How Does The Rain Affect Pests?

Rain is essential for our environment, particularly in the UK, helping plants grow and replenishing water sources. However, while a rainy day might be a welcome sight for gardeners, it can also bring about an increase in pest activity. Many pests and insects are highly sensitive to weather changes, and rainfall can drive them into homes and businesses in search of shelter, food, and warmth. Understanding how rain affects pests can help you take the necessary precautions to keep them at bay. 

Pest Behaviours

Different pests react to rain in various ways, depending on their biology and natural habitat. Some pests thrive in damp conditions, while others seek shelter to escape the downpour. Here are some common behaviours:

• Rodents – Rats and mice are notorious for invading homes and buildings during heavy rainfall. Their burrows and nests can become waterlogged, forcing them to seek higher ground or find dry places to shelter, often inside properties. 

• Cockroaches – These resilient pests love moisture but don’t like getting completely drenched. Rain can drive them out of sewers, drains, and other hiding spots, leading them to infest homes and businesses in search of dry areas. 

• Ants – Rain disrupts ant colonies by flooding their nests. This often triggers mass movement as they look for new places to establish their colonies, sometimes inside buildings. 

• Drain Flies - Rain creates more stagnant water, providing ideal egg-laying spots. Heavy rain can push organic matter to the surface, boosting food sources for larvae. Higher humidity encourages adult flies to emerge from drains. Debris buildup from rain creates perfect breeding conditions. 

• Midges and Mosquitoes – Stagnant water left behind by rain provides the ideal breeding ground for biting insects like midges and mosquitoes. Increased moisture leads to a surge in populations, which can become a nuisance especially in humid or damp areas, as they swarm in large numbers and deliver irritating bites. 

• Slugs and Snails – These pests thrive in wet conditions and often become more active during and after rain, particularly in gardens where they feed on plants. 

• Birds - Heavy rain can displace pest birds from their usual roosting or nesting sites, driving them to seek shelter in buildings, under eaves, or on ledges. Prolonged wet weather can also create waterlogged areas, attracting birds in search of food, such as worms and insects brought to the surface. Increased bird activity can lead to more droppings, noise, and potential damage to properties. 

Rainfall and Moisture

Rainfall creates the perfect conditions for many pests to thrive. High moisture levels can encourage breeding, while standing water offers ideal environments for insects like mosquitoes. Here’s how moisture influences different pests:

• Increased Breeding Grounds – Pools of water left after rain provide an excellent habitat for midges and drain flies to lay eggs. Even small puddles in plant pots, clogged gutters, or blocked drains can contribute to a surge in their populations. 

• Shelter-Seeking Behaviour – Many pests that normally live outdoors, such as rodents, cockroaches, and ants, will seek shelter in containers, warehouse units and storage lots when their natural habitats are disturbed by rain. 

• Rotting Organic Matter – Rain can cause organic material such as leaves, wood, and rubbish to decay, attracting flies and other insects looking for food sources. 

• Structural Damage – Bird debris, such as feathers, nesting materials, and droppings, can clog gutters after heavy rain. This can lead to water overflow, causing damp patches, leaks, and potential structural damage to buildings over time. 

Statistics

Understanding the impact of rain on pest populations is crucial for prevention and control. Here are some key statistics:

• Mosquitoes and Midges: Heavy rainfall can significantly boost mosquito populations by creating abundant breeding sites. For instance, studies have shown that increased precipitation leads to a rise in mosquito activity due to more standing water available for breeding. [Source]

• Rodents: Flooding and heavy rains can displace rodents from their natural habitats, pushing them into urban areas in search of shelter and food. This displacement often results in increased rodent activity in residential and commercial properties.  [Source]

• Ants: While specific statistics are limited, it's observed that heavy rainfall can flood ant nests, prompting colonies to relocate to drier areas, including homes and buildings, leading to a noticeable uptick in indoor ant infestations.  [Source]

• Cockroaches: Storms and heavy rains can overwhelm drainage systems, driving cockroaches to seek refuge indoors. Pest control services often report a surge in cockroach complaints following such weather events. [Source]

What To Do

If you want to prevent pests from invading your home or business during wet weather, consider the following steps:

• Seal Entry Points – Check for gaps in doors, windows, and walls where pests could enter, and seal any cracks or holes.
• Fix Leaks and Drainage Issues – Ensure gutters are clear and that water isn’t pooling around your property, as stagnant water attracts insects.
• Keep Food Sealed and Stored Properly – Pests are drawn to food sources, so keep food in airtight containers and clean up crumbs and spills.
• Remove Standing Water – Regularly check for and empty containers that collect rainwater, such as plant saucers, bins, and outdoor furniture.
• Maintain Your Garden – Trim overgrown vegetation and remove any organic debris to reduce shelter and breeding spots for pests.
• Use Professional Pest Control Services – If you’re dealing with persistent infestations, contacting a pest control expert can help implement long-term solutions.