Thursday, September 25, 2014

The amazing invertebrates of Ferncliff Camp

Every year the Arkansas Audubon Society rents classrooms at Ferncliff Camp and Conference Center for a weekend to teach nature courses (tree identification, native plant gardening, mammals, and so on). For the past several years Cheryl and I have taught classes in butterflies and in insect ecology. This past weekend we did butterflies.

The camp consists of 1200 acres nicely situated in mountains 10 miles west of Little Rock. There are meadows, woods, two big lakes, a stream running through it. It would be perfect, except someone there has this thing about tidiness (always antithetical to nature). Everything is mowed. The fields are mowed right down to the edge of the lakes. In dry years they can get their mowers into the ditches alongside the road, and the weedy flowers there are mowed. Butterflies look for flowers, but flowers are nonexistent.  There is an underpass to come off the highway and get down to the camp, and in the concrete structures above it there are places that so far their mowers have not reached, and that is often our single hope for a few wild flowers and a few butterflies. Because in those little unmowed patches, the wildflowers are quite good and teeming with butterflies and other insects.

So, as always, our hearts sank a bit as we drove in. What are we possibly going to be able to find for our classes? But again this time, as always, the insects turned out to be fantastic. We see bigger, more exotic creatures here than anywhere we know in the state. Of course part of reason is an intensive weekend of searching (somewhat desperate on our parts), but aided by the many sharp eyes of our eager classes.

We had come a day early to look the place over, and as we walked towards our classroom we came to a tree that had several large wounds in it bleeding sap, and there were butterflies attracted to the sap. That would be terrific to have this insect draw right outside the door. And the first thing we saw as we approached it was unbelievable, a beetle at least two inches long and in bright red and green and gold colors.  We looked at it almost stunned, and didn't get our cameras out until it started scampering up the trunk so that it was too far above us for a really good shot. But we did get this, anyway.

Our books told us its name was Plinthocoelium suaveolens. We had never seen it or even heard of it before. They are attracted to sap, so this was the place to find them, but we were lucky to see it anyway. When we told Brian "Bugs" Baldwin about it, he said it was very late in the year for it.

We had only been on site for half an hour, and already had a big new exotic insect. Now, what we had noticed in past years is that the place was outstanding for caterpillars. Partly it was because we came late in the year when caterpillars are at their peak, but partly it was the tremendous variety of trees, which is part of the reason the tree identification class here is so popular. (The main reason is because Eric Sundell is the teacher.)

Anyway we're very fond of caterpillars (we always have jars full of ones we are raising) and Cheryl with her sharp eyes is always watching for them. This day she was looking down at some bushes near that sap-leaking tree and began seeing caterpillars, probably half a dozen. They were quite pretty.

They were tussock caterpillars of some kind (there are dozens of kinds) and I was trying to remember which. "The orange brushes in the front make it Hickory Tussock Moth caterpillars? No, that's not quite right. Some tree name." Then I remembered: Sycamore Tussocks. We looked up and there was a sycamore tree right by us. These had all fallen out of the tree and would never get back. They were doomed to starve. We looked for a place where some sycamore leaves came within our reach, and very carefully held the caterpillars up to the leaves till they caught hold and climbed up for another chance at life.

But there must have been thousands and thousands of them up in the sycamore trees we could now see were all about us, because only a small fraction falls off, and when we looked around, they were swarming everywhere on the ground. Here they are sheltering under the window frames of the buildings. Multiply this by all the window frames of all the buildings around.

We pretty quickly gave up on trying to save all the thousands of fallen caterpillars. To tell the truth we were rather pleased that if all else failed, at least we would have this phenomenon to show our students. In fact, when our class was with us the next day and we were examining these caterpillars, we found that there was a second caterpillar in amongst them, another kind of Tussock Moth caterpillar, the White-marked Tussock.

