The Spotted Lanternfly (Lycorma delicatula) is an invasive planthopper that threatens agricultural and ornamental plants across the United States. Originating in Asia, this pest was first detected in the US in 2014. Its rapid spread is largely due to its broad host range and effective attraction mechanisms. Understanding what draws the insect to certain locations and plants is paramount for developing effective control and containment strategies.
Primary Host Plants and Feeding Preferences
The initial attraction of the spotted lanternfly is strongly driven by its need to feed on plant sap, specifically the phloem tissue. The insect uses specialized piercing-sucking mouthparts to extract the sugar-rich fluid from stems, trunks, and leaves. This feeding behavior supports its growth and development across all life stages.
The invasive tree Ailanthus altissima, commonly known as the Tree of Heaven, is the adult lanternfly’s most preferred host plant. This preference is so strong that the Tree of Heaven is believed to be necessary for the spotted lanternfly to complete its life cycle and maximize egg production.
However, the insect is a generalist feeder, with a host range that includes over 70 plant species. Beyond the Tree of Heaven, other highly attractive hosts include grapevines, which are a major target in agricultural settings, and certain hardwood trees. Adults are frequently found feeding on maples, black walnut, willow, and stone fruit trees like cherry and peach.
Visual and Environmental Cues
Attraction is not solely based on plant chemistry, as the lanternfly also responds strongly to physical cues. The insects are visually drawn to tall, vertical structures, a behavior that aids in their dispersal and aggregation. They frequently land on utility poles, buildings, and tree trunks, using these vertical surfaces to climb upward before launching themselves into flight.
This tendency to seek out height is a key part of their movement behavior, allowing them to ride air currents for long-distance travel. Observations suggest that the insects are attracted to the high-contrast silhouettes created by these objects against the sky. Lanternflies show a preference for dark, vertical surfaces, such as blacktop or dark-colored buildings, which may be linked to their need for warmth.
The Role of Fermentation and Excrement
A powerful chemical attraction loop is created by the lanternfly’s feeding habits and waste excretion. As the insects feed, they excrete large amounts of a sugary liquid waste product known as honeydew. This honeydew coats the plant and the ground below. Feeding wounds on the host plant can also cause sap to weep and ooze.
The combination of honeydew and weeping sap ferments rapidly, producing volatile organic compounds (VOCs). These fermentation odors act as powerful aggregation attractants, drawing more lanternflies to the infested site. Researchers have identified specific VOCs, such as benzyl acetate and 2-octanone, that draw both sexes to the location. This feedback loop explains why certain trees become overwhelmingly covered in a cluster of the insects while similar nearby trees remain unaffected.
Using Attraction Knowledge for Management
Understanding these attraction mechanisms allows for the development of targeted management strategies. The strong preference for the Tree of Heaven can be exploited using a “trap tree” method.
Most invasive Ailanthus altissima are removed, and the few remaining trees are treated with a systemic insecticide, attracting the lanternflies to the poisoned host where they are killed.
The insect’s attraction to vertical climbing surfaces is utilized with mechanical traps, such as sticky bands or circle traps, placed on tree trunks. These traps intercept the nymphs and adults as they climb, preventing them from moving to a new location.
Future management efforts focus on developing synthetic lures based on the attractive chemical compounds found in fermenting honeydew. These lures could enhance trap effectiveness, drawing the pests away from valuable crops and into control devices.