The common name “daddy long legs” refers to several different arthropods, causing confusion about their diet, especially regarding flies. Clarifying which animal is referenced is the first step to understanding their eating habits.
Defining “Daddy Long Legs”
The informal name “daddy long legs” describes three distinct arthropods. Harvestmen (Order Opiliones) are arachnids, not true spiders. They have a single, oval body segment, lack silk glands, and are not venomous.
Cellar spiders (Pholcidae) are true spiders, recognized by their long, thin legs. They construct messy, irregular webs in home corners. Unlike harvestmen, cellar spiders produce venom, harmless to humans.
Crane flies (Family Tipulidae) are insects often mistaken for large mosquitoes due to their long legs and slender bodies. They possess wings, distinguishing them from harvestmen and cellar spiders.
Dietary Habits of Harvestmen and Cellar Spiders
The diets of these “daddy long legs” vary. Harvestmen are omnivores or scavengers, consuming diverse organic material. Their diet includes small invertebrates (aphids, mites), decaying plant/animal matter, fungi, and small snails. They do not primarily hunt flies and ingest solid food, unlike spiders which consume liquefied prey.
Cellar spiders are predatory, hunting various insects and other spiders. They feed on mosquitoes, gnats, moths, and other small arthropods, including flies. They also prey on other spiders, even larger ones like black widows, by ensnaring them in their webs.
Adult crane flies feed on nectar or decaying plant matter; many species do not feed during their short adult lifespan. Crane fly larvae feed on plant roots, decaying wood, and other organic soil matter.
Ecological Role and Common Misconceptions
Harvestmen and cellar spiders play distinct ecological roles. Harvestmen act as decomposers, scavenging decaying organic material, and as minor predators of small pest insects. Their presence aids natural pest control in gardens.
Cellar spiders serve as natural pest control agents, especially within human dwellings, by preying on bothersome insects and other spiders. They help manage populations of pests like mosquitoes and flies in homes.
A common misconception suggests “daddy long legs,” specifically cellar spiders, possess potent venom but cannot bite humans due to short fangs. Cellar spiders are venomous, but their venom is not dangerous to humans, and they rarely bite. Harvestmen are not venomous, lack fangs, and pose no threat.