- Author: Jeannette Warnert
The spotted lanternfly is beautiful when its wings are open, showing off a striped yellow abdomen and ruby red and black polka dot wings. But the pest could become a menace in California.
Native to China, spotted lanternflies were first introduced into the United States in 2014 when their presence was confirmed in Berks County, Penn. They have since established populations in 17 states, as far west as Illinois. Spotted lanternflies are little more than a nuisance in their native range because they evolved along with controlling factors – such as predators and microbes – that achieved a natural balance. But when they arrive in new territory, the pest multiplies quickly and becomes a threat to the production of apples, grapes, stone fruits, roses, landscape trees and timber.
The inch-long adults are like giant aphids. The pest sucks sap out of plants and trees, depleting nutrients and reducing plant vigor. While feeding, they emit waste sugars that cover plant leaves and invite fungi to grow black sooty mold, a coating that inhibits the plants' photosynthesis.
In the eastern U.S., residents say spotted lanternflies affect their quality of life and ability to enjoy the outdoors. The pest covers trees, swarms in the air and their honeydew can coat decks and playground equipment.
Potential for cross-country spread
Spotted lanternfly movement is aided by females' ability to lay their nondescript egg masses on surfaces of natural and human-made objects, such as packages sent from distribution centers, long-haul trucks, railroad containers, recreational vehicles and ordinary cars. The egg masses are covered with a waxy gray-brown coating that looks like a splash of mud.
In fact, egg masses have already entered California. UC Integrated Pest Management advisor Cindy Kron detailed the incident at a recent webinar. A large art structure on a flatbed truck was stopped at the Truckee CDFA inspection station on March 17, 2024. Because of what appeared to be SLF egg masses on the structure, it was denied entry and ultimately more than 30 viable egg masses were found. After being power washed with soap and water in Nevada, it was cleared by inspectors with the Nevada Department Agriculture.
The structure was offloaded in Sonoma County and inspected by the local ag commissioner, who found three more egg masses.
“Each of the egg masses contain from 30 to 50 eggs,” Kron said. “This structure was carrying between 990 and 1,650 SLF eggs. That is enough to start a population.”
If the SLF egg masses had not been found, the pest could have been established in agriculture-rich California, underscoring the importance of vigilant monitoring.
“We're trying to prevent introduction, but we're not perfect,” Kron said. “We need help. We need the help of farmers, gardeners, the whole population to keep this insect out.”
Another concern for California in the face of a potential SLF infestation is the abundance of tree-of-heaven, itself an exotic pest from China and spotted lanternflies' favorite host. The tree's tendency to grow rapidly and multiply quickly has resulted in its designation as a noxious weed.
UC Master Gardeners are helping map the locations of tree-of-heaven in the state so CDFA can pro-actively reduce the number of trees available for the pest.
Learn more:
One-hour webinar by UC IPM advisor Cindy Kron about spotted lanternfly
UC Master Gardeners are part of a coordinated effort to eradicate invasive tree-of-heaven
Follow proven guidelines for successful tree-of-heaven removal
- Author: Jeannette Warnert
Tree-of-heaven is an invasive species from China that is found in many areas of Fresno County. The trees are easy to identify by their rapid growth, bark resembling cantaloupe rind, compound leaves and distinctive burnt peanut butter scent when leaves are crushed. Because of their extensive root system and tendency to resprout, removal of this nuisance tree is challenging. But removal of the tree is particularly important in the San Joaquin Valley because an invasive pest that loves tree-of-heaven is making its way across the United States. Spotted lanternfly arrived in Pennsylvania from China 12 years ago and has since been spreading westward, already as far as Illinois. If established in California, the pest will have a devasting impact on agriculture and natural areas.
In March, the Truckee Border Protection Station intercepted spotted lanternfly egg masses on a metal art installation headed to Sonoma County, according to a California Association of Wine Grape Growers press release. This is the first finding of lanternfly egg masses in California. The egg masses are easy to mistake for an innocuous splotch of mud. When laying eggs, the female secretes a white, waxy substance over the eggs that, when dried, look like a ¾-inch wide smudge of mud, cement or lichen. The egg masses can travel to California on cars, trucks, cargo, airplanes and other conveyances from parts of the country where the spotted lanternfly is found.
