Thursday, July 26, 2012
Around the house
I took this picture standing on the bridge leading to Hatchie Coon Island. This is part of the St. Francis floodway, normally a flowing channel, but, two weeks ago when I took this, down to a few glorified puddles. The egrets are cleaning up the last of the stranded fish. By now I expect even this water is gone.
In our yard we are trying to keep things watered so there will be nectar flowers blooming, so there will be fresh green leaves, but if you pay attention to the arthropods, you will note how relatively little activity there is. For instance, judging by the number of Argiope spiderlings present early in the year, each with its postage-stamp-sized web, I thought we would have the largest number of adults ever, and not long ago they were indeed beginning to molt into their adult size, each big female immediately acquiring one or more live-in boyfriends.
But something was happening: They weren't catching anything. Their abdomens weren't filling out with growing eggs. Snowberry Clearwings, a big day-flying moth that looks like a cross between a bumble bee and a hummingbird, are usually numerous in the yard, hovering in front of flowers, and they are a favorite prey of the big spiders. But lately if we see one in the yard it is an event. And something else is happening. One by one the Argiopes are disappearing. A raccoon comes through the yard every night, and maybe it has got an eye in for them, and is standing on its hind legs to pluck them out of their webs like succulent grapes. Or maybe bats are taking them out of the their webs at night, or the cardinals with their big beaks early in the morning.
In more normal summers in the past, when I would be working at my study and feel the need of a short break, I would walk around the yard until I could find ten species of butterfly. That usually took about five minutes, which was perfect. Of course some among those ten species, like Pearl Crescents or Least Skippers, would be in large numbers, a couple of dozen maybe. Just now, 11:30 in the morning, I searched the whole yard, and found two Pearl Crescents and one Silver-spotted Skipper. It's ninety degrees now, and perhaps some of the flowers have shut down nectar production, and a few more butterflies are hiding out somewhere. Big butterflies like swallowtails seem to be doing better than small ones. We have some small plants of bronze fennel and we have been getting Black Swallowtail eggs on them. Earlier we brought in five Black Swallowtail caterpillars to raise in the safety of the house. On an earlier blog I showed a picture of their chrysalises. Two of the butterflies have eclosed. First a female:
and shortly after, a more highly patterned male:
In a few days, we saw a female egg-laying on the bronze fennel, and a new generation was started.
Even though numbers of everything are way down in the drought, that doesn't mean there aren't almost daily surprises. For instance the other day when we walked by a woodpile in the backyard a huge moth flew up. We ran to keep up with it as it circled the yard several times, all black and with wings wider than those of any swallowtail. It looked like a bat but we knew immediately it was a Black Witch and waited for it to land somewhere to see if we would get a chance to photograph it. This spectacular big tropical species (six inches from wingtip to wingtip) wanders up from Mexico every few years, some of them getting as far as the Canadian border. A few times in the past they had made brief stops in our garage, but we had not seen one for years. This one finally flew over our chain-link fence to land on our neighbor's sheet-metal fence, picking out the single patch of orange rust on it to conceal its dark body.
On that very same day there was a second even more surprising visitor. Previously in our yard we had only had very small and spindly centipedes, scarcely worthy of the name. But on this day Cheryl lifted a pot and there was Scolopendra viridis, in the mainly tropical order that includes the biggest centipedes. This particular species reaches five inches in length. Its last pair of legs can give you a pinch like a crab's claw, but it is the two poison fangs in front which pack the real whallop. The species has been observed eating toads and lizards. They are not all evil, however: The female has been seen coiled about her children licking them. We knew these occurred in Arkansas but we had never seen one before, and certainly didn't expect our first one to be on our front porch.
Tuesday, July 24, 2012
Two recent (very successful) trips
On July 16th we drove up to the Harold Alexander WMA in Sharp County. This is one of our favorite places. In only 60 miles or so it gets us up out of the Delta and into the entirely different habitats of the Ozarks. We went up because we were getting cabin fever hiding out from the heat, and the forecast for the day was, that it was not going to be terrible: Partly cloudy and low 90s. When we got there we stopped at all our favorite places, and it was pretty empty of life. Very few butterflies, very few flowers blooming, very few robber flies. But we are into grasshoppers right now, and they are not as affected by the heat, and in the sparsely grassy places where we found them last year, two small slant-faces were out, Spotted-wing and Pasture Grasshoppers, and out on the dirt roads we found the first Wrinkled Grasshoppers of the year. These will soon be common everywhere. They are big grasshoppers, I think rather handsome with their big heads and bulky bodies.
Throughout the country, I read, they tend to have red wings, but a small percentage have yellow wings (the front wings on a grasshopper are sort of leathery covers for their flying wings, which are the ones with the sometimes bright butterfly-like colors that are concealed underneath until they take off). In Arkansas, however, this is reversed, and ours have dark yellow wings, except for about every twentieth, which surprises you by having bright red wings when it bursts up from your feet.
These were not the only new-for-the-season grasshoppers out. Also along the road we saw the quite charming Three-banded Range Grasshoppers, also large, with very nice marking. The dirt roads here are the only place we have found this species so far.
