They may not sting or bite, but moths can certainly interfere with your outdoor evening enjoyment as they fly around lights and bump into windows. Even if you aren't bothered by these nocturnal fliers, their caterpillars can wreak havoc in your yard and garden, defoliating trees and destroying fruit, vegetable and ornamental plants. Reclaim control of your outdoor space by reducing or eliminating the sources that attract moths.
While there is no answer as to why the phenomenon occurs, moths are attracted to light. They fly close, then endlessly spiral around outdoor lights. Moths, unlike humans, see light at the ultraviolet or blue-violet end of the spectrum. Getting rid of moths outdoors can be as simple as turning off your outdoor lights or replacing outdoor fluorescent and incandescent bulbs with yellow, orange or red bulbs. Close curtains or blinds at night to block indoor light from attracting moths to your windows and screens.
Moths feed on nectar and other sweet fluids. If you have a fruit tree, clean up fallen fruit around your yard as the sweet smell attracts moths. Like bees and butterflies, moths are flower pollinators. You may unintentionally be inviting moths to your yard with your flower choices. Plants with clustered, dull or white colored flowers that open in the afternoon or at night and have deep nectar sources are favorites of moths. Plants such as evening primrose (Oenothera spp.), which grows in U.S. Department of Agriculture plant hardiness zones 4 through 7; moon flower (Ipomoea alba), which grows in USDA zones 10 through 12; yucca (Yucca filamentosa) which grows in USDA zones 5 through 10; and flowering tobacco (Nicotania spp.) which grows in USDA zones 10 and 11, all attract moths.
Moths have some efficient nighttime predators. Bats eat hundreds of nocturnal bugs, including moths, during their nighttime flights. Attract bats to your yard to help get rid of pest moths by building or buying a bat house. Install the shelter in a sunny location, 15 to 30 feet above the ground to protect roosting bats from predators such as snakes and raccoons.
To reduce moth populations in your yard, get rid of their caterpillars early, before they mature into adult moths. Remove small caterpillar infestations by hand and drop them into a bucket of soapy water. For larger infestations, Bacillus thuringiensis bacteria target the gut of caterpillars, preventing them from eating and maturing into moth pests. The bacteria are available at garden centers and are safe for plants and wildlife. Always follow the manufacturer's recommendations for mixing and applying the bacteria. As an example, mix 1 tablespoon of concentrated Bt with 1 gallon of water in a garden sprayer. Spray both sides of leaves where caterpillars are present, shaking the sprayer frequently to keep the solution well-mixed. Wear protective eyewear and clothing, and avoiding breathing in the vapor. Apply another dose of Bt after heavy rain or after seven days, if necessary.
- University of Florida IFAS Extension: Insect Attractants and Traps
- Purdue University Extension: Insects See the Light
- U.S. Department of Agriculture Forest Service: Moth Pollination
- Colorado State University Cooperative Extension: The Night Shift
- Oregon State University Extension: Create Roosts for Bats in Your Yard
- Bat Conservation International: Artificial Roosts
Jean Godawa is a science educator and writer. She has been writing science-related articles for print and online publications for more than 15 years. Godawa holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She has conducted field research in the tropical rainforests of southeastern Asia and South America.