Notes on Steatoda Nobilis

False widow in the kitchen sink Copyright: Alan Brown
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Steatoda: Biting Experiences by Simon Moore

From The Newsletter No. 96 March 2003

Reports of spider bites seem to be on the increase— hardly surprising with present media attention coupled with the spread of Steatoda nobilis (Thorell, 1875) and S. grossa (C. L. Koch) across the South of England. In Newsletter 76 (1996) John Parker wrote a short article about British spider bites in which he mentioned Steatoda. Here are some more accounts of close encounters with members of this fascinating theridiid genus.

I first came across Steatoda grossa under some window seat cushions in a house at Bembridge (IOW) in 1971 (when it was still known as Teutana and was considered to be quite rare in the UK). Since then I have often come across S. bipunctata and was bitten by one during a sweaty day in 1986 cutting Japanese knotweed: I mistook its tickly legs for those of a horsefly (there were plenty about!) and swatted it. So it bit me, but I suffered no discomfort apart from a slight itch (similar to a nettle sting) which lasted only a couple of days.

Five years later I came across my first S. nobilis, brought to me to identify because of its resemblance to the Black Widow. 'Could it have been imported with fruit from southern Spain?' I was asked. This prompted me to ask around and Dick Jones told me that there had been a colony in the Portsmouth area for some considerable time (possibly c. 100 years, although he had first found it in 1979/80). The epigyne of the spider 'in the fruit' confirmed it to be nobilis.

In 1998 I was urgently summoned to Gosport to investigate 'poisonous-looking spiders' in great profusion in and around a house where there were small children. Sure enough, it was nobilis again and, although there were none actually inside the house, there were plenty in the small garden, hiding under the metal flanges that kept the fence together. I also noticed that there were hardly any traces of other spiders (the usual suspects such as Amaurobius, Tegenaria or Segestria). I informed the owners that the spiders were numerous and mildly venomous, but would only really be seen at night. I then gathered a few specimens for our collection, and later rang Peter Merrett, who confirmed that he had noticed S. nobilis everywhere in Swanage and that they were rapidly spreading along the south coast and (presumably) driving out many of the other wall/fence dwelling species.

At this time I saw on the local TV news, that a cleaning lady at a primary school on the Isle of Wight had been bitten on the shoulder and that the culprit had been identified as S. nobilis. She had experienced swelling and discomfort, and the school was temporarily closed for fumigation. I only recently discovered (via Dick Jones) that this spider was in fact S. grossa and I added the species to my list of more venomous spiders.

With spiders being imported, usually in fruit (at one time often with bananas, more recently with grapes), I am sometimes deluged with enquiries. An example of S. paykulliana, complete with the red semicircle around the front of the dorsal abdominal surface was passed to me for identification, having been imported from southern Europe in furniture.

In January 2003 a lady telephoned me: she urgently needed to know the name of a spider that had bitten her and which had produced some fairly severe symptoms. She informed me that the bite had occurred in her car whilst driving and that she hadn't found the flattened culprit until later. I dissected out the vital bits from the squashed husk that she had sent and Paul Hillyard confirmed the identity as S. nobilis. I had asked Mrs Dascombe to record her symptoms and reproduce her letter with permission.

The bite I received on 22nd December, 2002. I was in my car when I felt a slight burning sensation on the right hand side of my ribcage. This increased in intensity, like being scalded, spreading first to my right armpit then down into my right arm. Simultaneously, I felt stabbing pains, firstly in my ribs then spreading as described above. I also began to feel generally unwell, flu-like symptoms-aches, sweats, fatigue. I was perspiring, particularly at the site of the bite. However I felt cold and shaky. I then felt sick and giddy and slightly disorientated. This all occurred in little more than 10 minutes by which time (fortunately for me) I was driving by Bournemouth Hospital, so I turned straight into Accident & Emergency. I had a 30-minute wait to see the Triage nurse, during which time the above symptoms persisted, making me feel incredibly unwell and obviously anxious. My right arm felt cold, heavy and numb, it went quite purplish in colour and ached, it looked slightly puffy to me. The nurses noted that I was flushed, my face was a little puffy and I had a raised red area 5-6 cm in diameter with a visible bite mark. I was given piriton at that point and an hour or so later, when I saw the doctor, the red area was reduced and I was starting to feel better. My arm looked and certainly felt more normal. I was prescribed a course of piriton, penicillin and steroids (prednisolone), I believe to cover all angles as, at that stage, I had no idea what could have bitten me. I continued to feel unwell that day and it wasn't until Christmas Day that I actually felt more like my normal self. My car remained untouched between the 22nd and 25th and I discovered the squashed spider on my car seat on Christmas Day. Finally, 19 days later, I'm left with a tiny red raised mark which continues to itch and burn slightly.

