Monday, July 21, 2014

Home and away, Part One

Our yard has reached that degree of perfection that essentially come spring we don't plant anything, we don't weed anything, we just step back and let it all come up of its own accord, and each year it comes up taller and thicker. Our favorite habitat in the world is the tropical rain forest, and this is as close as we can come in our temperate clime. Oh, it might be a bit overgrown, in places there are thickets we no longer have access to, there is so much aquatic vegetation in our pond we can no longer see the water surface. But the only regret I might sometimes have is that when we were first here I kept planting more and more trees, tiny saplings that have now grown into big trees, and it is getting as shady as the woods across the road from us (which is itself getting overgrown), and that might reduce some biodiversity, but there is still plenty here to keep us occupied.

For example last year I found an amazing 104 species of spiders here in our yard (and house), and, when I used to keep track, we regularly found over 60 species of butterfly in the yard every year (though I doubt we still could find that many as the yard becomes more enclosed in the woods, and also as butterflies continue, as I suspect they are, their steep decline generally).

There is still lots of butterfly activity. The brash and bright colored Zabulon Skippers have taken over the pond and chase off everyone (including me) who comes by.

All in the hopes of winning the  heart of the quiet and gentle female of the species.

The handsome Black Swallowtails are laying their eggs on our bronze fennel, and these are hatching out and growing into big, striking caterpillars.

Horace's Duskywing (some classicist named a bunch of duskywings: Juvenal's and Propertius are others) are courting and mating.

A pretty little Sleepy Orange appeared in our garden, nectared on our flowers, then laid its eggs on our senna plants. The nearly microscopic eggs have now hatched and the rather ordinary looking caterpillars (the later instars are more attractive) are growing rapidly.

A Buckeye butterfly has just today eclosed from its chrysalis.

When it was ready, it flew off and we thought it was gone, but then Cheryl found it in a far corner of the yard and took this beautiful picture of what might be our most beautiful butterfly.

Of course there are a lot of interesting moths and moth caterpillars as well. We especially like this one, a Double-toothed Prominent. The back of the caterpillar mimics the double-toothed leaves of the elm trees on which it feeds. As it eats one leaf from the edge in towards the midrib, it fools birds into thinking it is merely the other half of the leaf.

There is a whole ecosystem beyond the lepidoptera, including a number of predators. For instance this very big Laphria grossa, a bumblebee-mimicking robber fly, here with its decorative prey (robber flies have a nice design sense), a flower scarab.

On a smaller scale, this tiny assassin bug has caught a Cuckoo Wasp. The wasp has such strong armor plating an entomologist would have a hard time sticking an insect pin into it, and yet this fragile bug has managed to stab it with its beak.

That was an assassin bug with prey. Here is an assassin bug as prey. The spider is the handsome Paraphidippus aurantius, the Emerald Jumper.

The Cuckoo Wasp was prey, but here are some wasps in their more usual role as predator. I read in my Eric Eaton Kaufman Field Guide to Insects that there are 280 species of wasps in the subfamily Eumeninae, the Mason Wasps and Potter Wasps. These are all very similar appearing black and white or black and yellow wasps that make use of abandoned nests of mud daubers or carpenter bees or other cavities for their own nests. They fill these cavities with paralyzed caterpillars and then lay an egg in them. One of these wasps right now is using a space where canvas is folded over the top of one of the chairs on our front porch. It seems like every time we come out it is dragging another hapless caterpillar up the chair leg.

Some members of this group, those in the genus Eumenes, are called potter wasps, because they make their own nests, exquisitely shaped clay pots using the coil method of construction that they invented millions of years before we did.

When I started this post I just called it "Home and Away," planning to contrast this account of what we are seeing around our home right now with what we see going out for the day to one of our favorite places. But now I see that I could go rambling on about what we are seeing around the house almost endlessly. So I'm going to stop here, and in the next post (Part Two) I'll do "Away."

Well, I'll mention one more thing. What I have done for the last couple of nights is to go out at late twilight and try to take pictures of the fireflies just at the instant they are flashing. What I do is run over to where I see flashing, look in its direction through the view finder focusing frantically back and forth till I catch the tiny flying black dot in the near darkness, follow it trying to keep focused on it, then try to catch it in mid flash. What I usually end up with after several tries is one picture where the firefly is in quite good focus, but not flashing, and one that is flashing, but out of focus. If I knew something about photo-shopping, maybe I could meld them together. Anyway, try it. It's fun.

