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The Changing Seasons

The number and behavior of rats and mice change throughout the year.

Each season brings a different environment--winter brings snow, spring brings rain and plant growth, summer brings hot weather, and fall brings cooler temperatures and disappearance of vegetation. It's important to know how these changes affect rats and mice and how best to apply control practices.

What happens each season?


  • Rodent populations are at their lowest and breeding is minimal.
  • Many rodents do not survive during periods of cold and snow.
  • Natural food sources (such as seeds and insects) are harder to find.
  • Rodents prefer warm places in or near buildings.


  • Rodents become more abundant by late spring.
  • Annual breeding cycles begin around March as the weather gets warmer.
  • Spring rains bring vegetation growth, providing breeding areas and additional food sources.
  • Young rats and mice wander and seek food and new homes.


  • Food and vegetation are abundant.
  • Rats and mice are more common because of spring breeding and available food.
  • Another peak in breeding occurs in early September as summer temperatures begin to cool.


  • Natural food sources and ground vegetation diminish as the weather turns colder.
  • Rodents are relatively abundant and seek winter shelter in and around buildings and homes.

Be aware that:

  • People see more rodents from April to June because of spring breeding, and also during October and November as the seasons change.
  • A mild winter means that fewer rats and mice die from natural causes, so more will be seen in the spring.
  • A rainy spring or summer brings more weeds (for shelter), water, and natural food sources (seeds, insects), so more rodents will breed and survive.
  • Rats and mice seek winter shelter inside buildings following the first cold spell each fall.

What you can do:

  • Take advantage of seasonal change. Make sure that rodents are controlled during winter and there will be fewer around to breed in the spring. This can help prevent a year of problems.
  • Store garbage in metal or heavy-duty plastic containers with tight-fitting lids. Keep kitchens clean and food stored in secure containers. Where rodents are present, use traps or poison bait to eliminate them. READ THE LABEL OF ANY BAIT YOU BUY, AND USE IT SAFELY.
  • Keep yards clean so that rats and mice don't have the shelter and food necessary for breeding, and so that any young rodents seeking a new home won't easily move in. This includes cleaning up weeds, trash piles, garbage, and pet food.
  • Inspect buildings carefully, especially in the early fall. Make sure there are no holes or cracks for rats and mice to gain entrance.

Remember: You can make rodent control work by reducing the food, water, and shelter that rodents need to thrive--and that's an important tip for every season of the year!


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