The solution begins with understanding what motivates pests.
Have you ever had a relative or someone else that you just didn’t care that much for, and you’d rather they didn’t come to stay at your house? Maybe you try to make things so that person doesn’t want to come over — you’re nice, but the person feels uninvited. This approach might not work with relatives, but it certainly can with pests.
It starts by understanding what motivates pests. Like people and all other animals, pests respond to food, water, shelter and temperature. They typically have such short life spans that each pest works hard to find the things it needs to survive. If your facility has plenty of what a particular pest needs, it is bound to gravitate to those sites in and around your building. The way you uninvite pests is to identify those factors or conditions that are attractive to pests and then eliminate or minimize them.
Temperature is critical to cold-blooded creatures like insects and spiders, less so for rodents and birds. We keep the inside of our buildings at a comfortable 68° to 75°F which is just fine for most insects. During summer, it might be the cool air currents exiting cracks around doors and windows that attract flies; during fall it is the warmer air currents and the warmth of walls that attract many pests. Insects live in a microclimate world and once on a building, they will seek out the temperatures most suitable for them. If you have openings or cracks in the outside walls and around doorways and windows, insects will find these and come inside.
Simply sealing as many cracks, gaps, and other openings as you can and ensuring tight-fitting screens over vents and windows goes along way toward excluding pests from gaining access inside.PageBreak
Moisture is also critical as all animals need water to survive. Insects, however, are particularly sensitive to drying out so most prefer someplace moist or humid. Puddles of water is what jumps to most people’s minds when thinking about moisture. But for insects, it’s the water trapped under heavy ground covering plants next to the foundation or the moisture associated with a pile of bricks, boards, or debris by the foundation. Once harboring and thriving in such locations so close to the building, ants, crickets, spiders, and other pests are more likely to find their way inside.
Take a look around the exterior of the building, especially near the foundation. Ground-covering vegetation (e.g., ivy, pachysandra, monkey grass) should be avoided near a building; instead, plant shrubs and flowers spaced apart to help reduce moisture. Also, mulch should not be more than 2 inches thick. Any more than that holds so much moisture that many pests actually prefer it.
When planting trees or shrubs, take into account their mature growth size. If a mature tree can span 30 feet in canopy then don’t plant it 12 feet from the building when it is a sapling. Otherwise the branches lie against walls or on the roof and hold moisture. Such branches also provide a path directly onto the building. Tree branches should be kept cut at least 6 feet from the roof — rats can jump that far. For shrubs, plant them far enough away from the building so that when full grown, you don’t have to keep pruning the branches back from the building. Adjust the irrigation system to avoid over watering and direct it away from the foundation.
Food is something that motivates all living things. Different pests require different types of foods. Flies are partial to garbage in the dumpster area as are rats and mice. Disposing of trash in plastic trash bags reduces odor and regular cleaning of dumpster and trash areas also limits flies. It is also helpful to locate trash areas as far from a building as possible. Both of these are extremely important during late summer when yellowjackets are most abundant.
Ants like to forage on plants with aphids — aphids exude a sweet substance as they feed called honeydew and worker ants need honeydew for energy. If a building has aphid-prone plants and trees next to it, it is more likely to become infested by ants. Changing such plants to those less attractive to aphids means fewer ants.PageBreak
Shelter, also known as harborage, often determines the numbers of a given pest that might be near a building. The more available harborage, the greater the population of pests provided enough moisture and food is present. In many cases the harborage also is what retains the moisture as with piles of items or thick ground covers. As mentioned earlier, minimizing or removing such items makes an area less inviting for pests.
Gaps and openings in the building walls or access via poorly sealed or screened attic and foundation vents are inviting to certain pests such as yellowjackets, paper wasps, and honey bees. Such pests find the voids behind such openings make an excellent nesting site, and sometimes the bees or wasps can make their way inside. Larger gaps are also used by rodents, birds, and wildlife to gain access to nest within the attic or walls. Sealing as many gaps and cracks as possible is helpful in minimizing inside presence of pests.
Outside lighting plays a significant role in the abundance of spiders on and inside a building. It is also is involved with invasions of many flying insects that may make their way inside, including crickets and ground beetles. Bright white lighting attracts innumerable night-flying insects which will serve as food for spiders. Spiders are especially numerous around properties located near ponds or streams due to the increased volume of flying aquatic insects attracted by lights.
Yellowish lighting is far less attractive than white lighting to insects. Changing commercial lights from metal halide or halogen bulbs to sodium vapor bulbs is recommended. For standard exterior fixtures, use yellow “bug-lite” bulbs or install yellow filters around the fixture. When fewer flying insects are present, far fewer spiders find enough food to survive.
Only a few pests such as German cockroaches, stored product pests, fleas, and bed bugs rely on us or our pets to be carried inside. Most of the pest infestations inside buildings originate from outside. Fewer pests surviving next to or flying to a building greatly reduces the chances of pests finding their way inside. By doing an inspection to identify sites or conditions that are inviting to pests then taking steps to reduce such attractions reduces the chances of inside pest infestations, particularly from pests such as rodents, ants, occasional invaders, and flies.
Stoy A. Hedges, BCE is a senior technical professional and Entomologist at Terminix International.