This post follows on from the post on this site entitled “Butterflies and Moths: Why are…
Most people take these spiders for granted because they are so familiar a sight, but very little information about them is actually available as there has been little research done on this family.
The Daddy-long-legs are easily recognised by virtue of their chevron marked cylindrical abdomens (6 – 15 mm long) and their extremely long, delicate legs (about four times longer than their body). Smeringopus is common throughout Zimbabwe in houses, gardens and the veld. They make their loose, untidy webs in the darker corners of buildings or among rocks, in caves and across animal burrows.
Their webs are sometimes composed of long threads criss-crossing in an irregular fashion; or at other times, the centre of the web consists of a large dome-shaped, more densely woven sheet with a network of irregular threads above and below it. The spider hangs inverted in the centre of the web. When prey enters the web, the spider normally touches it with its front legs, then rapidly rotates through 180o and wraps the prey in silk. After wrapping for about 2-3 minutes, and before feeding begins the spider usually then bites the prey a number of times, and carries it higher up into the web. As they prey on ants and other household pests, these spiders should be left alone and not indiscriminately killed.
A characteristic defensive behaviour of the Pholcidae is that when danger threatens, they cause a rapid vibrating of the web or “whirling”. This renders them as an inconspicuous blur. To whirl, the spider swings its body around in a circle, whilst its legs remain on the silk. Whirling usually lasts for only 5-30 seconds.
Daddy-long-legs spiders mate all year round and the female produces batches of 11-84 eggs at a time. She carries the agglutinated mass of eggs, unprotected by an enveloping cocoon, in her mouth parts. This behaviour is unique to this family of spiders. The spiderlings hatch in about three weeks, depending on the ambient temperature, and stay on the females’ web until their first moult. They reach sexual maturity in a year and can live for several years.
Daddy-long-legs spiders are completely harmless to man. Their jaws are very small and are unable to penetrate human skin. The myth that they are the most poisonous of all spiders is just that – a myth. There is no reference to any pholcid spider biting a human and causing any detrimental reaction. If these spiders were indeed deadly poisonous but couldn’t bite humans, then the only way we would know that they are poisonous is by milking them and injecting the venom into humans, and this research has never been done. Furthermore, there are no toxicological studies testing the lethality of pholcid venom on any mammalian system (this is usually done with mice).