Friday, July 28, 2017

The attraction of caterpillars

When we moved to Arkansas in 1976, we bought a little house outside of Jonesboro. It was on an acre of land, and we bought it because it had about a dozen fairly big trees on it, mainly different kinds of oaks. The rest of the yard was pretty much scraped clean. We began planting flowers on it, both for our pleasure, and to attract butterflies. The butterflies came, so it seemed only fair once they were here that we should also have appropriate plants for them to lay their eggs on and we began, one by one, year by year, adding plants specific to their needs. First we put in maypop, the local passion flower, and immediately got Gulf Fritillary butterflies to lay on them, and soon we saw their prickly red caterpillars on the vines.

And shortly came their near cousin, the Variegated Fritillary, and its caterpillar, just the same as the Gulf, but with a white line running its length.

Next we planted a sassafras tree, to see if we could attract a Spicebush Swallowtail, and sure enough, as soon as the tree was big enough to have a few leaves, we found one of them folded over to hide the snake-headed caterpillar.

And it was easy to plant a bit of parsley or fennel, and we immediately had Black Swallowtails. The early instar caterpillars mimic bird droppings, so nothing will be interested in eating them, and then their later instars pretend to be Monarch caterpillars, which are known to be poisonous from eating milkweed leaves.

We already had a sugarberry tree in the yard, so we already had Hackberry Butterflies, since that was the tree they laid their eggs on. The adult males post themselves around the yard, chasing females, and chasing off rival males.

Their somewhat slug-like caterpillars.

And we also already had winged elm trees in our yard, so we only had to look carefully to see we had Question Marks, with their odd way of stacking their eggs three or four high.

We wanted to have Pipevine Swallowtails breeding in our yard, so we got some pipevine and brought it into the yard in pots, and set the pots down in our back yard preparatory to planting them. Almost immediately a Pipevine Swallowtail appeared in the front yard and began flying in wide circles, coming closer to the pots with each sweep. We hastily planted the pots at the base of a large oak tree and the vines are now high up the tree, and if we search, we can often spot their big sinister looking black caterpillars.

 We planted a cherry tree, and birds spread seeds of it all over the yard, so we now have several, and almost any day you can see the Red-spotted Purples laying their eggs carefully at the tips of the leaves, and their caterpillars are easy to find.

Though they are less common than the Red-spotted Purples, we also get Eastern Tiger Swallowtails laying their eggs on the cherry leaves. Like many swallowtail species, their caterpillars start out by mimicking bird droppings, and later instars then become snake mimics.

We planted spring cress, and that lured tiny Falcate Orangetips into our yard to raise their beautiful caterpillars.

We planted senna to attract the various species of sulphurs, including the Cloudless Sulphur.

One day we were at the Arkansas Folk Center in the middle of the Ozarks and we bought a little pot of rue, which is a food plant for the Giant Swallowtail. We didn't have any appropriate plants in our area, so we brought it home and planted it. We only get Giant Swallowtails in our yard once or twice a year (perhaps because there are no plants of the right kind), and almost instantly a Giant came by and laid two eggs on our rue. The caterpillars gorged on the plant, growing bigger and bigger, and we realized they were going to eat all the rue before they were big enough to make their chrysalises. So we did what any besotted insectophile would do: We made the 300-mile round trip to the Folk Center for another pot of rue. Now to be a little safer, we have planted a wafer ash tree (another Giant Swallowtail food plant, this one much larger) and are waiting to see if it will work.

I haven't even mentioned yet the most obvious one of all: Naturally among our first plantings were milkweed plants, mainly common milkweed and butterfly weed.  On their northern flights the Monarchs would cover the plants with eggs, and the caterpillars would eat the plants right to the ground. The plants would then grow right back up, to be ready for any later Monarchs that were still laying eggs. Now, sadly, there are many fewer Monarchs coming through, and the milkweeds sometimes go untouched.

Well, that's thirteen. There are still many more. Once I started doing this I was surprised myself at how many had slowly accumulated over the years. I didn't get around to mentioning Sleepy Orange (on senna), Red Admiral (on nettle), Goatweed Leafwing (on Goatweed), Silver-spotted Skipper (on  indigo bush), Horace's Duskywing (on oak), Silvery Checkerspot (on black-eyed susans).

I don't believe we have ever planted a plant for the purpose of attracting a specific moth (well, I guess we planted a catalpa tree to attract catalpa hornworms), but if you have a variety of plants, you will get many moth caterpillars anyway. Moths in general can be rather drab (or, as my wife prefers, their beauty is more subtle), but on the other hand, their caterpillars go far beyond the usually rather staid butterfly caterpillars for spectacular patterns and shapes and behaviors and overall screwiness with tufts of hairs going in every direction and weird tendrils sticking up or hanging down. We are having such a banner year for caterpillars this year that I might make my next blog a moth-caterpillar-in-our-garden blog

Friday, June 23, 2017

More Arizona

Lately it seems like every time I sit down to write a new post, we are just back from Arizona and we've seen a whole new bunch of Sonoran flora and fauna.

