Tag Archives: orb weaver

Spiders on the Storm

24 Oct

The signs of impending winter are upon us.  While the heat made one final appearance for the Sports Day long weekend, nights and early mornings have become decidedly chilly.  The sun is setting early, and leaves are changing colour.

 

Recent news has been dominated with the landslides on Izu Oshima island, caused by Typhoon 26, which have resulted in over two-dozen confirmed deaths and nearly a dozen still missing.  To make matters worse, Typhoon 27 is following a similar path, and Typhoon 28 is also on the way.

 

It was on one of those warmer, sunny mornings (autumn is known as the season of clear skies, except when the typhoons come through and dump several hundred millimetres of rain in a few hours) when I noticed how big some of the jorogumo had become, and was spotting their webs in all kinds of places.  I saw around half a dozen in the 20+ mm  class along the Azuma River, their webs stretched between the cherry branches and the guard rail.  Further along I spotted a few more, smaller spiders with webs spanned between electricity poles and roadside hedges.

 

That was when I spotted a web with stabilimentum (web decoration), a linear zigzag pattern.  This web no doubt belonged to a member of the genus Argiope.  This was going to be worth examining more closely.

Aha! An orb-weaver. The web decoration is a dead giveaway.

 

Unfortunately, the spider had positioned herself on the other side of her web, facing the morning traffic.  Traffic is not only a genuine life-threatening risk, it is also the curse of arachnidian photography – every vehicle that passes caused the web to sway several centimetres, and out of focus.  The low, direct sun also played havoc with exposure, and I had to abandon my attempts, wondering if the spider would still be there after the typhoon…

 

…which it was.

 

Thanks to my field guide, I was able to quickly identify the spider as a wasp spider (Argiope bruennichi).  This spider has a wide range, and is found right across the Japanese archapeligo, much of the Asian mainland, parts of Africa to northern and central Europe.  Unfortunately, I have not been able to find the etymology of its English name.  The Japanese name, nagakoganegumo (長黄金蜘蛛), is somewhat easier to deal with; it suggests that it looks like the orb-web spider (Argiope amoena) or koganegumo, but is longer.

 

My best photo attempt – not easy with just a mobile phone. The shape of the body and stripes made identification easy.

Female wasp spiders can grow to 25 mm in length, and this one was about that size.  Males are typically about half the size of females, and their markings are not as distinct as the females’.  Like other orb-weaver species, males often do not survive mating.

 

While many other Argiope species spin X-shaped or diagonal stablimenta, wasp spiders tend to spin rings as juveniles and vertical linear patterns as adults.

The adult spider typically waits in the centre of its web, head downwards.

 

Closer up… notice that she is missing a leg?

The wasp spider is less agressive than A. amoena, and so are not used in spider-fighting bouts (I hope to get some good photos of  amoena next year and write a little about spider fighting).  Its venom is not known to be harmful to humans (usual caveats apply), and in some agricultural circles the spider is favoured as a predator of pests.  For example, in parts of Kochi it is known as ineushiwaka, or “Ushiwaka of the rice” (a reference to Ushiwakamaru, the childhood alias of warlord-cum-folk hero Minamoto no Yoshitsune)

 

These spiders have a single-year life cycle, and time for the adults to die is rapidly approaching as I write this.  Their eggs will already have been laid in their egg sacs – about 900 per sac – and will hatch next spring.  By August, the next generation of mature adults will be with us.

Faceoff

7 Aug

Like a scene from Alien vs. Predator… only for real.

An orb-weaver spider has set up home in the mandarin tree in our tiny garden.  Praying mantises also take advantage of the greenery and the insects it attracts.

What happens when two ambush hunters meet?

 

 

 

 

 

(In this case, nothing.  The mantis didn’t walk into the spider’s web, and the spider didn’t get within striking range of the mantis.)

Eight Legged Freaks

26 Sep

I am homeward-bound along route 50, the road connecting Tokorozawa with Sayama.  I pass the motley collection of garages and long-closed restaurants to the field.  And just a couple of dozen centimetres from my face, I cruise past one of the largest spiders I’ve ever seen.

 

Imagine this just 30 cm from your face!

 

This one had constructed a web from the electrical and fibre-optic cables to the ground, a neat classical web.  Some kind of orb-weaver, but with a large, triangular abdomen and no colour markings.