Even on the poorest days we never fail to see something extraordinary and unexpected at Harold Alexander. This day it was a robber fly, Microstylum morosum. It is almost two inches long, making it huge for a powerful predatory insect. It is one of the most dramatic insects I know of. They are found in open prairie or prairie-like areas in Texas and Oklahoma, with a few extending into extreme southwest Arkansas, at places like Grandview Prairie and Terre Noire. Most robber flies wait for a prey insect to fly overhead, then fly up and snatch it out of the air like a falcon. But these hunt more like accipiters, racing along close to the ground until they frighten a grasshopper into flight, which they then easily overtake and capture. A couple of years ago my friend Jeff Hoeper found a dead one near his cabin on the eastern shore of Lake Norfork in Baxter County. He lives in woods, not prairie, and his cabin is nearly on the Missouri border, more to the east than the west side of Arkansas. How he could possibly find one there was a mystery, and now the mystery is increased, because when we saw this one we were in deeper woods, and even farther to the east. But there it was, with its glowing green eyes, terrifying the grasshoppers along the dirt road where we had parked our car. Check out that beak, loaded with neurotoxins. Don't try to catch this one with your fingers.
Throughout the country, I read, they tend to have red wings, but a small percentage have yellow wings (the front wings on a grasshopper are sort of leathery covers for their flying wings, which are the ones with the sometimes bright butterfly-like colors that are concealed underneath until they take off). In Arkansas, however, this is reversed, and ours have dark yellow wings, except for about every twentieth, which surprises you by having bright red wings when it bursts up from your feet.
These were not the only new-for-the-season grasshoppers out. Also along the road we saw the quite charming Three-banded Range Grasshoppers, also large, with very nice marking. The dirt roads here are the only place we have found this species so far.
Even on the poorest days we never fail to see something extraordinary and unexpected at Harold Alexander. This day it was a robber fly, Microstylum morosum. It is almost two inches long, making it huge for a powerful predatory insect. It is one of the most dramatic insects I know of. They are found in open prairie or prairie-like areas in Texas and Oklahoma, with a few extending into extreme southwest Arkansas, at places like Grandview Prairie and Terre Noire. Most robber flies wait for a prey insect to fly overhead, then fly up and snatch it out of the air like a falcon. But these hunt more like accipiters, racing along close to the ground until they frighten a grasshopper into flight, which they then easily overtake and capture. A couple of years ago my friend Jeff Hoeper found a dead one near his cabin on the eastern shore of Lake Norfork in Baxter County. He lives in woods, not prairie, and his cabin is nearly on the Missouri border, more to the east than the west side of Arkansas. How he could possibly find one there was a mystery, and now the mystery is increased, because when we saw this one we were in deeper woods, and even farther to the east. But there it was, with its glowing green eyes, terrifying the grasshoppers along the dirt road where we had parked our car. Check out that beak, loaded with neurotoxins. Don't try to catch this one with your fingers.
July 22nd we drove up to Mountain View, in Stone County. Cheryl had booked a cabin for one night at the Folk Center. That way we could drive the 150 miles up Sunday morning, do stuff in the afternoon, do stuff the following morning, then drive home. We stock-piled enough food for our two cats, closed a door so they were in opposite sides of the house and couldn't tear each other's eyes out, and went. We didn't bother to look at the weather report.
We only take back roads if possible. So we went through Black Rock, Strawberry, Cave City. At Melbourne instead of turning off to go down the windy road to the White River and Mountain View, we kept on straight through and went to Calico Rock. We crossed the bridge into Stone County and came down 5 a little way and turned off at Culp Road and stopped by one of our favorite glades. Glades are wonderful specialized insect habitats where in the past we had gone to see the localized Arkansas population of Large Grassland Tiger Beetles (Cicindela obsoleta). The glade is a big open area with flat rock outcroppings, a kind of limestone pavement. Trees can't grow there, but there are small shrubby plants and low grass tufts, with lots of bare sandy soil. It was evidently too early in the year for the big tiger beetles, because we didn't see a one, but the place, even in the nearly 100-degree weather, was hopping with grasshoppers. Wrinkled Grasshoppers were out in numbers. And then, to our surprise, we found Rock-loving Grasshoppers, which evidently is a sign that, for all the limestone, the soil here is acidic. These are the famous lichen grasshoppers, whose pattern usually matches the particular lichen-covered rocks where they are found. Here's one.
The next morning we followed highway 14 on up into Searcy County and turned off at Spring Creek Road, and dropped on down the hill to the Buffalo River. This is another of our favorite places. Canoes put in here for float trips, and head off to the right towards Buffalo Point. We go down to the beach, and walk to the left along low dunes of flour-fine sand overgrown with willows. It's a good place for a variety of robber flies, but the two stars are Proctacanthus rufus and Proctacanthus hinei. These are large powerful robbers, and both largely red in color. They are very similar to each other, but P. rufus has a long and rather slender abdomen, and P. hinei has a long and double-thick abdomen. Normally they are found in two separate habitats, but in this one place they occur together, and in large numbers. The one thing that brings them together here is the especially fine powdery sand, in which both species deposit their eggs. Here is the pattern which we have pieced together in previous visits: In the morning the female P. rufus (we haven't seen P. hinei doing this) hunt along the river side of the piled up fine sand, searching in among the willows for horse flies and other large insects. Then, in mid morning, about 10:30, they start to move inland onto the small dunes to lay their eggs. The females have sharp-pointed digging tools at the tip of their abdomen, but instead of using them, it looks like they simply jam their abdomen deep into the very soft sand, and there they deposit their eggs.
The other side of the pattern is, at about 10:30 the males come flying in and set up territories along the softer fluffier patches of sand, waiting to waylay the females. By a little after noon they will all have vanished for the day.
