Summer time is mosquito time in the Old Pueblo. This was true even several centuries ago when Father Kino first wrote about the area. Back then there were a number of springs and running rivers around Tucson. Now the water is mostly underground and we have neighbors with stacks of tires, dog dishes, old cans and other trash to breed mosquitoes in.
Mere decades ago mosquitoes were repelled with strongly scented herbs like lemon grass, catnip and lemon balm. Modern mosquito repelling compounds are generally synthesized from petroleum products. Some folks prefer not to put such chemicals on their skin and are turning to the herbal remedies of yore. These “olde tyme” herbs do repel mosquitoes, but are hard to grow in our area. For mosquito-deterring plants you can add to your landscape — consider these Southwestern native plants.
Perennial marigolds. These marigolds live for many years but need afternoon shade in a Tucson summer. They are low-growing, semi-shrubby plants with golden yellow flowers in November and December. Palmer’s marigold (Tagetes palmeri) is from the mountains of Chihuahua, Mexico and does well in caliche. The Lemmon marigold (Tagetes lemmoni) is from Mt. Lemmon and other Sonoran Desert mountains and does better in sandy soils. Incidentally, both the plant and the mountain are named after the plant collector Sara Lemmon. Third is the sweet marigold (Tagetes lucida), also called Mt. Pima marigold, pericon and winter tarragon. This one deters mosquitoes and used can be used as a culinary herb. All wild perennial marigolds will deter mosquitoes; these are the three you may find in area nurseries.
Slender Poreleaf. For an unusual plant in your landscape consider the marigold cousin slender poreleaf (Porophyllum gracile). Native to the desert floor surrounding Tucson, this low-growing shrub has blue-green leaves and stems. Left alone it forms a lovely rounded mound about 18 inches high and topped with small white blooms in summer. It is also used as a culinary herb.
Turpentine bush. There are a number of plants with this common name, but to deter mosquitoes you need Ericameria laricifolia. Reaching around three feet high with bright green foliage, the shrub is crowned with golden yellow flowers late summer into fall. Every three years or so it will need a rejuvination pruning or it will get leggy and overgrown. It is not wildly popular because of this trait. While the leaves deter mosquitoes, the flowers attract a number of butterflies.
Note that with any mosquito-repelling plant, having it simply sit in the landscape is only a tiny part of the solution. The leaves must be crushed to release the chemical compounds that deter mosquitoes. Do not rub leaves on your body — until you test them first. Your skin might react badly to even natural anti-mosquito chemicals. Always do a test patch on your skin and wait 48 hours. These words of caution are because we live in litigious times. Most folks can use most herbs with no ill effects. And usually with positive effects, like messing with mosquitoes so they don’t mess with you.
(Editor’s Note: Dr. Soule is the author of nine books on gardening in the Southwest. In her most recent book “Southwest Fruit and Vegetable Gardening” (Cool Springs Press 2014), available at area botanical gardens and nurseries. Jacqueline offers numerous free lectures through the Pima Public Library. Learn more about growing and using native plants on her website: www.gardeningwithsoule.com.)