Friday, June 22, 2012

Longhorn Season

Longhorn Beetles (Cerambycidae) spend a great part of their lives as larvae, chewing and feeding on the inside of branches and twigs, under bark and even in the core wood of trees. Some live in the soil, feeding on roots and other plant matter. Even though a thumb-sized larva of the Palo Verde Rootborer  at the Arizona Desert Museum that accepted apple slices as surrogate food pupated and metamorphed into a big beetle just fine, most Cerambycids are specialists when it comes to their host plants and foods. Special requirements reach from the stalks of perennials to the living cambium of tree trunks, to freshly dead branches, and even to freshly burned wood for some species. Old dead wood is usually left to other groups like the Powderpost Beetles (Bostrichids).

 The feeding behavior within the plant is genetically programmed, and the shape and location of tunnels and holes in the wood, and whether those passage ways are filled with digested wood pulp or not, can tell the specialist a lot about the species and age of the larvae. (I can tell the family. That's something, too)

Cerambycid Larva, ready to chew
Insects that feed and pupate in the trunk of  hardwood trees like oaks are well protected. Tunneling within the wood is no problem for the strong mandibles of the larva whose only purpose is to accumulate nutrients and grow.  But the adult beetle is much more geared towards mobility, finding a partner, and propagation. After the metamorphosis there are wings, antennae, long legs, the ovipositor if it's a female, but the strong, wood chewing mandibles are gone. So how do the beetles get out of the wood?

Longhorn Beetle Pupa
It's all taken care of by the larva before pupation. It chews out a pupal chamber close to the surface, but under enough wood to protect the vulnerable pupa. The larva also prepares and exit way to the surface, but then carefully closes it with a plug of chewed wood pulp. In some species, like our beautiful three year oak cerambicyd Crioprosopus magnificus there are even two plugs. Thus protected in its chamber, the larva pupates, goes through the metamorphosis and finally ecloses as a finished beetle - and then stays in the puparium and waits. In different ecosystems there are different signals that will trigger the final emergence of the beetles. The signal may be a rise in temperature, or in day length if that can be perceived within the wood, signals coming from the tree, even the smell of a near-by fire that promises food for the next generation. Here in Arizona, most beetles wait for the monsoon rains. The triggering signals will synchronize the emergence of males and females. All the waiting adult beetles become active, push out those plugs and emerge simultaneously, immediately ready to find partners, mate, disperse and reproduce.

Crioprosopus magnificus pair
 For Crioprosopus magnificus who develops in small oak trees on rocky slopes in Cochise County,  this great event usually happens only every third year. Knowledgeable collectors have told me that the double plugs in the emergence hole probably fine-tune the timing: the beetles respond to an increase in humidity by removing the first plug and  push out the second just after the first heavy monsoon down pour. After that, if you are very lucky, you can see them flying over the crowns of the low-growing oaks.

Mallodon dasystomus, Hartwood Stump Borer
 In 2010 I was at Steward Campground in the Chiricahuas in early July just after the first rains. My black light, my dog and I were overrun by  Hardwood Stump Borers, big guys that my dog did not like very much. A month later I went back and couldn't find any.

Monochamus clamator from Rustler's Park
 Last Monday we must have been on Mt Lemmon just in time for another species, Monochamus clamator. This one isn't rare in other western states, but last year Patrick Gorring, a Cerambycid researcher, contacted every collector and entomologist in Arizona for help to find local specimens in our skyislands. I met him on Mt Graham by the end of his trip, and I don't think he got any Monochamus at all.  I had only once seen a specimen that a birding friend, Gary Waayers, spotted and netted in flight at Rustler's park in the Chiricahuas.

How many?
So one week after an unseasonably early rain Randy and the dogs were resting in the lush grass along Meadow Trail on Mt Lemmon and I was beating some pine branches without much enthusiasm because we hadn't found much until then. I was quite surprised when the first big male Monochamus  plopped into the beating sheet and calmly walked around on it with his long antennae extended in front of him. When a second one landed right afterwards I had a search image and began seeing more of them on pine branches and clinging to grasses. They all looked fresh and perfect, as if newly emerged. Their elegant checkered pattern camouflaged them efficiently. They were mostly in the branches of a live, upright pine, but a freshly dead tree was lying near by. Their larvae are known to bore in sick and dying pine trees, and there are still many fire -damaged trees from the big Mt Lemmon Fire (9 years ago? Time flies) that are succumbing only now.

