Family EupterotidaeThis was the most amazing sight. In Addo Elephant Park where I found them, I at first thought it was spiderwebs between the small bushes as each one was very large, about 40-50cm in diameter but on closer inspection found they belonged to the caterpillars of the White Monkey Moth.
There were thousands of caterpillars all over the place and one could not ride or walk without tramping on them.
There they call them Karoo Tented-caterpillars.
The caterpillars crawl along the lines spread out from the main nest in order to get to other host plants which were dead as it was winter but looks like it might be one of the Senicio species of plant.
Some of these web extensions were about 2m in length.