only a few berries had been squished by a hungry Green Fig Beetle (Cotinus mutabilis) I have learned not to expect phloem-juice-sucking treehoppers on bushes like that. With my close-range binoculars I finally spotted (from the car!) a lot of movement in a single Lycium bush that looked more than a little bedraggled.
Most of the movement that alerted me came from red-headed ants that were surprisingly difficult to photograph. They appeared to be all one species but different size casts (?) in addition to these constantly running ants, dozens of other species of insects kept appearing and hiding again while I watched just a small area of gnarled twiggs.
The only beetle sp. present, represented by a striking number of individuals, was a ladybug in the genus Hyperaspis perhaps sp. conspirans. This may provide a hint of what’s going on: Hyperaspis mainly feed on Aphids and scale insects. The lumps that made the twigs so gnarly were probably scale insects (or caused by them). While the ladybugs may have been actively hunting for those, all the other insects were probably there to lick the sweet honey dew that the sedentary bugs secrete.
These 2 wasps, a Crabronid and a Braconid are just examples of a variety of hymenopterans most of whom evaded the camera.
Flies of several species were also heavily represented in the melee.
Empress Leilia and American Snout stuck their probosces in, while none of the ubiquitous sulfurs seemed attracted to honey dew Sadly, I saw no trace of the Membracids (treehoppers) Enchenopa permutata that I was looking for, so I am showing male, the ‘horned’ female and a nymph from another trip which took me to Box Canyon, Santa Rita Mountains.
In the wetter spring of 2015, we found Enchenopa permutata in May, and now it’s September, so this may be the wrong season. But I had been hoping those small bugs might be multigenerational. I will keep looking.