Note: This is not information that your average character would know. Great Spiders rarely ally with other races directly and are a very private species, making their culture a mystery to most. While Great Spiders can speak, only the most unfortunate of humans are likely to have heard them converse. Most humans who have fought such creatures, or know of them through adventurers' tales, would only know that they are monstrous in size and actions, can spin webs as strong as rope, have terrifying insect-like eyes (as opposed to spider-like eyes, a distinction from the lesser creatures of their race), and can inflict upon their victims a paralyzing venom.

Lore

Ungoliant, the Mother of the Great Spiders

Ungoliant aided the evil Vala Melkor in his attack upon the Two Trees of Valinor, draining them of their sap after Melkor had injured them, extinguishing the source of light for the world. She also consumed the reserves of light from the wells of Varda. Afterward the light of the trees persisted only within the Silmarils of Fëanor. Ungoliant helped Melkor evade the Valar by shrouding them both in her impenetrable darkness, causing blindness and confusion amongst the hosts of the Valar that attempted to intercept them.

Melkor had promised Ungoliant that he would yield anything she wished in return for her aid, but betrayed this promise by attempting to withhold the Silmarils from her. This angered Ungoliant, who, having grown immensely powerful from ingesting the life force of the Two Trees, trapped Melkor in her webs. At this point he gave out a cry of such fear and intensity that it was heard in the depths of Angband, and the Balrogs rushed to the aid of their master, scourging Ungoliant with their whips of flame.

Ungoliant fled to the Ered Gorgoroth in Beleriand. At some point she gave birth to Giant Spiders, including the character Shelob in The Lord of the Rings. In The Silmarillion, it is stated that when she went into hiding, and her hunger was such that she would mate with spiders only to devour them later, with her offspring to be used as food once they were fully grown. Few of her off-spring survived, and Ungoliant herself is believed to have eventually died of starvation. Some even believe that her hunger grew so ravenous, that she devoured herself in despair. As a Maiar, however, Ungoliant's spirit is much like Sauron's; she can never truly die, though few in Middle-Earth would understand such a concept.

Lineage

Giant Spiders were a sentient race of Great Spiders that lived in Middle-Earth. They lived in the South of Middle-Earth in the First Age, but by the Third Age they had spread to other areas including Mirkwood. They were descended from the spider-creatures of the Ered Gorgoroth (Mountains of Terror); there, Ungoliant mated with the non-sentient giant spiders of the region and gave birth to a new, sentient race of giant spiders. The descendants of these Great Spiders infested the great forest of Greenwood the Great after the shadow of Sauron fell upon it and it became known as Mirkwood.

Of all of Ungoliant's children, only Shelob is known to have survived throughout the ages. Like Ungoliant, Shelob would devour as many of her own children as she could, and was an extremely powerful half-demon creature immune to age and natural mortality. The Great Spiders of Mirkwood, their power lessened over thousands of years, can trace their lineage back to Shelob and Ungoliant.

Culture

The Great Spiders are sentient creatures capable of speech. Unlike most spiders, which tend to be individualist hunters, the Great Spiders of Mirkwood are collaborative in their lifespan. They live in colonies, where they serve a Queen Spider by carrying out specific roles meant to ensure the survival and propagation of their race. Spider Queens are oftentimes much more ancient than the majority of the race, and thus closer to their demon lineage and more powerful. The most capable Great Spiders are allowed to mate with the Queen if she deems them worthy, but all spiders mate frequently with one another; because finding enough food to feed a whole colony of Great Spiders is a constant challenge, most newborn are eaten, and only the strongest of a new brood are allowed to live. In this way, reproduction serves as a major source of food for colonies.

Societal Roles

Queen

The Queen of a colony acts as its spiritual leader. She passes on her take of the story of the race to her servants, instructs them on how to deal with outside threats, and enforces brutal punishment upon any in the colony that grow strong-willed enough to act or speak against her rule. All Great Spiders that live to see their tenth year are given a name by the Queen; these names usually reflect the Queen's level of respect for the creature, as well as its role in the colony.

Hunter

Hunters seek out food sources to bring back to the colony. Because Great Spiders have an incredible, maddening appetite, Hunters tend to be the strongest and most clever of the brood. They are able to choose the best mates, and the strongest Hunters are often chosen to mate with the Queen herself. Despite their voracious appetites, Great Spiders are wise about selecting their prey; they will eat any living creature, but are wary to pose too much of a threat to nearby civilizations. Many stories have been told about the fates of reckless colonies that have fallen upon a tiny village, only to be rallied against and destroyed by the armies of men.
 

Small groups of travelers, solitary hunters, wargs, orcs, and beasts make up the bulk of the Great Spiders' prey. Though most Hunters tend to be male, there are plenty of female Hunters as well; strength and cunning is valued in this role, and gender is unimportant.

Breeder

Breeders are female members of the colony that are not deemed fit for other roles within the society. They have a heirarchy of their own as they churn out brood after brood; the Breeders who prove to lay the most eggs are the highest in value, due to the increased food supply they offer. After that, the Breeders who prove to give birth to the strongest children are deemed the next most valuable; oftentimes, the oldest Breeders fall into this category, as the strength of the Great Spiders' demonic heritage threatens to wane with each passing generation.

