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.

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