TECHNICAL | PPC109 October 2022

We asked BPCA Technical Support Officer John Horsley to tell us his top five steps, big or small, to improve pest management outcomes.

When we’re carrying out pest control we occasionally find that one site where nothing we do seems to work. You probably won’t have to think too far back to remember the last one that was a real head scratcher.

It can be hard enough to deal with a pest issue when just taking into account the location you find them. Add in environmental management, resistance and product restriction, and sometimes it can almost feel impossible to find that perfect solution.

However there are things you can do to make sure you deal with that pest as effectively as possible.

1. Identify the pest!

Pest identification will give you the majority of the information you need to best select the type of treatment you intend to complete.

If you don’t know what pest you’re dealing with, how can you possibly recommend the best proofing options, non-toxic treatments or even more importantly, the potential pesticide treatments you can legally use? 

And equally, how can you be sure the methods you’ve chosen will work? 

It’s not always possible to get visual identification so you may need to look for other clues.

Droppings can be a good tool to use to narrow your identification down. Small droppings around 5mm in size and pointed at both ends are typical of a mouse, whereas 10mm long droppings pointed at both ends will be a rat.  

From these droppings, it’s difficult to say if it’s a field mouse or house mouse but you’ve already begun to narrow your search.

The crumble test is a good tool for identifying bat droppings. Simply rub the dropping between your fingers and if it crumbles into a fine dust, maybe full of insect wings and exoskeletons, voila! 

For more info on identifying droppings, check out our article at bpca.org.uk/guesswhosepoo

Cached food could also be a good indicator of what type of pest you’re dealing with, and in some cases it can help with that field or house mouse dilemma. Field mice, as well as rats and grey squirrels, will store food for times when they need it, in winter for example.  

If you find mouse droppings in a garage and stored food in the same area, this points to field mice.

In bait boxes placed outside, you could find stored food and again, it would be important to identify what is storing this as it could be field mice or rats, both of which require different treatment options.

2. Find the cause of the infestation

“Sometimes you can become too fixated on one area, so try to get a second pair of eyes to look at it or speak with a colleague.”

To solve a problem and have the best chance of avoiding reinfestation, you will need to find the root cause. Otherwise you can treat and treat until you’re blue in the face, but the pests will keep coming!

This can be quite simple on some jobs, for instance if the problem is related to a hole in a wall, get those proofing materials out.

On others this could be more complex and may require you to do some good old-fashioned investigation work.

I remember a site that had repeated rat issues. Just inspecting the external areas for ingress points revealed several problem areas, from gaps under the doors to an old hydraulic lift and louvred plant room covers.  

It wasn’t clear which of these allowed pest ingress, so I began by proofing the ones I had materials for, and planned to return with materials for the other areas.  

Sometimes you can become too fixated on one area, so try to get a second pair of eyes to look at it or speak with a colleague. They may have experienced a similar situation or can give you a new perspective.

Just spending a little extra time on your first visit to find the root cause could save you significant time later.
This will also give you your baseline to track what you found and proofed, and to identify the outcome from that action.

3. Identify the extent of the infestation

A bit like the root cause, it’s a good idea to find what areas the pest is thriving in. You need to be able to identify old activity too, but understanding where pests are currently present will allow you to place the correct number of control points and gauge the size of the infestation.  

It’s easy to become focused on one area, without realising just the other side of the office wall could be more or another infestation.

This is of the utmost importance when dealing with house mice. Single house mouse territories are confined to only a few square metres and it’s tempting to stop searching and only treat that instance. But what if other territories are dotted about, say, a warehouse? 

By finding all the areas of activity you can place the correct number of bait points in the correct places to deal with that infestation. 

Don’t leave any stone unturned; as long as it’s safe to do so, look inside inspection hatches or behind closed doors. I’ve found lots of rodents nesting inside cavity walls or in that plant room cupboard that only gets opened once a year.  

Be respectful and be safe, but be inquisitive. You never know what you will find behind that locked door.

“Don’t leave any stone unturned; as long as it’s safe to do so, look inside inspection hatches or behind closed doors.”

4. Choose the correct pest control products

Only a bad pest controller will throw down whatever they have to hand, without considering formulation or amount (see part 5), or even resistance. 

For example, when we look at using rodenticides, it’s important to know what resistance might be present in your area. Resistance is an ever-increasing problem, so selecting an appropriate active ingredient that will work and won’t make resistance problems worse in your location is key. 

Using a product with known resistance in your area will only delay success or stop the treatment from being successful all together.

In recent years there has been a lot of work carried out around resistance and you can find out more about this through the Rodenticide Resistance Action Group (RRAG) bpca.org.uk/rrag

Bait quality is also important. Be mindful of the environment you are placing the bait in, as damp, mouldy, and dusty bait is less likely to be eaten. That’s right – pests are fussy!

In some environments, baits can become unpalatable in mere hours.

Manufacturers use good quality ingredients to make these baits as palatable as possible. Some also contain products to prolong their palatability in damp areas or have been individually wrapped to protect them.

When we look at trapping I think it goes without saying: using a mouse trap for rats isn’t going to work. Not only will you have a failed treatment, you will likely cause unnecessary suffering which breaks the law and is morally wrong.

And don’t forget some simple housekeeping tricks, like cleaning out bait boxes or traps if you’re reusing. Best practice says that giving these a brush out and a wipe over with a dry cloth is best practice. Boxes that are cleaned with disinfectants could leave enough of a scent for rodents to avoid entering them.

5. Follow manufacturer guidelines

“...never forget that the label is key.”

And finally! We all know it’s a legal requirement to follow the product label but it’s also important to understand them. 

If a product says that you can use 100g in a specific area, I recommend having a guide on how much 100g is.  

This could be measuring out 100g of bait on a set of scales and putting it in a sealed bag, which will give you a reference for what 100g of bait looks like. You could also take a measuring jug out with you, after putting the quantity of bait you require in the jug and marking where it comes to with a marker pen. This will give you an accurate guide to prevent under and over-baiting, which often leads to a treatment failure. 

This also links with bait positioning: it’s common for pesticides used in mouse control to be placed every metre or so. With rats, it’s five metres for heavy infestations and ten metres for light infestations.

We can’t place boxes closer than this if using the maximum amount of bait in each box. But equally, placing them further apart could lead to the boxes not being found by rodents.

And never forget that the label is key. You might think you know the labels by heart, but with restrictions on products forever changing and pests being removed, it’s always good to check labels regularly.

If you successfully put all these pieces of the pest control puzzle together, there’s no reason you won’t be well placed to put a successful treatment together.

Your tips here

Why do you think pest control treatments fail?
Send us your thoughts and we might print them in our next issue.
hello@bpca.org.uk

Source: PPC109