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High growth
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Silk stockings We share our house with a few spiders. This morning, one with a small body and long spindly legs trapped another squatter, darker spider in its web. How can this happen? Since spiders are adept at walking along strands of silk, why should one get trapped in another’s web?
n This predatory spider is
most probably of the Pholcus phalangioides species that was first described by entomologist Johann Kaspar Füssli and is also known as the cellar or skull spider. It cannot survive a cold winter outdoors in the UK, but it has become quite common in heated houses there. It is a specialist at feeding on other spiders. I once accidentally dislodged another species of spider, which fell into the clutches of a cellar spider. It was promptly dispatched, even though its body was somewhat larger. The intruder was quickly pounced on and transformed
“Spiders are not immune from being trapped in their own webs, but leave some strands of silk glue-free”
from being trapped in their own webs. They avoid getting stuck by leaving some strands of silk untreated with glue, which allows them to deftly pick their way around without becoming entangled. Blundering into a strange web, the intruder spider in the question didn’t know which strands were untreated. It also wandered into the domain of a spider that sees other spiders as a potential meal, rather than a threat. Terence Hollingworth Blagnac, France
into a silk parcel in an instant. The cellar spider clearly had the edge in speed and dexterity, which is all the more remarkable for an insect that has such a clumsy appearance. Contrary to what you might suppose, spiders are not immune
n Spider species can only be accurately identified by microscopic examination, so my explanation is based on the assumption that the spider in the question with the spindly legs is Pholcus phalangioides. This species, once confined to
The writers of answers published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. We are pleased to acknowledge financial support from Statoil in producing The Last Word. New Scientist retains total editorial control over the content. Reed Business Information Ltd reserves all rights to reuse question
and answer material that has been submitted by readers in any medium or in any format. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to lastword@newscientist. com or visit www.newscientist.com/topic/ lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
regions nearer the equator, is becoming much more common in the UK as a result of climate warming. It is known to prey on the common house spider, Tegenaria domestica.
Pholcus phalangioides can move very quickly, much quicker than a Tegenaria domestica. If it notices a nearby threat, such as a finger, it will gyrate so rapidly that it becomes a grey blur. It also has a particularly potent venom, though not so painful to humans. I would suggest that what your questioner observed is a Pholcus phalangioides that had immobilised its prey with its powerful venom and then wrapped it up in silk, ready to consume. The victim’s struggling gives the erroneous impression that it has become tangled in the web by its own efforts. I include my own photograph (top left) of a Pholcus phalangioides female with a silkwrapped house spider that it has already prepared for future consumption. Paul Dunford Cumbria, UK
This week’s question High growth
While at about 2000 metres altitude in Austria, I found lumps growing on the leaves of a plant (see photo, left). The smaller lumps were yellow, but they changed to orange, then red, as they got larger. They were growing directly from the leaves, not the stem. And they were also very cold – there was condensation on them. What are these fruit-like growths? Rob Ellis Birmingham, UK
The last word on energy Win £100 by answering our monthly question about energy issues How much energy is in a lightning bolt? Is it enough, and are there places where lightning strikes often enough, to think about flying kites to transfer that energy to the grid? Answers should reach us by 23.59 GMT on 14 January 2014 to [email protected] or visit www.newscientist.com/topic/ energy. Terms and conditions are also at this URL.
Last words past and present at newscientist.com/topic/lastword
sponsored by
Silk stockings We share our house with a few spiders. This morning, one with a small body and long spindly legs trapped another squatter, darker spider in its web. How can this happen? Since spiders are adept at walking along strands of silk, why should one get trapped in another’s web?
n This predatory spider is
most probably of the Pholcus phalangioides species that was first described by entomologist Johann Kaspar Füssli and is also known as the cellar or skull spider. It cannot survive a cold winter outdoors in the UK, but it has become quite common in heated houses there. It is a specialist at feeding on other spiders. I once accidentally dislodged another species of spider, which fell into the clutches of a cellar spider. It was promptly dispatched, even though its body was somewhat larger. The intruder was quickly pounced on and transformed
“Spiders are not immune from being trapped in their own webs, but leave some strands of silk glue-free”
from being trapped in their own webs. They avoid getting stuck by leaving some strands of silk untreated with glue, which allows them to deftly pick their way around without becoming entangled. Blundering into a strange web, the intruder spider in the question didn’t know which strands were untreated. It also wandered into the domain of a spider that sees other spiders as a potential meal, rather than a threat. Terence Hollingworth Blagnac, France
into a silk parcel in an instant. The cellar spider clearly had the edge in speed and dexterity, which is all the more remarkable for an insect that has such a clumsy appearance. Contrary to what you might suppose, spiders are not immune
n Spider species can only be accurately identified by microscopic examination, so my explanation is based on the assumption that the spider in the question with the spindly legs is Pholcus phalangioides. This species, once confined to
The writers of answers published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. We are pleased to acknowledge financial support from Statoil in producing The Last Word. New Scientist retains total editorial control over the content. Reed Business Information Ltd reserves all rights to reuse question
and answer material that has been submitted by readers in any medium or in any format. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to lastword@newscientist. com or visit www.newscientist.com/topic/ lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
regions nearer the equator, is becoming much more common in the UK as a result of climate warming. It is known to prey on the common house spider, Tegenaria domestica.
Pholcus phalangioides can move very quickly, much quicker than a Tegenaria domestica. If it notices a nearby threat, such as a finger, it will gyrate so rapidly that it becomes a grey blur. It also has a particularly potent venom, though not so painful to humans. I would suggest that what your questioner observed is a Pholcus phalangioides that had immobilised its prey with its powerful venom and then wrapped it up in silk, ready to consume. The victim’s struggling gives the erroneous impression that it has become tangled in the web by its own efforts. I include my own photograph (top left) of a Pholcus phalangioides female with a silkwrapped house spider that it has already prepared for future consumption. Paul Dunford Cumbria, UK
This week’s question High growth
While at about 2000 metres altitude in Austria, I found lumps growing on the leaves of a plant (see photo, left). The smaller lumps were yellow, but they changed to orange, then red, as they got larger. They were growing directly from the leaves, not the stem. And they were also very cold – there was condensation on them. What are these fruit-like growths? Rob Ellis Birmingham, UK
The last word on energy Win £100 by answering our monthly question about energy issues How much energy is in a lightning bolt? Is it enough, and are there places where lightning strikes often enough, to think about flying kites to transfer that energy to the grid? Answers should reach us by 23.59 GMT on 14 January 2014 to [email protected] or visit www.newscientist.com/topic/ energy. Terms and conditions are also at this URL.