Two animals, one name
The 'daddy long-legs' name has no scientific meaning — it's applied colloquially to at least three different arachnid groups in different parts of the world: cellar spiders (Pholcidae), harvestmen (Opiliones), and crane flies (a completely different insect group). In Metro Vancouver, you'll encounter two of these: Pholcus phalangioides in your basement and garage, and harvestmen in your garden and exterior walls. Understanding the difference explains two things: why the basement 'daddy long-legs' builds a web while the garden one doesn't, and why neither is dangerous despite persistent internet mythology.
Pholcus phalangioides: the cellar spider
Pholcus phalangioides is a true spider — order Araneae, family Pholcidae. It has two body parts (cephalothorax and abdomen), eight legs, chelicerae with fangs, silk glands with spinnerets, and produces venom used to immobilise prey. The body is small (7–9 mm) but the legs are extremely long relative to body size, giving the spider an overall span of 50–70 mm. It hangs inverted in a messy, irregular cobweb typically located on ceilings, in basement corners, and in bathrooms.
When disturbed, Pholcus performs a characteristic defensive behaviour: it vibrates rapidly in its web, creating a blur that makes it difficult for a predator to target. This is the 'whirring' many Metro Vancouver homeowners have noticed when brushing their basement ceiling. The vibration looks alarming but is purely defensive. Pholcus is also a documented predator of other spiders — including house spiders, false widows, and even other Pholcus. Basements with resident Pholcus populations typically have lower populations of other spider species.
Opiliones: harvestmen (not spiders)
Harvestmen (Order Opiliones) are arachnids — they're related to spiders — but they're not spiders. The key anatomical difference: harvestmen have a fused body (no waist between cephalothorax and abdomen), no silk glands (they can't build webs), no fangs as we recognise them in spiders, and critically, no venom glands. Harvestmen are omnivores and scavengers — they eat small insects, plant material, fungi, and carrion. They can't bite in any meaningful sense and have no venom whatsoever.
In Metro Vancouver, harvestmen are abundant in gardens from late summer through autumn. They're particularly visible on exterior walls, fences, compost heaps, and in dense vegetation. Several BC species reach 10–15 mm body with legs extending 40–70 mm. They walk with a characteristic bobbing motion (the 'harvesting' gait that gives them their name). They're completely harmless and ecologically beneficial — they consume decomposing organic material and are prey for birds and larger invertebrates.
| Feature | Pholcus (cellar spider) | Opiliones (harvestman) |
|---|---|---|
| Spider? | Yes — Order Araneae | No — Order Opiliones |
| Body segments | Two (cephalothorax + abdomen) | One (fused) |
| Webs? | Yes — messy ceiling cobweb | No silk production |
| Fangs (chelicerae)? | Yes — tiny but present | No functional fangs |
| Venom? | Yes — weak, insect-targeted | No venom glands |
| Where found | Indoors — ceilings, basements | Outdoors — walls, garden, compost |
| When disturbed | Vibrates in web | Runs; may release odour |
| Eyes | Eight small eyes in two clusters | Two small eyes on a knob |
Debunking the 'most venomous' myth
The internet claim that daddy long-legs are 'the most venomous spider in the world but can't bite through human skin' is false in multiple ways. For Pholcus: the spider can and does bite humans in the rare circumstance of being handled or squeezed against skin. Experiments by arachnologists have confirmed this — Pholcus bites produce a very brief, mild burning sensation that lasts a few seconds. The venom is not potent in humans. There is no toxicological evidence that Pholcus venom is more toxic to humans than any other spider in its size range.
For Opiliones (harvestmen): they have no venom glands and no functional biting apparatus capable of breaking human skin. They cannot bite in any meaningful sense. The 'most venomous' myth, applied to harvestmen, is simply wrong on basic anatomy. There is nothing to worry about from either animal. The myth persists because the animals look imposing and because internet misinformation recycles without fact-checking.