Stop that rat
Stop that rat
Most people recoil at the sight of a rat. And, as a carrier of potentially fatal diseases such as Weils and murine typhus, with good reason. Tom Allen-Stevens finds out how to keep them out of your grain store.
Source
1 BAITING the problem wont cure it. The first thing to do is to identify where the rats are coming from.
On the farm used here its been traced to rat holes behind the gamekeepers sheds; pheasant feed is an easily accessible source of food throughout the winter. The holes can be gassed with phosphine tablets (aluminium phosphide).
More often than not, however, theyll come in from the fields, and theyre especially fond of game cover. Half an oil drum with an access hole cut in it makes a good cover for a baiting point in a game patch.
The source of the problem is just your first line of defence. The second is the ingress point into the farmyard itself – often a ditch or drain. This is where bait boxes can be placed. Make sure that they are weather and pet proof.
Proofing
2Good proofing is the key with buildings. Concentrate on doorways and drainpipes. This door looks rodent-proof but it isnt; if you can stick a pen through a gap, a mouse will get through.
Rats use the gaps between drainpipes and walls to climb up and gain access. Keep the pipe away from the wall, collar it or smear it with grease to prevent this. Small holes in walls can be filled with wire mesh and expanding foam.
Safety/COSH*
3 Safety first when handling any poison, says Command Pest Control technician Andy Tuffs. Wear gloves at all times and ensure poison is safely locked away in sealed containers when not in use.
If using loose bait, lay down small amounts at a time. That way, if a baiting station is knocked over, there will be less poison to be picked up by a non-target animal.
Records are also important, both for COSH* and ACCS. Keep a written record of where the baiting stations are and when they are inspected, noting down the active ingredient used and the operative. The safest bet may be to use a qualified contractor, who will leave behind a detailed record of his visit that will comply to legal and farm assurance regulations.
Chemistry
4 There are a variety of tools in the chemical armoury against rats.
One of the best forms, and suitable for use in grain stores, are block baits of the anti-coagulants brodifacoum or flocoumafen. Rats will gnaw from the block as much as they need.
Loose bait is cheaper and perhaps more versatile, but care should be taken that it doesnt contaminate the grain and that non-target animals are not exposed to it.
A highly effective but hazardous form of poison is bromadiolone tracking dust. It should only be used in the least accessible points, such as narrow ducts or in rat holes in insulation, for example. Rats walk through the dust and then ingest it when cleaning themselves.
Mice
5 Controlling the rats can be easy, but mice can be more tricky. They dont carry the spectrum of harmful diseases a rat can bring with it, but they still need to be kept in check.
Alphachloralose is most effective in the right conditions: use the right mix and they will be knocked over on the spot. You need very little – about the size of your finger nail – and it needs to be sweetened, perhaps with a digestive biscuit.
Mortality relies on low temperatures, however. If it does not prove fatal it is addictive, so if used in summer, the mice may acquire immunity.
Combine
6The combine can be a haven for mice: its a ready source of food and is quiet and dark during the winter months. But damage can run into thousands of pounds if electrics are chewed, not to mention untold grain losses due to gnawed seals.
Baiting points should be in the cab, under the cab, on the straw walkers and either side of the combine where the electrics are. Cardboard boxes should be used rather than plastic since they are less likely to cause damage if run through the combine by mistake. Be careful to put a warning notice and a map of baiting points in the cab to ensure this is unlikely to happen.
The seed drill is another classic haven. If you find evidence of rats in the drill, clean it out thoroughly before drilling starts and check regularly for blockages for the first few bouts.
Tunnel
7Tell-tale signs of an infestation in a wind tunnel and ducting are droppings, the smell and black grease marks or smears.
Rodents tend to follow the same track from A to B and the smears show where they have been. Bait should be placed in their path, on the leeward side in the tunnel so that it doesnt blow over and scatter throughout the ducts when the fans are turned on. On the grain itself you can often see tailings – the groove left by a rats tail as it moves over the heap.
Beet/potatoes
8Root crops form a perfect food source because they provide the moisture source as well as the food; if rats dont have to search for water, it restricts your chances of catching them. And beware if you grow carrots: they are a useful source of vitamin K1 – its used as the antidote to many rodenticides.
Bales are often used as insulation in potato stores or walls of beet clamps which are an excellent home for rats. When building any straw stack or wall of bales, place baiting stations at likely access points. The stations themselves should be tamper-proof. These upturned bottles over pipes may look like a good idea, but if knocked they could scatter bait and contaminate the area.
Rat-zapping – the tricks of the trade
• Find out why you have a problem and where its coming from.
• To control ingress you need three lines of defence: control at source, control at ingress, and proofing at point of access.
• Look for smear trails – these can often be found along ledges and against walls.
• Lay baiting stations against the wall, especially outside, along a rodent trail.
• The best bait to use is the one most applicable to the individual situation.
Does non-chemical mean non-effective?
• Not always, there are some very good traps available. Look for the ones with single finger settings. Two traps placed back-to-back in a tube can be very effective.
• Ultrasonic devices are well-proven to ward off birds in the open, but are much less reliable in a building with rodents.
• Electric traps that claim to kill with a large electric shock may work in domestic situations, but could be less reliable where there are large numbers of rodents or if damp conditions prevail.