Press "start" to set going, and "stop" to halt. Clicking on any web will bring up data on that spider at the bottom, including a moving graph showing spider energy store (red), and start-builing-web trigger energy level (blue). The spiders are busy when the background to this graph is black, idle if it's white.

This simulation has 3 kinds of spiders making 3 different kinds of webs. Fly size is progressively reduced every 500 time units, depending on the energy store levels in the current spider population. Every 5000 units, the energy level is raised to a high level. A mass death (more than 5 spiders dying in any single 500 days) also results in fly size being increased. As flies die when there energy stores are exhausted, the remaining spiders shift up to make a space for a new spider at bottom right. The new spiders go +-5% further round the perimeter to make a strand in their web.This tends to result in the oldest spiders being found at top left. On a 133 MHz Pentium, it takes 4-5 hours for the results to settle down to one kind of spider making a relatively uniform size of web.

If the perimeter spiders manage to start with a web with a relatively small hole in the centre, they generally come to predominate. But it's equally likely that ladder web spiders or random web spiders will take over.