Sunday, July 6, 2014

The Black-and-yellow Garden Spider, Argiope aurantia

If you have an overgrown garden you have benignly neglected for many years, if you never use pesticides, if you have fervently absorbed Oliver Rackham's (in his great book, The Illustrated History of the [English] Countryside) sternest and most important dictum about having a garden, "Learn to detest neatness," then by mid summer you are bound to have at least a few Argiopes behind bushes or in ignored corners, those enormous golden garden spiders sitting in the center of their big webs with the zig-zag stabilimentum going down through the middle. I have been observing them for years, always learning new things.

Now, these big brightly colored spiders seem to appear out of nowhere. They aren't there one day, and the next day suddenly there they are. Well, if you start really looking you find they are there all the time, only in smaller, less recognizable instars. It might take you a couple of seasons, but eventually you push them back to the beginning. Maybe the first day of summer, June 20th, is a good day to start looking out for them.

What you'll see first, down low in thick vegetation, is a white thing about the size of a postage stamp.

Take a close-up with your digital camera and you will see a tiny spider. The only similarity it has with a full-grown Argiope is that it is sitting head down with two pairs of legs forward and two back. The stabilimentum, instead of going up and down in a zig zag, is a tightly woven squarish circle just the size to hold the spider's body and legs.

Nobody knows precisely the purpose of a stabilimentum, though recently it has been shown that they reflect ultra-violet light, and thus might act as an attractant to insects. But this baby stabilimentum has its own neat little function. Now you see the spider, but at the least disturbance, the spider vanishes quicker than you can see.

After another instar the silk mat is a bit larger, to hold a spider that is beginning to look more like an Argiope.

By another instar the spider is still too small to be noticed unless you are deliberately looking for it, but now the baby mat is beginning to extend into the up-and-down zig zag of the adult.

It can still perform its disappearing act.

With the next instar it has its adult stabilimentum.

And then, its adult color and pattern, though its abdomen still has its long narrow shape, not yet its rounded adult shape.

Interestingly, I saw all these different stages on the same day last week. The progress is very irregular. I think the tiniest spider must set up shop, and just wait for insects to come. If they don't, it stays the same size, if it makes a couple of lucky catches, it molts up to the next stage, and the more insects it catches, the quicker it moves from stage to stage, while the unlucky spider with a poor spot sits waiting. Even quite late in the summer I have seen that first postage stamp size, while the huge fat adult females are laying egg nest after egg nest.

At any rate, with decent luck, at last the spider reaches the penultimate molt, and males, battling one another, begin hanging around the edges of the web, to be the first one there when she sheds into full adulthood ready to mate. Here is that next to last molt, and she still has her girlish waistline, before it starts ballooning out with eggs.

If you want to follow the story, I've done an album of the life history of Argiope aurantia which includes a life history of Argyrodes, the tiny spiders that live parasitically in Argiope's web.

Click here

Tuesday, June 17, 2014

A mystery solved

Last year when we began making a concerted effort to learn the spiders of Arkansas, I spent several nights in my backyard with my headlamp on looking for and photographing the Arboreal Orbweaver, Neoscona crucifera, the commonest of the big orbweb-spinning spiders, and a good representative to study the behavior of this group of spiders. The Latin species name, crucifera, means 'cross-bearing,' referring to the cross-like marking on the abdomen.

The general procedure for these spiders is for the big females to come out at dusk and build a large orb-shaped web stretched out between  two trees. (When they are fairly close to the ground it is quite easy to run into them if you are walking around without a light.) They spend the night catching whatever blunders into their web (they are formidable hunters and can catch prey much bigger and heavier than they are), then when it begins to get light in the morning, they take the web down strand by strand, generally eating it to get back all the protein they had put into it. During the day they get in under the eaves or in some other protected spot, to eat at their leisure whatever they caught the night before. Typically they have sturdy legs, a small carapace, and a fat round abdomen.

As is often the case with spiders, the males are quite different.

They are small compared to the female. Proportionally, their legs are longer and slenderer, their carapace is broad, and their abdomen is tiny. On the female the palps are like a pair of miniature legs, thin and threadlike, on either side of her mouth, and are used to manipulate the food she is eating. The male's palps are like big boxing gloves and are full of complicated apparatus for carrying his sperm and inserting it into the female's reproductive opening. If you see a male at all, you will find him living off to the side of the female's web, where possibly he scrounges some food from her leavings, or possibly he eats nothing at all.

