Montgomery County Department of Transportation Asks Residents to Prepare for “Population Boom” of Spotted Lanternflies

Montgomery County residents should prepare for a boom in the spotted lanternfly population over the next three to five years, says the County Department of Transportation (MCDOT).  

The invasive species, native to Southeast Asia, was first detected in the United States in eastern Pennsylvania in September 2014, and spread to Cecil County, Maryland, in October 2018. The insects were first spotted in Montgomery County in 2022 and have grown in population ever since. 

MCDOT officials say some parts of the County may see population levels similar to the Cicada Brood X emergence in 2021. 

“The further northeast you are, the worse it’s going to be,” said MCDOT Division of Highway Services Arborist and Entomologist Ashley Dykes. “In certain parts of the County, particularly areas such as Damascus and Brookeville, while it’s not quite on par with peak cicada season numbers yet, we are getting there.” 

However, MCDOT officials reassure residents that although the insects are a nuisance, they are not considered harmful.  

“They do not sting or bite,” said Dykes. “And they contain no known toxins so they should not harm any pets that try to eat them.” 

The spotted lanternflies feed from the sap of trees, but MCDOT officials say there is no cause for concern about long-term damage.  

“Most trees are hardy enough to bounce back,” said Dykes. “As they feed, they will leave behind a substance called honeydew that grows a black sooty mold and cause a sticky mess. Residents should avoid parking cars near Tree of Heaven plants or other hosts.” 

Trees of Heaven are an invasive plant and the preferred host for spotted lanternflies, but they can feed on many varieties of trees, so eradicating them won’t help. At this time, MCDOT does not have plans to remove Tree of Heaven plants from County property. 

“The population is well-established at this point,” said Dykes. “Squashing them will not really help. The best way to prevent the population from spreading is to inspect your cars when driving in and out of regions with spotted lanternflies. They like to hitch rides on vehicles.” 

MCDOT also encourages residents to learn how to recognize and safely dispose of spotted lanternfly egg masses. The insects lay their eggs starting in late summer and into early winter, so residents should be on the lookout. Spotted lanternflies lay their eggs in columns covered in gray putty. The columns can be an inch and a half or longer and can appear on trees, stones, or other flat surfaces. Residents should scrape the egg masses into a sealed bag and then smash them before disposing. 

Spotted lanternflies develop in four distinct stages before performing one final molt into their winged adult stage. While most lanternflies are still crawling around in their final nymph stage, fully developed winged adults have already been spotted throughout the County.  

“We know the presence of an invasive species can cause concern for our residents,” said MCDOT Director Chris Conklin. “Although a nuisance, we do not expect to see a widespread negative impact on our native plants or species. We encourage our residents to help prevent further spread of the population by inspecting trees and other surfaces for egg masses and disposing of them.” 

The MCDOT Highway Services Division, Tree Maintenance section, maintains over 250,000 trees in the dedicated county right of way and another 200,000 in rural areas. In Fiscal Year 2025, the Tree Maintenance Section answered 15,485 resident requests through MC 311 and planted 2,487 trees in County right of way, mostly along neighborhood streets. Residents can request the planting of a street tree online. Residents can also request one of seven MCDOT Arborists to inspect, prune or consider removing a dead or diseased county-maintained tree on the MCDOT Tree Maintenance Section website.