An ant script saved from https://github.com/jywarren/antfarm

ant.js

onRun = function() {

  this.direction += Math.random()*10-5;
  if (this.green() > 0) {
    this.energy += this.green();
    this.green(0);
  }
  if (this.energy <= 0) this.die();
  this.color = "rgba("+this.energy+",0,0,1)";
  this.energy -= 1;
  this.trail('green', 255); // color, amount

}

onBump = function() {

  this.direction += 90;

}