Sunday, October 25, 2015

Fall trip to Tucson.

We left the house on the last day of September and drove out to Arizona to visit my son Gawain and his girlfriend Heather in Tucson. The monsoon was lingering late this year and there was tall grass growing along the roadsides as we entered the state, and the mountainsides were unexpectedly green. The sky was often cloudy for our stay, and we had occasional very heavy rains. The temperatures were comfortable, 80s by day (instead of 100), 60s at night. Afternoons and evenings and weekends we spent together, but during the day when they were busy with their work Cheryl and I were left on our own.

This was no hardship in Tucson and we spent beautiful days at our favorite places. For instance, the water conditioning plant with its acres of rich wetlands ringed with trails. This is a place mostly for birding (best, the day we went, was a handsome prairie falcon chasing killdeer around the waste ponds). Another day we went to Saguaro West with its many trails (we like walking up the dry washes), and we visited local botanical gardens, but over and over again we visited our favorite, Saguaro East, a thorn-forest wilderness that looks like a planted garden of desert plants and trees, each trail or dry wash passing through a different habitat.

It was a different time of year from our past visits so we were interested in what creatures we might see. Herps were interesting. Desert Spiny lizards we had seen before (they're fairly common) but this time they were more in the open and we saw them better. The particularly handsome local race is called Purple-backed Spiny Lizard. I like the way the yellow scales and blue scales meld into green scales down on the tail.

Because it had rained and there were some new surface puddles, the Red-spotted Spadefoot Toads were out. This was the first time we had timed it right to see them. In our walks we had caught glimpses of them disappearing down holes, but it wasn't until we visited our friends the Braddys on the edge of Tucson that we rescued one from their pool and so got to see it up close.

These little guys show one of the extreme measures amphibians can take to survive in the desert. A hard sharpened area on the inner edge of the inner toe on each leg (you can see the yellowish bump clearly at the base of the inside toes in the above picture) allows them to dig into the soil, where they remain for most of the year. When it rains, they are ready. They come hopping out and look for anything moving to put in their stomachs (this being their only chance to feed), meanwhile singing nonstop all night (this being their only chance to breed), then as quick as they can, they lay their eggs in every temporary pond, hoping their offspring can get through the tadpole-to-adult stage before the pond evaporates (in warm weather the whole process from egg hatch to metamorphosis takes as little as two weeks). Then everybody digs down into the soil to wait months for the next rain.

We also saw a couple of very nice small mammals. If you have walked through  the desert, you have seen packrat nests, a meter-diameter pile of old dried cactus fronds, other detritus, sticks and stones, anything else around that a small rodent could drag into the mix. The nests are obvious everywhere, but seeing the packrat that lives underneath (more correctly, the White-throated Wood Rat), is trickier. You aren't supposed to feed the wildlife, but we were eating our lunch, and before we knew it we had dropped a few large juicy grapes on the ground near a nest, which was enough to lure out the occupant. He was quite endearing, despite being, well, pretty ratty.

But the next animal we saw was the star of the trip. We walked around a corner of the trail, and a big animal went bounding off. Through the brush I saw a flashing white rump and huge ears.

"A deer!" I shouted at Cheryl, but I was already changing my mind. "Or was it a huge jackrabbit?"

Cheryl was a few paces ahead of me, and she saw it where it had come to a stop around the other side of a big bush.

"A jackrabbit," she said.

But it was quite unbelievable, an enormous woolly animal with a highly intelligent face, more like something from Alice in Wonderland or some other child's fiction. It was watching us with great interest. "I'm late," it might have said.

We had to wait for it to wander off before it would stick up its marvelous ears, and we could get a picture of them.

We looked him up: this was the Antelope Jackrabbit, the largest and heaviest of his kind. His name comes from the huge white antelope-like rump that he could flash when he was running away, probably to alert other rabbits in the vicinity that there was a predator approaching.

However this is meant to be a blog about invertebrates.

Just beyond where we saw the jackrabbit we walked up a rocky dry streambed and Filigree Skimmers were flying up ahead of us and landing on the next big boulder. These are fancy tropical dragonflies that don't come very far north of the Mexican border. A field guide I read said that identification was "unmistakable because of the wing pattern alone."