Finally, I recall someone writing in the Newsletter (years ago) to keep members informed of any British spider envenomations and which species might be considered to be our most venomous spider. In the light of recent experiences, perhaps this file might be re-opened, particularly as I am often asked this question.
 
Added by John Partridge at 20:20 on Fri 24th Feb 2012.

SOME NOTES ON THE LIFE HISTORY OF STEATODA NOBILIS (THORELL) by G.H. Locket

From The Newsletter No. 25 August 1979

Mr. R. Jones' account of the finding of Steatoda nobilis in Portsmouth (News Letter 24, p. 3) has stirred a memory and made me turn up some notes on this species made half a century ago and which, seeing them again, are perhaps of some interest. A female was found in a crevice in a wooden seat near Funchal, Madeira, in February 1924. At home in England it was installed in a box with a glass cover and fed regularly. During the summer, while I spent a final term at Oxford, it was neglected, but on returning I fed it and it made a cocoon from which young hatched and dispersed in my absence, all except three. Of these one died, one was a male and the other a female. Both were successfully reared and mated and from them four generations were descended, after which all eggs became infertile. The structure of the snare and its use are interesting for several reasons. In the early stages of its construction the web is quite irregular and resembles that of most Theridiidae, but as Mr. Jones noted, the spider waits in the lower part of the web. Soon a tubular retreat is formed at one side and this opens on the under side of a perfectly definite sheet, which however is formed gradually and is only seen fully developed when spinning takes place in an unconfined space (I never saw this until one specimen escaped in the laboratoryl). The advantage of this sheet among the usual irregular criss-cross threads is not altogether clear, because the spider always attacks in the typical theridiid way, throwing on sticky thread drawn out by the IVth legs, approaching and biting, usually the end of a limb of the prey, securing that limb to the rest of the web and, maybe, throwing on more thread before the prey ceases to move. In the ordinary way the spider moves on the under side of the sheet; if a fly falls on the upper surface, instead of running to the spot and biting through the sheet as a linyphiid would, she makes hor way round to the upper surface and there attacks in the usual theridiid way. On the other hand there is no doubt that the sheet makes horizontal movement easier, enabling this large heavy spider to reach its retreat more quickly when disturbed. Not knowing at that time of the discovery by Wiehle of the frequent occurrence of threads with sticky globules at the base of theridiid webs, I did not notice if these were present on that of S. nobilis.

Courtship and mating were observed several times, the following observations made on August 8th, 1925 were typical. A male was introduced into a female's (rather small) web at 8.50 p.m. He ran rapidly about two-thirds of the way up the outside of the silken retreat in short stages, whereupon the female, who was in and near the opening of the retreat, turned round to face him. The male then started (9.05 p.m.) a curious dancing movement with the second pair of legs. They were moved up and down (synchronized), the movement being slow at first (i.e. about twice a second) and getting more rapid, the whole body being finally involved. He approached the female, touching her with his front legs, and, after making several dabs at her epigyne, applied the left palp for 12 minutes 40 secs, the haematodocha being inflated every ten seconds and then gradually subsiding as usual. The spiders then separated, the leg movements were repeated and the right palp, after ten attempts, was fixed for 3 mins. (9.30 p.m.). The remaining actions are summarized thus: Spiders separated. Male began leg movements, quickening as he approached the female. Left palp applied (30 secs.). Separated. Approach as before. Left palp applied (4 mins. 40 secs.). Separated. Male danced again, turned round, walked down the retreat an inch, turned round, walked down the retreat an inch, turned again and continued to dance, the female advancing as he approached (there may have been an attempt here to induce her to come out into the open.). Male made 5 unsuccessful attempts to fix the palp, turned round and walked another inch down the tube dancing (9.47 p.m.). Made 18 unsuccessful attempts to fix the palp, walked away another inch, occasionally stopping to pass palps through chclicerae. Approached female as before, 11 efforts. Right palp applied 1 min. 40 secs. (9.57 p.m.). A few further courtship movements but then no more for 35 mins. when the male was removed. On another occasion the female approached the male, who only started courting as she drew near. Copulation followed immediately; left palp 72 secs. Interval and further courting then right palp 55 secs. Further courting followed but no further applications of either palp. The positions during copulation were indistinguishable from those of Steatoda (Lithyphantes) paykulliana (Walck.) figured by Bristowe (1930, P.402, Fig. 6). Sperm induction was never observed. The two sexes often lived together for some time and the males were seen to catch flies independently and to carry them to the retreat, although they were rather inadequately wrapped up. Remarkably, one male bit a fly buzzing on the sheet without first throwing on sticky thread. On some occasions a male was attacked by the female soon after mating and eaten and always, without being able to escape, eventually eaten, but surviving sometimes up to a month.

