Wednesday, October 31, 2012

Ten more signs that winter is coming.

Well, the temperature is a rather obvious sign. We have a few mornings now when we have waked up to temperatures in the 30's. That's been mixed in with some stormy weather, and we have now not seen our last remaining Long-tailed Skipper for several days. Supposedly the temperature will be back in the 70's later this week, and that will be the test to see if it is still around. Even if they are now all gone, a couple of weeks ago I achieved my goal of photographing two at once in the same picture. As I modestly reported to my friends, it was the first time in the three billion years of life on earth that anyone had ever photographed, in Arkansas, two Long-tailed Skippers in one picture.

Long-tailed Skippers began invading Arkansas in mid-August, so I suppose I can't use them as a sign of impending winter, which is my theme here. But late in the year many butterflies do begin moving around, so that it is a good time of year to begin looking for unusual species. Species we have noticed in the last few days moving in from the west, are Funereal Duskywing, a flat-winged skipper recognizable by the white border to its hind wings, and the beautiful Reakirt's Blue, which is very scarce here on the eastern side of the state and always a treat to find.

These are obvious signs of winter approaching. Some others are more subtle. For instance, if you have been looking carefully at grasshoppers all summer, you will notice now that the females of some species have grossly bloated and distended bellies, packed to bursting with eggs that they will soon be depositing in the ground.

Even more grossly, towards the end of the year male grasshoppers get the munchies, and while they are in the act of mating they begin eating the female's wings. This poor female has lost a leg somewhere along the line and can no longer hop. Now she can no longer fly. She still has eggs left to lay.

If you have been observing the various species of Polistes paper wasps in your garden during the year you will have noticed that during October they reached the point they were aiming at all year, and that is, they began producing a sexual generation, the males and females (virgin queens) that will create next year's nests. The males are easily noticed because they have white faces.

The queen and workers of this year's nests will all die not long after they have produced these sexuals. The next event, which you can see happening already on the sunnier calmer days of late fall, is that the virgin queens will appear, often in large numbers, outside old barns or hollow trees or roofs and attics they can get access to, looking for a place to hibernate this winter. That's where the white-faced males will be waiting to waylay them. So that as in the song in Shakespeare somewhere, the maids who (tried to) go in the door will come out the door as maids no more.

Having finished their vital work the males will all die (males never live very long among the bees and wasps), the impregnated females will hibernate all winter (actually on warm sunny days in winter they often come out in large numbers and perhaps get a drink somewhere) and emerge next year to start up new nests. But right now on sunny days the scene outside a popular hibernation site is quite chaotic with males of several species waiting for and attacking queens of every species.

For those insects not flying south or going into hibernation, there is sort of a general die off which, because they are so small, and so invisible lying in the dried leaf litter, you might not notice. But we have a white concrete driveway which shows up insects from a distance and I notice more and more insects sitting on the driveway, walking around morosely, ending up dead the next day. Here's a little gleaning.

I noticed today another rather grim end-of-season example. Argiopes, the big golden garden spiders which are usually very successful in our yard, this year for reasons we don't really understand, had a miserable year and we thought they were entirely gone. But we have just found one big female made it through until now. But something terrible happens to them at this time of year. What I have heard  is that spiders have a defined amount of web in their systems, and when that runs out, they're out of luck. I don't know if I quite believe it, but I do know that at a certain point they stop repairing their webs daily, or if they try to repair them, everything comes out wonky. Here is our one surviving Argiope.

Not all end-of-season things are grim. For some insects, this is their time, their chance at a life in the sun. A few blogs back I showed pictures of Laphria affinis, the big predatory fly that is such an expert mimic of bumblebees. This robber fly comes out later in the year than just about any other Arkansas robber fly, and lasts longer into winter than any other. Just seeing this fly is a sign of the season, but a happy and entertaining sign. I have on two different years found them still flying on November 30th. This year, if the weather is mild, I will try once again, to see if I can find one on December 1st. Another species of robber fly, Nicocles pictus, comes out in mid February. If I can get Laphria affinis into December, I can then boast that Arkansas robber flies are out every month except January, which is pretty good for a state this far north. If I find one this year, I will report it here, and you can share my excitement.