Now this was part of my general knowledge of the orb-web spinning spiders before I began, so when I went out one evening and saw what I am going to show you now, I was flummoxed, I didn't know what to think (you have no idea how emotional the study of spiders can be can be).

Here was a large Neoscona crucifera with the cross pattern and fat abdomen of a female, which had a big professional-looking web spread between trees, which was catching and wrapping up and feeding on big game such as this big strong beetle, and yet which had very obvious swollen male palps.

I was putting together an album of photographs of Arkansas spiders which I hoped would be helpful to people who were trying to identify them in the field, and which might show little interesting bits of behavior, if I were lucky enough to discover any. But this was inexplicable. Somewhat guiltily I hid these photos away in a file, and decided not to mention them.

The one thing I noticed about this spider was, it was a subadult, it was in its last instar before molting into adulthood. I could tell that by the fact that the palps were swollen and beginning to mature, but did not yet have their complex sexual machinery, which would only come with full maturity.

I took those pictures July 25th last year, and that's where things stood until now, nearly a year later. What happened is, I received as one of my birthday presents from Cheryl Bernd Heinrich's latest book, The Homing Instinct. He's my favorite naturalist/writer, and here is part of the reason why: With his constant close and dogged and trained observation of every living thing around him, he sees things no one else sees.

In this case he had an orb-web spinning spider living in the rafters of his Maine woods cabin. When he sat at his desk working, he could look up and observe the spider. He began throwing insects to it and learning different things about it. He thought it might be a male, except that it was big, and everyone said males, relative to females, were small. It had a big web, and everyone said, the males don't make a web. Anyway, one day it stopped feeding; no matter what he offered it, it wouldn't take any more. Its fat belly began to shrink. Then, it shed its skin, and when it came out its shrunken belly was even smaller than before. On the other hand, its legs were a third longer. And its palps had turned complicated. It never made another web. One day it took off running, presumably searching for a female to move in with.

Friday, May 30, 2014

Geolycosa and Geometer

Back in 2011 we were on the prairie portion of the Jonesboro Nature Center when Cheryl discovered a Geolycosa missouriensis, and took this very nice photo of it:

Here it looks more like a gopher or some other small burrowing animal. In fact it is a handsome and very interesting spider. Geolycosa, 'earth wolf,' is the genus name for the Burrowing Wolf Spiders. We were especially delighted with it because Peggy Dorris in the 60's and 70's published, in several papers, her wide-ranging survey of the spiders of Arkansas, and she had not found this species, nor any other burrowing wolf spiders, among the 435 she recorded. So, in addition to being handsome, it was rather uncommon, not very well known, and quite interesting in its behavior. But we were concentrating on grasshoppers that year, and didn't follow up on it.

This year, the beginning of our second year on spiders, we went back, and checked out the prairie with burrowing wolf spiders in mind. Here is what we discovered. We had often in the past noted, when we were in this sort of terrain (namely a rather flat area with sandy soil and lots of bare ground), that there were round holes in the ground often with bright orange fresh sand from recent digging scattered around them. There were also lots of solitary hunting wasps around, and we assumed these were wasp holes, dug to deposit an egg in along with a paralyzed caterpillar or whatever host animal they specialized in. This year we examined these holes more critically. If you look carefully at the picture above you will see that the sand right around the mouth of the spider burrow has been tied together with spider silk. Well, we noticed that was true of most of these holes we were examining, holes that in size went from a diameter too small to stick a pencil in, to one that would require a quarter to cover it. Some even had dried plant material sewn into the sand, to make a little turret around the entrance.

When we saw these holes in the past, they were always empty, and so were they this day. But I decided to sit down and wait quietly by one, and see what happened. I'm not a particularly patient person, but I thought I would give it a full minute, counting out sixty seconds, one one-thousand, two one-thousand....

And as you can see in the picture above, before I reached sixty, legs began appearing down inside the tube and slowly rising to the surface. I very quietly raised my camera and aimed it at the top of the hole.

I made the tiniest movement, and it disappeared in a flash.

You see the pattern of this spider: a black body with gray hairs over the top, two-tone black and orange legs, and the chelicerae, the sort of mustache in front of the face, covered with yellow hairs.