Another much commoner but equally unmistakable species of dragonfly was the Flame Skimmer.

It was near the end of the season, so many moth and butterfly caterpillars had reached their full size before pupating. Here are two butterfly species poisonous because of eating poisonous plants, first the Queen from eating milkweed, and then the Pipevine Swallowtail, from eating pipevine.

In keeping with the harsh desert scene, in addition to the poisonous species there were a number of venomous species (a neat distinction to keep).

This first caterpillar, though the photograph doesn't show it so much, looked so much like a lichen growing on this branch that Cheryl and I both passed it by, until Gawain called us back and pointed it out to us. It's a subtropical species related to our Io Moths, and like the Io Moth has spines that can sting you and raise a nettle-like rash on you if you carelessly brush against it.

  The next is quite interesting and one we have long wanted to find. It's a Puss Moth caterpillar, the name obviously coming from its hairy coat and what looks like a tail. If you brush against this one, the effects can be quite serious. "Sensitive individuals," says Wagner, the writer of our caterpillar  field guide, "who begin to develop systemic symptoms should seek immediate medical attention." We have heard of deaths occurring.

 In the last couple of years we have been mainly interested in learning something about spiders as a group, so we were particularly paying attention to the spiders. Mostly we were seeing here desert versions of species we have at home in Arkansas.

This jumping spider for example we are certain is Phidippus clarus, a familiar species at home, but here seemingly twice as big with its wide pancake abdomen.

And everywhere we found Green Lynx spiders (handsomer with a paler pattern than ours at home) clinging protectively to their egg nests, which they will continue to do all winter until they freeze or starve. Spiders are often quite good parents.

Most abundant was the Labyrinth Orbweaver, a species also fairly common in Arkansas. It is best known for weaving two separate kinds of webs side by side. First it has a tidy and typical orb web, round in shape with spokes radiating around it like a bicycle tire. And then, a little bit over to the side, it has a chaotic tangle of lines with no order to it (the "labyrinth"); perhaps these two webs each catch specific kinds of insects. A few lines connect the two webs to each other, and in between the webs the spider weaves a few leaves together to make a little retreat it can hide in if it's disturbed. That's how it does it at home, anyway.  Here is a typical Arkansas set-up with the orb web in the background, the tangled web in the foreground, and the spider itself in between in its refuge.

But in Arizona they do something different (this is our first season studying them, so perhaps those in Arkansas will do this same thing only a little bit later than the Arizona ones). In Arizona I did not see them in a little leaf bower, but rather, they began laying egg nests. Here is the first egg nest.

Here is a second. They are laid in a line, with the spider at one end. Notice how the spider resembles the egg nests.

The spiders keep on doing it.

And I think I get what their dodge is. At this time of year the mesquite trees their webs are located in or under all have their seed pods drying and ready to fall to the ground. The least breath of wind and there is a rain of these tiny strings of seeds. Frequently instead of reaching the ground, they are caught in a spider web. I think a hungry bird coming along and seeing this juicy spider with its nourishing eggs might pass it by thinking it is only a dry and tasteless mesquite pod.

Postcript added 26 October: After a comment made about the egg nests of the Labyrinth Orbweaver, I made the mistake of doing a little research, and what I find is, that the eastern Labyrinth Orbweaver, such as I see in Arkansas, Metepeira labyrinthea, is not the same species as I have just written about in Arizona. In fact there are at least five different Metepeira species in Arizona (numerous other species throughout the west), and only the eastern one should be called a Labyrinth Orbweaver, though the others are nearly identical in appearance and nest building and egg laying. This is why, I suppose, the one I photographed in Arizona might mimic mesquite seed pods when there are no mesquites in Arkansas. Everything is so much simpler in the east.

Friday, August 7, 2015

It's a jungle right here (if you're a frog)

Cheryl and I are addicted to the detective programs we get on Netflix and Google. The British ones are usually best but we also like the Swedish and Danish and Australian and New Zealand and Canadian ones. The same formulas run through all of them. Some woman is walking her dog along a beach, the dog digs in the sand and a bloody hand is revealed. Cut to the police there in their crime-scene suits, joking over their last bite of breakfast while the pathologist examines the cadaver. Special make-up people on the different programs compete with each other for the most gruesomely realistic split-open heads or maggot-crawling torsos.