Out of concern for spotted lanternfly's possible establishment in California, the California Department of Food and Agriculture (CDFA) is working on eradicating the lanternfly's favorite plant host, tree-of-heaven, along roadways, lakes and streams, on public lands, roads and highways. UC Master Gardener volunteers throughout the state are mapping the trees' locations so they can be prioritized for removal. Fresno County residents can help the effort by removing trees-of-heaven on their own property.
Careful treatment with an herbicide in July, August or September, followed by removal of the trees about 30 days later offers the greatest likelihood of success. According to CDFA, herbicides containing the active ingredients glyphosate or triclopyr are effective and pose minimal risk to nontarget plants.
Spray all the trees' leaves if tree height allows for safe application with a backpack or hand pump sprayer. For dense or extensive infestations and tall trees, treat small, low growth with a sprayer, then follow up with hack-and-squirt application on larger stems. Hack-and-squirt introduces the herbicide into the stem using spaced cuts below the last live branch. With a hatchet or similar device, make downward-angled incisions, evenly spaced around the stem. The cuts must penetrate through the bark into the living tissue or sapwood (the outer area of lighter-colored wood in the stem cross-section). Leaving uncut living tissue between the hacks will allow the herbicide to move to the roots. Using a low-volume backpack sprayer or spray bottle, fill the cuts with a concentrated mixture of the herbicide. (For detailed instructions, see pages 28-36 of the CDFA Spotted Lanternfly Action Plan.)
Thirty days later, cut down the trees. Follow up by monitoring the area for regrowth and repeating the treatment protocol as needed.
After tree-of-heaven has been treated with the herbicide and removed, homeowners can begin to consider what trees may be replanted in the area to offer shade and beauty to the landscape. For guidance, see the tree selection guide on the Fresno County UC Master Gardener website.
Read more:
Invasive tree-of-heaven is a preferred host for two invasive insect pests that cause economic damage in California agricultural crops, Cindy Kron, UC Cooperative Extension Area IPM Advisor
UC Master Gardeners are part of a coordinated effort to eradicate invasive tree-of-heaven, Jeannette Warnert, Fresno County UC Master Gardener
CDFA Spotted Lanternfly Action Plan, Plant Health and Pest Prevention Services Division, CDFA
Tree-of-heaven, Weed Control in Natural Areas in the Western United States, Weed Research and Information Center, UC Davis
/table>- Author: Jeannette Warnert
In contrast to its angelic name, tree-of-heaven is a noxious invasive plant that was introduced during the Gold Rush by Chinese miners who valued its medicinal properties. It is also the preferred host plant for two damaging exotic pests, the brown marmorated stink bug, already found in parts of California, and the spotted lanternfly, a leafhopper from China that officials want to keep out.
Tree-of-heaven is found in 39 California counties, including Fresno County. It is a deciduous tree that can reach 75 feet in height with a 12-inch diameter near the base. It has smooth bark that resembles cantaloupe rind and compound leaves that contain dozens of leaflets. The tree tolerates unfavorable growing conditions on every type of topography in California below the 7,000-foot elevation. It is not an easy tree to eradicate. When cut down, it resprouts readily, creating even more trees in dense stands.
“CDFA has funding for elimination of tree-of-heaven,” said Missy Gable, director of the UC Master Gardener Statewide Program. “They need to know where the trees are located so funds can be allocated to local agencies for removal. With UC Master Gardeners' extensive training and statewide reach, they are uniquely equipped to support the project.”
More than 6,000 volunteers across the state are trained and certified UC Master Gardeners. They are dedicated to educating the public on sustainable gardening and being involved in environmental stewardship in their communities. About 300 Master Gardener volunteers have been trained to identify tree-of-heaven by assessing the bark, leaves, flowers and seeds. Using a simple online scouting tool, they will record the locations, number of trees in the stand, and the approximate diameter of the largest tree at breast height. The tool generates a map that can be used by researchers, CDFA and local public works officials to prioritize trees for removal.
Fresno County residents can report locations of tree-of-heaven stands by entering the address below in the comments section of this post.