At some point pre-2011, an anomaly allows a colony of the giant burrowing insects through into the underground level of an under-construction shopping mall. The insects then burrow a network of underground tunnels beneath London, and go into hibernation in the shopping centre.
At around spring though, one of the insects awakes from hibernation, and searches the underground tunnel network for food for the rest of the colony once they wake up. When a worker accidentally creates a hole in the street into one of the insects' tunnels during roadworks, the scout burrower attacks him and takes him back to the colony to be cocooned.
Later, Matt, Abby and Becker arrive at the scene of the attack, and climb down into the tunnel which the creature made during its last attack. The burrower returns for the trio. Abby opts to tranquilise it and have it placed in the Menagerie, Matt however, that it's from the Future and therefore dangerous, tells Connor ans Abby that they have to kill it.They try to take the creature down with their EMDs, but the shots only slow the insect down due to its armour plating, forcing the three to narrowly escape to the surface.
The creature next surfaces at a backyard barbeque, attacking one of the neighbours, and dragging him underground back to the nest. When the team arrive, Matt uses vibrations from a lawnmower to successfully draw the insect back to up. It resurfaces, but due to Connor's untimely arrival, the creature is able to drag Connor back underground with it, but not before being shot several times with firearms in its unprotected face.
The insect then returns to the nest with Connor, and dies of its wounds before it can cocoon Connor. Connor then discovers the rest of the colony, still in hibernation, and unintentionally disturbs them while turning on the building's gas. As the creatures begin to awake, Matt arrives, and he and Connor retreat back to the shopping centre's underground level with one of the insects following close behind.
However, before it can capture Matt and Connor, the ARC team detonate explosives which ignite the gas in the building, and wipe all the insects out.
The Burrowers appear to measure between 7-10 feet long with two shovel-like forelimbs and two pair of antennae. The Burrower also appears to have small pincers.
The Burrowers appear to live in colonies, ranging from 20-50 animals. A nest that could hold all these animals would have to be big, and would take a while to build, even with so many workers. However, the Burrowers would also appear to use spaces (such as the shopping centre in the present).
The hibernating periods of these animals appears to copy that of modern day insects. Going into hibernation during the winter, and remaining dormant until the ground begins to get warmer. This would explain why only one Burrower was active in Episode 5.1. As it was the only active animal, and it was collecting food for the colony, it would suggest, though not prove for certain, that the first Burrower to awake would leave the nest and enter the tunnels to collect food for the rest of the colony once they wake up.
The Burrowers also appear to have armour plating resistant to bullets and EMDs, and are impressive burrowers. However, a Burrower's face is unprotected by its exoskeleton from bullets, making the face a weak point, and according to Matt, the Burrowers can't burrow through concrete.