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Infestation identification for facilities managers

07 April 2014 / by Victor® Pest Control (author) / Oakham
 (photo: Victor Pest Control)
/ (photo: Victor Pest Control)

Victor® Pest Control's guide to identifying pests from clues left in the vicinity of an infestation.

When encountering a pest problem it can be hard to figure out the first step to take. Do you clean down every surface with bleach and put poison everywhere? Do you use every commercially available pest control solution in a carpet-bomb attack on whatever might be lurking in the dark corners of your building?

Before flying into a panicked cleaning frenzy, it's best to figure out what kind of pest you have. This enables you to use pest control methods that are suitable for dealing with the type of intruder that has taken up residence nearby. This saves money and time by allowing you to only buy what you need to deal with the problem, and hopefully avoid the cost of calling out the exterminators. Luckily, it's fairly simple to figure out what kind of pest you're dealing with by carefully examining the area of infestation.


Droppings are probably the easiest way to figure out what you're dealing with, as chances are it was animal droppings that put you on to the problem in the first place. House mice produce 50-75 5mm long droppings a day. They can be identified by the distinct points at one or both ends of the dropping, their size and, unfortunately, their consistency. Mouse droppings will be soft and moist when fresh. They are often found in roof spaces, around boilers, under sinks and in insulation.

Norway Rat

In contrast, Norway rats faeces are around 3 times longer at 15mm, similar in length but thicker than a grain of rice. They produce around 45 of them a day and they are cylindrical with blunt ends. These droppings are normally found in small groups in a relatively small area, not spread out like the droppings of mice.

Finally, cockroach droppings: these are similar to rat droppings, but much smaller, only reach 1.5mm in size. They can resemble ground coffee and are often found in small clusters. While analysing droppings may be the easiest way to figure out what kind of pest problem you have, there are other indicators that can help you figure out what kind of unwanted house guest you are harbouring.

Nests and Burrows

Mice don't generally burrow, instead opting to build nests indoors where it is warm. These nests are often found in corners and cluttered spaces, particularly near heat sources. A pile of boxes and papers in a dark corner next to a heater would provide a perfect nest for mice. They will use shredded paper and cardboard for insulation and chew into any soft items like cushions or bedding that they can find.

Rats on the other hand do burrow into the ground. They are particularly pesky as their larger size and strength means that, over time, they can chew through wood or even concrete! These burrows are also found in the corners of the rooms under debris, or sometimes under floorboards. Rats can actually threaten the structural integrity of a builing by chewing into load bearing supports and brickwork, making their presence not just unhygeinic but downright dangerous. They love small spaces and will try to locate themselves near warm pipes or behind appliances that heat up, like ovens. Another sure sign of rats is the high pitched noises they make, generally at night, when fighting for food. Mice and rats will often scurry and scratch at night as well, meaning that some lurking around at night might be called for if you wish to locate your rodent problem.

Mice travel 2-10 metres from their nests, while rats will adventure as far as 30 metres. If you think you have a mouse problem them try looking very nearby for the nest, and check for rub marks along the walls. Both rats and mice like to travel along the borders of rooms for safety, and when they do so they rub against the wall which transfers oil from their fur, leaving greasy marks.Cockroaches, o the other hand, will hide away in places far from noise and sound. This can make them particularly hard to locate, but try searching around basement areas and less-visited parts of your facility.


Another key sign of a rodent infestation is holes appearing everywhere. This behaviour is quite similar in rats and mice, but there are some key differences in the results they leave behind. Mice chew on plastic, soft wood, cardboard boxes,  fabric and wiring. Mice are known for gnawing to keep their incisors worn down, but  they mainly gnaw to try to gain entrance to places that look like they will provide a valuable bounty of food or shelter. Rats have an appetite for all of the same things as mice, but supplement this diet with floor joists, wall studs and any wooden furniture.

You can easily tell what's chewing up your facility by examing the size of the hole. Mice tend to make holes less than 2cm wide with neat edges, while rats make holes around 5cm in diameter with much rougher, torn edges. You can also tell how recent a wood gnawing is by colour – lighter coloured edges to holes suggest that it hasn't been there for long, whereas darker edges indicate that the problem has been around for a while.

Identifying pests is only the first step – once you know what they are and where they are, you need to figure out how to get rid of them. Traps and deterrents or professional assistance may be needed, but at least you will be armed with the knowledge of what type of infestation you have.



Victor® Pest Control


Victor® Pest Control

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