The Spotted Laternfly
Oh, my! Will we gardeners ever get a break? Over the past decades we have been at war with new pests that have found their way into the country and into our gardens. A few of the recent foreign invasive pests include: the tree-eating gypsy moths, the malodorous brown marmorated stink bug, the tree-killing emerald ash borer, and now the latest stowaway to bug gardeners is the potentially devastating spotted lanternfly (Lycoma delicatula).
This undeniably colorful four-winged insect is native to China, India, and Vietnam, and was introduced into South Korea in 2006; by 2009, it was found throughout the southern Korean Peninsula where it had become a major pest on grape and peach crops. How the spotted lanternfly arrived in the US is not clear, but like many recent invaders, this one is an excellent stowaway, and egg masses likely arrived on a shipments of goods from Asia. The spotted lanternfly was first detected in Berks County, Pennsylvania, in September 2014. Despite local quarantine efforts to limit the movement of materials, the lanternfly range has expanded to include 13 counties in southeastern Pennsylvania, and into the neighboring states of New Jersey, New York, and Delaware. It was identified near Winchester, Virginia, on January 10, 2018.
The spotted lanternfly is not a fly but an invasive planthopper. It belongs to a group of insects known as fulgorids, part of a large family of insects called the Hemiptera, a clan that includes other sap-feeding pests, including aphids, soft scales, mealybugs, and whiteflies. Like the aforementioned rogues, lanternflies pierce plants with soda-straw-like mouthparts, tap into vascular tissue (phloem), and remove sap. Both adults and the youngsters, called nymphs, remove large quantities of sap from the tree as they feed. Their excess intake is excreted from their rear end as a sugary waste product called honeydew.
Adult lanternflies can fly, but it may be their least mobile stage. It is their egg masses that have the greatest potential for long distance travel. Spotted lanternfly eggs are inconspicuous, and females will lay their eggs on virtually any surface — trees, firewood, lumber, yard furniture, and vehicles. Combine that with the fact that their preferred host, ailanthus (tree of heaven) is an invasive itself that tends to grow in disturbed areas around parking lots, along highways and railroad tracks.
It doesn’t require a huge imagination to envision a railroad car, stopped along an ailanthus-lined railroad track or a semi parked next to an ailanthus tree at a rest stop or an out-of-town vehicle next to an a tree at a football stadium. A gravid female lanternfly drops down, deposits her eggs and soon the eggs are driven away to the next county or across the country.
Why the Concern
While the spotted lanternfly (SLF) prefers the Tree of Heaven, Ailanthus altissima, for part of their life cycle, the insect feeds on a wide range of plants (more than 70 species) — including grapes, peaches, plums, apples, hops, dogwood, maples, sycamore, black gum, oak, sassafras, tulip poplar, serviceberry, walnut and pines, just to name a few found in our area.
The SLF can cause extensive crop and tree damage. Limp tree branches have been observed shortly after an infestation. In infested areas, the adult SLF gather in masses, covering tree trunks, patios, and the sides of houses. While they don’t bite, the SLF are attracted to and land on people, moving among them, making themselves a nuisance to be around.
As the SLF sucks the phloem from trees and shrubs, it excretes large amounts of honeydew, a sticky sweet substance which attracts, wasps, ants, bees, and other insects drawn to the sweet substance. When walking under an infested tree canopy, the honeydew falls like rain.
To make maters worse, the honeydew is host to sooty mold, which colonizes on surfaces, where the honeydew has been excreted. These surfaces turn black as the mold colonies grow, rendering fruit such as grapes, apples, and peaches useless — not to mention the added ambiance this black gunk adds to a patio or deck below a tree infested with SLF.
The SLF is also prolific. In cold climates, the SLF has one life cycle per year, but can mate and lay egg masses several times, laying 30 to 50 eggs each time. The egg masses will be attached to any hard surface. Egg masses have been found on the bark of many tree species, and on rocks, motor vehicles, outdoor furniture, the sides of houses and more. In warmer climates south of the Mason- Dixon Line, the milder winters could give the bug year-round reproduction capability and reduce winter kill.