But, before I got distracted, I meant to say something more about the life history of this species. They are closely connected to pine trees, and are only found where pine trees are numerous. The best way to find one is to look for a place where there was a blow down of pines several years ago, and the fallen trunks are decaying. The larvae of Laphria affinis feed on the beetle larvae which feed on decaying pine trees, and the female Laphria lays her eggs in the tunnels of these larvae.  The male takes over a promising tree and defends it against other males and waits on his tree for the female to come by and lay her eggs, and he makes sure that he mates with her first. Here is a picture I took yesterday of a male waiting alertly at his log, and all the colors of autumn are behind him.

Last minute news item: While I was writing this, I went out and checked, and our Long-tailed Skipper is back.

Thursday, October 18, 2012

Ten signs that winter is coming

We were out walking the other day and found an unspectacular but nevertheless very pretty little orchid, the Common (or Nodding) Ladies' Tresses. It's a fall-blooming species, and is matched by a larger but similar species on the other side of the year, the Spring Ladies' Tresses.

It's only one of numerous signs that summer is ending. The Carolina mantis does not survive the winter, but it has been slaughtering insects all summer to build up the resources to fashion its hard woody egg cases to make sure its eggs survive winter to start the new generation next year. However preserving life over the winter season is full of risks. Here, a small parasitic wasp wants to insure the future of its eggs too, and it is laying them inside the nest so its larvae can feed on the mantis eggs. If you look closely you can see the wasp's ovipositor seemingly coming out of the base of its abdomen.

This is also the time when many caterpillars (such as this White-dotted Prominent) are wandering, looking for a safe place to pupate. Its a time of high risk for them as well, because they are more visible than usual. It's when we pick up several to keep in an aquarium over winter to see them eclose in the spring, but it's also when The Caterpillar Hunter, a spectacular and voracious big beetle, is out looking for them.

Another sign: Suddenly Crane Flies of several sizes are showing up everywhere. There are some species that are found all winter, and others at probably all times of the year, but they seem especially abundant in spring and fall, perhaps liking cooler weather. They look rather like mosquitoes in shape. Indeed some are as small and frail as mosquitoes. But the one you are likely to notice right now is a giant with a leg span of three-and-a-half inches. Whatever the size, they are all totally harmless creatures. In folk-science, which goes by appearance rather than behavior, the big one is called a "skeeter hawk" because it is thought to hunt down and kill mosquitoes.

A few rather showy butterflies are making their plans. Question Marks for example are emerging now in their exquisite fall "orange" version. Those that live on the east coast will migrate south, but around here I believe most overwinter in buildings or under bark or similar places, and come out early in spring. They mate then and create the "black" summer version, which lays eggs for the fall overwinter generation.

Another example is the Mourning Cloak, which I was surprised to see basking in my front yard lately. It was already a little banged-up looking, which also surprised me, because it was in the generation that was going to overwinter and breed next spring. I know at the end of winter they are torn and scraped, but I didn't know they went into winter already aging. So I read up on their confusing life history, and this is how I understand it: That overwintered generation breeds, lays eggs, and dies in the spring. The new brood ecloses as adults in mid summer and immediately aestivates (that was certainly a good strategy this summer) and comes out now when I saw this one, and either migrates southward, or overwinters here hidden away in shelters like the Question Mark. After we saw that one in our yard, we went out to Big Lake a few days later, and in the large open area of a wetland we noticed three or four passing by as if migrating. So for a short time in spring, sometimes for a short time in mid summer, and sometimes for a short period in fall, they are visible to us.

The Cloudless Sulphur, a very large butterfly with bright yellow wings in flight, and the Gulf Fritillary, a beautiful red-orange butterfly with silver teardrops on the underwing, are both year-round residents of the Gulf states, and because it's warm there all year, they have no strategy for getting through winter. In the summer, generation by generation they work their way north, reaching us later in the summer, and blissfully go on laying eggs and raising caterpillars till the frost kills them off. Well, some may move south. I don't think anyone knows for sure. They're beautiful to have in the yard, but it is a bit grim watching them and not being able to warn them the first frosts are coming.