That gave me a chance to talk to our class about mimicry in insects, one of my favorite topics. In my Caterpillars of Eastern North America (Wagner, 2005) book some twenty species of caterpillar are listed under the name Tussock (named for the tight bunches of bristles on their backs). These caterpillars come from different families, and only a few of them are "true" tussocks, and the rest are mimics. The White-marked is a true tussock. If you look at the picture above you will see there are two little red bumps on its back near the tail end. These are the "defensive glands," which contain a severe skin irritant.  (Indeed, in one species, the Browntail Moth, the irritant has caused allergic reactions that have even led to death.)  I had read that while grooming, they rubbed their hairs over these glands, to coat them with the irritant. While the class was studying one, we jostled the leaves it was on so much it became annoyed enough to begin crawling off, and that's when it stopped and went through motions that looked like it might have been rubbing its brushes over the little red cups. Birds know about the cups, and leave these caterpillars alone.

The moral of the story is that all these other Tussock Moth caterpillars were mimicking the true tussocks so that birds would leave them alone too. Judging by the ineptitude of the Sycamore Tussocks wandering all over the landscape, they needed all the help they could get.

In addition to neat caterpillars, Ferncliff also has wonderful spiders, the biggest of their kinds. One of the pleasures of teaching a class for these alert, intelligent, nature-loving people is that when we discovered an enormous spider on the wall of our classroom instead of shrieks and a stampede for the door, they were thrilled, and cameras were flashing at it from every direction, including mine.

This is an exceptionally large Tiger Wolf spider (tiger for the orange stripes on the legs). They live in burrows during the day and come out hunting at night, but as winter approaches, a number of spiders begin to move into more sheltered places, from hollow logs to warm classrooms.

And when we led them up a trail that followed a wooded path along a streamside, we found an even bigger spider. This was Dolomedes vittatus, one of the fishing spiders known for catching tadpoles and small fish and diving under water to escape their enemies. This large female spider had woven a little tent out of leaves and had cached its young spiderlings inside, and was now standing guard over them and would faithfully remain until it starved to death or froze this winter. Those babies certainly looked well guarded (just the spider's body was over an inch long). They should have a good start when they all go off in their separate directions in the spring.

And another spider of great interest to me, a male Geolycosa. I said in an earlier post that with spiders in the genus Geolycosa, the Burrowing Wolf Spiders, the females spend their whole life in or immediately around their burrows, but that the males, when they become sexually mature, leave their burrows and head out looking for females. I had never seen one of these males on the move, but here in rather deep woods where I hadn't expected it, we suddenly saw one.  It came by and was gone in a moment, but we got good pictures.  Here is Cheryl's very fine portrait.

There was at least one noteworthy vertebrate for the weekend. Some of the group were farther up the path with Cheryl when they saw a half-grown copperhead on the path, which quickly crawled off the path into the leaf litter which its pattern was designed to blend into.

The snake is centered in this photo, and the flash brings it up, so this probably won't work for you. But when I came up, the people who had stayed behind to point it out to me kept saying "It's right there," pointing their fingers as close to it as they dared, and saying it was under this stick and over that leaf, but I absolutely could not see it. And then, click! suddenly I could see it, and it was as if a light turned on, and it was perfectly clear and obvious, and each person who came up after me went through the same embarrassing experience of not being able to see it for the longest time, then suddenly there it was.

The camouflage pattern, matching the tangle of dead leaves, was perfect, but still, there was some other, psychological, thing blocking us from disentangling the snake out of it, which is why, once we broke out of it, it was then easy to see.