Monochamus clamator from Mt Lemmon

Saturday, June 16, 2012

Yeah! A Thunderstorm in June

Some precursors of the summer monsoons are appearing early this year: Tohonochul Park is announcing that  their first Desert Queen of the Night is ready to bloom any day now, but while our queens have promising buds, they are still weeks from blooming.

Our toads have been out for a while now, though. First several small Red-spotted toads and since the beginning of the week also many of the big Sonoran Desert Toads.

 Big blue wasps (more than 4 cm long) with orange wings, the Tarantula Hawks, can be seen at any time, even around the winter solstice, but now they are very active around our one blooming eucalyptus tree (we had a leaky irrigation line there) and appear at my black light at night. Luckily they haven't found the pretty tarantula that lives by the cloth line...

Other Arachnids are using my black lights as a hunting beacon. Solifugids and Scorpions are always around.

Our Mediterranean Night Gecko also hangs out around the lights - he knows that he'll find plenty of drowsy moths.
Scolopsella reticulata
This Fulgorid is a regular summertime visitor at my black light. Certainly one of the more memorable shapes. The first one showed up two days ago.

So far we had the typical June heat with clear blue skies, temperatures just above 100 F and very low humidity. Nevertheless, last night the first Palo Verde Beetle, all shiny and new, was sitting on the warm garage wall. We were surprised: they usually wait for the monsoon rains as their signal to emerge.

This morning there were some harmless little clouds in a blue sky. At noon, they looked like small thunderheads over Mt Wassem.

By 3pm it was getting dark over Tucson, then a sandstorm rolled through with gusts up to 50 mi/h - followed lightning, thunder (two of our dogs demanded to come inside) a 20 F temperature drop within 20 min, and then pouring rain. In June! It's unheard of! The acrid smell of the wet sand mingles with the aroma of the creosote bushes. We love it!

Now, at 5:15 pm,  the sun is shining again and we are ready to join our neighbors for an outdoor barbeque.

Thursday, June 14, 2012

The 7 Oaks of Mount Lemmon

Some Arizona Oaks after Vol. 27, J. of the Arizona-Nevada Academy of Science. Click on image to see more clearly
 As a biologist I have a a background in both botany and zoology. In the forest behind our house in Germany I could have named any flower or tree with both botanical and popular names. Here in Arizona I still often don't get past the family or if I'm lucky the genus of trees and herbs, while learning much more about bugs, herps, birds and mammals of the area. But the plant societies form the basis for most of the ecological niches that animals live in.
Understanding and often even identification of many insects in particular depends on knowledge of their host plants.
For the last couple of months I have been on a quest to collect and photograph local caterpillars. By June, most herbaceous food plants in the lower desert are drying up, but the oaks of high elevations are still a good place to look. There are so many species here! Arizona Flora by Thomas H. Keraney (University of California Press) gives a key to 12 Arizona species.

Yesterday botanist Bob Schmalzel took Charlie O'Brien and me on a tour of Mt Lemmon to teach us how to recognize and find 7 of the species along Catalina Highway. It was a beautiful day: Driving up the mountain, we enjoyed gorgeous views, steadily falling temperatures, deep forest greens (I miss those!), soft gopher churned soil under our feet, the sweet song of solitary thrushes, the aromatic smell (and loads of pollen) of pine and fir trees. I wanted to stay up there!

Mexican Blue Oak, Quercus oblongifolia
But back to learning about oaks:  Impressive Mexican Blue Oaks (Quercus oblongifolia) can be found quite low in Molino Basin where the little creek runs most of the year. The mature leaves are oval with a squared base, leathery and waxy. This gives the tree its typical blue-gray color. Mexican Blue Oaks keep their leaves during the winter. Like many wintergreen trees, their frost-hardiness is limited and during the cold spell of Jan. 2011 there was concern that we would lose this tree that reaches its northern most extension here in Arizona.
Q. oblongifolia with fresh leaves in April
When I hiked Brown Canyon in the Baboquivaries in early April, fresh leaves were just growing, giving the oaks a gold-bronze hue. In years of (even greater) drought,  the trees can delay leafing out and stand bare until the first heavy monsoon storms arrive. They are drought deciduous. Mexican Oaks bloom in April and the acorns ripen in December. Q. oblongifolia grows in the lower elevations, the foothills.

