Spiders – Web of Terror

Autumn, the time of year when leaves are swept from drives, apples are ripe, mushrooms bubble up through lawns and scary, hairy, leggy creatures appear from nowhere to frighten the living daylights out of arachnophobes everywhere. That’s right, the spiders are out to play.

Spin doctor

Spin doctor

So why is it that spiders are so common this time of year?
Male spiders leave their webs and come out of hiding in autumn in order to mate. This means that the webs you see around and about are more likely to belong to female spiders as the male spiders (ref)

The spiders we find in our homes have not, in fact, “come in from the cold” as is sometimes thought, but are (mostly) different species to those you might find in your garden and are specifically adapted to living inside. The common house spider (Tegenaria domestica), for example, has adapted to poor water and food supplies and to living in an environment with constant temperature and humidity (spider myths link).

Given that houses are a ‘water-poor environment’ and spiders need to drink, one of the most common places to find spiders is in bathrooms struggling to get out of baths or sinks. This is not, as some might think, because the spider has climbed up through the plumbing. In actual fact the spider was probably watching the X-factor with you from under the sofa, when the ad-break came on and it decided to go get a drink from the nearest tap. As baths and sinks are slippery, the poor thing was unable to climb out again.

House spiders I’ve found in my house (smug):

1. Tegenaria duellica, T. saeva and T. domestica– Can be found indoors, or in funnel shaped webs in garages, sheds and outbuildings. T. duellica normally found scurrying suddenly from underneath sofas when you least expect it.

Found this bad boy under the sofa I was sitting on at the time...

Found this bad boy under the sofa I was sitting on at the time…

2. Pholcus sphalangoides and Psilochorus simoni– The spiders with the tiny body and long spindly legs. Both create large messy webs in corners or behind furniture or radiators.
IMG_4931

3. European Garden Spider: Araneus diadematus– Easily identified by the white marks on its abdomen that form a cross, also called the garden cross spider.
IMG_4927

I thought I’d been lucky on my search of the house and not found any lurking in my room until I saw this…

Lovely.

Lovely.


For a list of other species that you might find lurking in your house go here.

Why spiders are excellent:
1. If you have lots in your house you will have significantly fewer flies, moths, mosquitoes and insect larvae.
2. They also eat aphids and other garden insect pests so act as a biological pest control (for free!).
3. By eating these common species of insect, they keep the population numbers down, thereby playing an important part in the ecosystem.

Can you deter spiders?
Basically, no. If spiders are removed from the house, new ones will come in to take their place via cracks under doors, down chimneys, through windows and some can even float in on the breeze on long strands of silk. However some people, (grandmas), swear by conkers as spider deterrents. The chemical in the skin of the conker, triterpenoid saponin, does indeed appear to repel insects such as moths. However various experiments done by the public and the Royal Society of Chemistry show that they are highly unlikely to repel spiders. Although the RSC’s experiment (hilarious video) is rather questionable and involved shoving a conker on a wooden spoon in the spiders face vs. the same treatment with a table tennis ball as a “control”, the children of Roselyon School in Cornwall did some rigorous and much more scientific studies and found that spiders didn’t really seem to mind the presence of conkers (video). However if it gives you arachnophobes peace of mind, go ahead, they look pretty so if they do deter spiders it is a bonus for you.

The Society of Biology are currently doing an autumn spider watch as not much is known about the Tegenaria species. They are collecting data in order to deduce when the spiders start appearing, if it’s the same time all over the uk and whether or not it is related to weather conditions. In order to take part go here.

So, to conclude, if you see a spider in your house, don’t kill it or “put it back outside”, catch it, photograph it and then wave it on its merry way. And maybe leave a towel hanging over the side of the bath during the X-factor.

Websites/ More Info:
http://www.bbc.co.uk/nature/23898679
https://www.societyofbiology.org/get-involved/biologyweek/house-spider-survey
http://societyofbiologyblog.org/spiderman-or-spiderwoman/
https://www.societyofbiology.org/images/pdf/SpiderFAQ.pdf
http://www.burkemuseum.org/spidermyth/myths/bathtub.html
http://www.bbc.co.uk/blogs/natureuk/posts/A-life-story-of-large-house-spiders
http://www.bbc.co.uk/nature/23898679
http://www.thereaction.net/news/y2010/m10/spiders_versus_conkers_definitive_guide.aspx
http://www.rsc.org/AboutUs/News/PressReleases/2010/Conkerswin.asp

The Badger Cull

There has been a lot of talk recently of the badger cull taking place in south west England and a lot of animal rights activists have been having hissy fits over the destruction of our native and protected species, the badger (Meles meles). For once it appears that scientific evidence is on their side, so why is the cull taking place?

What is actually happening?
Badgers are being culled (shot, preferably in the head,) in two main areas of England; West Gloucestershire and West Somerset, as part of a trial to see if getting rid of the badgers has any effect on the levels of bovine TB (bTB) found in the area.

