Spotted lanternfly sounds like an attractive garden guest, but the U.S. Department of Agriculture (USDA) is asking everyone to stay vigilant and eliminate it on sight. Although Lycorma delicatula is primarily a serious threat to fruit growers and orchardists, backyard gardeners will be dismayed by the spotted lanternfly’s swarming behavior, the sooty black mold it propagates, and the damage it causes to ornamental shrubs by sucking their sap.
Gardeners can also play a role in helping to track and prevent the bug’s encroachment, as it is known to catch a ride on nursery stock; currently, there are known infestations in Pennsylvania, Connecticut, and New Jersey.
A spotted lanternfly (Lycorma delicatula) winged adult (top) and instar nymph, which is black and bright red. (Photo courtesy Stephen Ausmus, USDA)
In fact, the Massachusetts Department of Agricultural Resources (MDAR) is spreading the word that plant stock has been shipped from areas with infestations and is asking residents to look out for hatching egg masses and the small black and white wingless nymphs that emerge. Residents should be especially careful to check the bark and branches of maple and crabapple trees recently purchased from nurseries. Infestations have already been found in Fitchburg and Shrewsbury, and individuals have been spotted in Concord, Leominster, and Northborough.
In general, the invasive planthopper doesn’t fly very far on its own; rather, it lays its eggs on many different types of materials that may be transported long distance-. Likely, this was how it entered the U.S. in 2012 on an international shipment of crushed stone. A breeding population of spotted lanternfly was first detected in Berks County, Pennsylvania in 2014, and the state’s department of agriculture quarantined the affected counties. Given the potential to ruin crops, the plant nursery industry, and hardwoods, the Pennsylvania Department of Agriculture estimated in a 2019 study that the insect could wreak $324 million worth of damage in the state if unchecked. The USDA has even created a pilot program with dogs to sniff out lanternfly eggs in order to stop their spread.
Egg masses—which may be laid on rocks, trees, plant containers, outdoor furniture, or just about anything stored outside—appear dry and muddy and measure 1/2 to 1 inch long. At present, the insect would likely be found as an early stage nymph, a small black bug with many white spots measuring up to 1/4 inch long. The insect molts several times as it develops, changing in appearance and size each time until midsummer, when its instar will appear red with white and black markings. Finally, in late summer, it takes on the adult form with four wings, two of which are bright red. Although there are some look-alikes, since it is a true bug and not a moth, it is not fuzzy and it doesn’t have long antennae. It has fairly long legs that may be a noticeable feature.
The insect sucks the sap out of stems and branches—it has a long proboscis for this work—thus causing damage to numerous crops, including apples, peaches, and grapes. The only plant it is likely to kill outright is the invasive tree of heaven, Ailanthus altissima, the adult bug’s preferred host found in patches around Harvard. However, it does not exclusively feed on this host, which is why the USDA considers it a serious potential threat to fruit growers and the general public.
Thus far it has been observed feeding on over 100 different types of plants, especially in the nymph and juvenile stages. Some of its meals include trees such as American beech, linden and sycamore, pine, maple, oak, and willow, as well as shrubby ornamentals like serviceberry and roses. After feeding, spotted lanternflies leave behind a sticky waste product, honeydew, which attracts other insects and promotes the growth of sooty black mold. This mold can kill nearby plants by covering their leaves and starving them of photosynthesis, especially under the infested trees. Further, the insects tend to swarm in the thousands, creating an unpleasant nuisance in the backyard.
Harvard’s orchards could be especially vulnerable to the pest, which is a compelling reason for Harvard gardeners to be on the lookout for the lanternfly.
If you see a spotted lanternfly, please report it to the Massachusetts Introduced Pests Outreach Project, the state and UMass folks working to address the problem, at https://massnrc.org/pests/pestFAQsheets/spottedlanternfly.html. Try to take photos and capture the bug, putting it in a jar with rubbing alcohol or in the freezer to kill it.
For more information
To find a variety of educational resources or to report a sighting, check out the website for the Massachusetts Introduced Pests Outreach Project (a combined program of the MDAR and the UMass Extension programs) at https://massnrc.org/pests/slfreport.aspx. For an online fact sheet, see https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly.
