Spotted Lanternflies
As many of you have been noticing, the spotted lanternfly (Lycorma delicatula) has been spreading in the Mid Atlantic over the last few years. Also known as SLF, the spotted lanternfly is native to China and parts of Vietnam where its populations are kept under control since it is eaten by parasitic wasps. But, in the U.S., the spotted lanternfly are considered invasive and cause damage to grape vines, apples, stone fruits, and various trees.
The spotted lanternfly has made its appearance in Willowsford and the rest of Northern Virginia in much greater numbers this summer than last year and the bad news is: they are here to stay. The Willowsford Conservancy has been in close contact with the USDA, the Virginia Department of Forestry (VDOF), and our local Virginia Cooperative Extension office since the spotted lanternfly was first sighted in Loudoun County over two years ago. We have worked with them closely to understand expectations, explore possible management practices, and stay up to speed with how the state and local governments intend to address it. Despite these efforts, the final verdict is the same as it was in Pennsylvania, Maryland, and West Virginia: the spotted lanternfly is here to stay in Virginia, and we cannot prevent it.
The Virginia Department of Agriculture and Consumer Services are not proposing any special measures or support for eradicating SLF. The bug has established itself in 50% of the state of Virginia and it is no longer feasible to eradicate. The invasion of this bug in the U.S. first occurred in Pennsylvania more than 10 years ago, and we can set our expectations based on their experience. Over the next two years we will see the spotted lanternfly population get much worse before local fauna learn that they can eat them. Once natural controls take place, the populations will gradually reduce, and they will be very similar to the non-native stinkbugs and Japanese beetles we deal with currently—annoying but not overwhelming.
Unfortunately, Willowsford Conservancy does not have the ability to keep thousands of lanternflies out of more than 4,000 acres of land in our community. Although we cannot eradicate them from our area completely, there are some steps we will be taking in our land management areas to help reduce the SLF population. Homeowners can follow these actions as well to reduce the populations in their yard.
- Learn how to identify the insect in all of its stages, so the nymph stage as well as the adult insect we all recognize.
- Scrape the egg masses each spring on any trees in your yard. The Conservancy hopes to organize a scrape the egg masses volunteer event similar to the popular and successful Scrape for the Grape event [Hyperlink to https://www.loudouninvasives.com/scrape-for-the-grape ] organized by the Loudoun Invasive Removal Alliance which is a collective group of many HOAs, including ours.
- Squashing them whenever you see them. This can work for small infestations or the occasional SLF.
- Spraying them directly with a mixture of soapy water and distilled white vinegar can kill the bugs. You can squash them if they are in small numbers or even suck them up with a shop vacuum and then dispose of them.
- Willowsford Conservancy strongly discourages the use of pesticides to kill SLF, as there are no insecticides that target SLF specifically and spraying could result in the loss of many beneficial bugs, such as pollinators, and could damage landscaping. Killing all bugs can result in a population imbalance that is a leading cause of landscaping issues in neighborhoods such as ours.
- If there is an infestation in Conservancy open space that a resident would like to address themselves, they can reach out to us at info@willowsfordconservancy.org and request to do a project in the open space.
It is important to understand what to expect for the next few years. The spotted lanternfly population will initially get significantly worse. They most likely will be present in the hundreds and thousands over the next two years before the population starts to decline. SLF produce a sticky substance called honeydew, which attracts pollinators such as wasps to feed on the sugary substance. But the honeydew can also encourage the growth of black sooty mold, which will cover plant leaves and can stain fences and furniture. When their populations are high, it is very likely you will see bees and wasps in the area and the black mildew on low growing plants.
Tree of Heaven is a favorite tree for them, and often is the host tree for their egg masses, but SLF will be very happy feeding and nesting on maple trees, black walnuts, grape vines, and more. So far spotted lanternflies have been seen feeding and laying eggs on 103 different native species. Although you may not initially notice them on a tree, they are often at the very top of the canopy covering the upper branches and completely out of sight. Their willingness to feed on a variety of species, and ability to go undetected until fully established makes it a challenge to address all the different trees and shrubs for their removal. For these reasons, including many others, it is unfortunate to say that eradication of SLF is no longer possible within Virginia. But Willowsford Conservancy is committed to helping our community through the next few years of population boom and we will continue to keep residents updated.
Tree of Heaven
The discussion of spotted lanternflies goes hand-in-hand with the problem of the problematic and pervasive Tree-of-Heaven (Ailanthus altissima). Tree-of-Heaven is an invasive tree that is also the natural host tree for the spotted lanternfly. This tree thrives on recently disturbed sites and forest edges. It grows and establishes very quickly and aggressively sprouts new trees from the root system, making it hard to truly kill. In addition to its rapid growth rate, Tree-of-Heaven is also allelopathic, meaning it secrets a toxic chemical the suppresses the growth of other vegetation.
Within Willowsford, this tree is very commonly found behind resident homes or in other areas that were heavily impacted during the development of the community. Some of these trees have grown to be quite big and often act as a visual screen between properties. This makes it not only a challenge to remove, but also requires us to replant an area with large trees after removal.
Killing the invasive Tree-of-Heaven poses several challenges to the Conservancy in particular. The most commonly used and effective way to kill Tree-of-Heaven is by injecting herbicide into the trunk or by making cuts into the trunk and applying herbicide directly, then waiting for the tree to die and either remove the tree or allow it to remain standing. The timing is paramount. Poisoning the trees must be done in the fall when the tree is redirecting its energy to storing nutrients in the root system, taking the poison with it and killing the plant down to the roots. If treatment is mistimed, it can trigger the tree to send up rapidly growing sprouts from the root system, turning one tree into 20 trees! It is also possible to hand pull small saplings when the soil is moist enough to ensure the entire root system is removed with the tree.
The Conservancy is actively working to address the Tree-of-Heaven growing in easy-to-access areas where they can be killed and either removed or left as spars which provide habitat to wildlife. However, the Conservancy is extremely limited on how many sites can be addressed behind resident homes. The cost of tree treatment, removal, and replacement is high and restricts us to performing limited projects at a time. Both entities are actively pursuing grant funding to help offset the costs, but there are ways our community can help if they are interested.
Residents can pursue an Open Space Project where they work alongside the Conservancy and through a signed agreement carry out invasive tree removal through contractors on behalf of the Conservancy. Many neighbors in our community are contributing time and resources to help remove and replace invasive plants in the Open Space behind their homes. In some cases, the Conservancy can assist with cost-sharing to help residents complete an invasive plant removal or restoration project. We value our community’s involvement, and with such limited time and resources within the Conservancy, we value working with Willowsford residents who embrace our mission alongside us. For more information on how to get involved, reach out to us via our contact form or read more on Open Space Projects on our website: Open Space Projects | Willowsford Conservancy & Farm.
Thank you for your attention and assistance in tackling these invasive challenges.