“Daddy long legs” are a common sight in many homes, often prompting questions about their role in controlling household pests like cockroaches. The popular name, however, causes confusion as it refers to at least two distinct arachnids: harvestmen and cellar spiders. Understanding the differences between these creatures is key to determining their actual dietary habits and whether they contribute to cockroach control.
Unpacking “Daddy Long Legs”
The term “daddy long legs” broadly refers to two arachnid groups: harvestmen (Opiliones) and cellar spiders (Pholcidae). Despite their similar appearance, they have distinct classifications and characteristics. Harvestmen possess a single, fused body segment, making a separate cephalothorax and abdomen difficult to discern. In contrast, cellar spiders, like all true spiders, have two distinct body segments: a cephalothorax and an abdomen, joined by a narrow “waist.” Cellar spiders also produce silk and build webs, whereas harvestmen do not.
Harvestmen: Diet and Role
Harvestmen, often called “daddy long legs,” are primarily scavengers and omnivores, not active predators. Their diet typically includes decaying plant matter, fungi, and small, dead invertebrates, playing a role in decomposition and nutrient cycling.
While they might opportunistically feed on small, soft-bodied insects or dead organisms, they do not actively hunt larger insects like cockroaches. Their feeding mechanism involves chewing solid food, unlike spiders that typically liquefy their prey. Therefore, harvestmen are not an effective or primary solution for managing cockroach populations.
Cellar Spiders: Predatory Behavior
Cellar spiders, also known as “daddy long legs spiders,” are active generalist predators that construct messy, irregular webs to capture prey. Their diet consists of various insects and other spiders, including flies, mosquitoes, and gnats.
Regarding cockroaches, cellar spiders can prey on smaller or juvenile cockroaches that become entangled in their webs. They use their silk to ensnare and immobilize prey, then deliver a venomous bite. However, larger, adult cockroaches are not their primary food, making them inefficient for significant infestations.
Dispelling the Venom Myth
An urban legend claims “daddy long legs” possess potent venom but fangs too short to bite humans. This is inaccurate for both harvestmen and cellar spiders. Harvestmen (Opiliones) do not produce venom at all and lack fangs, posing no danger to humans.
Cellar spiders (Pholcidae) possess venom, like most spiders, which they use to subdue prey. However, their venom is not medically significant or harmful to humans, resulting in a mild sting at most. While their fangs are short, they are capable of piercing human skin, though bites are rare and typically harmless. The myth may have originated from cellar spiders preying on other dangerous spiders, such as black widows, leading to the false assumption of potent venom.
Presence in Human Environments
Both harvestmen and cellar spiders can be found in and around human environments, each contributing to the household ecosystem in different ways. Harvestmen are often found in damp, dark outdoor areas like leaf litter or under rocks, though they may wander indoors. They act as scavengers, breaking down organic matter.
Cellar spiders commonly inhabit undisturbed indoor spaces such as basements, attics, and corners, where they build their characteristic messy webs. They consume common household pests like flies, mosquitoes, and other spiders, offering natural pest control. While cellar spiders might occasionally prey on small or injured cockroaches, neither species should be relied upon as a dedicated or effective solution for a significant cockroach infestation. Their presence indicates a complex indoor ecosystem where they manage populations of various small invertebrates.