We arrived after ten and walked along the beach side of the dunes. After we had gone a little way, I chased up a large insect carrying another large insect. It landed at a distance from me, and I looked with my binoculars and saw it was a female P. rufus carrying a large red paper wasp. When I approached more closely and looked again, I saw black marks on the thorax of the otherwise red wasp, which I believe made the species Polistes perplexus. The robber fly was very shy and kept flying away from me, but I finally got close enough for a distant shot which I have blown-up a bit to show you here.
By now we had gone as far up the beach as the dunes went, so we turned around, and followed back a path that was on the inside of the dunes. It was now after eleven, and the first of the males were arriving, and I took a picture of a big male P. hinei sitting on his territory. The females are shy and difficult to approach, and so are the males generally, but once a male gets on a good territory, it seems like nothing will make him move.
By this time the heat (it was 99) and the effort of slogging through the soft sand, had worn us down so much we got back to our car with relief, turned on the air-conditioner, had numerous drinks, and headed back to Jonesboro.
Saturday, July 21, 2012
Grasshoppers
We've been studying robber flies for years, and now, starting last year and continuing this year, we have begun studying grasshoppers. What a difference. We have gone from a top predator to the bottom of the food chain. Robber flies eat every insect they can catch, and it is surprising what big fierce insects they go after; grasshoppers are eaten by virtually everything, even human beings in many parts of the world, perhaps eventually even here. It's like studying lions, then switching to wildebeests.
The first thing I notice is, you might go into a meadow and see fifty or a hundred grasshoppers, and only five or ten robber flies. These are of course typical predator/prey ratios. A robber fly might eat a hundred insects in its lifetime, and so it needs these numbers. And it won't want stiff competition from other predators, so individuals will space themselves out.
There is also a life history difference. Robber flies have full metamorphosis. For a year or a couple of years they are out of sight as larvae living underground or inside rotting logs feeding on beetle larvae. We only see them when they emerge for a relatively short time as adults. Grasshoppers have partial metamorphosis, which means they are present, often, all summer long as nymphs, chomping on grass mainly, just as they will when they are adults. They are in fact small wingless sexless versions of the adults (but very difficult to identify till they reach their final stages). There are some species that overwinter as nymphs and emerge as adults in the spring, but most are only now, as we get into July, becoming adults with wings and functional genitals and identifiable markings so we have some chance to learn what they are. It sometimes seems to us like we have been waiting a very long time for the season to finally begin.
But now it is beginning to happen. For a long time there was a skittering of tiny nymphs ahead of us when we walked through the garden, but with each instar they looked more like the adults they would become, and now, one after the other, they are becoming adults. Here are some of the ones that are around now just in our garden.
Grasshoppers are divided into three major groups. First, the Slant-faced Grasshoppers, generally rather small, often slender species with a slanting facial profile, usually staying in thick vegetation. The first ones out in our garden were Short-winged Green Grasshoppers. Here is the female and smaller male. They are around half an inch long, and you can clearly see the slanting face.
The next slant-face out, larger and more elaborate, is the Handsome Grasshopper. These are very common everywhere, especially in short grass. Because they are large enough to have some meat on them, but still not as burly and powerful as some of the larger grasshoppers, they are a favorite prey of jumping spiders and robber flies.
The next major group is the Band-winged Grasshoppers. These are medium to large grasshoppers with long wings which are often brightly colored (orange, yellow, blue) and they can look rather like butterflies when they are in flight. Sometimes they hover in one place for an extended period, trying to look attractive for any females around. These are species of wide open places, fields, barrens, beaches, which is why we don't have many in our closely planted garden. Here, however, is the Northern Green-striped Grasshopper, which is common almost everywhere, and is probably the commonest grasshopper in the state if not in the nation. They can be recognized by the line through the eye that gives them a sad expression, and the blade-like keel that sticks up on their pronotum (the saddle-like structure over their thorax). The females are usually some shade of green, and the smaller males some shade of brown.
The last of the three major groups are the Spur-throated Grasshoppers. These include some of the commonest, and some of the most agriculturally destructive grasshoppers. If you have a garden, and if you let it run a little bit wild, you are likely to have the next grasshopper I am going to figure here, the Differential Grasshopper, and if your garden is like ours, you are going to have so many of them, they are going to eat you out of house and home and drive you to despair, but not, I hope, to the extent of using insecticides, which will also kill everything else in your yard. I don't know what this year will bring, but we have in the past, in really bad years, gathered them in mason jars, and carried them to the other side of the woods across the road from us, and released them. Here is a big heavy hungry Differential Grasshopper, easily recognizable by its size, and the jet black herringbone pattern on its hind leg.
There is a huge number of species, and a huge variety of sizes and shapes among the spur-throated grasshoppers, but they all have in common a little lump (the "spur") that sticks up between their front legs. I will change the angle of the above photograph so you can see the little yellow lump catching the light on both of these.
There is another spur-throat common in our garden now, very different in appearance from the Differential, and that is, the Olive-green Swamp Grasshopper. I enjoy having them here because they are quite attractive and interesting in their behavior, and also because the published range maps show them as occurring in the eastern half of the U.S., but not crossing the Mississippi to enter Arkansas.
In fact, just in our initial explorations we are finding the maps so inaccurate and incomplete I suspect very little work has been done on grasshoppers in Arkansas, and suspect if we stay with it we will be able to make some contributions to science, which is really fun for amateurs like us.
The first thing I notice is, you might go into a meadow and see fifty or a hundred grasshoppers, and only five or ten robber flies. These are of course typical predator/prey ratios. A robber fly might eat a hundred insects in its lifetime, and so it needs these numbers. And it won't want stiff competition from other predators, so individuals will space themselves out.