Note the horn-like knobs on the abdomen.

“Onigumo?” I ask myself as I struggle to get what photos I can with my mobile phone in the fading light – my cause not helped by the trucks going past, blowing the web and its owner out of my focus point.

 

No, that is NOT a spider climbling the power cables… but it was almost big enough!

 

Back home, I dive into my recently-acquired A Field Guide to the Plants and Animals of Saitama and confirm that, yes, it is onigumo.  The problem is, which one?  You see, onigumo (鬼蜘蛛) in Japanese refers not only to a species (Araneus ventricosus), but also to the whole Araneus genus of spiders – that’s some 650 species!!  Furthermore, I am unable to find a common English name.  (Ghost spider has been suggested, but this term refers to several different species)

 

The word “oni” in Japanese means “demon” or “ogre”, but can be a reference to size – the largest dragonflies (Anotogaster sieboldii) are known as oniyanma (usually 鬼蜻蜓, but sometimes馬大頭), and the tiger lily is called oniyuri (鬼百合).  That said, the bumps on the spider’s triangular-shaped abdomen are reminiscent of a demon’s horns…

 

A web search indicates that Araneus ventricosus is the most likely candidate.  The literature indicates that females may reach 30mm across the body, and my spider would be pretty close to that mark.

They are night-active orb weavers, famous for disassembling their webs every morning and for the speed at which they spin new webs.  I must have encountered this one soon after she (yes, anything that big in the arachnidian world is female – males reach just over half of that) completed her web for the evening.  She was ready to catch moths, crickets and unwary cyclists.

 

Spider awaiting the arrival of a cyclist, er, meal?

 

 

Meanwhile, other spiders had been in the news for other reasons…

 

From the Mainichi:

http://mainichi.jp/english/english/newsselect/news/20120904p2a00m0na005000c.html

Woman bitten by redback spider at Fukuoka rest home

          A redback spider is pictured in this photograph provided by the Fukuoka Municipal Government.
A redback spider is pictured in this photograph provided by the Fukuoka Municipal Government.

FUKUOKA — An elderly woman who was bitten on the leg by a redback spider at a welfare facility here was treated with expired antivenin, municipal government officials have announced.

Officials said the 86-year-old woman was bitten in the morning on Sept. 3, and was taken to a hospital in the city’s Nishi Ward. At one point she was suffering breathing problems, but her condition started improving after she was given the serum.

About 30 redback spiders were subsequently found in the area around the welfare facility, and staff exterminated them.

The antivenin was purchased by the Fukuoka Children’s Hospital and Medical Center for Infectious Diseases in Fukuoka’s Chuo Ward in October 2010. It expired on Aug. 10 this year. Staff noticed that the hospital’s stock had expired on Aug. 23 and ordered more, but supplies had not arrived by the time the woman was bitten. A doctor at the facility administered the expired serum after judging that it would have some effect.

“We’re sorry for our lax administration of the serum,” a representative of the city’s Public Health and Welfare Bureau commented.

It is expected to take some time for new serum stock to arrive, and the medical center is asking other prefectures to help out with supplies in the meantime.

Redback spider bites can cause pain, perspiration and nausea, and can leave children and elderly people in serious condition. About 10 people are bitten by the spiders in Japan each year, but the latest case was the first reported in Fukuoka Prefecture.

September 04, 2012(Mainichi Japan)

Click here for the original Japanese story

And the Daily Yomiuri:

http://www.yomiuri.co.jp/dy/national/T120906004839.htm

 

Over 100 poisonous spiders found

The Yomiuri Shimbun

AMAGASAKI, Hyogo–Authorities on Thursday exterminated more than 100 poisonous redback spiders spotted near the Inagawa river the day before, police said.

According to the police, a local man spotted a swarm of spiders at about 7:30 p.m. Wednesday in Amagasaki, Hyogo Prefecture and reported it to police.

Police officers rushed to the scene and found more than 100 spiders inside a drainage pipe in a river wall about five meters high located along a walkway.

Officials of a local health center later confirmed the spiders to be redbacks, a species legally designated as invasive and foreign. They were exterminated by health center officials Thursday morning.

(Sep. 7, 2012)

 

 

The TV news reported that some 30 council workers and police were deployed to kill the spiders.  I don’t know why they didn’t just recruit a couple of Aussies with a can of Mortein each…

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