Green roofs — beloved by residents and pests alike

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Tim Husen, Ph.D, Technical Services Manager, Orkin, LLC
Tim Husen, Ph.D, Technical Services Manager, Orkin, LLC

From their social and emotional benefits to potential for credits toward Leadership in Energy and Environment Design (LEED) certification, green roofs remain a popular trend in healthcare buildings across the country.

However, they also can increase pest pressures, which is a key concern for long-term care facilities. The good news? There are a few easy ways for facility managers to mitigate this risk and keep pest activity to a minimum.

Before implementing a green roof, it's important to understand the pest control implications of vegetative roof systems. Questions to ask include: Which pests are a threat? Which landscaping and vegetation can impact pest pressure? And, which maintenance and sanitation routines can help mitigate risks? Maintaining a healthy green roof can be a strong part of quality resident care, and pest control is critical to that success. Here are a few tips to get started:

1.  Identify the pests that are a frequent threat

If pests are not caught early, their populations can explode. Knowledge of which pests could put your green roof at risk can help you manage them more effectively. Pests to watch for include:

•  Rodents — The most common green roof pests, rodents take refuge in the lush greenery, burrowing through vegetation and mulch. As they dig and gnaw, rodents damage plantings, wires, utility lines, doors and poles. Mice can fit through just a dime-sized hole, and their droppings, which are about the size of an ice cream sprinkle, can pose a serious health hazard by carrying dangerous bacteria and diseases like Hantavirus.

•  Plant-feeding pests — Plant-feeding pests like caterpillars, aphids and beetles can damage the stems and leaves of many plants, where they shelter. They produce a honeydew sap that draws in other pests, especially ants. Ants, the top invader of any kind of building, can nest almost anywhere, especially where there's a water source like a fountain. Controlling ant populations can be difficult, as their colonies can number up to 500,000 individuals, so it's important to catch them early.

•  Stinging pests — Stinging pests like hornets, bees, wasps and yellow jackets are attracted to flowering plants. They can be harmful to patients, especially those with allergies to their stings. Green roofs are a great nesting place for them. They tend to build nests in gutters, trees, bushes and on the corners of a building.

•  Birds — There are a lot of places for birds to nest and feed on a green roof: trees, vegetation, and eaves make for great nesting sites while bird feeders or fountains are good water sources. Birds are a double threat, causing both physical damage and health concerns. Bird droppings can corrode building materials, clog gutters or short out electrical equipment. Meanwhile, droppings and bird mites carry diseases while feather dander can cause respiratory problems. Nests can be difficult to remove, so it's best to consult your pest management professional for a removal process.

•  Mosquitoes — Mosquitoes thrive during the warmer months, and are attracted to standing water like ponds, water fountains, planters and gutters. Their bites can spread infectious diseases, like Zika virus, and cause skin irritation ranging from mild swelling to intense inflammation.

2.  Evaluate landscaping and vegetation

The features that make a green roof nice for your patients also attract pests. Flowers, plants, and water lure pests to your green roof where they find a perfect new home. There are many ways to strategically manage your landscaping and vegetation to keep pest populations to a minimum, such as:

•  Minimize plant species that attract pests. Work with your pest management or landscape provider to identify and install plants that do not produce nuts, seeds and fruits.

•  Healthy plants are less likely to attract pests, so be sure to maintain your vegetation.

•  Use cedar mulch instead of organic mulch to help repel certain types of ants.

•  Try to avoid ivy overgrowth to minimize the food and shelter it provides to pests.

•  Keep water circulating in ponds and fountains, and avoid overwatering plants, as standing water is an ideal place for mosquitoes to lay eggs.

•  Examine active growth areas at the top and underside of plants and leaves for evidence of pest activity.

3. Examine monitoring, maintenance and sanitation techniques

The green roof can be a commonly forgotten place in maintenance routines, but it needs as much attention as the rest of your facility. The most effective way to combat pest problems is to implement an Integrated Pest Management (IPM) plan. IPM strategies emphasize nonchemical techniques, focusing on facility maintenance and sanitation before considering chemical solutions.

Regular monitoring and maintenance can help prevent pest activity and help detect any pest problems early. Some pests can enter a building through even the smallest of holes and cracks from the size of a nickel to 1/16 of an inch. To keep these pests out, here are a few things that you can do:

•  Seal gaps around doors to the green roof or any pipes, fixtures and other potential entry points with water-resistant sealant and/or metal mesh.

•  Caulk around utility connections and outlets.

•  Install door sweeps and weather stripping to make sure pests don't walk in doors and keep doors closed as much as possible.

•  Minimize water accumulation from leaky taps, air conditioning units and plant irrigation. Fix any blocked drains and repair leaks.

•  Repair or replace torn or missing vent screens.

•  Line garbage receptacles and keep the lids tightly sealed. Empty trash regularly, as the odors can attract pests looking for food.

•  Schedule frequent roof inspections to keep up with roof maintenance.

•  Work with your pest control provider to educate your staff on pest management. Schedule staff trainings so that your cleaning and maintenance crews know the signs of pest activity and how to proactively combat them.

If you are considering a green roof — an attractive feature for residents that can go a long way in improving patient health and moral — don't be deterred by potential pest pressure. Work with your pest management professional to identify weak points and create an IPM plan that is tailored to your facility's needs. With the right tools, your green roof can thrive and patients can enjoy pest-free time outdoors.

Tim Husen, Ph.D., BCE, is Technical Services Manager for Orkin. A board-certified entomologist specializing in urban entomology, he has more than a decade of experience in the industry. For more information, email thusen@rollins.com or visit www.orkincommercial.com.


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