Why?
Bovine TB is a chronic infectious disease affecting a broad range of mammalian hosts including humans, badgers and cattle. Bovine TB is usually transmitted to humans via infected milk, which in the developed world is a rare occurrence due to the fact that milk is pasteurised. TB testing in cattle also means that any cattle harbouring the disease are immediately destroyed to prevent it spreading. Cattle TB can also be passed on to humans via aerosols but this is very rare and can be prevented by not letting cows cough or sneeze in your face.
Other than possible health risks to humans the second (and probably more relevant) reason for trying to control bTB is that it causes serious health problems in cattle. Tens of thousands are killed every year which can be shattering for farmers economically and emotionally. It also costs the government and the taxpayer millions of pounds a year (government doc.).

“We shall not be mooooved!”

Why is the cull happening now?
The current cull is taking place as a further study after the Randomised Badger Culling Trial of 1997. The RBCT was done in the areas of England with the highest levels of bovine TB. The cull was carried out in 30 areas which were grouped into ten sets of three. In the first area badgers were killed every year (proactive culling), the second area badgers were only killed on or near farms that had recently contracted cattle TB (reactive culling), and in the third no culling took place but the levels of bTB were monitored. The trial was concluded in 2003 with three observations:

Observation 1
Reactive culling caused around a 20% increase in bovine TB incidence
Observation 2
Proactive culling reduced cattle TB inside the tested area but increased it on neighbouring land due to the fact that killing the badgers disrupted their social groups and caused surviving animals to move out of the area spreading the TB further afield.
Observation 3
It took four years of killing badgers before there was an overall drop in cattle TB and this drop was small and expensive.

These observations led to two main conclusions:
a) That although badgers did contribute to cattle TB, badger culling made “no meaningful contribution to cattle TB control” and in some cases actually make the situation worse.
b) That cattle themselves contribute significantly to the persistence and spread of TB and in some cases may actually be the main source of infection due to weaknesses in cattle testing regimes (Badger pdf).

The previous government, in light of this information, decided that a badger cull would not be worth doing as there was “no guarantee of success” and there was “potential for making the disease worse”. However the National Farmers Union strongly (and understandably) disagreed and stated that this conclusion was an “abdication of responsibility”. Despite the fact that culling had been trialled and was seen to be unhelpful in combating TB and in some cases made it worse, the current Minister was desperate to be seen to be doing something to help the farmers. So as farmers could do the shooting themselves and the cull was therefore cheaper than funding the cattle and badger vaccination programmes, the south west of England cull was given the go-ahead (house of commons pdf.).

Why they think the cull might work
In other developed countries such as America, Australia, New Zealand and Ireland, cattle TB is just as much of a problem, however the difference is that in those countries the wildlife source of TB is being culled. White tailed deer and water buffalo in America, the possum in Australia and New Zealand and the badger in Ireland, and it is the latter that is the most relevant according to the Environment Minister Owen Paterson. As the number of cattle needing to be destroyed per year in Ireland has decreased by around 6000 in the eight years since the cull was implemented he thinks that that culling badgers in England will work just as effectively. (Video of Paterson)

However according to this slightly suspicious graph I found on the internet, the number of cattle having to be destroyed because of TB in Ireland was already decreasing by the time the cull was in place, and in fact increased the year after it started. It has taken ten years for the number of cattle being destroyed to decrease to half its original number, and only eight of those years had a cull implemented (graph website)

Why I think the cull is pointless
• Culling the badgers will either cause an increase in bTB incidence in the south west, or an increase in the surrounding areas due to the emigration of the badgers.
• The method for killing the badgers (shooting by farmers), is different to the cull done in 1997 meaning that the results may be different. As the original cull trapped the badgers first, injured badgers could not move to other areas. However the current cull does not include the trapping of badgers meaning that non-vital injuries could cause an increase in the spread of bTB to nearby areas.
• Badgers can be vaccinated and research is being done into oral vaccines for cattle and badgers.
The most effective way of vaccinating badgers in the short term is with the human TB vaccine, M. bovis Bacille Calmette-Guérin (BCG). However this vaccine generally doesn’t work unless it is live and as live vaccines are killed off by stomach acid, oral distribution of the vaccine, which would be the most cost and time effective method, is not applicable as of yet. The development of a successful oral vaccine would depend on it still being live once consumed by the badgers as well as when contained in the bait, which is why it is unlikely to be developed until at least 2015 (Defra).

quit badgering me


All in all it’s a bit of a muddle and from the devastating effects bTB has on the farming community, to the horrible consequences of the cull on badger populations, it is hard to decide who is in the right. It’s at times like these that I look with admiration to Wales. For, despite announcing an order to destroy badgers in 2011, they later stated that they would review the scientific evidence and have since begun a project of badger vaccination (bva website). So, from a scientific point of view, at least we will be able to review the bTB situation a few years down the line and compare it with the levels of the disease in Wales and will therefore be able to deduce which form of “treatment” is better. TB or no TB, that will be the question.