Sunday, August 31, 2014

Another species of Geolycosa?

In May I did a post about Geolycosa missouriensis, the handsome gray and yellow Burrowing Wolf Spiders.  I don't know exactly why it is that everyone (well, every biologist) who discovers Burrowing Wolf Spiders is so charmed by them. There is something mysterious about them in their underground retreats, and yet something we can easily identify with, as they sit in their retreats watching for prey, as we might sit in a duck blind (sorry, make that a photographic hide). They are in a way so little known to naturalists that when you find them, you feel you have really achieved something. On the other hand, whatever scientist finds them seems to become enchanted, and to devote years to carefully studying them. So we know their life histories very well: In the first part of their life males and females each have their own burrows, getting larger diameters as the spiders grow larger. The female never strays from her burrow, but at a certain point (when they molt into their mature skin) the males say, "This isn't getting me anywhere," and leave the burrow to wander, probably never eating again, in search of female burrows. As is the case with many or most spiders the male mates, then dies shortly after. The female lays her eggs in the burrow, and the young spiderlings live with her in the burrow until they are ready to leave and begin with their own first tiny burrows.

Well, we had the fun of discovering G. missouriensis when no Geolycosa species had previously been found in Arkansas. Now I think we might have found a second species. I know, we are new spiderers, and we might be at that stage new birdwatchers are, when they try to turn every unfamiliar species into some great rarity. Here is what happened. When we were at Scatter Creek in Green County in May (as I reported in my post of that time) we found G. missouriensis by the score. In August we revisited the area, and found that they were nearly gone, only a few small ones (pencil-size or smaller burrows) still present in the quarries where they had been densest.

That was a disappointment, but compensated for by what we found instead. First we found a large burrow with what appeared to be a high turret, made on one side by a straightened up leaf, but rather trampled down on the other. There was movement near the surface, which we saw with our binoculars was caused by swarming baby spiders.  

We sat quietly and waited the usual length of time for the owner of the burrow to rise up.

If you remember, missouriensis had yellow and black legs, and gray patches over the carapace and abdomen. This spider was just plain black, or at least all that we could see (its back was mostly covered by its babies). Missouriensis (this was one of its field marks) had yellow hairs covering the chelicerae (the big features below the eyes that cover the fangs). This spider had black hair. Now, of the half dozen species of Geolycosa in this country, only missouriensis has the yellow hair, and of those non-yellow-haired species there was only one that seemed, from a geographical standpoint, at all possible in Arkansas, and that was G. turricola, named, I presumed, for the very tall turret it put around its burrow. Did the sort of partial broken-down turret on this spider count as a very big turret?

Cheryl had spotted this one, and after we had wandered down towards the area where previously there had been the most Geolycosid activity, she also found the second one, a tall turret (over one centimeter high) that there was no doubt about.

The spider, when it rose up, was another large dark one (not as black as the first) with some perhaps graying on the chelicerae, but nothing that could be called yellow. The underside of the femora (the first long joint of the legs), was yellow. We would have to read up on legs to see if that was significant. Anyway, we had two characters of turricola: high turret, and no yellow on chelicerae.

We went home and I did some more reading. The first thing I found was, the marking on the first two pairs of legs (called, in spider descriptese, I and II) was indeed significant. This will be tedious to explain, and will require some terminology.

Here is some other spider that happens to have its legs in a convenient position. Reading from right to left, the long joint on the right is the femur, the next knee-like short joint is the patella, followed, heading left, by the tibia, metatarsus, and tarsus, or foot. It's the knee-like patella that is critical.

According to Bradley (Common Spiders of North America), on missouriensis "the bases of the front two pairs of legs [in this case, the femora and patelli] are light below....The tibia, metatarsi, and tarsi of these legs are dark below." On turricola "the undersides of the patellae, tibiae, metatarsi, and tarsi of legs I and II are black." In other words, the patella is the swing vote: light underneath for missouriensis, dark underneath for turricola.

The next day hop in the car and drive all the way back up. That's the easy part. The hard part is trying to get a picture of the underside of the legs of a rather shy spider you are more or less looking down on because it is down inside a hole in the ground.

Here's one attempt with the first spider:

The right front femur is showing a side view, with the dark upperside and pale underside. The patella is the next joint, and it is not easy to see exactly what angle we are getting on it, or how far it extends down before we are looking at the tibia, but there is no obvious lighter color to be seen, so it is quite possible that the patella is dark (the turricola pattern).

Here is another try at this spider.

Here we seem to have a pretty good side view from the patella on, and everything seems to be dark on the underside (again, the turricola pattern).

We then went down to the second spider and got this shot:

The angle of the legs is a little bit confusing. The spider's left front femur is going straight up in the air, showing its pale underside. The patella and tibia, showing the black upperside, then fold sharply back down, and the last two segments of the leg fold under the body. The second leg is angled back, and is out of sight behind the body except for just the tip of the pale underside of the femur poking up (above the eyes). The leg then bends to the right showing the patella and tibia from side view (the rest of the leg is then concealed behind the front leg).  The side view shows patella and tibia undersides to be black (the turricola pattern).