Emory Oak, Quercus emoryi with young acorns in June
Oaks with very dark trunks and glossy, spiky green leaves can be found around the Picnic tables at Molino Basin and genarally occupy sunnier, drier spots half way up the Catalina Mts. These are Emory Oaks. Many on the Catalina slopes were only brush sized, but old specimens can be big trees with weeping branches. Like the Mexican Blue Oaks, Emorys are marcescent, not dropping dead leaves until spring when they also bloom. Their acorn production is very quick: the acorns are ripe in July/August. Local Apache women still watch eagerly for the right time to collect the bounty of nutritious, low tannin fruit. Even though they are now falling out of favor like other traditional foods, Emory acorns used to be a very important staple for the Apache tribes.

Arizona Oak, Quercus arizonica/grisea
Higher up the mountain the road crosses the elevation where Arizona Cypress grows in shady canyons along boulder rich streams. Just above this area we stopped at  Middle Bear to see three more species of oaks: The Arizona Oak resembles Emory's somewhat but seems to like cooler, moister places in a forest setting among Alligator Juniper, Cherries, Walnuts and the first pines. Like Emory's Oak leaves Arizona Oak leaves are a little spiky, but not glossy, softer and greyish green. The best character to immediately tell them from Emory's is the light grey trunk. In Bob's notes it says Q. arizonica is subsumed now into Q. grisea.

Net-leaf Oak, Quercus rugosa/reticulata
Also at Middle Bear, the small bushy Net-leaf Oak, Quercus rugosa/reticulata has rounded irregular leaves, sculpted by a net of prominent veins and fuzzy with golden hairs on the underside. Young acorns were protruding from the branches on petioles that were several inches long. Bob pointed out that the leaf size is extremely variable and can reach hand-size. I imagine that this is an adaption to this oak's preference for shady, wet canyons and north facing slopes.

Silverleaf Oak, Quercus hypoleucoides
Silverleaf Oak with their narrow, willow-like leaves that are surprisingly thick and leathery, dominate the slopes from Middle Bear to just under 8000 feet. In cool, wet Madera Canyon in the Santa Ritas, their reign begins much lower. Silverleaf Oaks and Emory's Oak are the only Black Oaks of the Southwest. Malacosoma caterpillars seem to understand this relationship better than I do and freely wander from one species to the other.

Lophocampa mixta and a tentatively identified Punkie, Meganola sp. on Silverleaf Oak
 Since it got warm Silverleaf Oaks yield by far the most divers insect population: Weevils, Ants, Flea beetles, other Leaf Beetles, Jumping Spiders, Tree Hoppers, Mirids, Ladybugs, and in some years Clicking Cicadas tumble into the beating sheet when I tap the branches. This time there were also some very interesting hairy caterpillars.    .

Quercus chrysolepis
 A few specimens of a small bushy oak with tiny holly-shaped leaves grow in the slopes around San Pedro Vista. The leaves are covered on both sides with golden hairs. There are two closely related species that are both considered as very primitive oaks: Q. palmeri and Q. chrysolepis (no common name) the Catalina population seems to belong to Q. chrysolepis which develops acorns  whose cup are hugging the fruit as opposed to the flat saucer-like ones of Q. palmeri.

Gambel's Oak, Quercus gambelii
The only oak that really looks like a classic oak to European eyes, the Gambel's Oak, belongs to the White Oaks. It is the only winter-deciduous oak on Mt Lemmon, meaning it stands bare through the winter. Its large lobed leaves are more leathery than its Northern European relative's, but softer and thinner that those of the non-deciduous live oaks. Accordingly, it lives in elevations above 6000 feet, together with Black locust, Aspen, Maple and conifers, where the winters are cold, stormy and snow-rich  and the summers are cool and pleasant.

Poison Oak/Ivy, Rhus radicans
Poison Oak, or Ivy as it is called here, is of course no real oak at all, but it shares the habitat of the shade and moisture loving ones, so we ran into this nicely blooming plant while looking for caterpillars on Gambel's Oak. Poison Oak is in the Sumac or Cashew Family and contains oils that can cause skin eruptions. Its leaves are compounds of three leaflets.

 Abert's Squirrel, Sciurus aberti
This guy was waiting for all those acorns at Marshall Gulch. In German, squirrels are called Eichhoernchen because of their love for the fruits (Eicheln) of oaks (Eichen). He may be in luck, so far it looks like a year of rich crops in the highly variable annual production of the Mt Lemmon oaks.

