The dreaded spotted lanternfly has landed in Belmont. After arriving in Pennsylvania in 2014 (likely imported as an egg mass on a pallet of landscaping stone), it headed north and has been flitting around Massachusetts since 2021. It is now definitely established in our area; I recently dispatched two I found on some Virginia creeper in my back garden.
Spotted lanternfly is an invasive plant hopper. It uses piercing mouth parts to feed on sap from a wide range of host plants, including trees, woody ornamentals, and perennials. Spotted lanternfly (SLF) will not hurt you and is unlikely to kill your plants, though they may be weakened by a large infestation. The greatest threat is to agriculture, particularly vineyards, and forests.
On the home front, a backyard teeming with lantern flies is perhaps not the experience most of us would wish for. The honeydew they excrete leaves sticky spots on lawn furniture and is a substrate for sooty mold. Sooty mold itself is not harmful, but in large amounts it can block photosynthesis—as seen on plants at the base of heavily infested trees.
What is a gardener to do? While home gardens are typically at low risk, vigilance is key to slow the spread of lanternflies and preserve Massachusetts’ forests and vineyards. The first line of defense is to destroy the insect when you see it; squish or stomp with abandon. Take twilight safaris through the garden; the flies tend to congregate on trunks and stems in the evening. They are awkward flyers but, being plant hoppers, are quite good at jumping. They also do the classic insect trick of simply falling away when danger approaches. Hold a small pail of soapy water under the beast before you bring your hand near; often it will fall right in (this also works with Japanese beetles). Large infestations can be vacuumed up. The battering they receive kills most, but wait a day or two before carefully emptying the vacuum to ensure they have all succumbed. Do not leave them much longer or they will begin to rot, and the smell is putrid.
SLF has four instars (larval stages). The first nymphs are up to ¼ inch long, black with white spots and black legs. With their flat, circular-ish body and pointed heads, you might mistake them for ticks. Second- and third-instar nymphs have the same coloring. The fourth instar is about ¾ of an inch long and has distinctive coloring: a red body with black stripes, white spots, and black legs. All the juveniles are very good at jumping. Adults are about an inch long. They are an attractive insect, grey-pink with black spots when their wings are folded. Open wings reveal a startlingly red body—if you see red, you know your target is preparing to flee.
SLF overwinter as eggs, which are laid from September to December; larvae begin to emerge in May. Look for and destroy the egg masses; they resemble grayish blobs of mud or putty and may be mistaken for lichen. You can find them almost anywhere. Look for them on tree trunks and the underside of branches. Check lawn furniture, outdoor structures, rocks, automobiles, car tires – wood, plastic, metal, stone, plants- all have equal value as potential nesting sites for this pest. Lantern flies are well-documented hitchhikers; carefully check your vehicle and look over any purchased firewood for egg masses.
Scrape off the egg masses—an old credit card works well—into sealable plastic bags or containers of alcohol or hand sanitizer. Or crush them with a trowel. SLF egg masses hold 30 to 50 eggs; destroying them can definitely help reduce the spread. Some will be out of your reach in the treetops, but you will make a dent in the population.
Although they have a broad palette of more than 100 host plants (grape vines, maple, birch, willow and walnut trees, hops, Virginia creeper, fruit trees, particularly stone fruits, and many more), their favorite host by far is the tree of heaven, Ailanthus altissima, an invasive, weedy tree. (Consuming ailanthus makes SLF taste bad, discouraging predators.) If you have ailanthus on your property, now is a good time to consider removing it. It is a bit complicated because simply cutting it down will cause it to sprout along its root system, and then you will have a grove of ailanthus where you previously had only one. Best to consult an experienced arborist.
For more information and to report lanternfly sightings, go to mass.gov/spotted-lanternfly
Dorothy gardens in Belmont, where she lives with her husband, Steve, and their two dogs, Rosie and Jasper. She has six grandchildren — all perfect by definition — and has enjoyed introducing them to gardening. She has an abiding interest in nature and is always amazed by the wonders to be found in her own backyard.
Praying mantis and spotted lanternfly.
