We now have four giant spider webs in Texas, all apparently being made by the same species of long-jawed orbweaver, the Tetragnatha guatemalensis. When we compare the locations of these sites, we notice something interesting. Have a look at these maps. The yellow dots indicate known webs. You may click on a map to pull up the location on Google Maps.
All four locations occur on a large lake. Two are on Lake Tawakoni, and two are on Lake Travis. Moreover, they are all on points that project into the water at a place where the lake is wide, or they are islands in a wide region of the lake. This may be coincidental, but there is reason to suspect otherwise.
At Lake Tawakoni State Park, millions of midges would fly in from the lake at dawn and again at dusk. Midges are flies that look like mosquitoes to most people, although many have a greenish tinge. Here are some photos:
Just like mosquitoes, midges live as larvae in the water and emerge from the water as adults. They look like mosquitoes as adults, except that female doesn’t have the needle proboscis for sucking blood. Unlike mosquitoes, midges don’t bite.
We don’t have an identification on the midges yet, but there are some things we can safely say about them without knowing their exact species. The adults fly in clouds to mate. At Lake Tawakoni, I could hear the hum of these clouds above the lake when they emerged. It lasted for about an hour at dusk and for about half an hour at dawn. As I stood on the lake shore, the loud hum unmistakeably came from the lake, as the inland vegetation was comparatively quiet.
After the emergence, the hum would die down, and I would walk back to the giant web. Close to the giant web I could hear the hum again, coming from the direction of the web. I knew there was a bog on the other side of the web, so I thought maybe it was coming from there. However, when I walked around to the side with the bog, it was relatively quiet and I heard the hum again coming from the direction of the web. Since the web was catching hordes of midges, it seemed obvious that the loud hum was the sound of thousands and thousands of midges caught in the web.
I thought the mystery was solved, until one night I walked out to the web at dusk. As I walked the trail I heard a loud hum coming from a new direction, a direction away from the web. I excitedly thought that I may have discovered another web, and I diligently walked towards the sound, traipsing through the woods as necessary (the park had given me permission to go off trail).
However, the more I walked, the more confused I got. The hum would get really loud, and I would see no web. I’d walk in all directions around a loud area, eager to find that nearby web, but in every direction I walked, the hum would grow quiet again. I felt like I was in a fantasy novel, lost in an ever-changing maze.
I continued walking and suddenly noticed the pattern. Walking in a clearing was quiet, walking in the woods was loud, and walking through tall, dense trees was the loudest. The more volume the vegetation filled in a place, the louder the hum was in that place.
The midges weren’t humming because they were stuck in the web! The midges were humming because they were roosting in the vegetation! And they were particularly dense in the trees, which provided the most volume for roosting. No wonder the spiders made their webs in the trees. That’s were the midges were going.
So this may be the reason why the spiders are making their webs on points and islands. That’s where the midges are dense. Midges appear to be attracted the nearest land mass, and a land mass surrounded by water might get a lot of midges. These webs exist only because of the super abundance of food—the super abundance of midges—and so it may be that the midges are themselves choosing the locations of the webs. But why doesn’t this happen on every point and island, in every year? Texas had an especially rainy year, after a long draught, and that may answer half the question. Perhaps the high water levels made especially suitable shallows for midge larvae to develop.
Here’s a video of midge clouds and spider feasts. Early scenes show clouds of midges, but one scene shows dragonflies scouring the shoreline scooping up midges. There are also scenes of especially greedy spiders collecting midges into midge-balls and eating the midge-balls like they are corn-on-the-cob. The final scenes appear to show the long-jawed spiders scavenging, plucking apparently dead midges off the web. Enjoy!