Rats are very widespread throughout all of Auckland. The two main types being the water rat and the roof rat.
Rats favourite food in the wild are macadamia nuts (they can bite right through the nuts shell) and feijoa fruit. In fact it can be difficult to get them to eat anything else when these two fruits are in season and for this reason we sometimes put feijoa slices in the bait stations with the bait to encourage the rats to start eating. A new chemical on the market recently is a synthetic peanut butter aerosol. This smells just like peanut butter but very much stronger. We have found this to be very effective in attracting rats to the bait stations to start feeding as they can smell it from up to fifty metres away.
Rats tend to nest inside over the winter months where it is warm and dry and produce a liter of up to twelve baby rats every two months.Once these rats are two months old they start producing their own babies. They particularly like inset lights as they protrude into the ceiling space and the rats can cluster around them for warmth.
Rats and mice teeth never stop growing and they are continuously gnawing to wear their teeth down. You can suddenly find that your lights stop working as they have gnawed through the power cord. They can also smell water inside plastic water pipes in the ceiling and can gnaw into these, flooding the house.
Mice are smaller and rounder than rats but breed more quickly. Mice often enter the house by climbing up the hoses at the back of the dishwasher and quite often bite into the high pressure water hose flooding the kitchen.
Both rats and mice are very skilled climbers and can get through any space large enough to take their jawbone.. Trying to keep them out by blocking up holes is a waste of time as they simply gnaw another one. We have even seen a concrete block wall that rats had gnawed a hole through.
AAA Pest Control use two commercial baits to treat both rats and mice. The problem with using bait in the house is that the rodents can die in the roof cavity or inside the wall cavity and create a smell as they decompose. To minimise the chances of this happening we use a low dose bait which kills the rodents over several days but also massively overheats them so that they cannot stand being in a confined space and go outside for cold air.
Also most baits on the market contain a chemical called Bitex which is a bittering agent so that if a child puts a bait block in their mouth it is so bitter that they immediately spit it out again. Unfortunately, rats and mice are not too keen on Bitex either and are reluctant to eat it if there is another food source available.
The bait used inside premises by AAA Pest Control works on body mass and does not contain Bitex. This bait contains chocolate which rats and mice will fight each other to get at. We have found by experience that this bait is highly effective. It is also manufactured in New Zealand.
When all else failed in a job in the Remuera, St Johns area we used placebo blocks that look and smell just like the active bait blocks to the rat but have no harmfull ingredients. The older rats that have gone bait shy will ignore this bait as well but the younger rats will start eating it and when they are seen to thrive on it then gradually the older rats will start eating it too. After a suitable period of time we replace the placebo blocks with the active blocks and wipe out the entire colony.
One of the hardest jobs we have had in recent years was a house in the Devonport, Northcote area. This woman had a large rat coming into her kitchen at night and eating the apples in her fruit bowl. No apple, no rat. Judging by the size of the droppings this was a very large rat indeed.
We baited under the house and used a sticky trap in the kitchen (we could not use a snap trap as she had a dog in the house) with non poisonous bait on it. The rat ignored both baits and continued to eat the apples in the fruit bowl. Obviously this rat had survived a bait and trapping program somewhere else and had learned it could survive by eating apples and only apples. We removed the apples from the fruit bowl and using a cut down empty carton with just a small lip on it we sprinkled "Racuman Powder" (a very light powder containing the same active ingredient as our bait) over the bottom of the carton and placed an apple in the middle. The next morning a large chunk had been eaten out of the apple and the powder had been considerably disturbed. This would have got into the rats fur and when he later groomed himself he injested the powder and we got him.
We have since used this powder in the Remuera, St Johns area where rats were taking the bait but storing it as they had access to feijoas. We placed the bait on a plank under the house covered in Racuman Powder and got all of them.
Rats are very intellegent and learn very quickly. Quite often if you introduce a new food source the older rats will sit back and let the younger rats eat it. The older rats will wait a day or so to see if the young rats survive. For this reason we use a slow acting bait so that the whole colony eats it.
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