Weaver 

Weavers are the builders of a colony's infrastructure, and are respected second only to the Queen. Like Breeders, Weavers rarely fight, unless a colony is directly attacked. Instead, Weavers tend to wounded Great Spiders and decide whether or not a creature is worth attempting to save. Weavers also build elaborate webbed structures in and around the colony. There are several purposes to these structures; they serve to make breeding a large number of eggs an organized matter, they serve to mark a colony's territory as it expands to keep out threats, they serve to prepare traps and fortifications to protect a colony and its Queen, and they serve the Great Spiders' simple religious beliefs. While Hunters and Breeders are necessary for the sustenance and survival of the colony's most basic needs, the Weavers are the most intelligent (and often, oldest) spiders within a colony. Their work is the most obvious proof that Great Spiders have more of a culture than other beasts, and in some ways are not so different than the more primitive races of Man.

Religion

Great Spiders share common beliefs that are passed down through their Queen in a tradition of programming. They believe that the Dark Mother, Ungoliant, is a Goddess that created their race to spread across the world. Because Great Spiders do actually contain Ungoliant's tainted blood, they cannot stand by the light of day (it causes them maddening pain), but are fascinated with it. They create webbed structures to block out daylight both for rational reasons, and as an homage to Ungoliant's devouring of the Two Trees of Valinor. Most of the world is not seen as habitable to the Great Spiders, and they largely avoid wide open swathes of wilderness with little cover.

However, all Great Spiders believe that one day, Ungoliant will return from death and be born again. This re-birth will signal the start of a new era, where Ungoliant will once again extinguish all light in the world, and her children will inherit it without fear. In this idyllic, utopian future for the Great Spiders, they believe that the other races will be nothing more than cattle under their rule.

Each colony's Queen tells different stories of what tasks must be completed by the colony to help bring about the prophetic resurrection of the Dark Mother. In this way, many Queens (some who may have even been grandchildren, or great-grandchildren of Ungoliant herself) use this basic religion to control the actions of a colony and to fortify her own strength.

The Mirkwood Colonies

Though it's likely that smaller colonies of Great Spiders are inhabiting Mirkwood, there are two major colonies. Colonies are most often named after their Queen, and the two largest colonies in Mirkwood are no different.

Narkuumat's Colony 

Narkuumat (the "Never-Dying") is the Queen of the largest colony of Great Spiders in known Middle-Earth. The colony dominates much of the region of Mirkwood Forest south of the Old Road and north of Dol Guldur, though the spiders avoid the Eastern Bigh entirely as it offers little cover from daylight. Narkuumat, the Queen of the colony, claims that she is the daughter of Ungoliant; this is a lie (though her Mother's Mother's Mother's Mother is Shelob, the daughter of Ungoliant, and she is quite ancient). She professes that the time of Ungoliant's rebirth has come. She believes that Ungoliant's spirit has come to Dol Guldur, and speaks to her in her dreams; when the colony of Narkuumat has appeased the spirit enough, Ungoliant will take form once more and devour all of the light in the world. Because of this, Narkuumat's followers are zealous in following her commands.

The truth is that Narkuumat does believe what she professes, and the ancient Spider Queen is given dark dreams. But it is not Ungoliant's spirit in Dol Guldur; the Necromancer has cast a powerful spell over the Queen and her progeny, and uses their beliefs to manipulate them. For this reason, the Great Spiders of Narkuumat tend to speak less often, and more monotonously when they do speak. They are single-minded, and their unwitting servitude to the Necromancer grows stronger yearly. Though Great Spiders do not form armies, the southern colony of Narkuumat is one of the Necromancer's greatest tools right now in Middle Earth.

Burzumlub's Colony

Meanwhile, Burzumlub (the "Daughter of Darkness") is the Queen of the colony north of the Elf Path in the most northern regions of Mirkwood Forest. While this colony is not as efficient, or quite as large as Narkuumat's, the Necromancer's influence has not yet fallen upon Burzumlub. Burzumlub is, other than Shelob herself, the most ancient of the Great Spiders; she is Shelob's only known living daughter. Because of the relative purity of her demonic heritage, Burzumlub is an incredibly powerful creature. Over four-hundred years ago, she haunted Rhovanion near the town of Angost; her hunger became too great, though, and she was driven into hiding within Moria by an angry mob of villagers and Gondorian Knights. There, in Moria, a tribe of orcs came to worship Burzumlub, and called themselves the Crimson Arms of Burzumlub. A vain creature, the Queen reveled in the orcs' worship, and dwelt deep within the ancient dwarvish ruins until she eventually stirred the ire of the Balrog that lived there. Burzumlub and the Balrog battled, and Burzumlub was injured. Again she fled, this time to Mirkwood. Aware of the Necromancer, she settled north in the region; she had tasted true power in Moria, and had no desire to be bent to Sauron's dark will.

Burzumlub's colony is independent and loyal only to its queen. The Great Spiders of the colony are more social than the creatures of Narkuumat, though they still believe in the prophecy of Ungoliant's resurrection. Burzumlub professes to them that she, herself, is the vessel for Ungoliant's return. Should the colony grow great enough, and should enough sacrifices and food be heaped upon Burzumlub, she will transform into Ungoliant and devour all of the light in the world. Because of these teachings, the colony reveres Burzumlub as something like a Goddess. This zealotry alone has, so far, kept the Necromancer's will from dominating the northern colony of Great Spiders in the way that it has many of the other creatures living beneath the boughs of Mirkwood Forest.