Progress in Pest Technologies
- Despite some serious attention the perfect trap still eludes us.
by Scott Sambell

In 1897 James Henry Atkinson lodged a patent for the “snap rat trap”. It used a wire bar pressurised by a spring held in place by a lever which was activated by a pressure sensitive plate. The rat pushed on the plate – the bar slammed down on its head.

Pretty basic stuff really.

Of course you have to take into account that this was the same decade that man invented the dry-plate camera, the fountain pen and the incandescent light bulb. Nowadays we have digital cameras that take photos in a resolution 4x greater than the human eye can distinguish, anything involving a pen has been made redundant by any number of items with the prefix “i”, and if you are caught with an incandescent bulb in your house (as opposed to an LED or CFL) you are liable to be named and shamed on a current affairs program.

So what massive advancements have we made in rat traps in the last 116 years? Well I recently purchased 50 units of the most advanced trap commercially available, and the difference to Atkinson’s invention are two fold – Firstly its mostly made of plastic and secondly, you can set it with one hand. In a nut shell, not much really.

Illustration from an early patent for
a continuous rat trapping device.

We could spend the next page and half discussing why the communications industry has progressed from Marconi’s radio (1895) to a computer program that searches 18 billion web pages in under 0.05 seconds, whilst the conservation industry has progressed from a wooden base to a plastic one – but that would possibly cause us to stray from the topic slightly.

So, what do we have at our disposal now? Well apart from the one-handed version of Atkinson’s trap we have – poison. We’ve been through Warfarin, coumatetralyl, bromodialone, diphacinone, sodium monoflouroacetate (1080) and the weapon of choice these days seems to be brodificoum. We’ve tried them as pellets, blocks and paste. We’ve put them in stations, tunnels, pipes, hand spread them and dropped them out of helicopters. And in our defence we have gotten a lot better at killing the stuff we are supposed to be killing and missing the stuff we are supposed to be saving. Of course it’s still not perfect by any means.

As Ralph Waldo Emerson once famously said: “Build a better mouse trap and the world will beat a path to your door”. Well in our case we are after rats but thats a technicality in the grand scheme of things. Basically “the perfect trap” has alluded mankind for centuries. There are those of us at least who believe we know the criteria for such a revolution. That is, it must:

a) Kill the rat every time

b) Not rely on the rat doing anything which wasn’t part of its daily intentions anyway

c) Reset itself many times

d) Not kill anything it isn’t supposed to.

There have been some good hard cracks at it in recent history, and all those of any worth coming out of New Zealand where we are rightly recognised as the world leader in these things, but so far all have fallen short.
There was the gas-powered-self-resetting-humane-neck breaker a couple of years ago. Unfortunately it assumed the rat was eager to climb up to a bright orange appendage and stick its head into a hole to manipulate a small wire that couldn’t be less alluring if it had a neon sign above it stating “rat deaths here”. Not surprisingly
it failed on requirement “b”.

Then there was the Flying-bolt-of-death trap that also assumed the suicidal rats were not only planning to stick their head in a small hole that day but also that they wouldn’t work out that if they approached from the opposite direction, they could eat through a thin plastic housing and make an informed choice between a hydraulic ram to the head and nice feed of peanut butter. Suffice to say most rats chose the peanut butter.

Of course I must mention the electric shock traps that – although they make extremely entertaining youtube videos – fail on pretty much all four counts the moment you take them out of the controlled environment of a television studio.

So where to from here?

Well there are two inventions in the ‘research and development stage’ in New Zealand that are vying for the Ralph Waldo Emerson Ultimate Prize.

Neither involve the rat doing anything more extraordinary than walking through a tunnel – certainly a favoured activity of all the rats I have spent the last 5 years studying. One tunnel has a pressure plate which senses the rat according to its weight, the other has multiple infra-red beams that sense a rat shaped presence. Both are ticking all the boxes so far.

Once the traps conclude they are indeed hosting a rodent which they wish to dispose of, they both shoot it – with poison. One inventor has perfected his lethal cocktail and assures me that it will be absorbed through the rat’s skin into its blood stream thus killing the rat but (and here is the beautiful part) be totally inert to any third party who decides to eat the recently deceased rodent. The other inventor is yet to crack the formula but she tells me her potion will rely on the rat grooming itself post-spray (as they are such vain creatures) and ingesting the lethal dose.

Both are close but still so far from ‘production stage’. However, when they are ready to go, I will be at the head of the queue, beating a path to their door.

Maori brought the pacific rat or kiore with them when they migrated to Aotearoa and they obviously had confidence in their trapping ability and techniques to liberate this food source. Some of fixed location traps are illustrated here along with a fine image of a portable trap or tawhiti makamaka.

 Images courtesy of
Te Papa Collection