What’s affecting your rodenticide efficacy?
By Austin M. Frishman, Ph.D.
Although the number of palatable rodenticides has increased over time, there are situations where some rodents refuse to accept the bait. The following potential explanations can help you analyze your situations and make appropriate adjustments.
Rodenticides can absorb odors that reduce palatability
- For example, the rodenticide applicator may be a smoker. Solution: wear nonabsorbent gloves and don’t smoke right before applying any rodenticide.
- Pesticide odors can also saturate the rodenticide. Solution: store rodenticides separately from other pesticides and keep them in tightly sealed containers.
Alternative food in the vicinity tastes better to them
- Rodents will continue to feed on what they already like. Solution: have the competitive food cleaned up and unavailable.
Rodent bait stations are placed in the wrong locations
- You can’t place bait stations based on autopilot thinking of one station per x linear feet. Solution: look for signs of rodent behavior and ask the client where they see activity.
Ants/other arthropod pests eat or infest all the bait before the rodents do
- I have observed pest control companies lose good accounts because the technicians didn’t bother to check for other arthropod activity. Solution: bait for other pests appropriately.
You miscalculated the extent of the rodent population
- A few rats ate all the bait and there was none left for the remaining rats. Solution: add more bait more frequently.
The bait becomes moldy and repulsive
- You placed the bait in a very wet area, your bait is sitting on the floor instead of up higher on rods. Solution: look at each factor and correct it.
Debris has blown into the bait station, creating a non-appetizing environment
- Solution: raise the bait station up on a flat surface. You may even have to insert a section of PVC pipe into each opening.
More rodents keep coming from an adjacent area
- Solution: for interior situations, be sure to rodent proof. For exterior areas, inspect potential harborage areas away from structure and go further out from the building to implement your control methods.
Humans or non-target animals are "stealing" the bait
- Solution: use a camera to record the culprit, and/or or move the bait station to a nearby location that is better protected.
An alpha rat or mouse has taken up residence inside the bait station
- Solution: conduct mass baiting or trapping to knock down the initial population.
Rats stored food ahead of rain or snowstorms
- Solution: talk to the customer to explain the extra time before bait acceptance may occur.
The longer you engage in this work, the more unusual rodent situations you may encounter, which may create more items to add to this list. This is what makes pest management interesting and, at times, very challenging!
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