Worker

(From 3.5e Monster Manual I - 2003):

Formians hail from the plane of Mechanus. They seek to colonize all that they see and incorporate all living things into their hive as workers. 

Expansionist in the extreme, formians are dedicated to spreading their colonies until they have taken over everything and their order is unquestioned. To further this end, they attack all other creatures, usually to put them to work building and expanding cities. Formians maintain these “conscripted” workers as well as those mentally dominated by the power of their taskmasters. 

A formian resembles a cross between an ant and a centaur. All formians are covered in a brownish-red carapace; size and appearance differs for each variety.

Formians build fabulous hive-cities in which hundreds of the creatures dwell. They are born into their station, with no ability to progress. Workers obey orders given by warriors, myrmarchs, or the queen. Warriors carry out the will of their myrmarch commanders or the queen. Myrmarchs take orders only from the queen herself, although they have different ranks depending on services rendered. These are not positions of power but of prestige. The most prestigious of the myrmarchs guard the queen. Taskmasters are equal in rank to warriors but seldom interact with other formians.

The Worker: This creature is about the size of a jackal or bulldog. It looks like an ant, but holds its head and thorax upright. It has humanlike shoulders and arms ending in rudimentary hands with blunt claws.

Workers are the lowest-ranking and most common formians. They exist only to serve, performing all the necessary, lowly tasks that the hive needs done. 

While workers cannot speak, they can convey simple concepts (such as danger) by body movements. Through the hive mind, however, they can communicate just fine—although their intelligence still limits the concepts that they can grasp. 

A worker is about 3 feet long and about 2-1/2 feet high at the front. It weighs about 60 pounds. Its hands are suitable only for manual labor.

Combat: Formian workers fight only to defend their hive-cities, using their mandibled bite. 

A formian worker’s natural weapons, as well as any weapons it wields, are treated as lawful-aligned for the purpose of overcoming damage reduction. 

Cure Serious Wounds (Sp): Eight workers together can heal a creature’s wounds as though using the cure serious wounds spell (caster level 7th). This is a full-round action for all eight workers. 

Make Whole (Sp): Three workers together can repair an object as though using the make whole spell (caster level 7th). This is a full-round action for all three workers.

(From Planescape: Planes of Law Monstrous Supplement - 1995):

"Had mine eyes ever beheld such beauty? To think, all fashioned by a bug!"

- Unknown traveler upon reaching a formian city

Native to Arcadia, formians are also called centaur ants. As their moniker indicates, they appear to he uprightwalking ants, but their sentience is that of warmblooded creatures as opposed to insects. They’ve always inhabited Arcadia, and sages say they always will. Though formians found on the Prime make war on each other, Arcadian formians of different hives have learned to live together peaceably. 

Similar to true ants, there are three basic types of formians: the worker, the wamor, and the myrmarch. (A fourth type, the queen, is extremely rare.) Unlike ants, formians’ waists are flexible; thus, they often move with only four legs, their heads and thoraces raised. Their forelegs are jointed at the wrist and have three opposing claws, which they can use to manipulate objects and to attack. Formians come in various subdued colors, which serve no function other than to indicate their cities of  origin.

Formians of warrior level and higher can communicate with humans, though their version of common sounds more like eerie chittering. They communicate with one another in their own speech, which is incomprehensible to most other beings.

The Worker: The smallest of the four formian types is also the most commonly encountered. It’s about the size of a large dog. Its claws are somewhat clumsy, though they make efficient tools for manual labor. 

Combat: When workers attack (a rare occurrence, for they’re used only if a city’s under siege), they use their small mandibles to bite for ld4 points of damage.