This type of Bug appeared as a large armored Arachnid that shared a physiology similar to a crab. Their faces consisted of eight eyes and a hard shell protecting them from attacks. Its powerful four legs allowed it to easily hop through its surroundings allowing the Bug to easily jump from one tree to another or to make rapid attacks in its environments. In addition, it had a wicked set of pincers around its mouth that can leave near fatal bites on its prey. Furthermore, borrowing from their name, the Jungle Spider can shoot out a sticky web from its abdomen that can quickly cocoon enemies for later use. This allowed the creatures to quickly take out individual enemies without killing them.
There are apparently two types of Jungle Spiders; a rare larger version that is much bigger than a normal and a smaller type. The larger type are especially hardier and can take a great deal of weapon fire to eventually kill it. They are also able to cocoon enemies in their webbing and hold them around their abdomen for transportation through the trees. Jungle Spiders are noted as being quite fast and dangerous which allowed them to be used as shock troops in combat.
Its not known when the spiders were first created as "Colonel" T'Phai was unaware of their existence on Tophet. The first encounter with this subspecies was the Tesca Campaign where a single large specimen engaged in commando operations against the Roughnecks. This single spider managed to cocoon various troopers within the Mobile Infantry and place them for later consumption. Its actions managed to take out the majority of the Roughnecks leaving Private T'Phai and Johnny Rico the only free members of the squad. Whilst capturing Dizzy Flores, the creature damaged Private T'Phai's environment suit leading him to slowly die of the cold due to the different environment. It was only after being cocooned by the Jungle Spider did he survive as the webbing preserved him long enough for Jeff Gossard to save him. T'Phai also helped Rico in eliminating the Jungle Spider which was mortally wounded by a grenade shot before it fell from a cave ledge onto a bed of spiky rocks.
After the initial encounter, the subspecies became more common on the battlefield with numerous smaller Jungle Spiders engaging Mobile Infantry forces. During a mission to a suspected Brain Bug base, the Roughnecks managed to break into the Arachnid base from underwater. After breaking through into the colony, a number of Jungle Spiders arrived and used their webbing to seal the break where water was flooding the hive. A number of Jungle Spiders also captured a pair of Seal Sharks that broke into the hive and cocooned them whereupon they were taken to the hatchery where Nurser Bugs used their genetic material to evolve future Bug strains. Roughnecks' Jeff Gossard was first injured by a small Jungle Spider, suffering a corneal abrasion that restricted his vision. Team medic Doc LaCroix advised Lieutenant Razak to assign a replacement for Gossard's Marauder unit. Johnny Rico was first assigned the replacement for Gossard's Marauder. During the mission to locate the Brain Bug base, Rico was critically wounded by a small Jungle Spider after abandoning the Marauder suit after its power supply was completely drained.