Auckland
Kate Evans takes a closer look at the Urbin, the rat-trapping compost bin.
Like most gardeners, I’d also like to see birds flourishing in my garden and in the bush nearby. Unfortunately, glimpses of scuttling brown and recurring tunnels among my food scraps have led me to suspect that my compost has, in fact, become a prime habitat for rats.
Then, at WOMAD just before the ra¯hui, I met Hannah Smith, displaying her latest invention – an upcycled, plastic-free compost bin that is simultaneously a rat trap. The idea seemed genius and I had to know more.
Hannah grew up wanting to be just like her Dad, James Wilson. He was a farmer in Manawatu¯ and an inveterate inventor – constantly coming up with clever ways to improve life on the farm, from round cattleyards to a hay-bale cover with pockets that fill with rainwater to hold
it in place. So Hannah studied industrial design, hoping to be an inventor, too. “And then I never had a single idea,” she says.
She became a prop-maker in the film industry instead, and now lives in Muriwai.
But as she approached 50, the ideas finally started coming – ideas to solve the problems she encountered in daily life.
“Around the world there are hardly any women designing any of the products that mostly women use,” she says. “Mops, I really hated. They’re so disgusting. They just sit there rusting in the corner and you feel like you’re smearing dirt around the floor.”
So of course she invented the Mopsock, a microfibre cover that goes over the head of a vacuum cleaner or broom and can be thrown in the washing machine after each session.
The next problem was the family of rats living in her compost pile.
Hannah tried every kind of trap, but none caught a single rat. When she rang the manufacturers to complain, they told her, “Rats love compost more than they love any bait ever invented.”
That was the lightbulb moment that led her to design the Urbin – the compost binrat killer.
There are three parts: a spinnable drum, a removable rat trap, and a wooden box where the compost is made that becomes a raised garden bed when it’s full.
You put your kitchen scraps in the drum each day, add a chunk of compacted wood shavings – “no-one puts enough carbon into their compost, we’re all guilty of it” – and give the drum a spin.
At night, your rat will climb onto the drum and through the easy, one-way entrance. But the only way out is through a narrow exit set with a pressure pad rat trap. It’s a quick, humane kill. “With a family of rats you’ll catch one each night until they’re gone.”
In the morning, you remove the rat – you don’t have to touch it – and drop it into the bed below. Then you open the drum’s hatch and cover the rat with compost.
Your problem is now an asset. “The microbes love it, so your compost is better than it would have been without the dead rat,” she adds.
Hannah’s last bed had 18 dead rats tipped into it but when she dug out the compost there was no sign of them at all.
“You’re not going to be killing all the rats in the world, but at least you’re not going to be raising families of rats with your own waste.”
It took Hannah six years to perfect the concept.
The Urbin is made of wood and upcycled washing machine drums that the Helensville Community Recycling Centre saves for her – the result of another eureka moment.
“You couldn’t design something that worked better! They’re very high quality steel, but no-one takes them out of the machines, they just all get smashed.”
Hannah has started making larger versions for schools too. “They’re a kinetic tool for learning about design, predator control, and microbiology,” she explains.
She’s not after fame or fortune – she’s just stoked she’s solved her rat problem in such an elegant way. “When I go down and find a rat in my Urbin, it makes me so happy. It’s my greatest thrill having a product that works well.”
And she’s got one more thing in common with her Dad (now living in Picton) – he’s involved in community predator control. “I guess he’s proud! He and I spend hours talking about ways of trapping rats.” ✤
You can place an order at mopsock.co.nz.