So, we have absence of yellow on the chelicerae, a high turret on the burrow, and dark undersides to the patelli, the three characters that separate turricola from missouriensis. Here, for the sake of comparison, is a picture of missouriensis:

Here you see pale underside to patella (pale upperside as well), yellow hair covering chelicerae, no turret but sand sort of woven together around edge of burrow.

But just when you think you have it nailed down, you go back and reread the descriptions, and you begin hearing the weasel words. Missouriensis "often" has yellow hair on the chelicerae, it "sometimes" makes turrets. In other words, nothing is one hundred percent. (Maybe the leg color is dependable?) This is our first season with these spiders. For all we know, they darken with age. The more technical studies say you can only certainly identify them by careful inspection of the genitalia. But I'm a field man, my pleasure is in trying to identify species through binoculars or photographs without disturbing them.

On a less frustrating note: On an earlier post I showed The Laugher caterpillar wrapping itself up in an oak leaf and making its cocoon, and I said with luck we would see it next spring as a moth. In fact they turn out to have two generations a year, and within two weeks ours had hatched out and we found it on the bathroom floor where we photographed it, then turned it loose.

Monday, August 18, 2014

Time for another Home and Away

This is the home part.

On the last one, if you remember, I told you Sleepy Orange butterflies had visited our Senna bushes and laid a few eggs, and I showed you some pictures of their very ordinary green wormy-looking caterpillars. I remember saying they would get better looking as they got bigger. Cheryl saw that and said "No they don't." She was right, they went on being ordinary, but then they made neat chrysalises.

All the sulphur butterflies use this shape chrysalis, which I guess is meant to suggest a hanging leaf. (The one on the right has already emptied out its full-grown butterfly.) When we looked a few days later, the remaining chrysalis was beginning to go transparent, revealing some of the orange of the waiting butterfly.

I took these pictures this morning. When the chrysalis is in this state, it means it will open tomorrow. We looked around the senna plant some more, and found a chrysalis like this.

The outer skin is transparent, meaning it is completely separated from the butterfly within. What you are seeing is the upper side of the forewing, still mostly rolled up. When it looks like this, it means the butterfly will be coming out this day. When this butterfly is out, its upper wing will be bright orange with a black border around it. Inside the black border you can see a little black mark like a dash. Most species of sulphurs, in this part of their wing, have a small round black spot, usually called in descriptive parlance an "eye." In the case of this species, the "eye" appears to be "closed." Hence the name of the species, the Sleepy Orange.

Sure enough, a couple of hours after taking that picture, I checked again, and the butterfly was out.

The various species of Sulphurs virtually always land with their wings closed, showing only the underside. So that glimpse of the Sleepy Orange's upperside through the pupal skin was your last chance to see the closed eye.

What else is going on around the house? A big pizza-shaped wasp nest is flourishing under the eaves in front of the house. It's one of the paper wasps, Polistes exclamans. These are quite pretty and very peaceful (if we leave them alone) so we tolerate them. The big all red paper wasps, P. carolina, tend to attack us, so I'm afraid we get rid of them. If you look in the cells you can see larvae of all different ages. A few have spun white cocoons and are pupating.

A large moth I had noticed roosting during the hot days in the rafters of our garage has finally revealed itself as a Widow Underwing.

Our milkweed plants only raised about four Monarchs this spring, in this very down year for the species. Though we did not see a Monarch in the yard lately, to our surprise we found a caterpillar munching away on the leathery late summer leaves. Monarchs are so precious now, we brought the caterpillar into the house to raise it in a predator-free environment. It has now made its chrysalis and should emerge in about ten days.

Last year was such a poor year for the big Argiope garden spiders, that by late summer we only had one left. This year by contrast we have them by the score, and some of the biggest ones I've ever seen.  But I've been looking for Argyrodes, the tiny silver kleptoparasitic spiders that live in the webs with them, and haven't seen a one. I guess a bad year for the host spider leads to a bad year for the parasite, and the parasite has still not recovered this year. But that does not mean the big spiders are free from annoying pests. The equally tiny Milichiid Flies, that follow wasps or robber flies around, often riding on their backs, or hang around spider webs, waiting for a kill to be made so they can swarm in and drink the blood and other fluids from the prey animals, are having a wonderful year. There are about a dozen in this picture. You can see the spider from time to time trying to shake them off. In the second picture, the spider had wrapped up a Polistes exclamans (very likely from the nest pictured above) and set it aside for a snack later, but the flies couldn't wait.

One day my pet scorpion was standing up looking out of the glass of its aquarium, and in so doing revealed an interesting part of its anatomy.

The funny processes coming down from between its hind legs are called pectines, or combs. Scorpions are nearly blind, and the pectines, sensitive to vibrations, are its main sense organs.

