Your green roof is an incredible engineering feat that provides insulation and stormwater management, but could its lush greenery be putting you at risk for an invasion of pests?
Vegetated roofs are often touted as a way to encourage biodiversity, but that isn’t limited to the plant selection. Whether your roof has low grass, flowers, shrubs, or food gardens, insects and animals will inevitably be attracted to the foliage.
Integrated pest management can help you stay ahead of pest activity and ensure any infestations are treated in an environmentally sensitive manner. Follow these tips to ensure your roof will thrive without becoming overrun with wildlife.
1) Understand Which Pests Frequent Vegetated Roofs
Animals need three things to survive – food, water, and shelter – so it’s no surprise that a manicured green roof can provide these in abundance.
“Green roofs are living architecture,” explains Pat Copps, a board certified entomologist and technical services manager for Orkin. “As soon as you start putting plants up there, pests will start moving in.”
Pests run the gamut from those that are attracted to ornamental plants to ones that thrive in urban areas:
- Insects such as ants (fire or carpenter), spiders, hornets and wasps, and silverfish are typically the biggest group of unwanted guests.
- Birds, mice and rats, and even nocturnal creatures such as raccoons and possums may become an issue.
- Mosquitoes can create a problem, particularly if there is ponding water for them to lay eggs in.
- “Large cockroach species often thrive in heavily mulched areas,” notes Judy Black, a board certified entomologist for the pest management firm Steritech. “Occasional invaders such as earwigs may also be brought in on potting soil, and ground beetles may be initially attracted to lights at night and then take up residence in soil and mulch.”
- Termites are less common but not unheard of, adds Paul Curtis, a board certified entomologist and entomology and regulatory services with Terminix Commercial.
Because your roof is designed to be a habitat, keep in mind that one pest problem usually encourages another. For example, birds may become more attracted to the area because there are better nesting opportunities and a greater amount of insects to eat. In turn, feathered friends may be carrying mites that will then establish a population on your roof. It’s the circle of life, but it can be managed so it doesn’t get out of hand.
2) Recognize the Risks to Your Building and Occupants
A pest infestation on your roof is a three-fold problem that can cause structural issues, spread to other areas of your building, and scare off occupants.
“One of the main concerns is that the pests will make their way from outside and into workspaces below,” says Black.
Not only could this be problematic as you try to keep pests from expanding into new areas, but it can also impact your business operations. Imagine the issue of having insects invade healthcare facilities or laboratory and manufacturing settings with clean rooms that must be absolutely sterile, notes Copps, much less the general cause for alarm when someone sees an ant or cockroach.
Mice and rats not only leave behind contaminated droppings, but they can chew and burrow straight into your building as they create nests, Copps says. They may gnaw through wiring, irrigation systems, the roof membrane, and other structural components, adds Curtis.