I guess I should at least have one butterfly picture, since that is what we were meant to be directing our class towards. There was fog fruit growing along the lake edge (a low growing plant that managed to keep underneath the mowing blades). That's the caterpillar food for the Phaon Crescent, a handsome little butterfly, and there was a small population of adults hanging around the plant, which our students could get acquainted with and practice using their close-focusing binoculars on. Otherwise, there weren't many species of butterfly about, and those that were about were the very commonest species, Cloudless Sulphurs, Eastern Tailed Blues, Pearl Crescents, Red-spotted Purples and other species like that. If Cheryl and I were there alone and looking for butterflies, it would have been disappointing, and we worried that we wouldn't have enough to show our students. But we were wrong. For a class of mainly beginners it was just right, a small amount of information for them to practice learning field marks on, without being totally overwhelmed. And because we kept veering off to look at spiders or snakes or phantom crane flies I think we might have helped them discover the intense pleasure not just of finding butterflies, but of seeing every living thing.

Sunday, September 14, 2014

If you build it (a no-pesticide, getting-out-of-control garden) they will come

We've lived in this house for nearly forty years, and we can still step outside the door on virtually any reasonable day and find some species of arthropod we have never seen before, or some interesting bit of behavior we have never witnessed before. We are on an acre lot (abbreviated a bit because the county road has an easement across the front, and beyond that the railroad tracks have another easement that cuts off some more of our front). Beyond those two cuts is an upland oak-hickory woods of, I don't know, five or ten acres, which was clear-cut in 1935, but since then has not been touched. To the north and east behind our house are row-crops, rotating between rice, corn, and soybeans, to the south three or four houses, then more row crops.

The yard was bare when we moved in, except for six or seven big oak trees, but over the years I have planted so many trees (dug up as saplings from the woods across the street) and they have grown so much, that now we are more or less an extension of the woods, except with a richer understory, as we have added flowering plants to be attractive to insects, and every year at least one more plant specific for the caterpillar of some moth or butterfly (passion flower for Gulf Fritillaries, milkweed for Monarchs, pipevine and sassafras and fennel for swallowtails, senna for sulphurs, and so on).

We were in the country, but now the city is beginning to press on us. When we drive by the houses of all the new subdivisions we see the perfect lawns, taken care of by lawn services that lay down so much poison you can smell the rotting carcases of the worms. At some point the owner has come out with a string to make a perfectly straight line on which to put, evenly spaced, the three Bradford Pear trees. Against the house six specimen plants spaced equidistant. Perhaps a pole is erected with a cute birdhouse which has only a painted entry hole. That way you don't have all the mess of birds living there.

There are tens of millions of yards like this in America (there are 25 to 50 million acres of single-family homes), so sterile (intentionally: who wants a lot of bugs around) they are sometimes called environmental black holes. What if those yards were more like ours? What would life be like?

Let me take you on a tour of recent sightings in the yard.

Some thirty years ago there was a terrific flowering of Spider Lilies in all the ditches along the railroad right-of-way. I dug up a few roots and planted them in the yard. This many years later when the spider lilies are long gone by the tracks (poisoned out by the railroad company), ours still send up their strong green leaves in early summer, and then, sometime in August, stalks shoot up seemingly overnight with buds at the top, and then for a month each day a new set of buds wait for twilight, then pop open.

Here's a jumping spider, Thiodina sylvana, in the adult male "red" form. It's fairly common, but it was so pretty and lively on the wall of my study I couldn't resist taking yet another picture of this species.

A bit more sinister, here was a large Tabanid Horse Fly laying a million eggs under a leaf of an aquatic iris in our pond. Now I have the moral dilemma: Do I get rid of this scourge and its offspring, or, now that I've photographed it, and have sort of a relationship with it, do I let it live? (I did what I usually do: I put the question out of my mind.)

I went out on a night op and didn't see many spiders, but saw this very nice creature, the Moonseed Moth, named after the vine its also very interesting caterpillar feeds on.

Well, I saw one nice spider on the night op, Neoscona crucifera, the Arboreal Orbweaver, very common but with an impressive web spread six feet across the lower branches of a tree. These big adult orbweavers don't become noticeable until late in the summer when suitably large flying insects are also at their peak.

