The rat and mouse calls are coming thick and fast following the recent cold snap as rodents head indoors.

One unfortunate family recently suffered $25000 worth of damage when a rat chewed through a water feed line that flooded and destroyed their laminated timber flooring. A single young ship rat was the culprit.

There is much that can be done prior to winter to reduce the chances of a rodent invasion and some of this is not just about actual control. Reducing the amount of food items available to rodents in utility buildings and feed pens is often an important factor, palletising/shelving stored grains etc and regularly sweeping up any spilt food stuffs both reduces the amount of available food and also allows for easier checks for rodent presence.

There are often key areas that rodents use to access our buildings so it’s well worth finding and reducing these by doing things like sealing up gaps around drainage fittings and beams with chook mesh (timber, plastic and rubber can all be chewed through by rodents). The removal of vegetation/trees that give rodents direct access to gaps under roofing iron is also a great starting point. The more of these passive techniques that you employ, the more effective your actual control will be at the sites where access cannot be completely stopped.

In terms of control, there are a huge variety of traps and poison baits available off the shelf. The choice between these methods needs some careful consideration. Traps are great as you know exactly how many animals you have caught and you won’t end up with poisoned rats mouldering away behind wall boards or other inaccessible areas. Unfortunately traps alone are not often adequate in dealing with larger infestations and many find that initial knock-down with poison followed by some trapping is required.

Traps should be baited with peanut butter, this is a highly palatable rodent bait and the animals won’t often remove it all without setting the trap off. For best results it’s worth leaving the trap baited but un-set and only setting it once the bait starts disappearing. This gets multiple animals used to the trap and higher capture rates should be the result.

When trapping mice you may need a trap every 10-15 feet for effective control but this can be increased to 25-50 feet for rats. Traps set outside should be covered by a tunnel approx 400mm long and large enough to allow the trap to work, this will protect the trap and bait from the weather and avoid non-target captures such as birds.

Poison bait should always be placed in a bait-station that protects the bait from the elements, excludes non-target animals, pets and children, and also prevents rodents from taking the bait away and ‘caching’ it.  Place bait-stations adjacent to areas where damage is occurring, in roof cavities, under buildings and at suspected access points.  Baits should be replaced as they are consumed and/or if baits are deteriorating in quality. Always consult the manufacturer’s directions for best results with toxins as many require a number of consecutive feeds to be effective. 

There are a wide variety of toxins on the market, most of which will do the trick but it’s probably wise to steer clear of any in small quantity ‘boutique’ type packaging as sold through some hardware outlets. Much of my residential rodent work comes from people that have spent a small fortune on these products without any joy.

A NZ company, Connovation Ltd has recently developed a range of rodent control toxins with a particular focus on reducing toxic residues in the environment. For more information about this innovative company and its products check out www.connovation.co.nz.