As is the case with most invasive pests, the SLF does not have an enemy in this country to help control its population. The brilliant colors–– red, black, and white — of the spotted lanternfly reveal one of the reasons why it is difficult to control by using natural enemies. Its hues are warning colors that alert predators to the fact that the lanternfly is toxic due to poisons called cytotoxic alkaloids, which it metabolizes from some of its host plants. While the coloration of the forewings helps camouflage the lanternfly against a tree trunk, the sudden flash of its vivid hind wings, when opened, startles predators and scares them away. Some birds have been seen vomiting after ingesting the insect. Although it is also toxic to humans, the lanternfly has been used in low quantities by practitioners of traditional Chinese medicine to treat consumption and swelling.
The soft-bodied spotted lanternfly (SLF) adult looks similar to a moth or butterfly. It is approximately 1” long and ½” wide at rest. The forewing is grey with black spots and the wing tips are reticulated black blocks outlined in grey. The hind wings have contrasting patches of red and black with a white band. The legs and head are black; the abdomen is yellow with broad black bands. Despite the large wings, the insect does not fly very well, but jumps from plant to plant or tree to tree.
Eggs hatch in spring and early summer and then undergo four nymphal instars. Immature stages are black with white spots, but the nymphs turn red just before becoming adults in July. Adults begin laying eggs in September and continue through November until the onset of winter.
Newly-laid egg masses have a grey mud-like covering which can take on a dry, cracked appearance over time. Old egg masses appear as rows of 30-50 brownish seed-like deposits in 4 to 7 columns on the trunk, roughly an inch long.
The Spotted Lanternfly Life Cycle in Virginia:
Source: “Spotted Lanternfly Life Cycle in Virginia” , VCE Publication-268 NP
Signs & Symptoms
As mentioned above, nymph and adult SLF typically gather in large numbers on host plants. They are easier to spot at dusk or night as they migrate up and down the trunk of the plant. Trees will develop weeping wounds that leave a greyish or black trail along the trunk. This sap will attract other insects to feed, notably wasps and ants. In late fall, you will be able to spot egg masses on host trees and nearby smooth surfaces like stone, outdoor furniture, vehicles, lawn mowers, and structures.
What needs to be done now
If you see a spotted lanternfly, please report it immediately to the local extension office or local agriculture department. Even a suspected sighting should be reported. Collect a specimen, if possible, and place it in a vial filled with alcohol, note the location, and drop it off at your local Virginia Cooperative Extension Office.
- Take a photograph of any spotted lanternfly at any life stage and submit to: https://ask.extension.org/groups/1981/ask
- Businesses should contact the Virginia Department of Agriculture and Consumer Services (VDACS) at 804-786-3515. Their business hours are Monday to Friday, 8 am to 5 pm.
- If traveling within Virginia and you observe the SLF at a rest stop for instance, you should contact VDACS. Please leave a message if after hours or on the weekend.
Current Control Measures
- Control Mechanically – Swatting or crushing is possible, however they are able to quickly jump away so this is not easy to achieve. You are most likely to see the adults feeding in late summer and fall.
- Search and Destroy the Invasive Tree of Heaven (Ailanthus altissima) – It is believed that the SLF must feed on these trees at some point in their lifecycle. A good time to cut down these trees is during National Invasive Species Awareness Week, February 26 to March 2, 2018. Brush should be chipped or burned on site and not moved to another location if the SLF has been identified. Treat the stumps with an herbicide to prevent from growing back.
- Scrape Egg Masses – Egg masses are live and viable from about October through July. One can scrape them off of trees or smooth surfaces, double-bag them, and throw them in the garbage, or place the eggs in alcohol or hand sanitizer to destroy.
- Install Band Barrier Tree Wraps – Tree banding involves a sticky band that traps the insects.
- Use Insecticidal Soap – This is only effective in areas with low populations and has varying efficacy. To be effective, it should be applied regularly.
- Investigate Pesticide Options – There is limited information on pesticides because it is a new pest to this area. However, Penn State Extension researchers are conducting testing. Contact you local extension office or local certified pesticide company with a commercial license for more information.
The spotted lanternfly’s ability to overwinter, along with a wide range of host plants and lack of natural native enemies will in all probability result in a rapid population growth and spread of this destructive, invasive pest.
Thanks for stopping by The Garden Shed. We look forward to your visit next month.
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