I've described the habitat. Sandy soil, because sand is easy to dig in. The land mainly flat, but with some areas raised a few feet in elevation from the rest, or places with gradual hillsides, and those were the places where we found all the holes (often half a dozen in view at a time). Obviously a design to avoid flooding in heavy rains. The holes always appeared empty to us because the spiders are so sensitive to the least vibration in the ground, and have such sharp eyesight, that before we got close enough to see into the hole, they had already dived to the bottom. The one-minute rule, however, appeared to be standard for all of them.

To the north of Jonesboro in Greene County is Scatter Creek WMA. There is an area there of abandoned quarries which had all the proper ingredients, and when we checked it, it was similarly full of holes in appropriate locations. Here are pictures of one spider I waited by, keeping very still so that I didn't disturb it before it was fully out.

After the sixty-second count it was up just below the top. There was a cautious wait there, and then it moved up so it could see over the top. Another wait. When it felt completely secure, it moved its second pair of legs straight out in front, and that was its final comfortable position for surveying the landscape in front of it for prey. I didn't catch it in the act myself, but Cheryl was watching another spider on the side of a hill when she saw a small beetle trundling down the slope towards it. When it was four or five inches away the spider noticeably tensed, the beetle suddenly froze, then the spider rushed out and grabbed it and carried it back down into the burrow.

If you are a follower of this blog you might remember that I showed some pictures of another large wolf spider, Hogna carolinensis, which had a burrow with a similar turret, but otherwise their behavior is different. Many of the Hognas make burrows that they conceal themselves in during the day, then at night they come out and wander around looking for prey. Geolycosa comes out by day, sitting at the top of its burrow waiting for prey. I don't know this for sure, but I suspect they go back down into their burrows to rest during the night. There are other parts of their behavior I will try to learn more about this summer while I have these two big populations to monitor. My understanding is that at this time of year both males and females live in their burrows, but in late summer and fall, the fully grown males leave their burrows and go looking for females.

Now, on a different subject, look at this picture and tell me what you see.

Geometers make up a large family of moths. Geo, 'earth,' meter, 'measurer.' Its the family whose caterpillars are the familiar "inchworms," or "measuring worms," that progress by arching up their long bodies and sending the front of their body as far forward as it will go, then arching up their body again to pull the back half up to catch up with the front. But some of the caterpillars in the geometer group have a much more remarkable ability. They can hold their long bodies absolutely straight, and keep them stiff and rigid for hours at a time. To go along with this ability, often their markings precisely mimic the wood and bark and complicated joints of twigs. Birds feeding on caterpillars use the shape of a caterpillar as a search image, and caterpillars go to extraordinary lengths to break up that pattern and look instead like something inedible.

Last week we found (droppings underneath it provided a clue) what must be the world champion in this type is dissimulation. The caterpillar (that's what you were looking at) is on the trunk of a small bald cypress in our front yard. Several new cypress shoots are growing on the trunk at just that angle, in just that color and texture. Since we discovered it, we have been keeping an eye on it, and it holds that position all day long. It's been doing it for at least the week we have been watching it (a bird with a good memory might note that it is in a slightly different place each day.) Last night we finally remembered to go out and check on it at night.

Sure enough, that was when the caterpillar (we still are unsure of its identity) climbed up into the cypress tree foliage to feed.

Sunday, May 11, 2014

The last days of the bird feeder

When winter closed in last year, and there were fewer and fewer insects and spiders around, we gave in to the inevitable and set up bird feeders. We  hung up a tube feeder of sunflowers seeds, a white sock of niger seeds, hung up some suet cages and scattered finch seeds and sunflower seeds on the ground outside our dining room window, and down our second, largely unused, driveway outside the kitchen window.

Of course you argue that you are saving the birds from starving during the bleak cold winter, but the truth is in most winters the birds can shift for themselves as they did for the thousands of years before our arrival. No, the feeders are set up so you have the pleasure of drawing the birds to your yard so you can watch them from close up. And you especially hope the gabble of feeding birds will be a magnet for any rarities that happen to be in the neighborhood.

Well, we did have all those pleasures this winter, more so than usual. You see, I used to be a keen bird watcher, but over the last fifteen or so years I have become enamored of insects, and more recently of spiders, and what I like most of all is recording them on camera, especially their behavior. I'm not primarily a "photographer," which is to say, I am not interested in the technical aspects of my equipment, nor do I know much about it. The camera is just a means to an end. I have an SLR with a 100mm Macro lens which I usually use with extension tubes so I can take pictures from only a few inches away. Cheryl has a very small camera which she carries in her pocket, with which she can focus on objects from less than an inch away. I can get large reasonably sharp images of shyer creatures from a few inches back; she can get up tight on extremely small subjects, especially ones in awkward corners my bigger camera can't get into.