Monday, June 11, 2012

A Nest of Black-throated Sparrows

 In desert scrub and mesquite grassland the metallic trilling song of the male Black-throated Sparrow is a familiar sound earlier in spring. By now, the territorial males have quieted down because they are busy with their share of incubating eggs and feeding  hungry nestlings.

Last week I visited Carol and Fred Skilman at their place  in Cochise County. Fred is a great bug-hunting companion, and when I'm staying at their mesquite studded 'Longhorn Ranch' with view of Cochise Stronghold, I always enjoy bird watching with Carol. This time she had found a Black-throated Sparrow nest in a small cholla cactus, not much more than a foot off the ground.

When I first saw it in the morning, a parent was sitting on the eggs. The bird determinedly ignored us even when we pushed camera lenses close. Fred and I then left for a day of beetle and caterpillar hunting in the Chiricahua Mts.

We found that big areas were destroyed by last years fires, but there were other places, often just across a path or a creek from the burned spots, that were green and thriving. Some vegetation types suffered more than others - big pines will take a long time to grow back. But we collected some very interesting beetles anyway.

When we returned to the Skillmans' 'Longhorn Ranch' I finally got to see the content of the sparrow nest: as Carol had described, it held two kinds of eggs. We looked it up in her field guide to bird eggs: the speckled one had been smuggled in by a Brown-headed Cowbird. I have written about their form of brood-parasitism before: the sparrow eggs that the pair was so faithfully incubating were doomed. Would have been, anyway, without Fred's interference. He made a quick calculation: three lives versus one? He had just lost his long stinky-stinging-bug forceps in New Mexico but he'd fashioned a wire noose from a coat hanger in no time and made the intruders egg disappear like a magician.
Yesterday he called to report that the first sparrow chick hatched - he'll send baby pictures soon.

Friday, June 8, 2012

Tent Caterpillar Nests and Surprises

Noel McFarland and David Wagner
 This spring the author of several great books on caterpillars, David Wagner, visited us at the University of Arizona Insect Collection. Working out of the University of Connecticut, he had concentrated mostly on eastern species (Caterpillars of Eastern North America, Princeton University Press, 2005) but now he's progressed to the real thing, working on a guide to Arizona, or better southwestern caterpillars.

Caterpillars and provisions ready for over-night shipping across the US
Inspired by him, I have been looking at caterpillars with renewed interest. Most specimens that I found were shipped as quickly as possible to Connecticut to (in)star in the new book.

This year we had  an impressive outbreak of Tent-Caterpillars of the genus Malacosoma on Mount Lemmon in the Catalina Mts. One of my collecting trips in mid May was mostly devoted to these guys.

Western Tent Caterpillars Malacosoma californicum on aspen, left, Sonoran Tent Caterpillar, Malacosoma tigris, on Silverleaf Oak, right
 Different host plants yielded at least two different species: The caterpillars on oaks were probably Malacosoma tigris, the Sonoran Tent Caterpillar.

 Of the oak feeders, I only found early instar caterpillars in very rudimentary nests, all the larger caterpillars were by themselves. I learned later that this solitary life style is typical for the species.

 The oak feeders spin flocculent cocoons under and between oak leaves to pupate.

 The caterpillars on Cherry, Aspen, and Willows at Marshall Gulch are probably M. californicum, the Western Tent Caterpillar.  The final word (from Dave Wagner) on these ids will come when the adult moths hatch. He confirmed it later.

Western Tent Caterpillar nest on Cherry
The Western Tent Caterpillars on aspen, cherry and high-elevation willow spin communal nests between branches of their food plant. When they leave the nest to forage they seem to follow scouts and leaders, and around the nests I found silky threads marking their highways. After feeding, the caterpillars return to the safety  (and warmth) of their nest to digest their food. The protection of these communal nests is profound. In Greece I once tried to open an empty nest of the related Procession Spinner. The urticating hairs left in the old nest caused my hands to blister so badly that it nearly spoiled the whole trip.

On Mt Lemmon I also found big gatherings of the aspen feeders resting out in the open on tree trunks and fence posts.

One of the caterpillars spun its cocoon on the way home from the mountain - anchoring it to a plastic bag instead of leaves of the food plant.  Note the infusion with a yellowish powder, typical for some Malacosoma species.

