Timely Viticulture Timeline: Mid Season, Pre-Harvest, and Harvest
Updated: August 23, 2023
By Dr. Joseph Fiola , and Dr. Kelly Hamby

Spotted Lanternfly (SLF) I—Background

The Spotted Lanternfly (SLF) is now confirmed in most counties in Maryland, and populations in northern and Eastern Shore Maryland (and moving south) and populations in Pennsylvania, New Jersey, Delaware, and Virginia continue to expand. The pest had initially severely impacted vineyards in Pennsylvania; however, growers are now confident that the insect can be managed and significant damage avoided. 

What is clear at this junction is that (1) grapevines are a favorite host of this pest, and (2) heavy feeding damage coupled with winter cold stress can cause vine death. At ground zero in Pennsylvania, feeding on this pest, combined with the moderately cold winters of 2017/18 and 2018/19, has done significant damage to multiple commercial vineyards.

This Timely Viticulture was created to give growers some background on the SLF. The subsequent TimelyVit Spotted Lanternfly (SLF) II - Scouting and Management will address management options. This is a “newly introduced” pest, and we are rapidly learning its biology and habits. Beware, it has the potential to be a very significant challenge in vineyards. However, it can easily be controlled with proper management strategies.

Background and Hosts

  • The Spotted Lanternfly, Lycorma delicatula, is an invasive planthopper that was introduced from Asia.
  • It was first discovered in Berks County, PA, in 2014, and despite major quarantine efforts, it has spread rapidly to the surrounding counties, as well as New Jersey, Delaware, and Virginia.
  • This pest is native to China, India, Japan, and Vietnam. It was introduced into Korea where it has been recorded to be a pest on 65 different plant species (25 of these are known in Pennsylvania).
  • SLF has a very wide host range and attacks many fruit crops including grapes, apples, and stone fruits; it has the potential for great impact on these crops, as well as ornamentals and hedgerow plants.
  • The Tree of Heaven (TOH—an invasive tree), Ailanthus altissima, is preferred by adults, but the host range is significant.
  • Eggs have been found on vehicles and other objects, so it is very easy for this pest to be moved to another area (a “hitchhiker”).


  • Newly laid egg masses are about 1” long with a grey “mud-like” covering over the eggs which, cracks over time (figure A).
  • Older egg masses appear as 4-7 columns of 30-50 brownish seed-like deposits on the trunk, in a mass that is roughly 1” long (figure F).
  • Eggs are commonly laid on the Tree of Heaven but can be laid on inanimate objects such as rocks, vehicles, etc.
  • Young immature stages (1-3 instars) are smaller than a dime and black with white spots (figure B)
  • The last immature stage (4th instar) develops bright red patches and is over 1/2” long (figure C).
  • The adult SLF is approximately 1.5" long and 1/2" wide and has four wings which fold across their back while resting (figure D).
    • The forewings are grey with black spots; the wingtips are outlined in grey (figure E).
    • The hind wings have contrasting patches of red and black separated by a white band (figure E).
    • The legs and head are black; the abdomen is yellow with broad black bands (figure E).
Spotted Lanternfly Life Cycle

Life cycle

  • Adult females lay eggs in the fall; they cover their newly laid egg masses with a grey pitch-like substance (figure A) that protects them.
  • Eggs are commonly laid on the Tree of Heaven but can be laid on grapevines, other hosts, and objects such as rock, furniture, vehicles, etc.
  • SLF overwinters as eggs; adults are not known to overwinter.
  • After hatching in late April or early May, the nymphs will move off the Tree of Heaven and search for other hosts in the spring.
  • Life stages include eggs, 4 instar nymphal stages (do not fly), and adults.
    • Early nymphal stages move to the vineyard in late spring; later stages have been noted in vineyards in mid-summer.
    • All stages have been noted in vineyards at the same time.
  • Adults typically appear in late July through October are mobile (can fly), and can be active through early winter.
  • Currently only 1 generation per season has been documented in the region.

SLF as a vineyard pest

  • All nymphal stages can feed and therefore cause damage to grapes and susceptible crops.
  • SLF are vascular feeders (phloem, xylem). Nymphs primarily feed on growing shoots, while adults can feed on trunks, cordons, and canes.
  • SLF do not typically feed on the foliage or the fruit; they may be found on/in the clusters seeking warmth.
  • At night they migrate to ground level and then crawl back up the next morning.
  • Early in the fall, the adults will congregate mainly on trunks and cordons, following the maximum sap flow. (figure G)
  • Honeydew secreted by the insects can stick to leaves and fruit and can lead to patches of sooty mold, which can cause secondary problems and reduce fruit quality (figure H).
  • Feeding damage and mold will attract ants, yellow jackets, and hornets (so caution is advised).
  • It is not known whether the presence of insects in the must can taint the wine.
  • As was stated previously, feeding from this pest, combined with cold winter temperatures, can cause major damage or death to grapevines.



  • Penn State University Faculty: Heather Leach, Michela Centinari, Julie Urban, Erica Smyers, Emelie Swackhamer, Dave Biddinger, Greg Krawchek, Michael Saunders.

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