And then, there was a mystery, in fact, a crime scene, which I am trying to use my forensic skill on, developed by watching hours of detective thrillers on Netflix. As I was waking down the driveway I saw at my feet a fresh healthy looking dragonfly (Pantala hymenaea), without a mark on it, but stone dead. As proof that it was alive and functioning at the moment of its suspicious death, it was carrying in its jaws an insect it had just caught. Here is what I saw:

I carefully examined the insect it had captured, and discovered it was an assassin bug (a surface killer vs. an aerial killer). The bug has a long thick jointed beak backed up by strong venom and digestive enzymes. The beak was not now stuck into the dragonfly, but could the bug, while being fatally chomped by the dragon, have got in a defensive stab?

I was about to write this blog, when I got another piece of luck (if finding a dead dragonfly can be considered "luck"): I happened upon one of my favorite caterpillars, The Laugher, named for the uproarious expression on his face.

We brought him in, he wrapped himself in an oak leaf, and inside the oak leaf he spun a coccoon, and we will not see him again until next spring when he appears as a handsome moth. But in our brief view of him I got what I wanted, a chance to end this blog with a happy face.

Wednesday, August 6, 2014

Home and away, Part Two

For the "away" part of this two-part post, the other day we visited one of our hot spots that we try to hit two or three times a year, Shirey Bay-Rainey Brake WMA near Lynn in Lawrence County. Where we first enter, on a hill overlooking the area, we take a path through a damp woods which is  really good for robber flies (there is almost never a time we can't find at least seven species of robber fly,  including some species we don't find anywhere else), and also good for rare butterflies, for a number of other insects we don't see anywhere else, and for big spiders. Whenever we come, there are always surprises, and we almost always end up seeing something we have never seen before.

My first surprise came when I was on my hands and knees trying to photograph something and this huge, loudly buzzing, complicatedly structured thing rose up before me and went flying across the path and crash-landed into some tall grass. It took me a moment to realize it was so big because it was two things, both large. It was a pair of Swamp Darners, one of our largest dragonflies, in mating tandem, flying along hooked together, one doing all the work, the other hanging on and supplying so much dead weight they could scarcely get off the ground, and when they landed on some wispy stem of vegetation they weighted it down to the ground.

The female here, about four inches long, and with impossibly blue eyes, is upright, the male is lying on his back.

The next thing we saw trundling along the path was a Bess Beetle, harmless but imposing as it was as big as the last joint on my thumb. These feed on wood and are often to be found under the bark of fallen trees. They are famous for their good parenting, carefully feeding their larvae which live together with them and are completely dependent on them for food. They have a sort of language they use to communicate with each other, made up of different squeaks they make flexing their joints. Wood is mainly cellulose, and the beetles need lots of gut microorganisms to help digest it, and the adults hand the microorganisms on to the young by feeding them pulp pre-chewed and pre-mixed in their own guts. Very specialized mites live on the bodies of these beetles, seldom leaving them. These mites don't feed on the beetles. I guess they feed on decaying wood too and just use the beetles for transportation from one good log to the next. The relationship is called phoresis, from a Greek word for carrying, and is rather common among a number of insects.

The path (just by the skin of its teeth) lived up to its robber fly reputation. We quickly saw five very common species, and then for the sixth, we saw one of the specials for this habitat (shady and rather damp), a Machimus snowii, a rather slight and neatly dressed species that feeds on the moths that it finds in the shadows.

And for the seventh and last species of the day, we saw what looked like a very small bee (6-7 mm) but which we knew instantly from our years of searching for robbers was a robber with a banded bee-like abdomen (a robber fly in bee's clothing). This one was named Psilocurus birdii.

When we take this particular path there is one creature we are especially looking for. This is one of two known sites in Arkansas for a big woodland butterfly, the Appalachian Brown. It was not a good day for them. I myself didn't see any, but Cheryl, walking along parallel to the path but about thirty feet off in the rough, caught a glimpse of one flying away.

But all of these were not the most fun of the day. This path is often too wet and muddy to walk on, but on this day it had been dry for a long time and even the deep puddles in the middle of the path were dry, and they were full of abandoned crayfish holes and broken off chimneys. Cheryl was the first to notice that rather large creatures were diving down these tunnels as we approached, and when we looked into one of them, we could see a large spider disappearing underground.

We came to the end of the path and turned around to start back to our car, and this time we came up on the crayfish holes very quietly. We found the spiders outside the holes, very shy and ready to disappear in a flash, but we still managed to sneak up close enough for some photos. We were on our hands and knees, and finally on our stomachs.

These were all large wolf spiders in the genus Hogna, H. georgicola I am pretty sure.

Well, we were almost back to the car, thinking, or at least I was, rather smugly that there is not very much we miss with our special way of walking slowly, searching high and low, under and over, when Cheryl suddenly shouted at me to stop. I had nearly stepped on a small flower growing in the center of the path, I must nearly have stepped on it on the way down. It was bright pink, about a foot tall, standing in the open in plain sight. And I would have missed it again, walking straight past it again. It was one of the rarest orchids in the state, in full bloom. It was the Purple Fringeless Orchid.

Let's look at it from closer up.

It looks pretty much like it has a fringe at the lip, but it is called "fringeless" to distinguish it from the Purple Fringed Orchid, which evidently really has fringes.

This is our favorite way to spend the day (even though it means spending the evening picking off tiny nearly invisible ticks, and scratching our new sets of chigger bites).