The latest info on plant pests, pathogens, and weeds.

Pennsylvania Spotted Lanternfly Quarantine Expands Again

On March 10th 2021, Pennsylvania announced the addition of eight other counties to its Spotted Lanternfly quarantine. This brings the total number of quarantined counties in the state up to 34.

The most recent map of SLF quarantines in Pennsylvania and surrounding states.

While the situation in Massachusetts remains unchanged for now, this is a good reminder that SLF continues to spread across the northeast and has multiple pathways to move to new areas. Vehicles and shipped or imported goods can harbor SLF or their eggs, so it remains important to check for signs of SLF and report anything you find.

National Invasive Species Awareness Week


Every year, the North American Invasive Species Management Association  hosts National Invasive Species Awareness Week (NISAW). This year, NISAW has been split into two events, with an Information and Advocacy Session February 22-26. The week will feature a series of daily webinars covering a variety of topics, from management priorities to plant health.

The Massachusetts Department of Agricultural Resources is also offering two opportunities during NISAW to learn about invasive species in Massachusetts:

  • On February 25th, Dr. Jennifer Forman Orth will be the featured speaker for the Massachusetts Nursery and Landscape Association’ss Green Industry Virtual Forum, with the topic “Dealing with Invasive Plants: What To Know and What To Watch Out For.” You can register for this talk or other talks in the series here. Massachusetts Certified Horticulturists  can receive one MCH credit for attending.
  • Also on February 25th, the Forest Pest Outreach Coordinator, Joshua Bruckner, will be giving a presentation to Quinsigamond Community College’s Environmental & Physical Science program. The focus of the talk will be on invasive insects in Massachusetts, including the spotted lanternfly, and also how climate change affects the spread of invasive species . While the presentation will only be available for members of the class, a similar talk by Joshua is archived here.

Is your organization interested in arranging a presentation from MDAR about invasive species? MDAR staff are always available to present for free on a variety of topics, reach out to Joshua Bruckner for more information.

Emerald ash borer update: February 2021

Emerald ash borer  remains a pest of concern throughout the state. As of February 1, 2021, 6 new municipalities in 6 different Massachusetts counties have been confirmed to have emerald ash borer. The communities are as follows:

Bristol County

  • North Attleborough

Essex County

  • Merrimac

Hampden County

  • Holland

Hampshire County

  • Chesterfield

Norfolk County

  • Quincy

Worcester County

  • Oxford

This brings the total number of municipalities in Massachusetts with EAB up to 175 (50%). The only remaining town in Hampden County without confirmed EAB is Chicopee. An updated map is below (click on the map to zoom:

If you suspect you have seen EAB in an area not indicated on the map above, get a photo of the damage if you can, and report it here. If you missed our November update, you can read that here.

Update on Spotted Lanternfly Tracking Efforts

Wondering what’s being done this year to combat the spread of spotted lanternfly (Lycorma delicatula, “SLF”) in Massachusetts? You can read this brief article from UMass Amherst Extension that details the survey and trapping efforts that are currently underway.

While SLF is not yet established in Massachusetts, the increased number of finds in 2020 are cause for concern, and the state’s efforts to find and control the invasive pest have summarily increased.

If you have found evidence of spotted lanternfly or SLF egg masses, take a photo and report it at our website.

SLF Guidance for Nurseries and Landscapers

Spotted lanternfly (Lycorma delicatula, “SLF”) is a growing threat to the environmental and economic resources of Massachusetts. In 2020, SLF was found in municipalities in Middlesex, Norfolk, and Worcester Counties, and in each case the introductions were traced back to materials shipped from SLF-infested areas in Pennsylvania. While we still have not found a confirmed infestation in our state, nurseries and other green businesses need to be aware of the risk that importing nursery stock or other materials may pose in unintentionally bringing SLF into Massachusetts.

If you own or work for a nursery, landscaping company, or other green industry business, the Mass. Dept. of Agricultural Resources (MDAR) recently released a new guidance document with Best Management Practices (BMPs) for detecting and preventing the spread of spotted lanternfly. We encourage you to share copies of this document with all employees as well as any companies you deal with (including trucking companies, moving companies, and other nurseries and landscapers). Careful examination of nursery stock, pallets, outdoor furniture, and other materials at your place of business will also help prevent the further spread of SLF.

To order multiple copies of these BMPs or other free SLF outreach materials, to display or to distribute to your staff or customers, use this online form.

Are Christmas trees a risk for spreading spotted lanternfly?