Something like that is going on in our garden. We are out innocently looking for bugs and suddenly discover gory, half-eaten, and very human looking remains.

These are green treefrogs but we're not quite sure who the murderer is. Green treefrogs are murderers themselves, sticking to our windows at night to feed on moths attracted to the lights, or waiting under flowers for butterflies to approach. But they are also the main small vertebrate prey for just about everything else. Ribbon snakes for instance hunt them mercilessly and are probably their chief predator. But ribbon snakes swallow their prey whole, leaving no bodies behind.

Green treefrogs can hide or hop away, but they don't otherwise have many defenses against ambush or trap-setting hunters, no teeth or claws or poisonous skin . And, they are just small enough to occasionally become prey to invertebrates, which seems almost against the laws of nature.

For example, our backyard ponds are so dense with aquatic vegetation the surface of the water is not visible, and that vegetation is densely populated with day-roosting green treefrogs, but also with enormous black-and-yellow garden spiders, Argiope aurantia. I was observing their interactions last summer, and the spiders, after they were nearly full-grown, were feeding almost entirely on treefrogs.

But the spiders did not leave behind half-chewed remains either.

However, we had a clue. The very wet spring this year, which had led to an unusual number of treefrogs, and an unusual number of Argiopes, had also led to, we noticed earlier in the summer, an unusual number of Chinese mantises, and they had steadily been going through their instars, getting bigger and bigger. Here's one from the beginning of July, still a long way from adulthood, but already an impressive size.

This one looks like it is feeding on a roadkill skunk but it's actually a Milkweed Tussock Moth caterpillar, a creature that came out in the hundreds this year and chomped all our milkweed plants to the ground (after the Monarchs failed to come).

Now the mantises are molting into adulthood, four-inch-long giants that look fully capable of catching a treefrog.

Take a closer look at the spines in the powerful grasping arms.

So there was our prime suspect, an animal with a ferocious reputation and the tools to back it up. Finally we caught one in the act. We were eating breakfast and Cheryl looked out the window and said, "There's a mantis with a frog." We rushed out with our cameras. I suppose it would have been more in keeping with the crime programs if we had rushed out with our cell phones.

So, with the snakes and spiders and mantises after them, what is happening to treefrog populations in our backyard? Well, so far as I can see, it's not even making a dent.

Thursday, July 16, 2015

The month of June

When I step outside the house, even when its just for a moment, I try to remember to sling on my camera. If I don't I'm sure to see some interesting creature or bit of behavior that won't be there seconds later.  I often forget, but I often remember and get some of my best pictures. So when I recently glanced through the pictures I took in June, it was quick reminder of some of the neat things I had seen last month. Here are a few.

First, a Western Lynx Spider, a spider I was pleased to see because I thought they were strictly western and didn't occur in Arkansas. Lynx spiders are notorious for the long spines on their legs, but this one has what looks like an almost painful surplus of spines.

Except for its special status and comical spines it's sort of a dull little spider. By contrast here is a jumping spider, Paraphidippus aurantius, that is especially colorful, but very common. It has just caught a small katydid.

In folk wisdom here the very big crane flies we get in the spring are called Skeeter Hawks, and it is believed they hunt down and kill mosquitoes. The logic is obvious: they look like mosquitoes, but are way bigger. Actually there really is something here rather like a Skeeter Hawk. This very large and colorful mosquito (Toxorhynchites sp.) looks formidable to us, but in fact, as you can see by its droopy mandibles, this mosquito does not bite. It feeds innocently on nectar. But its larvae really and truly hunt down and eat the larvae of regular (i.e. biting) mosquitoes. Don't swat this one.

In a previous post I showed some of the courtship of the cellar spiders that occupy my study with me. The last picture I showed was of my favorite female with her new egg sac. I can add another step to the saga now, since those eggs have hatched.

I think they're kind of cute.

