These are small floating, mechanical gunships dubbed "hovernets" by those who survived the first encounter with these things. They are aptly named - they hover above the ground through unknown means, and like hornets then can be extremely dangerous. They are armed with a light tachyon cannon. They can fly up and down without any restrictions, and they move very fast. It appears these machines are a sort of security system, deployed in case a landed or crashed UFO is attacked.