Protecting Pollinators
Turn off the lights to help local pollinators
Many of us are already aware of declining populations of pollinators and other beneficial fauna and flora due to human development, pesticide use, and climate change. However, a lesser-known but equally important cause of these declines is the use of artificial light at night. This light pollution is endangering pollinators, as well as mammals, birds, amphibians, and plants, because they depend on Earth’s daily cycle of light and dark for food, reproduction, sleep, and navigation.
Light pollution harms pollinators in a number of ways. Nocturnal moths are drawn to light and are prone to visit lights instead of pollinating flowers. Other pollinators, such as some species of pollinating beetles, avoid flowers under artificial light; as a result, plants exposed to nighttime artificial light do not receive enough visits from pollinators. This results in these plants to be less stimulated to produce pollen, which then diminishes the amount of pollen available as a food source for diurnal pollinators such as bees and butterflies. Light pollution also reduces pollinators’ sleep and recovery time, making it more difficult to survive and reproduce. In addition, light pollution alters the ability of plants to sense and react to natural light, which can harm their ability to flower and provide food for pollinators.
Furthermore, light pollution is causing declines in populations of fireflies (also called lightning bugs). Fireflies are bioluminescent—they create light of their own to find mates. Light pollution obscures this natural firefly bioluminescence, making their populations more vulnerable by reducing their ability to find mates.
Light pollution doesn’t only affect insects. It can cause birds to migrate at the wrong time. It can also disorient migrating birds, luring them off course and causing them to collide with illuminated buildings. Light pollution can even cause sleep disorders in humans, with negative consequences for our own health.
While artificial light makes many of us feel safer, there is no evidence that increased outdoor night lighting deters crimes. Studies conducted by the Illinois Criminal Justice Information Authority, the American Medical Association, and a variety of university researchers found no evidence that increased outdoor lighting deters crimes. In fact, a significant amount of property crime occurs during the day. Moreover, some studies have found artificial light actually decreases safety by making victims and property easier to see.
Reducing nighttime light pollution will benefit wildlife and humans alike. In addition to improving our health, it will allow us to better appreciate the beautiful night sky and to enjoy June evenings as fireflies sparkle in our yards. Here are some steps we can all take to help:
- Use longer-wavelength LEDs (red spectrum) instead of bright-white lights. These will lessen the impact on both wildlife and humans.
- Use timers or motion sensors on outdoor lighting, so that lights turn on only when necessary.
- Use outdoor lighting fixtures that shield the light, so they minimize glare and directly illuminate the target.
- Keep outdoor lights low to the ground (no higher than 10 feet) and use dimmers.
- Turn off unnecessary indoor lighting, such as in empty rooms, and use curtains to prevent indoor light from being seen outside.
From the City's Bee City Committee
Bees in Trees
Flowering trees are one of the exciting first signs that spring has finally arrived, but these trees play a much more significant role than you might realize in our local ecosystem. Native trees are a very important source of food and shelter for pollinators. When you think of spring trees you probably picture prolific bloomers such as cherry trees, dogwoods, and redbuds. Non-flowering native trees also produce flowers that benefit pollinators, such as Maples, Oaks, and Pines have very small flowers that go unnoticed by most individuals. As bees go about their day collecting nectar from plants, they spread pollen from flower to flower and play a vital role in the production of our most important fruits and vegetables. However, bee and other pollinator populations are decreasing at an alarming rate, which could lead to disaster for our natural landscapes and food production.
The U.S. Fish and Wildlife Service identifies the four primary threats to pollinators in North America to be shrinking habitats, invasive plants, pesticides, and climate change. So, what can we do to protect and encourage the growth of bee and pollinator populations in our own yards? Plant more native pollinator plants! While talk of pollinator gardens often brings to mind flowers and other herbaceous plants, trees play an integral role in building a pollinator friendly ecosystem. Due to their size and long lifespans, trees can provide reliable, long term, and abundant resources for these populations. As trees grow, they can support greater numbers of pollinators at a time and provide safe shelter up high where they and their larvae aren’t as susceptible to garden tools, pesticides, and pets.
It’s extremely important to plant trees that are native to our area in order to ensure they are a suitable food source for local species and can bridge the gap between habitats for migratory species as well. Invasive plants not only limit food sources but can also play a role in spreading disease to plants that support pollinators, or even to the pollinators themselves. Some recommended native trees that are especially beneficial to pollinators in our area are Eastern Redbud, Dogwood, Serviceberry, Tulip Tree, Hawthorn, American Linden, and Crabapple. You can also find an extensive list of Maryland native trees at the Maryland Department of Natural Resources website. So please consider planting a native tree to support local pollinators this spring!
For more information, visit
From the City's Tree & Landscape Board