April is National Native Plant Month!
This is the second in a series of articles by Climate Action Coffee that seek to engage readers in understanding the importance of native plants and pollinator insects. Today we focus on how native plants can both support pollinators, and help manage mosquitoes in your yard without using pesticides.
A March 17 post on my neighborhood listserv had a one word subject: Mosquito. And a one-line post : “I was shocked to see some larvae/wigglers today in a pot sitting on my patio! “
Did you know that Maryland has approx 50 species of mosquitoes? In Montgomery County, three are of most concern for carrying diseases: The Aedes aegypti (yellow fever mosquito), Aedes albopictus (Asian tiger mosquito) and Culex pipiens (common house mosquito).
Most mosquitoes become active when the weather is consistently over 50 degrees. Mosquitoes lay eggs in or near water–fresh or stagnant. That pot on my neighbor’s patio most likely had collected some rain water, creating a perfect spot for a female mosquito to lay her eggs. Those “wigglers” (mosquito larvae) have long since transformed into pupae, and then adult, flying mosquitoes. And so it begins–welcome to mosquito season in the DMV!
While it may be tempting to hire a mosquito control company like Mosquito Joe to treat your yard, these companies use chemical or synthetic, broad-spectrum, insecticides (pyrethrins/pyrethroids) that are highly toxic to many insects–not just the mosquitoes you are targeting. These chemicals penetrate the soil where many desirable insects live and nest with other living microorganisms that improve the soil, and which native plants rely upon to thrive. Killing them disrupts the very foundation of the ecosystem.
These non-targeted insects include native pollinators and other beneficial insects such as bees, butterflies, moths, caterpillars, dragonflies and ladybugs, all of which become collateral damage in the war against mosquitoes. Insects are in decline worldwide for many complex reasons, including habitat loss, climate change, and disease. But use of insecticides in suburban yards is also a major contributor.
Many of the mosquito-control companies offer “natural” or “organic” treatment options such as garlic sprays, or sprays made with essential oils like lemongrass, rosemary, or peppermint, which are marketed as less dangerous. Are these options harmful to pollinators?
Yes! Experts discourage the use of these sprays for precisely the same reason they discourage use of pyrethroid sprays–they may also kill non-targeted insects. According to the National Wildlife Federation, these oils can still be harmful to bees and other beneficial insects upon direct contact, so they should not be used on flowering plants or during the day when bees are active. Experts agree: ”Mosquito treatments, including the alleged “all natural” variety can harm you and your environment while not actually reducing mosquito populations.”
Luckily there are ways we can help manage mosquitoes without resorting to spraying our yards with harmful pesticides. Start now to make your outdoor spaces as mosquito free as possible, using natural and safe alternatives.
- Because mosquitoes lay eggs in or near water, make it a weekly habit to carefully inspect your outdoor spaces for any containers that may collect water –recycling buckets, garbage can lids, flower pots, toys. Keep wheelbarrows and kiddie pools upside down while not in use. Last summer I noticed a neighbor’s snow saucer collecting water in a shady spot between our houses, and simply turned it over. Remove any debris from your gutters.
- Removing non-native invasive species from your yards, and replacing them with native plants, will support pollinators by providing food for larval and adult insects. But did you know that they can also help control mosquitoes? English ivy, for example, is a common groundcover in our area. It’s also a highly invasive non-native plant that shelters Asian tiger mosquitoes. The dense ground cover provides the kind of moist, shady environment that mosquitoes love. It also climbs up and chokes trees, and has spread widely into our parks and other natural areas, where it crowds out native plants. Fortunately, English ivy is easy to remove and can be replaced with a variety of native plant alternatives that will attract pollinating insects to your yard, instead of mosquitoes. Our local native plant societies suggest that pussytoes, wild ginger, golden ragwort, green and gold, Virginia creeper, woodland phlox, and a variety of ferns can work well as alternative groundcovers. Native plants can be purchased at a number of local nurseries and at spring plant exchanges.
- Be on the lookout for other non-native invasive plants that are emerging now and try to remove them before they seed. Not all of them shelter mosquitoes, but all non-native invasives spread rapidly and can crowd out native plants. For the first time this spring, my yard has lesser celandine–also called fig buttercup–which has crept in from nearby Sligo Creek Park, where sadly it now carpets much of the forest floor. Although it has pretty yellow flowers and may look attractive in spring, if left in place it will spread rapidly and crowd out the ferns and spring ephemerals I am nurturing in my woodland garden. I’ll also be watching for Garlic Mustard, which arrives in force every spring, but is easily removed. Try to pull up the plants before they set seed, because the action of yanking the plant from the ground will spread the seed. A good time to pull garlic mustard is after it rains, when it’s easier to get all or most of the long tap root. After you have pulled the plants, bag them up and throw them out with your garbage; do not compost.
- Over 20 plants are known to help repel mosquitoes including a number of herbs that many of us plant each summer in our kitchen gardens–rosemary, basil, sage, and mint. Lavender, marigolds, scented geranium (citronella), beebalm, allium, lemongrass, flossflower and catnip may also act as repellents. Most of these are annuals and can be grown in pots or containers and placed near seating areas and doorways to help repel mosquitoes.
Happy Native Plant Month! There could not be a better time or reason to plant more natives!
For a deeper dive into insecticide sprays, watch this webinar with Aaron Anderson, Pesticide Program Specialist at the Xerces Society:
Ecologically – Sound Mosquito Management at Home
Help Stop the Insect Apocalypse by Protecting Pollinators and Native Biodiversity
Maureen Malloy
Climate Action Coffee