by David Moore
Manager of Technical Services and Board Certified Entomologist
with contributions by Eric Smith, PhD, BCE

Good outdoor preventative maintenance is the first step of preventing pests from intruding into your home. The best way to reduce pest intrusion is to proactively control invading outdoor pests before they can enter a structure. The second step is to seal any potential entry such as holes in exterior walls, closing gaps under doors, screening windows and vents. Taking these measures will help reduce the amount of time required to inspect and find a pest’s entry point and can reduce the amount of pesticide that may be required to solve your problem.

What does a pest need to survive?

Moisture

Almost all pests have a problem with losing water through their exoskeleton. Therefore, many are found in areas of high humidity which surround buildings. Mulched shrubbery and plant beds, under decks and porches, and among dense ground cover such as ivy are all common places that pests can be found living to retain proper moisture levels.

Food

Immature and in many cases adult invading pests feed primarily on decaying organic matter, fungi, and bacteria which is found in areas of high moisture. Others are predacious and will be found in the same areas since this is where their prey live.
Activity periods. Many pests are primarily active from dusk until dawn because this is when the relative humidity in the air is highest, which helps reduce their water loss. Ants which feed on plant recreations or honeydew are also active during the daytime. Ground beetles and moths are usually attracted to lights at night.

Resource sites

High moisture, high organic matter containing areas typically function as breeding and population spawning areas. These areas are highly favorable for their survival, and then they enter buildings when the area becomes overpopulated and/or environmental conditions become too wet or too dry for their survival.

What the homeowner should do

Exclusion and moisture control are key. The objective is to remove conditions that are conducive to pests to create a hostile or dry environment immediately around the building, to reduce other factors which attract pests to the building, and to physically prevent pest entry.

Reduce or remove high-moisture harborage

Lawn

Keep the grass cut short and keep the thatch build up to a minimum.

Mulch

    • It’s best if this is kept to a minimum thickness (2″ or less) and that cypress or other mulch which is resistant to decay is used. 
    • There should be a gap of 12-18″ between the mulch and foundation, with a barrier of rock to reduce pest pressure.

Leaves and other debris

  • All debris should be removed from around the base of the building to prevent a buildup and a favorable living habitat.
  • Firewood should be stacked up off the ground , the top covered, and be located 10 ft or more away from the building.
  • Create a hostile or dry environment next to the building.

Grade of lot

The soil should drop or decrease from the foundation wall to move rain away from the foundation.

Vegetation gap

Create at least a one foot gap between the foundation and vegetation to allow air to circulate, which reduces moisture. For commercial buildings, this gap should be at least 18″ wide and paved with gravel, blacktop, or cement. This air gap will also prolong the life of the masonry and any siding.

Trees and shrubs

It’s best that there are gaps between the trees and shrubs which allow sunlight to reach the ground. Also, no tree branches should overhang the building. Insects and rodents use these as a highway onto the roof of structures.

Reduce attraction factors

Flowering plants

Do not plant flowering trees and flowering shrubs close to homes. They are very attractive to a wide variety of insects and will make your home more likely for invasion.

Gutters and downspouts

These should be functional and in good repair. They should empty away from the building to reduce moisture build up, pest attraction, and possible wood decay. The further the water can be carried the better.

Patios, porches, decks, sidewalks, and driveways

These should all slope away from the building to reduce water accumulation around the building. This will help maintain the structural integrity of the building as well.

Compost piles

These should be located as far away from the building as possible. Proper management helps reduce their attractiveness to both insect and wildlife.

Garbage cans, dumpsters, trash compactors

These should always be tight sealing and periodically cleaned. They should be emptied on a timely basis to reduce their attractiveness. They should be located away from entrance doors to reduce fly entry.

Lighting

Change mercury vapor to sodium vapor bulbs, which are much less attractive to insects. Moving the light fixtures off the building but so that they shine onto the building will further reduce the building’s draw. Also, do not locate lights directly above entrance doors or insects will enter the structure to find shelter or when a door gets opened.

Proactive physical prevention

  • Doors should be tight fitting so no light is able escape to the outside.
  • Doors should have self-closing devices on them where practical, especially on screen doors if present.
  • Windows should be tight fitting and securely screened if they can be opened.
  • Door and window frames should be completely caulked.
  • All holes through the exterior walls should be sealed.
  • The junction of facia boards and siding should be tight fitting or caulked.
  • Attic and soffit vents should be screened.

Realize that the above list has many things that can and should be done to reduce the attractiveness of the area around a building to pests and to prevent their entry. Understand that it is not necessary that all or even most of these be done to have a successful pest management program, but each and everyone can contribute to reducing your risk of an intrusion. Call a pest management professional for assistance in identifying and determining which of the above items are most important to help solve your pest management problem. In many cases, the pest management professional can locate these areas more efficiently than you. Additionally, they can help you create an action plan to be proactive for your pest control needs and ongoing control options.