The vast majority of the over 50,000 known spider species lead solitary lives, making the idea of a “group” a biological anomaly. This independent nature presents a linguistic curiosity, prompting the question of what term we use when these typically isolated hunters are found in proximity. Examining this question requires understanding the complex biological behaviors that govern when and why spiders might temporarily share space.
The Direct Answer: Collective Nouns for Spiders
While collective nouns like a “flock” of birds or a “pride” of lions are widely recognized, the terms for a group of spiders are less established. The most commonly cited collective noun is a “cluster,” which describes a close, temporary grouping of the arachnids.
Another frequently mentioned term is a “clutter” of spiders. Less common terms include a “troop,” an “army,” or a “venom” of spiders. These imaginative names reflect a human reaction to seeing many spiders together, rather than a formal biological classification.
Since true, stable social groups are incredibly rare in the spider world, these collective nouns are primarily linguistic features. They are rarely used by arachnologists, who focus on the specific ecological reasons behind any observed mass grouping. The lack of a single, widely accepted term reflects that groups of spiders are not a common or defining feature of their lives.
The Reality of Spider Sociality
The reason for the linguistic uncertainty is the default biological behavior of nearly all spider species, which is overwhelmingly solitary. Spiders are primarily territorial organisms, meaning they actively defend their web or hunting ground against others. This territoriality is essential for survival, as it secures the individual’s access to prey resources.
The most significant factor preventing the formation of large, stable groups is the high prevalence of cannibalism. For many spiders, another member of the same species is viewed as a potential meal, especially when food is scarce. This intraspecific predation acts as a powerful evolutionary barrier against social living.
A common example is the intense aggression observed between female spiders, which often extends to the consumption of males during courtship, known as sexual cannibalism. Juvenile spiders also frequently cannibalize their siblings shortly after hatching, which naturally limits the size of any family group. This aggressive and solitary nature explains why spider diversity consists of isolated hunters.
When Spiders Do Gather: Social Species and Temporary Clusters
Social Species
Despite the solitary rule, rare exceptions exist where spiders form genuine, long-term societies, providing a biological context for a collective noun like a “colony.” True social spiders, such as certain species in the genus Anelosimus, live in enormous, permanent communal webs. These groups exhibit cooperative behaviors, including sharing prey capture and maintenance of the massive silk structure.
The tropical species Anelosimus eximius, for instance, can form colonies containing thousands of individuals. They cooperate to subdue prey much larger than any single spider could manage and share in brood care, with multiple generations contributing to the communal rearing of the young. This cooperative lifestyle is found in only about 25 species globally, making it an extremely rare evolutionary trait.
Temporary Clusters
Beyond these true societies, many solitary species form temporary clusters driven by life cycle events. A mass grouping may occur immediately after hatching, when hundreds of spiderlings emerge from a single egg sac, forming a dense huddle before they disperse. This initial cluster is short-lived, as competition and cannibalism quickly drive the siblings apart.
Another common temporary grouping is associated with “ballooning,” the primary dispersal method for spiderlings. On calm, warm days, hundreds of young spiders climb to high points, release strands of silk to catch the wind, and become airborne. These mass dispersal events can sometimes lead to a “shower” of spiders that temporarily creates a visually striking cluster when they all land in the same area.