We should see plenty of action in an hour, Dr John Dunbar says assuredly via email, excited at the prospect. As a venom expert, many nights are spent combing the walls and railings of Dublin housing estates for Ireland’s highly-poisonous false widow spider.
Alone in the dark, armed with extended tweezers and a headlamp, he carefully places each one inside long plastic tubes as the residents sleep inside, blissfully unaware.
On a chilly evening thousands of such spiders are scattered just out of sight along Beech Park, a long quiet suburban road in Lucan lined with detached homes and webbed hedges. The noble false widow – or steatoda nobilis – first recorded in Ireland in 1999 is far more common than most people realise and its numbers are increasing alarmingly.
Within two minutes Dr Dunbar is poking at a web string. He has spotted two long, thin protruding legs, inconspicuous to the passerby. It is the first trophy of 94 that night.
Although he has handled thousands, Dr Dunbar has never been bitten. Twenty bites have been recorded in Ireland, he declares, and the bite is one to be avoided.
Hospitalised
“In some cases [bite symptoms] are so mild they just observed it for a couple of hours and it was pretty much gone,” Dr Dunbar explains. “Then we’ve had other cases where people have been hospitalised.”
In some cases victims have experienced severe bacterial infections, debilitating pain and body tremors.
Steatoda nobilis is compared to the notorious black widow for a number of reasons including notable similarities in appearance, genetics and toxins. It is known as the “false widow” because in regions where they co-exist it can be difficult to tell them apart.
Smaller than the native house spider, chocolate brown with a large bulbous abdomen and an intricate cream pattern sometimes resembling a skull, the false widow is easy to identify.
Five or six years ago researchers would have had to look hard for one. Today, a single hunter can expect to bag between 100 and 150 in a few hours in any suburban estate.
Thought to have originated in the Atlantic archipelagos of Madeira and the Canaries, it arrived in the United Kingdom and Europe on banana boats. Throughout the 20th century it established thriving populations throughout England and Wales, and later colonised parts of western Europe, California, Chile and the Middle East.
Although found in Co Wicklow a little more than two decades ago, little was known about its presence here until more recently. A 2017 Royal Irish Academy study confirmed the species in at least 16 counties, but most significantly in the greater Dublin area where it is abundant in urban buildings and around street furniture.
As Dr Dunbar walks slowly from suburban home to home, he identifies and scoops up the spiders from virtually every single driveway pillar he examines. His head torch illuminates the undersides of wall ledges, shrubs, gates, guttering, the back of ESB boxes. They are everywhere. After just a short while it seems other native species are relatively difficult to come by.
“[Their urban habitats] bring them in conflict with humans,” Dr Dunbar explains. “Usually the spider accidentally gets entangled in clothing or bed sheets and when they’re unintentionally pinned or squashed the spider actually bites, purely in defence. They’re actually quite a docile species.
Potent venom
“But they do have a venom that’s a little bit more potent than what we’re used to. It’s very similar to the venom of black widows, not quite as potent, but still kind of getting there.”
The risk posed are similar to ones posed by bees and wasps. Each spider can give about half of one microlitre of venom, about one thousandth of a millilitre. On his regular hunts Dr Dunbar tells the gardaí he will be prowling. The glow from his headlamp and his intricate inspection of neighbourhood walls are common, as are encounters with neighbours.
Just as he is plucking a sample with his extended tweezers, a resident approaches with a fair idea of what is going on but curious all the same. “They are obviously everywhere in this area,” Colm Gallagher says resignedly. “I know what the implications are; they have venom and whatever else. But they’re not terribly dangerous.”
They do go inside houses, but not usually. Whether for the curious resident, the arachnophobe or the scientist, there is still a lot to learn about these creatures and a race to learn it.
“They are here to stay, there is no way we’re going to get rid of them,” he says. “But we really need to monitor them while we can over the next years and see what happens. Now science must tell us what we are dealing with,” he said.
