SciTech

Everything you need to know about spotted lanternflies

Spotted lanternflies have made their reappearance this summer in full force. After arriving in the Pittsburgh area in 2019, it seems that these bugs are only growing in numbers. But how did this species get here in the first place, and what can be done about it?

Spotted lanternflies are an invasive species in the United States originating from China. In recent years, they have spread across the eastern United States and are gradually working their way inland from the coast. Lanternflies have no natural predators here, which has led to uncontrolled population growth. They eat sap from a variety of plants and trees, but have a particular preference for the Tree-of-Heaven, another invasive species native to Asia.

To feed, lanternflies unfurl their mouthparts and ingest the sap from trees. They take in the nutrients from the plant and then excrete a sugary substance. This substance is a perfect breeding ground for mold and fungus that cover plant leaves and subsequently block photosynthesis, causing the plant to die. The environmental impact of the lanternflies' presence is already being felt, with crops such as grapes, cherries, apples, and plums under threat from the insects.

To humans, lanternflies pose no physical danger. They do not bite humans, but they are not afraid of us and will fly around or land on us with no hesitation. The insects are certainly a nuisance for every community that they infest, whether that be destroying crops or simply overtaking sidewalks, lampposts, and areas around buildings.

Currently, the most common method of lanternfly eradication is a public-driven movement to kill lanternflies on sight. State-by-state, citizens are advised to report lanternfly sightings and destroy their egg masses, which have the appearance of dried mud. However, scientists have also been experimenting with other methods of controlling the lanternfly population.

One option is pesticides, although these chemicals are harmful to other animals within the ecosystem and cannot be used to exclusively target lanternflies. Another approach is outfitting trees with bug traps to catch lanternflies climbing up the trunks. The most effective way of trapping lanternflies was found to be the circle trunk trap, a conical net fitted around a tree trunk that becomes narrower at the top, and then has a small opening connected to a bag. The bugs crawl into the net and when they try to fly away, they have nowhere to go except for inside the bag. Once trapped, they can be removed or killed.

Aside from these human-engineered methods, scientists have been investigating the potential use of a tiny parasitic wasp known as Anastatus orientalis, which is native to China and is a lanternfly predator. The wasps are so small that they cannot even be seen by the human eye, and they pose no threat to humans or plants. Scientists are considering releasing these wasps in the U.S. to prevent the lanternflies from destroying crops and infesting ecosystems. However, first they must study how the wasp would affect other insects before they can release them into a new environment.

The eastern U.S. is not the first place that lanternflies have invaded. In 2004, the species invaded South Korea. To deal with this, Korean scientists released A. orientalis, and in a few years, the lanternfly population dramatically decreased. But U.S. scientists still need to do more research to determine if the wasp is safe to release here.

So far, it has been shown that the wasp may attack some insect species native to the U.S. as well as lanternflies, so the risk of releasing the wasp into the environment may be greater than the reward of getting rid of the invasive bug. That decision, while extremely difficult to make, will regardless require more scientific research.

The safety testing, while frustrating to farmers and other communities overwhelmed with lanternflies, is necessary to ensure that we preserve our natural ecosystems and do not cause any excess harm to the insects that were here first. For now, we must simply wait for the scientists to do their work and try to kill lanternflies when we see them.