Winter 2013 True Natural Health Magazine – Your Questions Answered
By Roger French


QUESTION:   How can we prevent these little pests from getting into our homes? Are naphthalene flakes effective in deterring mice? 



As usual, I will cover the topic somewhat comprehensively.

Mice want to get to places where food is available, and physical barriers can upset their plans. To keep mice out of the home, or at least the kitchen where food is stored, seal all holes and openings that are wider than 6 mm (¼ inch). Use tough materials that will resist gnawing, including concrete mortar, galvanized sheeting or perhaps hardwood.

If mice are eating your veg. garden seedlings, surround the garden bed with wire-netting screens, and bury the bottoms of the screens in the soil five to eight centimetres deep.

Repellents are a humane way of being free of mice. But they can only be effective in small enclosed areas, so are usually not a solution. The naphthalene that you ask about, which comes in the form of mothballs or flakes, may work in small enclosed areas if sufficient concentration of the chemical in the air can be attained. Other aromatic compounds such as the concentrated oils of mint or cedar have not been found to be effective.

Your home can be made less attractive to mice by minimising any cover that enables them to move around without being vulnerable to predators. Remove weeds and other vegetative cover as well as litter in and around the home and keep lawns well mown.

Wherever possible, store food in rodent-proof containers and keep kitchen benches clear of food scraps and crumbs. Sweep floors frequently to remove crumbs and to permit early detection of mouse droppings. Keep garbage areas clean and lids fitting neatly on bins.

In offices, mice can hide behind cabinets and other furniture, so be sure to clean up crumbs and food on scraps after lunch or morning tea.

Another way of deterring mice is a device that frightens them away. There are commercial devices that emit very-high-frequency signals that are uncomfortable to mice, although they are limited by direction and distance, because their intensity drops off rapidly with distance. Nevertheless, they could be worth investigating.

Poisoning mice is not humane and many readers of this magazine would not do it. The most common rodenticides are anticoagulants, such as Warfarin, Rozol or diphacinone. More recently available are anticoagulant baits that can be lethal in a single feeding, such as brodifacoum and bromodialone. Anticoagulants can be lethal to all animals, so they should be kept well away from pets, native animals and livestock.

There are other rodenticides besides anticoagulants, including strychnine, zinc phosphide and bromethalin. These baits would be used mainly where anticoagulants are not feasible, because the mice eventually become wary of them and they are a big hazard to other animals.

Fumigants in the hands of licensed pest controllers can be very effective, but there is the problem for the human residents of breathing residual toxic fumes. 

Mouse traps can be effective, but can be cruel, and many people would not use them.