The making of the egg cocoon was observed on June 20th (1931 ) when at 9.30 a.m. a gravid female was observed applying her spinners to a place in the upper part of the tubular retreat and drawing them away with a regular rhythmic movement. (Generally a female would construct a cocoon round herself or block the entrance of the retreat before constructing an egg cocoon, but this time the entrance was left open and it was possible to see what was going on inside more clearly.) The spinners were applied and withdrawn about once in every two or three seconds while the spider slowly turned round. She was forming a platform of silk above herself. The motion had a carding action and made the structure fluffy. The spinners were usually wide-spread as they were drawn away. 9.30 a.m. - Took 1 minute to get round, making 36 dabs with the spinners; platform beginning to be definite. 9.35 a.m. - Reversed way of going round, 9.40 a.m. - A tendency to work at the edges; the structure becoming deeper with the fluffy silk. 10.05 a.m. The eggs were laid from below in a light yellow mass very quickly, in 5 minutes, The spider then made rhythmic movements, first with the epigyne against the egg mass (as though to press it together) and then a little further away the action being now as before the eggs were laid. The upper half of the structure was larger than the lower and had a fairly clear-cut edge, there being only a very fine covering as yet over the bottom of the egg mass. The same action continued until there was a covering of silk all round the eggs. 10.15 a.m. - Motions continuing, the cocoon being turned a little, though not yet free to rotate. At one time she threw on some threads as when attacking a fly, but at once resumed the former steady action of applying and withdrawing the spinners, walking round the cocoon and covering it with silk uniformly. The work continued until 11.00 a.m. At 1.35 p.m. the spider was seen outside the tube on the edge of the web. The whole operation was observed with another specimen on another occasion but the procedure seemed to be the same.

Fertility of females. The length of time for which the sperm remained active and alive in the spermathecae of the females are quite interesting.

Specimen No... Date of mating... Date of egg-laying.. Time sperm remained alive (months)
......(1).......... 8. VIII. 25 ...........25.V.26 ................9.5
......."................".................7.VII.26................11
......."................"...............ca.7.IX.26................13
......(A).......... 4.XI.27.............. 18.VI.28.................7
......."................"..................6.VI.29................18 (has this ever been exceeded?)
......(e).......... 19. IX. 29............ 1.VI.30................ 8.5
......."................"................29.VII.30................10
......."................"..................3.XI.30................11.5
.....(iv).......... 7.X. 30...............12.VI.31.................8
......."................"..................20.X.31................10.5

The young were seen, some seven weeks after the eggs were laid. They took anything from 8 to 15 months to reach maturity, depending on whether they spent the winter in cold rooms or at the temperature of the laboratory. They underwent 4 to 5 moults after leaving the cocoon.

Other observations included the following. On several occasions after unsuccessful attacks on flies, spiders were seen to eat the viscid globules which had been thrown on the prey. The poison was potent, for instance the bite on the leg of a large fly by a small spider caused death in 3 minutes. A young specimen was found feeding on the body of a dead spider which had occupied the case previously, having wound it up as with living prey. Sometimes the dried bodies of flies cast out of the web would be collected and examined carefully as though being tested as possible food.

Reference:
Bristowe, W.S. 1930. "A supplementary note on the mating habits of spiders" Proc. zool. Soc. London. 1930 Pt 2. 395-413, 12 figs.
 
Added by John Partridge at 16:42 on Mon 9th Jan 2012. Return to Summary for Steatoda Nobilis