There is also a life history difference. Robber flies have full metamorphosis. For a year or a couple of years they are out of sight as larvae living underground or inside rotting logs feeding on beetle larvae. We only see them when they emerge for a relatively short time as adults. Grasshoppers have partial metamorphosis, which means they are present, often, all summer long as nymphs, chomping on grass mainly, just as they will when they are adults. They are in fact small wingless sexless versions of the adults (but very difficult to identify till they reach their final stages). There are some species that overwinter as nymphs and emerge as adults in the spring, but most are only now, as we get into July, becoming adults with wings and functional genitals and identifiable markings so we have some chance to learn what they are. It sometimes seems to us like we have been waiting a very long time for the season to finally begin.
But now it is beginning to happen. For a long time there was a skittering of tiny nymphs ahead of us when we walked through the garden, but with each instar they looked more like the adults they would become, and now, one after the other, they are becoming adults. Here are some of the ones that are around now just in our garden.
Grasshoppers are divided into three major groups. First, the Slant-faced Grasshoppers, generally rather small, often slender species with a slanting facial profile, usually staying in thick vegetation. The first ones out in our garden were Short-winged Green Grasshoppers. Here is the female and smaller male. They are around half an inch long, and you can clearly see the slanting face.
The next slant-face out, larger and more elaborate, is the Handsome Grasshopper. These are very common everywhere, especially in short grass. Because they are large enough to have some meat on them, but still not as burly and powerful as some of the larger grasshoppers, they are a favorite prey of jumping spiders and robber flies.
The next major group is the Band-winged Grasshoppers. These are medium to large grasshoppers with long wings which are often brightly colored (orange, yellow, blue) and they can look rather like butterflies when they are in flight. Sometimes they hover in one place for an extended period, trying to look attractive for any females around. These are species of wide open places, fields, barrens, beaches, which is why we don't have many in our closely planted garden. Here, however, is the Northern Green-striped Grasshopper, which is common almost everywhere, and is probably the commonest grasshopper in the state if not in the nation. They can be recognized by the line through the eye that gives them a sad expression, and the blade-like keel that sticks up on their pronotum (the saddle-like structure over their thorax). The females are usually some shade of green, and the smaller males some shade of brown.
The last of the three major groups are the Spur-throated Grasshoppers. These include some of the commonest, and some of the most agriculturally destructive grasshoppers. If you have a garden, and if you let it run a little bit wild, you are likely to have the next grasshopper I am going to figure here, the Differential Grasshopper, and if your garden is like ours, you are going to have so many of them, they are going to eat you out of house and home and drive you to despair, but not, I hope, to the extent of using insecticides, which will also kill everything else in your yard. I don't know what this year will bring, but we have in the past, in really bad years, gathered them in mason jars, and carried them to the other side of the woods across the road from us, and released them. Here is a big heavy hungry Differential Grasshopper, easily recognizable by its size, and the jet black herringbone pattern on its hind leg.
There is a huge number of species, and a huge variety of sizes and shapes among the spur-throated grasshoppers, but they all have in common a little lump (the "spur") that sticks up between their front legs. I will change the angle of the above photograph so you can see the little yellow lump catching the light on both of these.
There is another spur-throat common in our garden now, very different in appearance from the Differential, and that is, the Olive-green Swamp Grasshopper. I enjoy having them here because they are quite attractive and interesting in their behavior, and also because the published range maps show them as occurring in the eastern half of the U.S., but not crossing the Mississippi to enter Arkansas.
In fact, just in our initial explorations we are finding the maps so inaccurate and incomplete I suspect very little work has been done on grasshoppers in Arkansas, and suspect if we stay with it we will be able to make some contributions to science, which is really fun for amateurs like us.
Friday, July 13, 2012
Defensive and offensive strategies
When a powerful predator attacks a soft and defenseless prey, the prey animal must use some strategy to save itself. But also, when a soft and defenseless predator attacks a strong and dangerous prey, it too must use some strategy, if it wants to gain a meal. Here is an example of each I happened to witness in the last two days.
The Goatweed Butterfly is a bright orange butterfly you might encounter flying up before you as you are walking on a path through open woodland. The caterpillar of this butterfly feeds, as you might guess, on goatweed, a tough and gritty weed of rough places. During its development from egg to chrysalis, the caterpillar uses various ingenious strategies to preserve itself from being eaten. The one I am talking about here was a fully grown caterpillar, and its first strategy was to roll a thick and tough goatweed leaf into a tube and secrete itself inside that tube. As further protection, the caterpillar's skin exactly resembled the color and texture of the goatweed leaf, making the caterpillar virtually invisible. For the final stroke, if a predator looked down the tube to see what was inside, the caterpillar, with the aid of two fake eyes, resembled some very formidable sharp-toothed creature looking back out. Here are two illustrations of a goatweed caterpillar demonstrating these strategies. (The tiny pale bump at the bottom of the "face" is the actual head; all the rest is fakery.)
