Sunday, 18 December 2011

Pholcus phalangioides, the Daddy Long-leg spider

ResearchBlogging.orgIn dark, forgotten corners of houses and outbuildings, a spindly-legged spider hangs upside down - motionless - from a loose, barely visible web made of very fine threads. It is Pholcus phalangioides, the Daddy Long-leg Spider or Cellar Spider. Today, several hang from underneath a wooden shelf in my outside toilet, including the male above. This species is cosmopolitan but has recently expanded its range northwards in the UK, and it is almost always found associated to buildings.
A male showing its palps.
Mating pair. After an initial male approach and web and leg tapping, if the female accepts him, the partners approach their ventral surfaces and the male inseminates the female using his palps.
Pholcus is a very generalist predator and has no trouble subduing large prey. I have seen it with captured Tegenaria (above) even Dysdera (below), the latter a spider with enormous chelicerae. Pholcus is able to do so thanks to its long legs, as it throws silk to its prey and wraps it on silk while keeping a safe distance. It can also invade other spiders' webs and then makes them vibrate simulating the effect of an entangled prey, in order to attract the owners and catch them, a deceptive behaviour known as aggressive mimicry. It will also eat other spider's eggs and trapped prey. If Pholcus is disturbed in its own web it has a defensive behaviour called whirling: it moves its body rapidly in a circle, becoming a blur, while keeping its legs on the web, this might deter other spiders from entering its web but even so, Pholcus can often capture and eat these spiders.
 Pholcus is even able to capture and feed on woodlice, which often walk up the walls in my conservatory.
Female Pholcus are dedicated mothers. They hold their egg clutch of about 20 to 30 eggs by their chelicerae. The eggs in this clutch are close to hatching. The spiderlings' legs are visible through the egg shell as white threads.

 The spiderlings stay close to their mother for some days after hatching. She hasn't fed since she laid the eggs and she will have to wait until the spiderlings disperse.
 Pholcus go through five moults before maturity. The one below is molting.
Apparently, the most effective enemy of these spiders is that noisy generalist predator, the vacuum cleaner.

More information
Check this website for detailed information on Pholcidae.

Maciej Bartos (1998) Quantitative analyses of male courtship behaviour in Pholcus phalangioides
(Fuesslin, 1775) (Araneae, Pholcidae). In: P. A. Selden (ed.). Proceedings of the 17th European Colloquium of Arachnology, Edinburgh 1997. 171-176. here.

Kazuyoshi Miyashita (1988a) Development of Pholcus Phalangioides (Fuesslin) (Araneae, Pholcidae) under Long and Short Photoperiods. Journal of Arachnology, 16 (1), pp. 126-129.

Kazuyoshi Miyashita (1988b) Egg Production in Pholcus Phalangioides (Fuesslin) (Araneae, Pholcidae) under a Constant Temperature and Photoperiod. Journal of Arachnology, 16 (1), 129-131.

Jackson, R., & Brassington, R. (1987). The biology of Pholcus phalangioides (Araneae, Pholcidae): predatory versatility, araneophagy and aggressive mimicry Journal of Zoology, 211 (2), 227-238 DOI: 10.1111/j.1469-7998.1987.tb01531.x

7 comments:

Bill Grange said...

A wonderful series of pictures on a spider I have great affection for - though it doesn't, as far as I know, occur as far north as Derby,where I live.

Have you heard that the great spider authority, the late W. Bristowe, toured Britain by motorbike, ostensibly seeking b@b, but was really monitoring the distribution of Pholcus phalangiodes? Bill Grange

Africa Gómez said...

Hi Bill, Thank you for your comments and the anecdote on W. Bristowe. I don't see why Pholcus shouldn't live in Derby if it has reached up to Shetland (check this NBN gateway distribution map: http://data.nbn.org.uk/gridMap/gridMap.jsp?allDs=1&srchSpKey=NBNSYS0000008639) Maybe it has got local hotspots and one of them is my house!

Anonymous said...

I have one of these spiders, plus some of its surviving babies, living in my flat in London (very small, second floor flat). I do not wish to kill them but neither do I want a total infestation. If I moved them to loft would they survive, given that the loft is very cold in winter/

Frida said...

I live in the cool, temperate north-west of the South Island of New Zealand and I, like many, have a love-hate relationship with spiders. I cultivate one or two house spiders in my litle 2-bedroom cottage, but I am plagued by daddy long legs - Pholcus phalangioides - so the ol' (yes - old) vacuum cleaner comes out and away they go, to return in volumes within a day or two. As the beginning of our summer is cool (8 degree C at night), which is right now, and cooler than usual at this time of year, I guess when one lot leaves (ungraciously long legs torn off bodies as vacuumed) another arrives to set up in my warm ceilings - with all sorts of camouflage colours as well. One reason I don't like them is that they attack my house spiders, while white tails dance along my walls. The big prob now is that I think they are communicating with me. They know I am a good person and don't want me to hate them like I do - I wouldn't mind if they were well-behaved, like on the east coast, where they live a bit more sedately. The night after the second to last time I hoovered, that night I woke from being bitten near my lip - it was just a slight burning sensation that quickly disappeared. The last time I hoovered legs and all, that night I was bitten just under my eye - just a slight burning sensation (thanks Mythbusters, I can confirm your findings). Strangely, these are the only times ever I am aware of that I have been bitten by them, and read about the Mythbusters experiment after the fact. We live in a survival of the fittest world - these Pholcus are predators AND CANNIBALS - I should feel justified in tearing their legs off and sucking their lifeblood out, just as they do. What I want to know is - when do they come in, why don't they knock and ask first, and where do they come in, what is the smallest gap they can squeeze through? Are there whole colonies waiting in queues under my house, to jostle as they hear the dreaded vacuum? Whatever, I'm slowly putting screens on the windows I insist on keeping open year round so I can breath beautiful, pristine cool night air every night.

Frida said...

One more thing - my house spiders are usually protected by their webs but if I clean their lairs they are much more vulnerable to the longies. Spiders are messy and don't seem to clean up after themselves - they leave piles of white, calcified poop below their lairs, and also the carcasses of their meals.

lyndsey, st.helens uk said...

hi i think I have discovered this spider with babies on my ceiling is it okay to just leave them and the babies will just disperse. Got two children who are a bit worried about being over run with spiders. I tried to attach a picture but it wouldnt let me. thanks

Africa Gómez said...

Hi Lyndsey, It might appear a bit firghtening to think of tens of spiders running around the house. Fortunately - for your family - there is a lot of mortality early on when the spiderlings disperse. Other spiders - including other Pholcus - will eat them when small. Pholcus also is a powerful hunter of other spiders, and rarely move from their corner in ceilings, so it is small price to pay to have a few in the house.