Good riddance to bad rats

Question

How can I get rid of a family of rats that treats my greenhouse like a snack bar? Lettuces, strawberries ripening in hanging baskets and pepper seedlings have all been chewed up. I can’t use poison because my cat catches and eats rats. What traps and baits do you recommend?

Answer

Rats like the same living conditions we do – warm, dry with food close at hand – so they quickly take advantage of places we build for ourselves – sheds, greenhouses, garages and even our homes.

Rat infestations are a very common problem so readers of New Zealand gardenerGet Growing’s weekly email newsletter was quick to respond with rat eradication tips when asked for advice.

Traps can be designed to kill a rat instantly or capture it alive, although that leaves the problem of what to do with a live rat in a cage.

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We use a wire cage trap and a Goodnature self-adjusting trap.

JILL MCFARLANE / Stuff

We use a wire cage trap and a Goodnature self-adjusting trap.

  • We don’t use poison but have two traps. The wire cage we purchased from Hunting and Fishing was very effective at catching the rats. We bait the hook inside the trap with a nut from our trees and put some peanut butter on it, it seems to work every time. The trap does not kill the rat, so you always have to deal with a live rat. I leave that to my husband! We also use this trap under our baited tamarillo with a piece of tamarillo which also works well. The only problem with using the trap outdoors is that sometimes curious birds get inside the trap. It doesn’t hurt the birds and since we check the traps often, we just let the birds go. We also had great success with a trap from Goodnature. There’s a kill counter on it so we know he killed a lot of them, but we can’t find the dead rat because usually the cats take them away. The only time we see a sign of dead prayer is when we put it in the greenhouse, because usually the door is closed. This method also does not use poison and is also good for killing mice. We find both methods to be very effective, but the vermin control is endless. Jill McFarlane, Dunedin
The trap does not kill the rat, so you always have to deal with a live rat.  I leave that to my husband!

JILL MCFARLANE / Stuff

The trap does not kill the rat, so you always have to deal with a live rat. I leave that to my husband!

Wood traps are often available through groups of volunteers who organize targeted rat traps in a local area. Visit Predator Free New Zealand to find a band near you. If there aren’t any nearby, grab your neighbors and start your own group.

  • As a volunteer trapper, I highly recommend a wooden tunnel with a good sturdy trap baited with peanut butter. Cats can’t get in, rats approach the trap from the best angle for a clean kill, and if they end up being eaten by pets, the bodies aren’t poisonous. The photo above shows one of our tunnels as a guide. One end has a stapled welded mesh with a rat-sized hole cut out. The other is a sturdy rectangle of mesh with hinges and a simple hook and nail closure. Rachel Paul, Cambridge

Goodnature automatic traps are powered by CO2 gas and use non-toxic chocolate and coconut bait.  They are designed to kill rats and stoats.

Robyn Edie / Stuff

Goodnature automatic traps are powered by CO2 gas and use non-toxic chocolate and coconut bait. They are designed to kill rats and stoats.

Goodnature Self-Resetting Traps come highly recommended by many Get Growing readers.

  • Don’t bother with anything other than a Goodnature trap. For years we have spent money on bait and various traps with mediocre success. A simple Goodnature trap is highly effective, safe and permanently installed. It requires minimal maintenance and operates 24/7! Marilyn Odinot, Wellington
  • I use a Goodnature A24 rat trap. It’s not cheap, but it’s a catch-and-reset trap. I had my trap for about 5 years. Mine has a counter that lets you know when it’s been triggered. It also comes with test patches to find their tracks, so you can locate your trap in the right place. Wayne Duncan, Katikati

Readers have found that electronic devices known to keep rats away by emitting sound waves were less effective than traps.

  • I had a barn overrun with rats. I tried two versions of the electronic devices, without success. One day I walked into the barn to find a rat sitting on the device! Today I have a combination of three different rat traps and a cat. Occasionally I find rat tracks, if I forget to check and reset the traps, but never for long. I mainly use peanut butter as bait and occasionally corn. Carol Parsons, Tauranga
  • I had a rat problem in my garage and used an ultrasonic device but it had no effect. The rat kept coming in and chewing up all my plastic storage boxes and cleaning everything up. I had peanut butter rat traps but never caught anything. I ended up lining the lower walls with plywood which stopped the entrance to the garage from the tiny gaps where the metal meets the frame. No more rat problems preventing access to the area. I then used the Goodnature Rat and Stoat Trap and caught four mice. I also set up a wooden trap tunnel with a rat trap inside and caught four huge rats. It also had no bait. It worked better for catching rats and is much cheaper than the Goodnature system. There is a karo on the side of the garage that the rats love to eat the pods from so I collect and remove them from time to time to get rid of their food source as they used to take this back to the nest they made in my firewood pile storage. Jason Kenna, Porirua

Any trapping or poisoning effort must be safe for children, pets and birds. Place poison in closed bait stations and spring-loaded traps in tunnels that only rats can access.

  • I suggest that the cat go on vacation to a nice cattery for a week to 10 days and intensively bait the rats. Nothing less will eradicate them, and you will have ongoing costs for trying to do so that will easily exceed the cost of staying in the cattery. By the time the cat returns, all the rats will be dead, and the cats don’t eat dead rats, so the cat will be safe. I live bait on a wooden board. Rats cannot remove bait, so you can see when they are no longer eating bait. You need to leave it for a few days after that to get newly mature rats. Once the second wave was over, the infestation disappeared. Sue Taylor, Dunedin

Several readers have suggested making homemade baits with various mixtures of flour, baking soda, plaster of Paris, sugar, or instant soup powder. Similar recipes are easily found online. The theory is that rats are attracted to sugar, flour or powdered soup. Once they eat the bait, the baking soda reacts with the stomach acids and eventually kills the rat. These baits work, but the rats have to eat large amounts, the reaction is painful, and it takes a week or more for the victim to die. Traps are still deadly, but they are more humane.

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