Yesterday I was walking by a patch of goatweed idly looking to see if any of the leaves were rolled. What I found was a rolled leaf under attack. A red paper wasp (Polistes carolinus) was after the caterpillar. Although adult wasps for the most part feed on nectar, their larvae are meat eaters, and this species of wasp feeds its young entirely on caterpillars. The adult is big and powerful and uses no strategy beyond brute strength to overpower caterpillars, then chew them up into a ball and carry them back to the nest. But perhaps this wasp had looked down the opening in the tube and been put off by the eyes and fangs it saw staring back. When I saw it, the wasp was doing its best to chew through the tough leaf to get at the caterpillar directly. It went round and round, opening up a hole big enough that the caterpillar was visible inside, and several times I thought the wasp would grab it by the head and yank it out, but evidently it didn't actually to see it, even though it was chewing at the leaf directly by the caterpillar's head. I was waiting for the caterpillar to be dismembered when to my surprise the wasp gave up and flew off to look for some easier-to-reach prey. I thought the wasp would return, but when I myself came back by the leaf fifteen or twenty minutes later, the caterpillar was still visible inside, evidently unhurt.
Now for the other side of the equation. The eaves of our house, and the outer window frames, are filled with House Spiders. These little gray spiders are about as soft and defenseless as you can imagine. Sometimes in the morning I see a mud dauber wasp flying along at the level of the eaves, almost like a milkman doing his rounds, stopping at each cobweb, pretending briefly to be caught in it, and if a House Spider foolishly runs out, matter-of-factly picking it up and carrying it off. But these spiders have diabolical webs. Not the cobwebby tangle, but the guy wires that go from the top of the window frame down to the window sill. I was eating lunch looking out the window, when I saw a wasp that was walking along the window sill, get its hind legs tangled in one of these guy wires. In its effort to pull free, it snapped the wire, which evidently had been pulled taut with great elastic stress. It immediately jerked the wasp's abdomen upward. The wasp dug its front claws into the window frame, and held on, literally, for dear life. I grabbed my camera and rushed outside and did my best to record what happened next.
The spider dropped down in an instant and immediately began wrapping lines around the wasp's wings to contain them, and attached further guy wires to its rear end and hind legs. The wasp dug in the claws of its front four feet.
As long as the wasp was attached to the ground, which gave it a base to push against, its greater weight, its armored body, its muscular legs, made it a hundred times stronger than the frail spider. The spider now carried the guy wires up to the top to attach them, each under great elastic tension.
And finally it was too much, and the wasp was jerked up into the air. In an instant the wasp's powerful legs were helplessly flailing in the air.
The wasp seemed to realize how desperate its situation was. Its jaws gaped wide open, waiting for any part of the spider that came within reach. Its sting was fully extended, probing and probing for a target. In a calm and businesslike manner, the spider worked in close, but just out of reach of the wasp's weapons, spinning the spider around as it completely hog-tied it.
Now it was time to deliberately seek out a soft place between the armored segments, and deliver the fatal bite.
It was all over.
These two stories may seem to come down rather hard on the poor wasps, but that was just what made them unusual and, for me, interesting to record. In the millions of years of wasp vs. caterpillar, or wasp vs. spider, I would guess the wasps are ahead several million to one.
The Goatweed Butterfly is a bright orange butterfly you might encounter flying up before you as you are walking on a path through open woodland. The caterpillar of this butterfly feeds, as you might guess, on goatweed, a tough and gritty weed of rough places. During its development from egg to chrysalis, the caterpillar uses various ingenious strategies to preserve itself from being eaten. The one I am talking about here was a fully grown caterpillar, and its first strategy was to roll a thick and tough goatweed leaf into a tube and secrete itself inside that tube. As further protection, the caterpillar's skin exactly resembled the color and texture of the goatweed leaf, making the caterpillar virtually invisible. For the final stroke, if a predator looked down the tube to see what was inside, the caterpillar, with the aid of two fake eyes, resembled some very formidable sharp-toothed creature looking back out. Here are two illustrations of a goatweed caterpillar demonstrating these strategies. (The tiny pale bump at the bottom of the "face" is the actual head; all the rest is fakery.)
Yesterday I was walking by a patch of goatweed idly looking to see if any of the leaves were rolled. What I found was a rolled leaf under attack. A red paper wasp (Polistes carolinus) was after the caterpillar. Although adult wasps for the most part feed on nectar, their larvae are meat eaters, and this species of wasp feeds its young entirely on caterpillars. The adult is big and powerful and uses no strategy beyond brute strength to overpower caterpillars, then chew them up into a ball and carry them back to the nest. But perhaps this wasp had looked down the opening in the tube and been put off by the eyes and fangs it saw staring back. When I saw it, the wasp was doing its best to chew through the tough leaf to get at the caterpillar directly. It went round and round, opening up a hole big enough that the caterpillar was visible inside, and several times I thought the wasp would grab it by the head and yank it out, but evidently it didn't actually to see it, even though it was chewing at the leaf directly by the caterpillar's head. I was waiting for the caterpillar to be dismembered when to my surprise the wasp gave up and flew off to look for some easier-to-reach prey. I thought the wasp would return, but when I myself came back by the leaf fifteen or twenty minutes later, the caterpillar was still visible inside, evidently unhurt.
Now for the other side of the equation. The eaves of our house, and the outer window frames, are filled with House Spiders. These little gray spiders are about as soft and defenseless as you can imagine. Sometimes in the morning I see a mud dauber wasp flying along at the level of the eaves, almost like a milkman doing his rounds, stopping at each cobweb, pretending briefly to be caught in it, and if a House Spider foolishly runs out, matter-of-factly picking it up and carrying it off. But these spiders have diabolical webs. Not the cobwebby tangle, but the guy wires that go from the top of the window frame down to the window sill. I was eating lunch looking out the window, when I saw a wasp that was walking along the window sill, get its hind legs tangled in one of these guy wires. In its effort to pull free, it snapped the wire, which evidently had been pulled taut with great elastic stress. It immediately jerked the wasp's abdomen upward. The wasp dug its front claws into the window frame, and held on, literally, for dear life. I grabbed my camera and rushed outside and did my best to record what happened next.