At MDAR, we always have invasive insects on the brain, even at the start of the holiday season. Given all the new discoveries of Spotted Lanternfly (Lycorma delicatula, “SLF”) in Massachusetts this year, you maybe be thinking about them too. While SLF adults die off with the first hard frost, their eggs will survive through the winter until they hatch in spring. SLF will lay their eggs on any flat surface, which may make you wonder if live Christmas trees can harbor SLF or their eggs!

SLF egg masses have been found on a Christmas tree, in an isolated incident in Warren County, NJ in 2018. While there is little evidence to suggest SLF feeds on conifers or evergreen trees like fir or pine and that Christmas  trees are not a common route for the spread of  SLF, they can lay their eggs on nearly any flat surface, so the possibility does exist.

That said, we encourage you to buy your live Christmas trees from a local farm to help support our farmers and agricultural industry, and it’s always a good idea to check your tree for any SLF egg masses, just in case.

Both living and dead SLF adults have been confirmed in six (6) different Massachusetts municipalities so far (Billerica, Boston, Concord, Milford, Norwood, and Sharon). There is no evidence of a breeding population in Massachusetts yet, so all SLF that have been found presumably hitched a ride here from out of state.

On the left, dried sap on a Christmas tree. On the right, an SLF egg mass. Photo by Emelie Swackhamer

SLF egg masses are highly camouflaged and notoriously difficult to spot, and none have been found yet in Massachusetts. The SLF egg masses are usually oval in shape and covered in a substance that resembles cracked, dried gray mud. Occasionally, the eggs will show through the dried covering and might look like seeds. Scraping away the covering of an SLF egg mass will reveal the eggs beneath. Dried tree sap may have a similar texture but is usually more irregular in shape, and may resemble liquid running down the tree, and can have a distinct piney smell.

If you think you have found a spotted lanternfly egg mass, please photograph what you see and report it here. After reporting your find, you can remove any egg masses you find by scraping them off with an SLF ID card (which can be ordered for free here) or a credit card. The eggs should be scraped into a zippered plastic bag or vial with rubbing alcohol or hand sanitizer to kill them. You should hold onto them in case an inspector asks for the specimen.

Pest ID Tools: Spotted Lanternfly Egg Masses

With the first hard frost of the year behind us, any spotted lanternflies around may have died off, but any eggs they laid will remain, surviving over the winter until they hatch in May. Now is an important time to check for signs of SLF egg masses, since the eggs will be easiest to see on bare trees.. Female spotted lanternflies will lay eggs on nearly any flat surface, which makes them a challenge to survey for, and means there is a big risk of them being accidentally introduced into our state from vehicles or goods that come here from infested states. That makes it critical for as many people as possible to learn to identify these egg masses and distinguish them from any lookalikes.

Spotted lanternfly egg masses, covered (bottom) and uncovered (top). Photo credit Pennsylvania Department of Agriculture

SLF egg masses have been found on some unusual items, not just trees, as these photos from Pennsylvania show:

Female spotted lanternflies lay one or two egg masses, with 30 to 50 eggs in each mass. The masses are usually covered in a protective coating that looks like a waxy putty, starting out white when fresh and later drying to resemble a gray, cracked, patch of mud. This rough gray surface works well as a camouflage on many surfaces, including tree bark, rocks, and weathered wood. Exposed or uncovered eggs resemble strings of connected seeds.

The easiest things to confuse with SLF egg masses would be the egg masses of the gypsy moth (Lymantria dispar). Gypsy moth egg masses can be found from late August until May on almost any vertical surface. They can be distinguished from SLF egg masses by their buff or yellowish fuzzy coating, and also often have tiny pinprick holes on the surface, evidence of parasitic wasp activity. The eggs themselves, which can be seen by scraping away the fuzzy covering, are small and spherical, compared to the larger and more oval eggs of lanternflies.

SLF egg mass on the left, next to a gypsy moth egg mass. Photo credit Emelie Swackhamer with Penn State Extension

You may also come across mud wasp or mud dauber nests on the sides of structures or under roof overhangs. Mud daubers are solitary wasps and are a native insect that create cylinders of mud to house their eggs. The shape and large size set them apart from SLF egg masses.

A black and yellow mud dauber with a nest. Image from Bugwood Wiki.

We also sometimes get reports from people who confuse SLF egg masses with lichens. Lichens are a hybrid of algae and fungus and found in many habitats. They have a wide variety of appearances but commonly have a scaly-looking appearance and some of the most common ones are flat and have a bluish-green tinge. These are harmless, naturally-occurring growths and can be left alone. However, SLF egg masses could be camouflaged amongst a lichen-covered surface, so you should always check to make!

