by Sally Colby
When the spotted lanternfly first made its appearance in a Berks County, Pennsylvania township in 2014, the Pennsylvania Department of Agriculture (PDA) immediately developed a strategy to manage it. Unfortunately, several years later, the invasive pest has spread and despite drastic measures, continues to spread.
Sven-Eric Spichiger, entomology program manager for the PDA, addressed concerned growers at the Mid-Atlantic Fruit and Vegetable Convention held recently in Hershey, PA.
“On September 22, 2014, we received a report form an off-duty game commission educator about damage to his tree-of-heaven and the presence of an insect he didn’t recognize,” said Spichiger, explaining the first report of the insect in the U.S. “By the end of the day, we had collected several specimen and identified them as Lycorma delicatula, or spotted lanternfly.”
In response, the PDA established an immediate quarantine. This past fall, the quarantine was extended to 13 southeastern counties. “The quarantine prevents the movement of the pest in all its life stages,” said Spichiger. “There are a lot of things it may be transported on.”
The spotted lanternfly is a planthopper, one of 700 in the world and 17 in North America. This one is native to Asia – China, Bangladesh and Viet Nam and later introduced to Japan, South Korea and now Pennsylvania. Spichiger says that a single dead specimen has been found in New York and there have been several separate interceptions in New Jersey that he says are still unofficial. A dead specimen was also found in Delaware; and Virginia has officially announced that they have an active population in at least one location.
“This is going to continue to spread,” said Spichiger. “It’s a highly prolific pest. It has spread outside Berks County to Cumberland County, and also to the Philadelphia area.
For perspective on the invasive nature of this pest, Spichiger says the spotted lanternfly was first detected in South Korea, which is only slightly smaller than Pennsylvania, in 2006. By 2009, it had spread throughout the entire country. South Korea attempted no regulatory action and only cut some trees down. Some limited control measures for grapes were developed, but no further action was taken.
“In South Korea, this was immediately considered to be a pest of grapes and peaches,” said Spichiger. “In Pennsylvania, we knew right away we’d have to do something about grapes.
The spotted lanternfly has been found on more than 70 different species. Its primary host in North America is the tree-of-heaven (Ailanthus altissima). Spichiger suggests that those unfamiliar with this species learn to recognize it in order to reduce this particular host. Not only is it a weed tree and very hard to kill, it’s also the main harbor for this pest. This tree grows nearly everywhere in North America, and there is some yet unknown relationship between the tree and the insect, so there’s potential for the spotted lanternfly to spread further than it already has.
Researchers are learning about its biology and found that it has one generation per year in Pennsylvania. “If this ends up in Florida or southern California, we aren’t sure what will happen,” said Spichiger. “What we know is that if egg masses are brought indoors and not refrigerated, they hatch out. What that tells us is that we could have population that keeps going and going once it gets to a more favorable climate – which is what they’ve experienced in southern China.”
Males and females are very active maters. They mate multiple times, and females are capable of laying multiple egg masses. One female can produce several hundred new spotted lanternflies the next season.
Egg masses are laid in October and remain on trees and anything else the insect selected. Throughout May, eggs begin to hatch, followed by four immature nymph stages, or instars. “The first three instars are black with white spots, and resemble ticks,” Spichiger explained, adding that these instars are active hoppers. “The last instar, which starts to appear around the end of June and into July, starts to develop furry red patches. Adults emerge starting in late July and will be present throughout the first couple of hard frosts.” In 2014, adults were found until Dec. 10. This past year, two consecutive 19-degree nights in early October killed them.
Eggs are laid in rows of 30 to 50 eggs per bunch and are covered with a waxy substance that dries to look like mud. “Unfortunately, the insect lays egg masses everywhere,” said Spichiger. “Think gypsy moths. If you have a surface of any kind outside, a spotted lanternfly could lay eggs on it. They prefer rusty metal, barn planks, dead trees. Even though you can search for egg masses, they’re well-hidden and difficult to find all of them in a given area.”
The egg masses can be killed easily with appropriately labeled products. Egg masses can also be removed mechanically, but that might be an exercise in futility since masses are likely to be missed. But even though killing egg masses mechanically (by scraping) might seem pointless, Spichiger says every egg mass that’s killed eliminates 30 to 50 of the next generation. Spichiger noted that gypsy moth survey protocols used for spotted lanternfly detection were only about 50 percent accurate. “Gauging a population by counting egg masses in a wild setting isn’t really possible,” he said. “It may be possible in an orchard or a vineyard.”
The immature lanternflies crawl up the tree every day, then drop off. “It’s a strange life strategy but you can use it against them,” said Spichiger. “You can use brown sticky bands (on trees). It’s the closest thing to an environmentally friendly control method. But organic growers are going to be hurting if they get this insect.”
Every life stage is an active hitchhiker, which means personal biosecurity of equipment and product is important. “Avoid parking under tree lines,” said Spichiger. “Avoid keeping windows open even if it’s hot. The adults are the real risk but egg masses are laid on everything. Think about hunting – tree stands, ATVs, camping, RVs parked under a treeline until they’re needed for summer travel. Make sure you walk around it, look for life stages and remove them before you leave the area.”
This insect inflicts severe damage to grapes and hops. Like other treehoppers, the spotted lanternfly doesn’t feed on fruits and doesn’t chew on leaves. It has a long, piercing- sucking mouthpart that goes straight into a vine, stem or trunk of a tree and removes the phloem. “The phloem is too much for them to handle, so they eject a waste product called honeydew,” Spichiger explained. “This coats everything around where they’re feeding.” On grape leaves, the result is likely to be sooty mold in a very short time. Although rain washes the honeydew away, that isn’t a reliable control.
Insect feeding ultimately leads to dieback decline. “These insects are literally removing sugar from the grape plant,” said Spichiger. “We got a report of them feeding on hops at the end of 2016. By the end of 2017, the hops extension entomologist from Ohio took a look at one of the crops we visited and said ‘this is unmarketable’. Hops will be severely affected by this insect. The real damage is from the honeydew that is all over everything.”
There’s potential that the insect may cause severe damage to the hardwood industry. Spichiger says that in 2017, hardwood stands in Pennsylvania were affected by the fourth instar doing heavy feeding, which resulted in dieback and decline.
Prior to September of 2017, there were no reports of the insect in apple orchards, but it has now been detected on apples. “Are they swarming, is it dispersal or laying eggs? We don’t know yet because it’s too soon.” Spichiger believes that they were feeding, which leaves the trees open to pathogens and potentially affects future growth.
U.S. Secretary of Agriculture Sonny Perdue recently announced $17.5 million in emergency funding to stop the spread of the spotted lanternfly, and Pennsylvania is continuing efforts to contain the insect.
For color photos to help identify the spotted lanternfly and a reporting hotline, visit https://tinyurl.com/y8enjm7a .
Spotted lanternfly spreads its wings
by Sally Colby