The spider dropped down in an instant and immediately began wrapping lines around the wasp's wings to contain them, and attached further guy wires to its rear end and hind legs. The wasp dug in the claws of its front four feet.
As long as the wasp was attached to the ground, which gave it a base to push against, its greater weight, its armored body, its muscular legs, made it a hundred times stronger than the frail spider. The spider now carried the guy wires up to the top to attach them, each under great elastic tension.
And finally it was too much, and the wasp was jerked up into the air. In an instant the wasp's powerful legs were helplessly flailing in the air.
The wasp seemed to realize how desperate its situation was. Its jaws gaped wide open, waiting for any part of the spider that came within reach. Its sting was fully extended, probing and probing for a target. In a calm and businesslike manner, the spider worked in close, but just out of reach of the wasp's weapons, spinning the spider around as it completely hog-tied it.
Now it was time to deliberately seek out a soft place between the armored segments, and deliver the fatal bite.
It was all over.
These two stories may seem to come down rather hard on the poor wasps, but that was just what made them unusual and, for me, interesting to record. In the millions of years of wasp vs. caterpillar, or wasp vs. spider, I would guess the wasps are ahead several million to one.
Monday, July 9, 2012
Still stuck in the garden
But we're still finding stuff. Let's start with this wonderful shot Cheryl got of a jumping spider with the enormous horse fly it had just caught.
Only a while before that she had taken another terrific spider picture, this one an arachnophobe might think she had taken under great stress, except she's not afraid of spiders, and didn't think a thing about it. A trapdoor spider had come up above ground and was running across the yard. Cheryl tried to slow it down so she could take a picture of it. She put all kinds of obstacles in front of it, but it kept running, until she put her hand down to block it, and it climbed up on her hand and stood still, and she took the picture with the camera in her other hand. It was a wonderful rubbery looking spider that might have been a plastic one you buy for a Halloween prank.
A last note on spider developments in the yard: The dozens of baby Argiope Golden Garden Spiders have been working themselves up the ranks. I believe they sit patiently in their webs until they've made a couple of good kills, which fattens them up enough to molt into the next instar. Some that have never caught anything are still dots in postage-stamp size webs. But the females who cast their nets in the most favorable spots are now in their penultimate molt. With one more molt they will be fully adult and ready for mating. Here is one of the successful ones (although frankly her web looks like one of those 1950's experiments where they fed spiders LSD to see what would happen). She may not realize it yet, but she already has a tiny boyfriend waiting in the background to be the first one on the spot when her big moment comes.
To switch now from fierce predator to mild nectar sipper: Because of all the acre-feet of water we are pouring into our garden to keep it at least half alive, we seem to have a fix on the neighborhood's butterflies, with many recognizable individuals spending every day with us. For instance, early in the spring the duskywings, a kind of large dark skipper, were out in droves, with Juvenal's, Horace's, and Sleepy Duskywing common, and the much scarcer Wild Indigo Duskywing occasional. Well, the first three have long since faded away, and now we notice we have two or three Wild Indigos visiting our flowers every day. It's odd to have the sometime rarest species become the commonest. Here is one of them.
Duskywings are an acquired taste. The different species all look practically identical, and they can be really frustrating to try to sort out. Often it's a question of examining tiny white marks on their upper wings. Sleepy has no white spots, Wild Indigo has a few, Juvenal's and Horace's have a few more, but in a different configuration from each other. If you're interested, click on the link (above) to Robber Flies of Crowley's Ridge, scroll down to the bottom of the page on the left, and click on Spreadwing Skippers.
Swallowtails are easier to tell apart. I reported on an earlier blog that, to try to keep them safe, we brought in some of our Black Swallowtail caterpillars to raise in the house. They have all made chrysalises now. Those on brown stalks made brown chrysalises and those on green stalks green chrysalises (don't ask me how).
They aren't in the clear yet. It's possible that before we brought them in a short-tailed ichneumon (a kind of parasitic wasp) laid an egg inside them. In that species the larva waits until the caterpillar forms a chrysalis, and it then systematically devours it from the inside, and in the course of time instead of a swallowtail butterfly an orange wasp-like insect emerges from the chrysalis. It's always a bit disappointing, but on the other hand, without these natural controls, swallowtail butterflies could cover the earth several feet deep.
More positively, the Spicebush Swallowtails that visit our phlox every day are in courtship mode. Here is a picture of a male hot after a female, and in this picture you can learn how to sex them: the female has bright blue on her hind wings, the male a paler sort of gray-blue.
The more closely you observe insects, sometimes the more bizarre they become. They are shape-shifters, many devote amazing, even artistic, energy to looking like something else. Look at this wonderful praying mantis behaving like a blade of dried grass.
He has a double purpose to be invisible. One, he wants to avoid being seen by a bird that might eat him, and Two, he doesn't want to be seen by an unsuspecting small insect that might land within reach of his spiky arms. Now here's a red wasp that wants to be seen. Its bright color advertises its painful sting, which will discourage most predators from trying to make a meal out of it.
Okay, now what if you used the back half of that dangerous looking wasp, and then stuck the front half of a praying mantis on it, and maybe for good measure added Lucy-in-the-sky-with-diamonds eyes? You would get something like this.