Paper wasps of the genus Polistes all die in autumn except for the newly mated young females who overwinter and start up new nests the following spring. Most of those nests fail. The new queen must chew up wood and turn it into paper and start a nest from scratch, often under the eaves of our house. They have to build a few cells, lay eggs in them, and when the new larvae hatch, go out and gather caterpillars to feed them, much like a bird bringing food to its nest. The queen sallying out for food puts herself in the way of several dangers, and if something happens to her, it is all over. Once she can raise the first few up to be workers, then she can remain safely at home laying eggs while the others do the work and take the chances. But it takes a long time to reach that point. Especially with our slow wet spring it was difficult to get started this year, and I saw several attempts fail. But there is one on the edge of a window around the side of our house I have been following.  Here she is, glaring at me for being a little too nosy.

The species I think is Polistes exclamans. The first few grubs have woven cocoons. She has started some new cells and put eggs in them. If she can just get past this moment.

A day later, an important event: She has a worker.

It seems to be a good year for moths shaping up. We were up at Ninestone in the NW corner of the state helping with a bioblitz. We put out a black light and this handsome Giant Leopard Moth was one of the stars of the evening.

A few feet away we found this spectacular Promethea caterpillar feeding on a tulip tree.

The next three pictures we saw during a visit to the central part of the state.

Here is a nice wasp-mimic moth, a Grape Root Borer. This male has got all his pheromone-producing equipment hanging out.

This might be the prettiest creature we saw during the month, a Meadow Purple-striped Grasshopper.

This might be the most bizarre, Rhomphaea fictilium, a spider that often lives parasitically in the web of another spider. The long thing hanging down is its abdomen, which is flexible and bends in the middle.

And, coming back home, this might be the most ordinary. It's a Corn Earworm. We get a lot of our produce from the local farmers' market, and I don't know about you, but I don't mind a bit getting a reminder that this is unsprayed organic food.

Now, tell me, he that knows: What do people who don't love bugs do with their lives?

Sunday, May 31, 2015

What's happening right this minute.

The eastern United States is the only place you can see periodic cicadas. They are one of the world's marvels, but the catch is you can only see them every few years, and then for only a few weeks. There are three species of seventeen-year cicadas, and four species of thirteen-year cicadas. As I'm sure you all know the name stands for the number of years they spend underground as nymphs sucking the juice out of tree roots. There must be so many millions of them it is another marvel that the trees survive. They don't all emerge together on the thirteenth or seventeenth year. All those in a certain population do, but the generations are staggered. They are so well studied that all the differing populations have been named and numbered, so that biologists can say almost to the day when population XI or whatever will come out of the ground, change into adults (leaving their thousands of exuviae hanging to trees and bushes) and the males start singing to attract mates. That's still another marvel, their loud voices constantly in hearing over sometimes a square mile.

We learned early this year that thirteen-year cicadas would be emerging this summer in parts of Arkansas. So I wasn't surprised when, a few days ago, I arrived in Craighead Forest Park in Jonesboro, turned off my engine and opened the door to hear that sound. It was the first time in years.

They were some distance away, and I was in a hurry that day, so I didn't pursue them. But the next day Cheryl and I went to another area where we had seen them in the past, Lake Hogue in Bayou de View WMA in Poinsett Co. Sure enough they were singing at full volume when we arrived. There seemed to be at least two songs going, a high pitched melodic one which appeared to be constant on the same tone, and then a raspier one that surged up and down in volume. We walked a dirt road and saw them flying out from the tops of the trees like swarming bees. Their life as mating adults is so short we were already finding dead and dying on the road and picked up a dozen or so to take home and study. They were different sizes and slightly different colors. We knew there could be up to four species but we had no idea what to look for to try to separate them.

We had looked them up before and only found charts with roman numerals to designate the different populations and cohorts and emergence dates and it was so confusing that it made our (or anyway my) head swim, which is why we had never got anywhere trying to sort them out. But this time Cheryl made us stick to it and try to get some bearings, and we made a second trip and took photographs more intelligently and collected specimens with a better idea of what we were looking for, and we believe we found all four species. (However this was our first attempt at identifying the species, the color differences are subtle, the dead specimens perhaps changing color rapidly.)

Here's what we found, and here is our rationale, but keep in mind that our voice is very tentative.

If you have ever seen them, you will remember their dramatic appearance: big shiny black insects with bright red eyes and yellow veins on their large wings (they should only emerge during Halloween). Look at this first one.