Here is a rather plain little butterfly, the Ocola Skipper, that also works its way north from the Gulf states generation by generation, ending up here late in summer. It looks like a number of other small brown skippers, except it has exceptionally long forewings. It also has no way of getting back south again.

Why do these species  come all the way up here, if even their best efforts to breed up a population will come to nothing? Perhaps after all they will have the last laugh as a warming climate moves north. They are pioneers. They will be the first to take over the new territory. When we moved to this house 35 years ago, the USDA Plant Hardiness Zones showed Jonesboro to be at the very top of Zone 7a. The Common Buckeye (abundant in fields right now), cannot survive the winter north of Zone 8. Well, now Jonesboro, 35 years later, is in Zone 7b, half the way down to Zone 8.

So if I can hold on for another 35 years, I might have the sub-tropical climate I always wanted to live in.

Sunday, October 14, 2012

Hanging desperately onto summer.

We dragged all through a dreary insectless winter waiting for summer to arrive, got a few promising weeks of spring, then it came in hot and dry, and we (and all the insects) hunkered down through most of the summer months waiting for it to let up a little. And now, overnight, it's turned cool, dark, and drizzly.

We feel like we've been cheated out of a season.

The event of the year I guess has been the irruption of neo-tropical butterflies into Arkansas, or at least the SW part of it, Charles Mills sitting pretty at Lake Millwood ticking off Dorantes Longtail, Ceraunus Blue, and Queen so far. Someone else had a Mexican Yellow.

We hadn't been to the southern part of the state all year, and thought we would go down to SE Arkansas looking for grasshoppers, and at the same time keep our eye out for our own exotic butterflies coming up from the Gulf. We went down Sunday (the 8th) and rented a motel in McGehee, in Desha County, for three nights. Monday morning we met up with our friends Carl Ramm and Susan Alexander (she is assistant refuge manager at Felsenthal) and they showed us some special parts of Felsenthal we had not seen before, mainly a sand prairie (ideal for grasshoppers and interesting wasps). From now on when we come down, it is the first place we'll visit. We had a terrific walk through it this time, but it was mainly overcast, and the temperature never quite reached 60 degrees, so I'm sure we didn't see nearly what we might have on a sunny warm day. Even so it was teeming with grasshoppers, especially Seaside Grasshoppers, which were in huge numbers, as they seem to be wherever there is white sand for their pale bodies to disappear into. They were constantly flushing before us, we would get a brief flash of bright lemon yellow wings, then they would vanish again. There were also nice butterflies, but not the Ceraunus Blues I had my eye out for.

In the afternoon our friends had things to do, and left us to continue noodling around the sand prairie. We then drove up and down the dirt road along the eastern edge of Lake Jack Lee, making stops where the road bridged over creeks. In past trips we had found the stone work under these bridges swarming with big cottonmouths, but we didn't see a one on this cool and cloudy day.

But we did find something nice. Because we were looking so closely for insects we suddenly realized there were grasshoppers sitting within the grooves of the trunks of big pine trees. Mostly they were at a level of three or four feet above the ground on the massive boles. We knew at once these were Pinetree Spurthroated Grasshoppers. The field guides always say something like "little is known about this mysterious grasshopper, that may be nocturnal, and spends almost its entire life up in trees." Though they are hard to see, we believe they are very common, at least in Arkansas, and we are learning more and more about them. Mainly we see females, and that is because they have to come down out of the trees in order to lay their eggs in the ground. And we know they are not found only on pine trees, since we have found them on eastern redcedar trees, and also oak trees. But these we were seeing this day were following the rules and living on pine trees. And every one we saw was a male, as we could tell by the large boot-shaped claspers at their tail end, a part of their complicated genitalia. Here is what we think was going on: Every female scattered all over this enormous tree has to come down past this relatively narrow trunk to reach a place on the ground to oviposit. We think the males were waiting there to waylay them, and make sure some of their own genetic material goes into the eggs. We have seen this in several kinds of insects: the males waiting at just the perfect egg-laying place the females are searching for.

