The Antlion Soldier is the most commonly encountered caste of Antlion in Half-Life 2 and its sequels. This creature is a large, four-legged insectoid beast around 3 to 5 feet in height and 6 feet in length. Their limbs are oddly configured, with the hind legs reaching to the front and vice versa. Their hard shells are mostly green with stripes of tan, yellow, purple and red. They have no visible eyes, and have three mouthparts arranged in a triangle on their face. Hidden beneath the Antlions' shells are wings which allow it to fly several feet in the air, making a loud buzzing noise as they take to the air. They are also quite powerful burrowers, able to tunnel through solid rock and even concrete.
Antlion Soldiers are charged with gathering food for their nests, using their keen senses of touch and smell to track their prey. Once they pinpoint a potential meal, they swarm the target relentlessly, biting and headbutting their prey until dead, after which they return to their nests with their kill to feed their hungry brood.
Antlions are vicious pack predators. Their favored method of accosting prey is to bury themselves in soft sand, sense for vibrations around them, then emerge and ambush the intruder. They usually form swarms so large that even a well-armed opponent will be quickly overwhelmed. Although they are blind they are extremely sensitive to vibration, which allows them to follow their enemies wherever they go once detected. This sensitivity can be turned against them; Thumpers, machines which pound the ground rhythmically, overload their senses causing them discomfort and preventing them from advancing on prey near them.
Antlions attack with their sharp claws and teeth. Those fleeing on foot or seeking higher ground will find no sanctuary from them; they will fly at opponents above or a distance away from them. They will fearlessly attack and pursue their target regardless of hazards they are faced with, and will continue charging even as fellow Antlions die in front of them. This includes charging into moving vehicles and into water, despite the fact they cannot swim. Antlions are both fiercely territorial and invasive. They will sweep into neighbouring territory if it is not properly protected.
Antlion Soldiers are fairly weak physically and their strength lies in their numbers. They are attracted by rhythmic vibrations so walking through Antlion territory is nothing short of suicidal unless properly equipped. Most small arms are enough to kill an Antlion, but they never hunt alone. The best way to avoid Antlions is to deter them using Thumper devices that produce vibrations to attract the creatures.
The Vortigaunt once practiced the ancient art of Antlion husbandry on their homeworld and they did this by harvesting pheromones from Antlion Guards. They produced Pheropods - also called Bugbait - which would release pheromones to attract Antlion Soldiers which would protect the Vortigaunt from potential threats. During the Combine occupation of Earth, the resistance in City 17 utilized Pheropods to summon Antlions to fight the Combine Overwatch.