Jun 7, 2011 – Marauding Mice
QUESTION:
We have a customer with warehouses used for storing bakery goods in waiting for sale to its customers. One of the main items stored is wholewheat flour on pallets stacked 10 to 15 feet high. They are complaining that mice are ruining some bags of flour. Upon inspection, small 3/4 inch holes can be seen in the bags of flour in one out of 50 bags. It also seems that these holes are in the top bags of the pallets only. No other penetrations are found in any other bags. It's almost like they are dropping from the ceiling 10 feet above and penetrating the top bags on the pallet, as there are no penetrations in the sides of the other bags of flour. All pallets are moved regularly and placed 3 feet from the walls for inspection, sticky traps placed throughout. However, sticky traps have proven to be non-effective. Maybe some way to keep them from getting on the pallets? These warehouses are "Open Bayed" meaning doors are open all day during operation. Upon inspection it seems like the mice may be running through the interior walls as well. This is not a food handling establishment and I am wondering if we can use tracking powder in the wall voids and Liqua-tox in those areas suitable for placement. The customers are very good at sanitation and sealing of holes, voids, etc., however the walls seem to be the travel points. It seems focusing on exterior and wall voids are where I need to focus. What are your opinions?
ANSWER:
First I think we need to recognize that this is indeed a food "handling" establishment, which is defined as "any place other than a private residence where food is held, prepared, processed, or served". The presence of all of these bags and pallets of food product stored there would qualify it as "food handling", even though the food may not necessarily be exposed.
Second, it would be important to determine just where these mice are coming from, and if in fact there are mice, since you don't specifically state that you know this damage is being caused by them. The use of a regular flashlight to examine all possible travel routes for evidence such as droppings, and an ultraviolet flashlight to inspect for urine, would be very helpful. This would allow you to inspect those overhead beams to see if somehow this is how the mice are getting onto the pallets. While mice could definitely drop a short distance to access food they also would easily climb up onto the pallets and bags, and this would seem like a more likely access for them.. Since they could not jump the 10 feet back up to the rafters they must be climbing down off the bags and heading back to their harborage, so I suspect that this is the more likely route. But, just to be sure it pays to inspect overhead as well, if only to eliminate that possibility. If you do find urine spots or footprints or droppings on the overhead beams then setting snap traps in stations along those beams would be effective.
I know it is typical for many warehouses to leave exterior doors open to facilitate movement of people and forklifts, but obviously this encourages rodents to enter and makes exclusion nearly impossible. Your inspection should include the entire exterior of the warehouse to see what openings do exist that could be permanently closed, and at the least this will narrow the entry of the mice to just the open doors, and now you can concentrate your initial defenses on either side of these doors. When a mouse first enters a structure it may spend up to an hour investigating things right in that immediate area, and if you have placed a number of stations on either side of the doorways you should get the mice quickly to enter the stations, now landing in traps or finding bait, depending on what choice you make. You also could place stations on the OUTside on either side of the doorways, hopefully intercepting them before they even get inside. Mice still are going to be nervous about traveling in exposed places, and will enter stations perceiving them to be secure places to hide temporarily.
I think that either a labeled tracking powder (used only in voids or in Tamper resistant stations) or Liqua-tox could be effective, and would be labeled for use in this kind of situation, ensuring that neither could get onto food or food surfaces. The liquid bait also would need to be in a station of course, and placed so that it would not get dumped by people or equipment running into the station.
But, an important beginning would be to determine for sure where the mice are traveling inside, and placing LOTS of traps and stations along those routes. Sealing off exterior entry points where possible will limit the entry potential to just a few open doors and you can concentrate your stations around these points for earlier interception of invading mice.
View past Ask Mr. Pest Control questions.
We have a customer with warehouses used for storing bakery goods in waiting for sale to its customers. One of the main items stored is wholewheat flour on pallets stacked 10 to 15 feet high. They are complaining that mice are ruining some bags of flour. Upon inspection, small 3/4 inch holes can be seen in the bags of flour in one out of 50 bags. It also seems that these holes are in the top bags of the pallets only. No other penetrations are found in any other bags. It's almost like they are dropping from the ceiling 10 feet above and penetrating the top bags on the pallet, as there are no penetrations in the sides of the other bags of flour. All pallets are moved regularly and placed 3 feet from the walls for inspection, sticky traps placed throughout. However, sticky traps have proven to be non-effective. Maybe some way to keep them from getting on the pallets? These warehouses are "Open Bayed" meaning doors are open all day during operation. Upon inspection it seems like the mice may be running through the interior walls as well. This is not a food handling establishment and I am wondering if we can use tracking powder in the wall voids and Liqua-tox in those areas suitable for placement. The customers are very good at sanitation and sealing of holes, voids, etc., however the walls seem to be the travel points. It seems focusing on exterior and wall voids are where I need to focus. What are your opinions?
ANSWER:
First I think we need to recognize that this is indeed a food "handling" establishment, which is defined as "any place other than a private residence where food is held, prepared, processed, or served". The presence of all of these bags and pallets of food product stored there would qualify it as "food handling", even though the food may not necessarily be exposed.
Second, it would be important to determine just where these mice are coming from, and if in fact there are mice, since you don't specifically state that you know this damage is being caused by them. The use of a regular flashlight to examine all possible travel routes for evidence such as droppings, and an ultraviolet flashlight to inspect for urine, would be very helpful. This would allow you to inspect those overhead beams to see if somehow this is how the mice are getting onto the pallets. While mice could definitely drop a short distance to access food they also would easily climb up onto the pallets and bags, and this would seem like a more likely access for them.. Since they could not jump the 10 feet back up to the rafters they must be climbing down off the bags and heading back to their harborage, so I suspect that this is the more likely route. But, just to be sure it pays to inspect overhead as well, if only to eliminate that possibility. If you do find urine spots or footprints or droppings on the overhead beams then setting snap traps in stations along those beams would be effective.
I know it is typical for many warehouses to leave exterior doors open to facilitate movement of people and forklifts, but obviously this encourages rodents to enter and makes exclusion nearly impossible. Your inspection should include the entire exterior of the warehouse to see what openings do exist that could be permanently closed, and at the least this will narrow the entry of the mice to just the open doors, and now you can concentrate your initial defenses on either side of these doors. When a mouse first enters a structure it may spend up to an hour investigating things right in that immediate area, and if you have placed a number of stations on either side of the doorways you should get the mice quickly to enter the stations, now landing in traps or finding bait, depending on what choice you make. You also could place stations on the OUTside on either side of the doorways, hopefully intercepting them before they even get inside. Mice still are going to be nervous about traveling in exposed places, and will enter stations perceiving them to be secure places to hide temporarily.
I think that either a labeled tracking powder (used only in voids or in Tamper resistant stations) or Liqua-tox could be effective, and would be labeled for use in this kind of situation, ensuring that neither could get onto food or food surfaces. The liquid bait also would need to be in a station of course, and placed so that it would not get dumped by people or equipment running into the station.
But, an important beginning would be to determine for sure where the mice are traveling inside, and placing LOTS of traps and stations along those routes. Sealing off exterior entry points where possible will limit the entry potential to just a few open doors and you can concentrate your stations around these points for earlier interception of invading mice.
View past Ask Mr. Pest Control questions.
