The number of rats and mice, and their behavior, changes throughout the year.

This is because 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 annual disappearance of vegetation. For rodent control, 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 annual low 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.
  

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

• 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 cool.
  

• Natural food sources and vegetation cover diminish, as the weather turns colder.
• Rodents are relatively abundant and seek winter homes.
  

• People see more rodents from May to July 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 – thus more will be seen in the spring.
• A rainy spring or summer brings more weeds (shelter), water, and natural food sources (seeds, insects) – thus more rodents will breed and survive.
• Rats and mice seek winter shelter inside buildings following the first cold spell each fall.
  

• 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.
• Keep yards clean, so that rats and mice don’t have shelter and food necessary for breeding – and so that any young rodents seeking a new home won’t easily establish. This includes cleanup of 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.