This is a Mantispid, a member of the very weird order of insects called Neuroptera, which includes Dobsonflies, Ant Lions, and Aescalaphids, creatures often looking like they were put together from the spare parts of other insects. A Mantispid's life history is stranger than anything you could imagine. As tiny just-hatched larvae they wander around until they find a spider, and they quickly climb onboard. If it's a female spider, they stick with it. If it's a male, they ride on it until it mates with a female, at which point they climb onto the female. They then wait until the female makes a nest and lays its eggs in it, and they get inside the nest too. Without complicating things to much, I can mention here that Mantispids undergo "hyper-metamorphosis." They have at least two larval forms, first the active one that climbs onto the spider, and second, a fat blobby one that sits grossly in the middle of the nest gorging on eggs and spiderlings. They do this until pupahood, and finally hatch out of the nest as adult mantispids, sometimes to the astonishment of arachnologists who thought they had brought home a nest of spiders to study. I'm just covering broad details, which are weirder and weirder the more deeply you go into it.
We've kept Mantispids for pets. They're very comical things, some mimicking the red Polistes wasps, others the black and yellow bands of yellow jackets. With astonishing speed they can catch a mosquito or other small insect in their grasping legs. These aren't large things, so unless you are watching for them, you are apt to miss them altogether, which would be a shame. Cheryl recently found the tiniest one we've ever seen, and photographed it next to one of her fingers for scale (her hands are the measure of all things when we are photographing insects). Here it is.
Only a while before that she had taken another terrific spider picture, this one an arachnophobe might think she had taken under great stress, except she's not afraid of spiders, and didn't think a thing about it. A trapdoor spider had come up above ground and was running across the yard. Cheryl tried to slow it down so she could take a picture of it. She put all kinds of obstacles in front of it, but it kept running, until she put her hand down to block it, and it climbed up on her hand and stood still, and she took the picture with the camera in her other hand. It was a wonderful rubbery looking spider that might have been a plastic one you buy for a Halloween prank.
A last note on spider developments in the yard: The dozens of baby Argiope Golden Garden Spiders have been working themselves up the ranks. I believe they sit patiently in their webs until they've made a couple of good kills, which fattens them up enough to molt into the next instar. Some that have never caught anything are still dots in postage-stamp size webs. But the females who cast their nets in the most favorable spots are now in their penultimate molt. With one more molt they will be fully adult and ready for mating. Here is one of the successful ones (although frankly her web looks like one of those 1950's experiments where they fed spiders LSD to see what would happen). She may not realize it yet, but she already has a tiny boyfriend waiting in the background to be the first one on the spot when her big moment comes.
To switch now from fierce predator to mild nectar sipper: Because of all the acre-feet of water we are pouring into our garden to keep it at least half alive, we seem to have a fix on the neighborhood's butterflies, with many recognizable individuals spending every day with us. For instance, early in the spring the duskywings, a kind of large dark skipper, were out in droves, with Juvenal's, Horace's, and Sleepy Duskywing common, and the much scarcer Wild Indigo Duskywing occasional. Well, the first three have long since faded away, and now we notice we have two or three Wild Indigos visiting our flowers every day. It's odd to have the sometime rarest species become the commonest. Here is one of them.
Duskywings are an acquired taste. The different species all look practically identical, and they can be really frustrating to try to sort out. Often it's a question of examining tiny white marks on their upper wings. Sleepy has no white spots, Wild Indigo has a few, Juvenal's and Horace's have a few more, but in a different configuration from each other. If you're interested, click on the link (above) to Robber Flies of Crowley's Ridge, scroll down to the bottom of the page on the left, and click on Spreadwing Skippers.
Swallowtails are easier to tell apart. I reported on an earlier blog that, to try to keep them safe, we brought in some of our Black Swallowtail caterpillars to raise in the house. They have all made chrysalises now. Those on brown stalks made brown chrysalises and those on green stalks green chrysalises (don't ask me how).
They aren't in the clear yet. It's possible that before we brought them in a short-tailed ichneumon (a kind of parasitic wasp) laid an egg inside them. In that species the larva waits until the caterpillar forms a chrysalis, and it then systematically devours it from the inside, and in the course of time instead of a swallowtail butterfly an orange wasp-like insect emerges from the chrysalis. It's always a bit disappointing, but on the other hand, without these natural controls, swallowtail butterflies could cover the earth several feet deep.
More positively, the Spicebush Swallowtails that visit our phlox every day are in courtship mode. Here is a picture of a male hot after a female, and in this picture you can learn how to sex them: the female has bright blue on her hind wings, the male a paler sort of gray-blue.
The more closely you observe insects, sometimes the more bizarre they become. They are shape-shifters, many devote amazing, even artistic, energy to looking like something else. Look at this wonderful praying mantis behaving like a blade of dried grass.
He has a double purpose to be invisible. One, he wants to avoid being seen by a bird that might eat him, and Two, he doesn't want to be seen by an unsuspecting small insect that might land within reach of his spiky arms. Now here's a red wasp that wants to be seen. Its bright color advertises its painful sting, which will discourage most predators from trying to make a meal out of it.
Okay, now what if you used the back half of that dangerous looking wasp, and then stuck the front half of a praying mantis on it, and maybe for good measure added Lucy-in-the-sky-with-diamonds eyes? You would get something like this.
