Showing posts with label Banana Spider. Show all posts
Showing posts with label Banana Spider. Show all posts

Tuesday, October 2, 2012

Golden

Golden Silk Orbweaver
By the time fall rolls around in Gainesville each year, the Golden Silk Orbweaver spiders (Nephila clavipes) (aka Banana Spiders) have grown into their full glory. They first appear in early summer, small and yellow, and tend to weave their webs in low areas, across paths and near doors. But as their webs are disturbed they move higher or tuck themselves into more protected paths. If you look up into the utility lines, you can see web after web of smart spiders taking advantage of the convenient distance between the wires. The spiders that don't get gobbled up by hungry birds can get huge. These majestic creatures can achieve a leg-span of 4-5 inches. Their webs are wondrous as well. They can also be huge--several feet across. The spider silk is golden, as their name implies, and is very strong.
Golden Silk
If you walk into one of the webs you can feel the strength of the strands. The webs have as much tensile strength as steel. Scientists noticed this and have tried to use Nephila silk to make stronger, lighter parachute straps, bullet proof vests, and other materials that need to be strong. Fishermen in Malaysia and Indonesia use webs from a related Nephila spider, wrapped around a branch, to catch fish. People have even used the silk to make glorious golden cloth. Here's a link to an incredible video about creating a cape from spider silk.

This spider set up a web under our living room window. The web is about 4 feet across, stretched between a tree and a bush. It is tucked out of the way of foot traffic, but will catch the insects drawn to the lights of the house.
House Spider
Looking closer at the web, I realized that at least 12 Orchard Orbweaver Spiders had used the strong strands of the web as supports for their own. Unlike web parasites, small spiders that live in a large spider's web and steal the insects that are caught on the periphery, this arrangement is more like camp ground. They catch their own food. Except that I can't see what's in it for the Orbweaver.

One of the "Campers"
There was another small spider in the web--the male. Male Golden Silk Orbweavers are comically small. People mistake them for baby spiders. They stay close, but not too close to the female, and hope to mate without getting eaten.
Male (upper left) and Female
When they do mate, the female will spin an egg sac. The spiderlings will overwinter in the egg sac and emerge in the spring. The big spiders usually die when the temperatures get too cold. Sometimes in the early winter I will find a wilted spider hanging limply from its web, only to see it revived when the day warms up. One year, a spider set itself up next to our front porch light and managed to stay warm enough from the heat of the light to last 2 full seasons. We knew it was the same spider because it was missing a leg.

When we first moved to Florida, I found the Golden Silk Orbweavers scary and intimidating, because of their huge size, and the sticky strong webs that I often found myself tangled in. But I quickly learned how to avoid the webs and love the spiders. They bite, but are not especially toxic or harmful to people (they say the bite is similar to a bee sting). I've never been bitten, which says something about their disposition--everything bites me. I also know now that they are very beneficial because of the numbers of insects they trap in their webs. I no longer fear them, but look forward to their return each year. And each fall I revel in their golden beauty.
Golden Silk Orbweaver abdomen, detail

Sunday, September 16, 2012

And So it Goes...

A couple of nights ago my husband and I were walking our dogs when I saw something moving on the sidewalk ahead of us. As we got closer we could see that it was a big Golden Orb Weaver Spider (aka "banana spider") and some sort of large wasp. The wasp flew off too fast for me to identify it. I think I saw some red, but it was dusk and it all happened too quickly for me to really see it. I thought that if we waited for a minute, the wasp would come back. I suspected from the color and behavior that it was a Mud Dauber wasp. These are the harmless (unless you're a spider) wasps that build those tubelike mud structures on our houses. Mud Daubers paralyze spiders to feed to their young. They pack the spiders into their mud nests and lay eggs inside. The spiders are there, alive but immobile, serving as fresh food for the newly hatched spiderlings. So, getting back to the spider, it made sense that the flying insect was a Mud Dauber. However, what didn't make sense was that the spider was too big for any wasp to carry anywhere. We waited for a few minutes, but the wasp didn't return. So we continued on our walk.

I didn't have my camera with me, so when we got home again I decided to go back and take some pictures. I figured that the wasp may go back and try to drag the spider away. I've seen wasps dragging some pretty big caterpillars, so why not? It took me a few minutes to find it, but when I got to the spot, the spider was still there, but no sign of the wasp. It made me a little sad. The big spider was so beautiful lying on the sidewalk with its hairy legs and elaborately painted abdomen. The legspan on this one was probably 3 inches. These are truly glorious creatures.
Golden Orbweaver Spider
As I looked at the spider more carefully, there were signs that it was dead and not just paralyzed. There was a puddle of something next to the spider, and as I looked closer, I could see ants underneath it, working furiously. I could see that there was a hole in the upper part of the abdomen. This spider was definitely dead. Maybe the wasp was a red herring. Something else could have killed the spider and the wasp was just passing by. Or maybe the wasp bit off more than it could chew and just gave up. I'll never know. In any case, the ants had discovered the spider and were making quick work of it.
Definitely Dead, With Ants Underneath.
The next morning I came back again to the spider to see how far the ants had come with their disassembling. The ants had been very busy. The spiders legs were still there, but the abdomen was flat and deflated. There was a liquid substance on the ground all around the spider's body. I suspect that the ants had emptied the contents of the abdomen because there were no shoe tread marks  and the rest of the spider was in place.
Next Morning
This morning I went back one last time, hoping to track the ants' progress. I was a little doubtful that I'd see anything because it rained yesterday afternoon. Also, the spider was on a sidewalk and could easily have been stepped on or swept away. But it was still there. It took me a few minutes to find it this time because there was almost no sign of the spider, only the dried up abdomen exoskeleton and some spider residue. The abdomen could easily have been mistaken for a piece of leaf along with other debris from the trees. There were no legs and no other signs of what had happened such a short time before. Just a shiny smear and a few meticulous ants scouring for crumbs. And so it goes...
Day Three. Note abdomen in upper left corner.