Donna Garde, the superintendant of Lake Tawakoni State Park in Texas, took the following photo on August 15, 2007:
Donna sent this and other photos to people at Texas Parks and Wildlife (TPW) in an email titled, “Hollywood Spiders.” She said she was seeing spiders that “can extend their legs front and appear to be reddish-brown twigs.” Long-jawed orbweavers (family Tetragnathidae) are well-known for camouflaging themselves as twigs. But they weave orb webs, not massive tree-engulfing sheets.
On August 24th I received an email from Mike Quinn, invertebrate biologist for TPW, with the photos attached. My immediate thought: caterpillars, not spiders. Others on the distribution were thinking similarly. Fall web worms were considered, as were bark lice, but both were quickly ruled out. By the end of the day there seemed to be only three possibilities:
- A colony of some undetermined species of funnel spiders.
- The social spider Anelosimus studiosus, a cobweb weaver.
- A failed mass-dispersal of spiderlings.
Mike Quinn immediately went to work documenting Anelosimus studiosus on his web site, TexasEnto.net, just in case it turned out to be this critter. He also began documenting a chronology of developments surrounding the web. However, the web didn’t look right for the social cobweb spider, and the only explanation that seemed to have any hope was a failed mass-dispersal event.
Soon after escaping their egg sacs, young spiderlings often release long strands of silk into the air. When the strand is long enough, the spider goes air-born and flies away. This is called “ballooning.” Each egg sac can yield hundreds of spiders, and there can be many egg sacs. If all of the spiderlings take to the air at the same time and all are carried to the same place and even the same few trees, it may be possible for the webs to engulf the trees in a fashion similar to what we were seeing here. This wouldn’t be what the spiders intended, though. The reason for taking to the air is to disperse themselves to reduce competition among them, not to land all in one spot.
But all of these hypotheses seemed unlikely. I was still thinking caterpillars and so was only half-interested. Besides, I was nursing a foot injury and didn’t think it wise to make the trip. So I forgot about the web…