Dweller: A lite version of lost Burrower drone, the Dweller is variety of worker drone. It head has now shrunk back into it's segmented body, and it's limbs have now been pulled in much closer to body and barbs removed. It's middle legs serrated ridges have been made less flexible as been adjusted to dig through most things faster than any worker could. It's given up most of it's IR vision and compound eyes are of much simpler function than that of a worker. Instead it's antenna has become sensitive to ground tremors and noise allowing it get into position for ambushing enemy infantry.
The dweller main focus is on digging trenches and lying in wait underground to drag oncoming enemy's into it's prepared pits. It weak in open combat but hiding underground makes up for it.
I rather do like the idea of an ant lion. That being said...
Symbiotic BloodwormsA new creature for the swarm, it's template structured based off of innumerable mundane parasites. It's life cycle is best described beginning with the pupae (we'll cycle back around to the larvae in a minute), which can exist in a dormant state within the bloodstream of any of the hive's creatures. In their pupal state, the bloodworms have virtually no impact on a Hive host organism.
When blood is exposed to atmosphere and begins to congeal, this triggers the pupal bloodworms to finish their morph and emerge from their pupae as minute, sluglike creatures. On a Hive creature, these bloodworms are capable of distinguishing between living and dead flesh, and will exclusively chew away dead tissue in order to combat infections that would otherwise burrow under chitin and fester. On humans (and animals) the bloodworms are less discriminant, and will consume relentlessly, devouring soft tissue.
In this mature state, the bloodworms will go through to major reproductive states: asexual multiplication, and egg-laying. Asexual multiplication is achieved through what amounts to budding, where individual bloodworms will clone themselves in order to more effectively utilize any resources they have available. When the colony of bloodworms reaches critical mass due to clone population density, the bloodworms will begin the coagulate and merge into a peculiar structure, somewhat akin in profile to a dandelion with a full seed-head, except the stalk and head are constructed from toughened flesh. Sexual reproduction occurs and fills the bulbous head of the structure with bloodworm eggs, some of which will remain dormant, and others of which will hatch, pupate, and emerge to slither back down the bulbous fruiting-body and rejoin the main mass of adult bloodworms.
In this manner, bloodworms can spread across a battlefield, an unsuspecting human, or a wounded Hive Warrior in short order. In the case of the battle-field, which changes the landscape until the ground is covered with fleshy growths topped in spherical bulbs of bloodworm eggs. For the wounded hive warrior, this can result in odd-seeming growths sprouting from injuries. The purpose of these growths is to recycle nourishment back into our hive warriors (and drones, if needed). When the seed-head is ingested, the bloodworm eggs burst and hatch, the minute larvae wriggling into the bloodstream via the mucus membranes, and then pupate withing the blood, ready to begin the cycle anew. The fleshy seed-pod itself, however, is designed to carry a great deal of the material the bloodworms consumed, and is nutritious in its own right.
Of course, any animal other than a hive creature who consumes one of the bulbs will rapidly be filled with bloodworms, which hatch as soon as they've finished pupating in any substance other than the blood of a hive creature. The resulting infestation is gruesome.
tl;dr: Convert battle-fields into long term food storage and give our hive creatures infectious blood!