"Daddy longlegs" is a name used for more than one species, as is the case with many common names or nicknames for plants and beasts. Needless to say, this can cause confusion. In the northern hemisphere "daddy longlegs" seems to be used most often for "harvestmen" - creatures which are arachnids, but not spiders. It is also used for "craneflies" which are flying insects. But the creature that I know by this name is a spider, Pholcus phalangioides, also known as the cellar spider - thus named because it tends to hang out in shadowy places, often in cellars or in warm quiet corners in houses, where it makes its rather raggedy tangled webs and can do good pest control service.
In a shady corner I saw this daddy longlegs at work.
Dangling above a hapless blowfly, it was wrapping it up in silk - first trapping its wings, then banding its legs in a tangle of white threads.
Apparently daddy longlegs can cast their silk at their prey, a bit like casting a fishing line. Once the prey is caught, they wrap it up ever tighter and then can deliver their venomous bite.
Despite their delicate appearance - their bodies are 6-9 mm long and their long legs are thin and translucent - they can catch prey much larger than themselves. In addition to flies, woodlice and so on, they are known to catch and eat nasties like the very venomous Australian Redback spider.
This may have led to the myth that their venom would be deadly to humans if only their mouthparts could puncture our skin. Wrong on both counts! Their venom is apparently not that bad on the scale of spider venom toxicity, and they are capable of making tiny little punctures in our skin. They just don't seem to do it that often, even though on the whole they prefer to live in our houses and are often there in great numbers. And watching this one, I'm happy not to be the object of its intentions.
The spider, having completely swaddled the fly, appears to be envenomating it - biting and poisoning it. And while I know that a spider has got to eat, it did feel like watching a horror movie, a chilling domestic drama. Sometimes it is hard not to anthropomorphise.
I didn't just witness a skilful killer at work, while doing my researches I also found a new word. Daddy longleg spiders are synanthropes (from the Greek for "together with" - syn, plus "human" - anthro). A synanthrope is a member of a species of wild animal that lives near and benefits from associating with humans and the environments we have shaped around us. It appears that we benefit from the hunger of the daddy longlegs too - they like to eat the bugs we don't like to have around the house.