Which brings up a mystery. Neosconas make their webs and come out at night. The yellow and black Argiope garden spiders are the day-shift big orbweavers, and we were having one of the best ever Argiope years (Cheryl stepped outside the front door one morning and there were three Argiopes feeding on tree frogs, and one feeding on a White-lined Sphinx, a very large day-flying hawk moth), but it seemed like every time an Argiope reached mature size and fattened up with eggs, it would suddenly disappear, leaving behind an empty web.

The empty web syndrome is still continuing, each time one of the younger spiders comes of age. I just checked, and there is not a single adult Argiope left in the yard. Something like this (but not quite as severe) happens most years, and I have wondered if hovering bats could pick them out of the center of their webs, or maybe a raccoon standing on its hind legs. My main suspect however is the pair of cardinals that live in our yard. I have seen what they do to our big caterpillars.

Speaking of caterpillars, a couple of weeks earlier we were surprised to suddenly spot a Monarch caterpillar in the dried and leathery late-season foliage of our milkweed plants. In the spring when we usually get eggs, we had only seen about four caterpillars, and we had managed to raise two of them to adulthood, when presumably they then headed north. At this time of year, late summer, we expect them to be heading south to the mountains of Mexico, with no intention of dallying along the way to lay more eggs. Anyway this fifth caterpillar of the year seemed precious, and we raised it in the house away from predators. It was already well grown when we brought it in the house, and quickly made its chrysalis.

A mere ten days later all the necessary changes and adjustments had been made, and the adult eclosed. We photographed it many times, then it took off on its maiden flight and never looked back.

We love caterpillars, they come in so many bizarre shapes, and have so many amazing behaviors. They're hard to find. They go to incredible lengths to blend into the background, or to not look like caterpillars. You must miss a hundred or a thousand for every one you see. But we suddenly had a little hot streak.

It started when I was trimming off the tips of some branches on a deciduous holly that were blocking a path, and as they fell away they revealed a very nice caterpillar, the Spotted Apatelodes.

It is interesting for being one of only two moth species in our area belonging to the Old World silk moth family (Bombycidae). Our Giant Silkworm Moths (Luna, Cecropia, etc.) belong to a New World family, the Saturniidae.

But while I was showing Cheryl this caterpillar, she looked a little farther along and found another beauty, a new one to us that we had to look up in our caterpillar book: The Interrupted Dagger. The names of moth caterpillars, it seems to me, can only be explained by the desperation of lepidopterists to find enough names to go around for the tens of thousands of species.

And then the high point of our hot streak. Cheryl suddenly pointed to a caterpillar that (judging by the number of chewed leaves around it) must have been in plain sight over the past few days, and that we must have walked by several times, a White Furcula. Just look at this amazing thing (that we had walked right by without seeing).

Here it is from some other angles.

The two hind legs have been converted into tentacles which, when the caterpillar is threatened, can be filled with hemolymph which greatly extends their length and they can then be whipped over the caterpillar's head to smack on the ground in front of it with an audible sound and a motion very like a scorpion striking with its stinger. Here's a picture I once took of one (well, of a close relation, the  Gray Furcula) doing it, and it is very impressive and I think quite likely to frighten off a small predator.

But this time we discovered another rather extraordinary ability this caterpillar has. It appeared to be full grown so we brought it into the house with some black cherry leaves, its food plant, and within a few days it suddenly changed color, to a sort of red-brown, a sign it was going to make its cocoon. We put in a bare twig for it, reading that that was where it would attach its cocoon, and then observed the operation.

First it used silk to attach itself to the twig.

It then wove itself into a thin cage.

From within the cage we could see the caterpillar twisting and turning as it wove a thick blanket about itself.

 It wove the inside cocoon thicker and thicker, until slowly it became opaque.

The next day it was complete, and resembled a woody thickening, perhaps like a stem gall, and that is how it is going to spend the winter, a little bite of protein in plain sight of everyone, but trusting to its power of deception.