Tuesday we went to Warren Prairie. A couple of years ago when we were there in the spring we had photographed nymphal Eastern Lubber Grasshoppers. This time we were hoping we would find some of the big brightly colored adults to photograph, but we didn't have any luck. Maybe this time we were too late. It was a bit warmer this day, and there were lots of butterflies out, but once again, all of the expected ones, and none of the exotic ones. But it was fun walking through the area, though we had to stick to the high ground. The low areas were ankle-deep in water, the drought evidently not as bad in the southern part of the state as it was up by us. There were dense patches of glaucous-colored goatweed along the road which we carefully checked for insects, and several times found the egg nests of Green Lynx Spiders, which seemed to be exactly the shape and color of the flowers. Each nest had a spiky-legged pale green mother spider wrapped protectively around it. (Here's a picture of one on goldenrod, which is a little easier to see them on.)

We still had much of the afternoon left, and on the way back towards the motel, stopped at Seven Devils Swamp. If Warren Prairie had been under water, it was the reverse here, and the swamp was bone dry. We threaded our way in among the roots and knees of the densely packed bald cypress and tupelo trees, and had the odd sensation that we were walking at the bottom of the sea. The landscape of twisted trunks ahead of us was both beautiful and sinister.

Wednesday morning we went east from McGehee to Arkansas City. During the great Mississippi flood the people of the town stood on the top of the high levee looking out on the river to see how far it would rise. They didn't realize a levee on the Arkansas River had breached behind them, until they turned around and found the flood water was rising up inside the levee faster than it was on the Mississippi side. That levee they stood on was the one we crossed now to go out to Choctaw Island. We drove out to the boat launch at the end of the road. This is always a good place for insects, and though it was still dull and overcast, the day was warmer, and there was more activity. Cheryl found a spectacular Festive Tiger Beetle in a full spectrum of glowing colors. I saw a jumping spider looking over the head of a butterfly it had caught. We decided it was a spider-headed were-butterfly.

We moseyed our way down the dirt road beyond the boat launch till it ended in a big sandy field full of Ridgeback Sand Grasshoppers nearly invisible against the substrate.

And then we saw something even more invisible, more like a bit of shadow than a living thing. It was one of the tiniest robber flies, only a few millimeters long, its name much longer than it was, Stichopogon colei. In Arkansas they are only found on sandy beaches of the Arkansas River. Choctaw Island is only a dozen miles south of where the Arkansas empties into the Mississippi and so the species extends its range down at least that far. We had not seen one for years. Cheryl got a terrific picture of it, looking more like a delicate midge than the powerful micro-predator that it is.

The real fun was when we turned around and came back along the road towards the boat launch. Perhaps during breaks in the overcast the weak sun had managed to warm the exposed roadway. Snakes sluggish with cold were crawling out onto it. First we saw a medium-sized cottonmouth still with a good bit of pattern (the bigger they get, the darker and more obscure the marking). We got closer and closer taking pictures of it. Until we crossed a certain line and it gaped its white fang-filled cotton mouth at us, showing where it got its name. We didn't get closer.

Down the way was another, this one darker and more obscurely marked. It also objected to our too near approach. But then the star performer of the day appeared, what looked to us like a near record-sized diamond-backed water snake. Don't think only venomous snakes have heart-shaped heads:

As a coda to the day, just before we headed back to Jonesboro, a juvenile cottonmouth came out. Notice the yellow tail tip. It's a feature of many species of pit viper, this yellow tail-tip, when they are young. It seems too incredible to believe, but herpetologists have witnessed it: The snake stealthily approaches a small lizard, and then waggles the yellow tip. The lizard rushes up to capture the waggling worm-like thing, and the snake nails it. It's where their first meals come from.