Daddy long-legs spider 

Daddy long-legs spider. Photograph by Norman Heke. Te Papa

Pholcus phalangioides

What do they look like?

These spiders have small slender bodies with very long legs. They usually sit upside down in their delicate but rather messy webs, which are typically constructed indoors in out-of-the-way spots such as ceiling corners and behind furniture. They also like living in basements and cellars, and this has led to them being named cellar spiders in some parts of the world.

The name ‘daddy longlegs’ is also sometimes applied to craneflies and the European harvestman Phalangium opilio. But while both these have long legs, they are quite different animals. Craneflies have wings and the European harvestman, while an arachnid, is not a spider - it has a one-part body and does not make a web. The daddy longlegs spider has a two-part body and is almost always found in a web.

Where are they found?

Daddy longlegs are found throughout much of the world and are strongly associated with human habitation. This is very much the case in New Zealand, and they are thought to have arrived here with European settlement. These spiders are quite a frequent sight around buildings throughout much of New Zealand, although less commonly seen in the cooler, southern South Island.

What are their habits?

Very little entering the web of a daddy longlegs spider escapes its notice. If the interloper is regarded as prey, the spider will swiftly fling out lengths of silk from a safe distance to bind it. Once the prey is helpless, the spider then wraps it further, turning it into a food parcel that can be eaten at the spider’s leisure. This strategy allows these spiders to easily deal with prey many times their own size, as well as quite dangerous prey such as other spiders.

What is their bite like?

There is an often-repeated urban myth that states ‘the daddy longlegs is the most poisonous spider in the world, but it can’t bite you because its fangs are too small’.

There is no evidence to support this story. First, there is no reason to believe the venom is particularly dangerous to people. Second, while the fangs are indeed very small and would have difficulty biting through human skin, there are anecdotal cases of bites, none of which proved fatal.

The myth may have its origins in reported observations of these spiders killing and eating the decidedly dangerous Australian redback spider - the assumption being that if daddy longlegs are able to kill deadly spiders they themselves must be highly lethal. This is not true, and the daddy longlegs’ ability to overcome large or dangerous prey is due to its strategy of ensnaring prey by throwing silk at it from a safe distance.