For instance, almost as soon as we arrived in Tucson Heather, my daughter-in-law, was showing me around the garden she was creating in what had been, when they bought their house, a fairly bare backyard. We were looking at a raised bed of squash, just coming into bloom, when a small but muscular creature, like a half-size hummingbird, came powering through the yard and began hovering over the squash. It was moving so fast we couldn't see much detail on it, so I got up as close to it as I could and began snapping pictures of it with my macro lens and we looked at this wonderful creature magnified on the viewing screen.

It was a clear-winged moth got up to look as much like hornet as possible, the furry red hind legs carried alongside the abdomen to make it look even bigger than it already was. It was a squash-borer moth, beautiful to see but possibly disastrous for the squash. Its caterpillars would bore their way into the stems and eat the plants inside out.

The red and black and bluish coloration was meant to be a warning. "If you try to eat me you will discover that I am deadly poisonous, or maybe I have a hidden sting." In this case I suspect it was a bluff, and the moth was perfectly good eating (if you like moths). But we later saw another big, warning-colored creature, a kind of blister beetle called the iron cross beetle. The warning here was genuine: if molested this beetle would squirt out Cantharidin, a blistering chemical.

Unusual for our trips to Tucson, we took a break and flew out to the San Francisco Bay Area to visit my sister, and her daughter and family. Nice to get back in close touch with everybody. Lots of good meals and good walks and a natural-history high point was visiting the UC Berkeley Botanical Garden, a huge area in Strawberry Canyon above the Berkeley campus frequented by mountain lions (which unfortunately we didn't see) and with plantings from all the temperate parts of the world. Featured on that day was the blooming of a puya, a plant from Chile, which we were told was the largest bromeliad in the world, and which had the largest bromeliad flower in the world. Now, most bromeliads are small scruffy epiphytic plants that grow on trees or telephone wires and are detached from any connection with the earth because they get all their nourishment and other needs from the air. Some of them have attractive flowers but you would hardly call them enormous. Well, the flower spikes on puya were advertised as being three to four meters long. Four meters is about fifteen feet. We thought we had better see this and had to ask directions several times to find the plant off in an obscure corner. Here is a picture of Cheryl photographing one flower spike which is only a disappointing ten feet tall.

The color is quite wonderful.

We came back to Tucson to continue our stay for another week, and went out to Sweetwater, which featured two White-faced Ibises sitting in a muddy field, and a family of Gambel's quail slipping through the brush.

There were lots of good mammals around, almost tame, as mammals quickly become when they are in places where they are not disturbed. Coyotes were common and virtually ignored our presence.

In past trips to Tucson we had often seen the big antelope jack rabbits; this time we saw, new to us, the much smaller desert cottontails (though their ears were nearly getting up to jack rabbit size).

Tucson is located at about 2000 feet, and has Mt. Lemon, an 8000 foot mountain, just out of town. It gets cooler as you go up, so you can dial-a-climate. We decided to go up. As you climb, the fauna changes, and we began to see birds like Bridled Titmice

and Yellow-eyed Juncos.

At one picnic ground a child had laid out all her toys on the table, then gone off somewhere else to play, and this Acorn Woodpecker could not resist coming over to say hello.

By the time we got to 8000 feet we knew we were getting into some real high mountain stuff when we saw this Abert's Squirrel. The abert's race is famous for being on the south side of Grand Canyon, with the kaibab race on the north side and never the twain can get across to meet. Both races are also famous for the super-long tassels on their ears, which unfortunately they only have during the winter.

Of course before we left for home we visited our favorite Saguaro East N.P., where as always we saw a number of neat things.  This small, chipmunk-like creature, for instance, is it own kind of rodent, an Antelope Squirrel, Harris's Antelope Squirrel, common in the Sonoran Desert.

And then we saw an insect we had always wanted to see. There is a group of wasps called velvet ants, because that's what they look like. They have long velvety fur, and the females are wingless, so they walk around on the ground like large furry ants. There are dozens of kinds in different sizes, but they all have an almost identical pattern, bright red with bands of black. The largest of them are called "cow killers" as an only slightly exaggerated description of the power of their stings, and so all the species have the same pattern to immediately warn any predator away from trying to attack one and risk the sting. Well, one species is so small it does not try the warning colors bit, and instead relies on camouflage, making itself resemble very perfectly thistledown, something there is lots of blowing around on the desert floor.

Cheryl, with her sharp eyes, spotted some Thistledown Velvet Ants (that's what they are called) by their frenetic movements. They don't walk, they hop and skip and jump in the most eccentric manner, making it very hard to catch up with them and focus a camera on them.