Anyway, it happened that all the guys decided it was better to photograph insects from a distance with a 300mm telephoto lens, usually mounted on a tripod for steadiness. This produced perfect pictures of, for instance, dragonflies. Well, I wanted to be one of the guys, so I got one of these big lenses, and while it produced some nice pictures of dragonflies, I found it cumbersome and not very useful for pictures of smaller, more active, insects. I stuck the lens in a drawer and tried to forget how much it had cost.

But this winter when the birds started coming to our feeder, one day I attached the big lens to my camera, idly pointed it out the window and snapped a picture of a bird. To my amazement, even hand-held and through double panes it produced a sharp picture, even showing those neat barbs in all the feathers that are the vogue with professional bird photographers these days.

I was quickly hooked, and spent a lot of otherwise boring insectless winter days taking pictures of birds. The long-lens more than paid for itself with the fun I had. At first I couldn't believe how good my pictures were. Then after about a month I looked back at them, and realized they weren't all that good, and the new ones I was taking were much better. I went through this cycle periodically over the winter, at first thinking I was taking prize-winners, then later realizing they weren't even keepers compared to the pictures I was THEN taking. What it meant was, I was learning a new skill.

The other part of the fun was, we were drawing in some special birds. Rusty Blackbirds, for instance are a species of concern, their numbers going down rapidly. We are asked to keep track of them here in the south where they spend the winter. Well, that was easy for us: in the coldest part of the winter a small flock moved in with us and stayed. They are a kind of blackbird, all black in their nesting territory on wetlands in the upper mid-west, but here in their winter plumage they are every possible pattern of rustiness.

And we got another nice bird, an American Tree Sparrow. This is a rather scarce pretty little sparrow that normally we would see once or twice during the winter, just a glimpse of it out in the country mixed in with a flock of commoner sparrows. But this bird appeared at our feeder and stayed all winter. We got to know it, something we had never been able to do with all our brief glimpses in the past.

But just as in summer the days rushed on to autumn, the days shortening and darkening, the insects reaching their maximum numbers, then quickly declining, so suddenly (now that we were having fun) just before we left on our trip to Arizona in April we noticed the big flock of American Goldfinches that spent the winter at our feeder were changing. Goldfinches often seem to disappear for the winter. They don't. They just put on their dull gray winter plumage and you no longer recognize them. But now our big gray flock was coming out in yellow spots.

By the time we got back from Arizona their transformation into summer plumage was virtually complete.

Here was hard irrefutable evidence that winter was over, and instead of cheering I felt a sense of regret.

But at just that moment, we had the highlight of the year, a real rarity. The White-winged Dove is a western bird that is beginning to invade Arkansas from the west, but many good Arkansas birders still have never seen one in the state. Here we are in the eastern side of the state, and one morning when we went outside, we were quite sure we could hear one calling in the woods across the road. Sure enough, the next morning there it was at our feeder. It looks rather like our common Mourning Dove, but has a big white patch in the wing that you can see even when the wing is closed.

He stayed around for a few days, eating our seeds, singing from our trees, cruising some of the female Mourning Doves till their husbands expressed disapproval. Then he moved on.

The time for the bird feeder was over. I was nearly out of birdseed and wasn't going to buy any more. What we suspected was a raccoon had come in the night and stolen our suet feeders. Most of the birds had deserted us and headed north anyway. And then a funny thing happened: Mammals began to take over.

I have already told you about the voles that came from underground to share the seeds with the birds, and the Gray Squirrels had been vacuuming up stuff we put out all winter. Now a Hispid Cotton Rat appeared (hispid refers to his rough shaggy fur) and began feeding on the leftovers.

Then, only slightly bigger, a tiny smooth baby rabbit appeared, using its nose to find buried seeds the birds had missed.

Then a big gangling cottontail that looked halfway to being a jack rabbit.

The final finisher came minutes before darkness (I took this picture at 3200 ISO), looking off into space while using his deft hands to scrape up hidden seeds under the mud, and using the puddle from a recent rain to wash them in.

So that's it.  Bring on the bugs and spiders!