The Spotted Lanternfly Expands Its Range

There’s an odd grayish mud patch on the car. That may not be a mud patch at all, but an egg mass from the spotted lanternfly (Lycorma delicatula), which is a pest native to Asia, but discovered in Pennsylvania in 2014. I did an article on the spotted lanternfly previously. However, they have since expanded their range and new information has also surfaced, so it seemed worth revisiting. (For the previous article, click on January 2019 in the archives sidebar).

They are native to China and South Asia and it is believed they were introduced into the U.S. in a stone shipment around 2012. They feed on sap from over 70 different species, including apple, plum, cherry, peach, nectarine, apricot, almond, grape, maple, oak, pine, walnut, poplar, willow, and sycamore. Removing the sap reduces photosynthesis, which weakens the tree. The adults also excrete honeydew which allows for the growth of a sooty mold, which can further reduce photosynthesis and attracts ants, flies, and wasps. They are confirmed in Pennsylvania, Connecticut, Delaware, Maryland New Jersey, New York, Virginia, W. Virginia, and Ohio. Signs of infestation include weeping wounds and trails of sap.

Ginger Nickerson, the Forest Pest Education Coordinator for the University of Vermont Extension, said there was more damage from stress than direct killing, though she said the spotted lanternfly has been known to kill the tree of heaven (Ailanthus altissima), which is also an invasive, walnut seedlings, and grape vines. She said the main concern was with agricultural plants and noted it was difficult to export products that were in a quarantined area. Emelie Swackhamer, the Horticulture Extension Educator for Penn State Extension, concurred and said that researchers have not seen the spotted lanternfly kill any trees, other than those previously mentioned, but she did say that heavy feeding reduces photosynthetic capabilities as well as carbohydrate storage. Swackhamer also said the long term effects were still being studied. It was previously thought the spotted lanternfly could not survive colder temperatures and this could limit their ability to spread. However, Swackhamer said one study showed the eggs could survive one month of 7 degrees Fahrenheit and it was “not likely” winter temperatures would kill the spotted lanternfly where they were already established. She said scientists “expected” there would be a northern limit as to where they could survive, but it was not clear what that was yet. The previous article also referenced a parasitic wasp that was being studied as potential biocontrol. Swackhamer said the USDA and associates were continuing these studies, but there were no results available yet.

A large number of invasive pests (emerald ash borer, Dutch elm disease, chestnut blight) target primarily one or two species and, in fact, their host plants are often contained in their common names. As was previously mentioned, the spotted lanternfly preys on over 70 different types of trees and plants. Swackhamer said it was unusual in that it does have so many hosts, but she did note that it does have its preferences. She said its wider range could make it more of nuisance in residential areas, but she also referenced the emerald ash borer, which has far fewer hosts but has killed millions of ash trees and she stated that in eastern PA there are countless dead ash trees that pose a hazard, due to the the possibility of them falling on power lines and buildings. Nickerson, however, said it was not “particularly unusual” and there were other invasive insects that had a wide host range.

The spotted lanternfly is a strong hitchhiker and will lay eggs on any smooth surface. As was mentioned in the introduction new egg masses (September-June) have grayish mud like covering, while old egg masses contain rows of 30-50 brownish seed like deposits in 4-7 columns. Adults (July-December) are approximately one inch long with a gray forewing that is speckled black at the base. The hindwing is bright red with a white stripe and a black tip. Young nymphs (April-July) are black with white spots. Nickerson and Swackhamer both said the insects should be killed if found and items should be inspected for adults or egg masses, especially if people are travelling to or from an area with a known infestation. In addition, any sightings, particularly in an area with previously unknown infestation, should be reported and Nickerson recommended or the Agency of Agriculture. In addition to automobiles, firewood is another way the spotted lanternfly and many other invasive insects travel. Nickerson said people should buy firewood that has been heat treated as well as purchasing wood as close to where it will be burned as possible. She gave the example of someone travelling 50 miles to a campsite and said wood should be bought near the campsite, rather than near where people live.

In this age of the global economy, plants and animals can travel easily. When a new species enters an area, it has few or no natural predators to keep it in check and it can spread easily. Once a species has been introduced, it is almost impossible to eradicate. The end result is that it can pose a serious threat to native species as well as costing millions of dollars in damage. Thus, it is becoming increasing necessary that people always know what they are carrying with them. However, with extra vigilance, it may be possible to keep the spotted lanternfly and other invasive pests to a more confined area.