Pupa and adult tachinid flies in the genera Exorista and Lespesia that hatched from Malacosoma pupae

Although several of my Malacosoma caterpillars eventually  wove their silky cocoons and pupated inside, I have not yet seen any adult moths. Instead, I soon found a big hole in each cocoon, and next to it a smaller pupa in the barrel shape characteristic for a dipteran (fly) cocoon. Over the last few days several adult Tachinid Flies of different genera, but no adult moths, eclosed.  I hope David has more luck with the caterpillars I sent him. Parasitism of caterpillars is common. As a child in Germany I wanted to raise our beautiful Peacock Butterfly, Inachis io. Instead I got a whole row of little wasp cocoons (Ichneumonid) attached to an empty,  hollowed out caterpillar skin.. The experience shocked me so much that I didn't try to raise any more caterpillars until I had to do it in a developmental physiology course during my biology studies. We worked with wax moths and repeated Kopec's ligation experiments - so again, I was deprived of any inspiringly beautiful results.

But - the limited success of this generation of tent caterpillars will probably save some aspen trees on Mt Lemmon from death by defoliation next year. And I am sure Nature will strike a balance in a way that will eventually allow me to see an adult Tent Caterpillar Moth.

June 17, 2012
 A moth eclosed from a pupa that I collected from Gambel's Oak at Summerhaven, behind the Community Center

David Wagner answered in three consecutive e mails::
* Malacosoma tigris is scarcely distinguishable from the others based on its phenotype and/or genitalia.   It is closest to constrictum, which, mercifully, is found only in California.
* adults of tigris, incurvum, and californicum are very close and in some cases indistinguishable
* adults of incurvum and californicum are especially close and no genital characters are known that distinguish them.
* Stehr's (and all subsequent) taxonomy is based larval phenotypes (and hosts).
* I plan to call Stehr tonight.
* the good news: there are only four species in the Southwest.

Called Fred.  He says egg color is definitive.  If you can find any of the old egg clusters on the cherry trees that had tents in April, Fred says we can get a definitive ID.  Incurvum eggs are white; californicum eggs are grayish white.
Also, which seems important: incurvum and californiucm are only marginally distinct as species....and could be lumped by some...or at least would still be expected to be in some genetic contact.
I am sticking with my original thoughts:  Malacosoma tigris for your oak-feeders and M. incurvum for all others on Mount Lemmon.  
 I have enough reared adults and larval images to feel that this is the best we can do until we see egg clusters.  These dets are consistent with the larval images recently sent to me by Terry Fitzgerald, a social caterpillar guy at SNY Cortland. Anyway, that's my story and I am sticking to it. 
 No M. californicum until you prove it! (Usually, and only usually, californicum caterpillars have a pale middorsal stripe.)
Dave Wagner

Sunday, June 3, 2012

Moulting into a mature female Arizona Unicorn Mantis

Here is the follow-up to my first Unicorn blog
This morning around 6 am while checking my e-mail I noticed that the unicorn mantis was ignoring some fluttering fat moths and instead anchored itself head down in a very neat symmetrical pose. Next time I looked up, the back skin head split open and the new, very large, bloated body was pushing itself out. Everything was still hanging only by the tarsi of the hind-legs, and even those were just an empty shell when the emerging Mantis freed its legs.
Three green triangular wing-buds were now clearly visible on the thorax. From its size and proportions I had thought that I collected the nymph during the last instar but now I began to wonder whether this wing-budded version would be followed by another molt?

Afraid that our swamp-cooled interior might be too cool for an exotherm creature that chose the morning after our record breaking 107 degree of June 2, 2012, I took the container with me for our usual breakfast on the patio.

Halfway through breakfast I noticed that the wing bud had sprouted into a long, sweeping veil of lime-green wings that were nearly fully inflated.
Insect wings are soft and vulnerable at this point, so I removed the mantis from the confining container to let her dry her wings with only the pressure in the wing veins and gravity as the forming forces.

After the wings were fully extended, two dark blotches appeared very slowly on each front wing which had been just lime-green in their earliest teneral state. The hind-wings turned dark. Drying, hardening and reaching the mature coloration  took all of the afternoon and the following night.

The next morning the mantis was constantly hanging belly up from branches. When I sprayed the terrarium with water, she immediately left her perch to lick up all water droplets  she could find. A couple of hours later she was finally ready to eat as well. She grabbed several moths that I offered. In the picture she is holding a freshly hatched Tent Caterpillar Moth