A lichen on a tree. Photo credit Bill Uhrich

If you think you have found a spotted lanternfly egg mass, please photograph what you see and report it here. If you are not able to take a photograph, you can use one of our plastic ID cards (order some for free here) or a credit card to scrape the eggs off, place them in a bag or other sealable container, and add rubbing alcohol as soon as you can – this will kill the eggs.

Free Forest Pest Webinars from DCR – Register now!

If you’re looking for something to do as colder weather arrives, and you want to learn more about the natural world around us, DCR has you covered! For the month of December, DCR’s Forest Health Program will be hosting a series of free webinars where you can learn about a variety of invasive pests and pathogens that impact our forests. Pesticide credits will be offered at each presentation. The seminars available are:

  • Gypsy Moth and Hardwood Defoliators of Massachusetts: Tuesday 12/1, 12:00 PM – 1:00 PM
  • Beech Leaf Disease in Massachusetts: Thursday 12/3, 7:00 PM – 8:00 PM
  • Emerald Ash Borer in Massachusetts: Tuesday 12/8, 12:00 PM – 1:00 PM
  • Identifying Oak Wilt Disease: Thursday 12/10, 7:00 PM – 8:00 PM
  • Asian Longhorned Beetle: Tuesday 12/15, 12:00 PM – 1:00 PM
  • Southern Pine Beetle: Thursday 12/17, 7:00 PM – 8:00 PM

More about each seminar is available here. To sign up, send an email to and let him know which webinar you’d like to attend. Space is limited, so be sure to sign up by the deadline listed for each session.

Emerald ash borer update: November 2020

As of November 3rd, 21 new municipalities have been confirmed to have populations of emerald ash borer. Berkshire County now has known EAB infestations in every municipality except New Marlborough and Otis, while Hampden County has EAB everywhere except Chicopee and Holland. The most recent detections occurred in:

Berkshire County

  • Adams
  • Clarksburg
  • Monterey
  • New Ashford
  • Sandisfield
  • Savoy
  • Williamstown

Franklin County

  • Colrain
  • Conway
  • Hawley
  • Leverett
  • Montague
  • Sunderland

Hampden County

  • Tolland

Hampshire County

  • Worthington

Middlesex County

  • Ashland
  • Lincoln
  • Maynard
  • Stow
  • Sudbury

Norfolk County:

  • Norfolk

This brings the total number of municipalities with EAB in the state to 161 (46%). An updated map is below (click on the map to zoom in):

If you suspect you have seen EAB in an area not indicated on the map above, get a photo of the damage if you can, and report it here. If you missed our October update, you can find that here.

Host Plants of Spotted Lanternfly, Part Three: Black Walnut

Now that the two most common hosts of Spotted Lanternfly (Lycorma delicatula, or “SLF”), tree of heaven and grape, have been covered, let’s branch out to cover some of the other major hosts, starting with black walnut (Juglans nigra). Research shows that black walnut is favored by spotted lanternfly in all its life stages. Residents in states with SLF infestations report observed large black walnut trees completely covered in these invasive insects.

Similar to tree of heaven, sumac, and other hardwood trees such as hickory and butternut, the leaves of black walnut are pinnately compound, with each large leaf consisting of 9-23 smaller leaflets, 2 to 3 inches long, with a serrated (toothed) margin. The terminal leaflet at the tip of the leaf is often missing, giving the appearance that it ends with a leaflet pair.

Black walnut leaves in early summer

Black walnut leaves in the fall. Photo by Jennifer Forman Orth

In the spring, black walnuts produces drooping catkins, similar to the flower of oak or birch trees.

Black walnut catkins. Photo credit Steven J. Baskauf

The bark of the black walnut is dark gray-black with deep furrows, and often has a diamond-shaped pattern.

Typical pattern and color of mature black walnut bark

Black walnut’s most distinct feature is its fruit. Fruits ripen in early autumn, and resemble large greenish tennis balls. They remain on the tree until about October and fall off before the leaves do. Once the fruit falls to the ground, the outer shell then ripens and rots, turning a dark color. The seed of black walnut is edible by both animals and humans, and you may find the discarded nut shells around the base of the tree, evidence of a previous year’s squirrel feast.

A still-ripening black walnut fruit, nestled among the leaves. Photo credit Nature Photographers Ltd

Dried shells of the black walnut.

Spotted Lanternfly is not just a threat to the animals that count on black walnut as a food source and as habitat; a study out of Pennsylvania showed a potential economic loss of $6.5 million due to SLF damaging this important agricultural resource, which is highly valued for its wood due to the beautiful dark color and resistance to rot.

With black walnuts growing along streets and in parks throughout Massachusetts, it is easy to imagine the impact that Spotted Lanternfly could have in this state. If you think you have seen evidence of Spotted Lanternfly, report it here.