This is a Mantispid, a member of the very weird order of insects called Neuroptera, which includes Dobsonflies, Ant Lions, and Aescalaphids, creatures often looking like they were put together from the spare parts of other insects. A Mantispid's life history is stranger than anything you could imagine. As tiny just-hatched larvae they wander around until they find a spider, and they quickly climb onboard. If it's a female spider, they stick with it. If it's a male, they ride on it until it mates with a female, at which point they climb onto the female. They then wait until the female makes a nest and lays its eggs in it, and they get inside the nest too. Without complicating things to much, I can mention here that Mantispids undergo "hyper-metamorphosis." They have at least two larval forms, first the active one that climbs onto the spider, and second, a fat blobby one that sits grossly in the middle of the nest gorging on eggs and spiderlings. They do this until pupahood, and finally hatch out of the nest as adult mantispids, sometimes to the astonishment of arachnologists who thought they had brought home a nest of spiders to study. I'm just covering broad details, which are weirder and weirder the more deeply you go into it.
We've kept Mantispids for pets. They're very comical things, some mimicking the red Polistes wasps, others the black and yellow bands of yellow jackets. With astonishing speed they can catch a mosquito or other small insect in their grasping legs. These aren't large things, so unless you are watching for them, you are apt to miss them altogether, which would be a shame. Cheryl recently found the tiniest one we've ever seen, and photographed it next to one of her fingers for scale (her hands are the measure of all things when we are photographing insects). Here it is.
Sunday, July 1, 2012
Estivating
This is no time to go out. We're lying low. If we go out at all, it's somewhere close, and we go for the morning only. We try to remember to hydrate ourselves in advance. Mostly now, we don't go out at all. We hydrate our yard, everything in the front yard gets watered one day; everything in the backyard the next. Luckily that means the insect life continues in our yard, and that is where we observe most of it.
The common moth here now is the pretty little Girlfriend Underwing.
By day a few roost in the garage and whirl up when I walk in, and hide in the trees outside. They are on our windows, and get into the house. Mostly we find them dead; perhaps their life is very short, like most moths, or perhaps they are drying up in the drought.
I go out to the pond first thing in the morning, and the bright orange Zabulon Skippers have staked out territories on the pickerelweed, or on the button bush, and chase off everything that moves while they wait for the shy females. But so far the females that come out have already mated, or anyway, reject the males' advances. I would love to get a picture of them mating, the two sexes are so different from each other, and both very pretty. Here is the male, then the female.
To add drama, there is often a robber fly hanging around, ready to snatch out of the air whatever flies by, but perhaps the little skippers are too fast even for that falcon-like killer.
Another thing we can do if we do it before the heat of the day when everything hides: We can follow the progress of our caterpillars. I have already mentioned our Milkweed Tussock caterpillars. They are continuing their march (something like Sherman's) from one Common Milkweed plant to another down our driveway. There are about 35 plants, so their work is cut out for them. Here is a picture of a plant yesterday, followed by a picture of that same plant today.
The first wave, a size bigger, has now moved on to the next plant.
A few years ago a friend gave us two small rue plants, and even before we got them out of their pots and into the ground a Giant Swallowtail (very rare in our neighborhood) had come by and laid an egg on each. We hatched them and raised them half way, but we could predict the rue plants would be gone before the caterpillars were ready to make their chrysalises, so eventually we had to make the 150-mile round trip back up to the Ozarks to beg for some more rue plants. We did successfully raise the two Giants. One of the rue plants survived and by this year had doubled its size, when one day we looked down to see (though we had seen no adult Giant Swallowtails in the yard) fully twelve Giant Swallowtail caterpillars on the plant.
This was an act of idiocy on the part of the butterfly since the plant had barely enough sustenance for one caterpillar. We were already planning our rescue trip to the Ozarks when we looked one morning, and all the caterpillars were gone. We suspected the cardinals that nest in our yard. When they get their eye in for one of our favorite caterpillars, they quickly eat every single one. Perhaps it was a good thing to get that mother swallowtail's genes purged from our Darwinian universe, but to continue: This year, friends had given us some small bronze fennel plants which we had scattered through our raised beds, and very quickly we had six or eight Black Swallowtail caterpillars which pleased us very much.
But the more we thought of them there, the more we worried about their vulnerability to our cardinals, so in the end we moved six of them into the house to raise them under more protection. And for the fun of hatching them out. And because we didn't want them eating our new bronze fennel plants down to the nub. We could go to Krogers and buy parsley for them. (Perhaps this very slightly compromised our evolutionary non-intervention principles.)
The other caterpillars that we knew of in the garden were a bit more secretive, and perhaps could take care of themselves a little better. We have a small cherry tree in the center of the backyard we keep because it gets such interesting caterpillars on it. It had, for instance, started this year with some web-spinning sawfly larvae on it, which we may report on later. Right now it had a few Red-spotted Purple caterpillars. The Red-spotted Purple butterflies lay single eggs right on the pointed tips of the cherry leaves, and when the caterpillar hatches out it stays on the center vein and begins eating the leaf down to the stem. Here's one, perhaps escaping notice by looking like a scrap of dried leaf.
A few Senna plants volunteer in the yard every year. I think it's a pest some places, but we like it because of the Pierid caterpillars that use it, most often the Sleepy Orange. We remembered seeing the butterflies stopping on the plant to lay single eggs on the tops of the leaves. But the caterpillars, when they came, were so hard to spot that we only knew they were there by the leaves that began disappearing, and we searched those areas closely, and even then it took Cheryl's sharp eyes to find them.
Here it is ten o'clock in the morning and the temperature has already cranked up to 93. Life, to tell the truth, is rather cruel to the eager entomologist, keeping him cooped up in the house all winter waiting for summer to finally arrive, and then when it does, he finds himself still cooped up in the house, waiting for the summer to go away at least a little. I guess the best I can do for a while is some more garden reports.
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