 This roadrunner stopped very close to us.

It must have been a young one; its feathers seemed only half developed. I thought I could see the primal dinosaur looking through its reptilian eyes. And then in fact we saw a genuinely primitive reptile, not dragging its belly as it moved, but carrying its body in the air as it walked on its muscular legs, swinging its head back and forth, its forked tongue appearing at intervals.  We are told that even most people who have lived here their whole life have never seen this creature: It was a Gila Monster.

Okay, this will seem like boasting, but we also saw an even rarer reptile, one probably never seen before by anyone: a Six Headed Turtle.

Monday, April 24, 2017

The Life History of the White Furcula

It's probably not an exaggeration to say that the majority of meat-eating animals (taking into account, not just tigers and lions, but all the parasitic wasps, birds, spiders, parasitic flies, and so on) feed primarily on caterpillars. The caterpillars didn't get a vote in this, so they have concentrated on creating millions of ploys to avoid being eaten.

For instance, some caterpillars have learned how to eat poisonous plants without themselves being poisoned. Instead they sequester the poison in their tissues, so that whatever creature tries to eat them will be poisoned. Others have venomous hairs or spines on their backs so that whatever creature mishandles them will be stung and even killed. Other caterpillars look exactly like a gooey revolting bird dropping which no one is interested in eating. Or they might get two large false eyes on their back and look so much like a snake head that a bird that suddenly spots one nearby in the leaves will fly off in fright. The commonest, of course, is just to look so much like the leaf they are sitting on that they become invisible.

Well, those are all familiar ploys. The caterpillar of the White Furcula moth provides some new ones.

First, let's straighten out some anatomical matters. A moth caterpillar is essentially a mouth  with a huge vacuum-cleaner bag behind it which it constantly stuffs with food in order to grow as fast as possible (before it becomes one of the vast majority that get eaten). If you look at the first picture above, you will see that the dark area low down where the head is (on the right) has three slender reddish pairs of legs which will be its regular legs when it converts into a moth. Behind them are four pairs of round fat elephant legs, to support its long body that trails behind the "real legs." These are prolegs, that work fine as legs, but will disappear when the caterpillar develops into a moth. Most caterpillars have these, followed by a gap, and then at the tail end, one more pair of prolegs. What has happened here is that the furcula caterpillar has converted these into two long tentacles that it normally carries behind it (see second picture), but that when approached by a predator, it can pump fluid into to extend their length almost double.

What it does then, which you must see to believe (which you will see in the next series of pictures), is, it faces the approaching predator (in this case, my finger), throws those tails up over its head, extends them as long as it can, then slaps them down on the ground in front of its head (actually making a sound you can hear from a few feet away). It has very much the appearance of a scorpion striking its venomous tail down, and a small predator might very well move away, thinking it got off with a close call.

Now that little trick, pretending to be dangerous when it is actually harmless, and constantly eating, may get the defenseless caterpillar through this perilous period of its life as fast as possible before something catches and eats it. But there is still a serious hurdle to get over. It must spend many months in a cocoon changing from larva to adult, a time when it will be even more defenseless, even more slow moving, in fact not moving at all. Now every caterpillar faces this, and there are a number of dodges they use to get through it, maybe buried underground or under the leaf litter or camouflaged as chip of wood or a dried winter leaf. The furcula does this in its own way.

As you might have noticed, the White Furcula caterpillar comes in two color phases, green like this one we photographed in the wild doing its scorpion trick, and the yellow phase we photographed at the beginning of this blog, a different individual, which we brought home with us because it looked full grown, and we thought it was close to making its cocoon, and we wanted to watch the process.

Sure enough, after about a week it flattened itself against a narrow stick which was about its own diameter and spun a thin cage around itself, thin enough that we could still see it inside busily continuing with its spinning.

After several hours it had woven enough silk around itself that the cage was now opaque, and had somehow taken on the color of the stick.

And here is how (if we had left it outside) it would have spent the winter, hiding in plain sight disguised as a little thickening around a stick. We kept ours in a jar (just in case its trick didn't work) out in the unheated garage, knowing that it needed to experience some freezing temperature in order to complete the metamorphosis pattern and emerge at the right time. It had made its cocoon August 19, 2016.

Once it warmed up in spring, we moved the jar into the house and kept it on the dining room table, so we could keep a careful eye on it. On April 21, 2017 while we ate breakfast, we checked the jar and saw a hole in the side of the cocoon.

We took the moth out on the porch that night, took some pictures of it in the twilight, then let it go. Perhaps its final ploy was to become a beautiful moth so that we would feel well rewarded for looking out for it for eight months, giving it a slightly better chance of finding a mate, getting some eggs laid, and perhaps projecting itself into the next generation.