A New Invasive Pest
The spotted lanternfly, Lycorma delicatula, is an invasive plant hopper native to China, Vietnam, and India. The spotted lanternfly was confirmed in Pennsylvania in September, 2014. Adults can lay eggs on any smooth surface like rocks, siding, or bricks which make them extremely easy to spread. If left unchecked, this pest can result in the major decline of many ornamental trees.
While a tree of heaven (Ailanthus) is the most common host tree, adult insects are known to feed on around 70+ species of plants including trees, shrubs, and agricultural crops.
Damage to Trees
Adults and nymphs feed by sucking sap from the leaves and stems of their host plants, causing the wounds to ooze and leaving a foul oder. Weakened plants are open to attack from other pests and diseases which can further stress or kill the plant.
Infested trees will exhibit weeping wounds that leave a dark gray trail along the trunk. Smooth gray egg masses can be seen on the trunk of the tree or other smooth services near the tree. The spotted lanternfly can gather in large groups on the tree which on sometimes be seen migrating up and down the tree during dawn and dusk.
On tree of heaven, its preferred host, trees typically die within 2-4 years after initial attack.
A Nuisance to People
Along with the physical damage these insects cause, they secrete a sticky substance (called ‘honeydew’), which spreads over anything underneath the attacked tree. Surfaces covered by the honeydew will subsequently be covered in a black sooty mold, resulting in a dirty appearance to patio furniture and other infrastructure as the mold grows.
Managing Spotted Lanternfly
Reduce the Spread
If you spot egg masses on the insect itself the best option is to contact your local Extension agency or your State Plant Regulatory Official. If you spot egg masses, make sure to follow these three steps:
1. Scrape them off.
2. Double bag them.
3. Throw them away or soak them in alcohol.
These egg masses can be found on the bark of host plants or any smooth surface such as cars, trailers, siding, brick, stone, and so on. Make sure to inspect vehicles before taking trips. Adults are easiest to spot at dusk when they congregate on host plants moving up and down the trunk.
Protecting Trees
Trees should be treated between mid-late May and August. We use a special spray that can be used as an annual treatment to protect high value trees. It a soil applied, systemic insecticide that provides season long control of a broad spectrum of pests. It can be used for a variety of situations where fast results are needed including recovery treatments on infested trees.
Other Tree Health Recommendations:
- Adequate water is a key factor in maintaining healthy trees. A slow, deep watering event once per week during dry conditions will help maintain soil moisture levels and minimize stress.
- Mulch is very beneficial for trees because it reduces competition with turf and moderates soil temperature and moisture levels. The addition of 2-4 inches of wood chips or shredded bark under the drip line can have a beneficial effect.
- Avoid compacting the soil, changing the soil grade or water drainage pattern, damaging the bark, allowing significant amounts of defoliation by insects or anything else that may stress the tree.