Here the critical thing to look for is the orange spot directly behind the eye. Next let's look at it from another angle.

The underside of the abdomen is pale orange or yellowish. If we are correct, this is Magicicada tredecim, which is a more scientific way of saying "thirteen-year cicada."
Now look at this mating pair.

One is dangling unceremoniously off the branch, but after waiting thirteen years for this moment nothing is going to make them let go.  On the sitting one you see a brown spot behind the eye; on the dangling one a highly contrasting banded underbelly.

Here they have regained their position and a little dignity. You can see on both of them the brown spot behind the eye, which I think is quite different from the orange spot behind the eye of the previous example. Again if we are correct, this is Magicicada neotredecim.

Those are large cicadas. The next two I'm going to show you are noticeably smaller. First, here is an all black one. (In the hand the eyes on this one were still reddish, though the camera has not picked that up.)

No colored spot behind the eye, no yellow bands on the abdomen. This, we believe, is Magicicada tredecassini. And finally, this slightly different species, all black, but with narrow orange banding on the abdomen.

We believe this is Magicicada tredecula.

These are active in Arkansas right this minute. If you are driving through dense deciduous woods, stop from time to time to listen. If you hear them (you can't miss the sound) get out and observe them. It will be a long wait before you see them again. Only thirteen-year cicadas are out in Arkansas this year. In some other states (Kansas, for instance), I believe there are some seventeen-year cicadas around. I think our corner of northeast Arkansas might be especially good for finding all four thirteen-year species together. I don't actually know if we get any seventeen-year cicadas.

There are three species of seventeen-year cicadas, each one a sister species (some would say the same species) to one of the thirteen-year cicadas, and it is almost impossible tell between the sister species except by timing and location.

If we get them, I can't wait for a seventeen-year cicada emergence.

Monday, May 18, 2015

In, on, and around the house

In the corner of my study a big very handsome Cellar Spider has been living for the past two or three years. She seems to feed quite well on spiders that wander into the house. She can catch spiders much bigger than she is by wrapping them up carefully at arm's length, which in her case is a good safe distance away.

 Lately she had been growing quite fat, which indicated she was filling up with eggs.

The local males had noticed this as well. Last week when I looked into her web, at least four hopeful males were hanging around in it. They were nervous around this spider hunter, and probably with good reason. You will understand why, when I explain some of the intricacies of spider mating. First note the male's heavy equipment on the palps on either side of his face. These carry intricate vessels that the male fills with semen when he is approaching a female.

Now here is the female from underneath.

The dark slit near the base of her abdomen has in its center the epigynum, into which the male (the female's deadly fangs hanging over his head) must pump the semen he holds in his palps. This risky maneuver is preceded by a great deal of stroking from the tip ends of his own very long legs, while he unfurls his apparatus and tries to judge her mood.

 Suddenly he dives in, does his job in less than a second, and dives away as fast as he can.

He was successful. In about a week she was cradling her new eggs.

About the same time the eggs appeared, Cheryl and I were outside and noticed what at first looked like a small ant walking along on the lid of our garbage can. But when we looked more closely, we saw it was a kind of jumping spider (Synemosyna formica) which mimics ants (no one knows exactly why, but perhaps it's because ants are known to be full of formic acid and therefore not very tasty to predators). This one walked along on six legs with an ant-like gait, and since, being a spider, it had eight legs, and no antennae, to complete its mask it carried its second pair of legs in the air and waved them like antennae.

On top of the lid near it was an ant just the size and color of the spider and so similar in appearance we decided this was the model the spider was imitating.

(This ant apparently led a warrior life; note the decapitated head of another ant which still has its jaws locked on this ant's antennae.)

From there we walked around the corner of the house not twenty feet and saw a completely unrelated spider (Two-banded Antmimic, Castianeira cingulata) which appeared to be imitating the same ant (only this time waving its first pair of legs like antennae).

And a few minutes later we had another nice observation. I went to check a chrysalis that was hanging on the back wall of my study, and a Question Mark butterfly had eclosed. It was so fresh it still had a number of delicate tints on its wings that would soon wear off.

Not a bad day, and we had scarcely stepped outside the house.