The Spotted Lanternfly is a relative newcomer to North America. It is native to Southeast Asia and when there it is an unassuming and stable part of the local ecosystem. However, in North America, it has the potential for being a significant pest species. It mostly prefers to host on Tree-of-Heaven which is itself a significant invasive species problem. However, the Spotted Lanternfly will happily expand to other species.
While it has at times been described as a crude biological control for the Tree-of-Heaven, issues begin when the Laternfly expands to other hosts. It seems to hold a particular fondness for grapevine and becomes a danger to both wild grapes and vineyards. It also enjoys hosting on members of Rosaceae. This family includes the invasive Multiflora Rose, but it also includes popular orchard trees such as apples, pears, plums, and cherries. This has both the issue of having important agricultural fields being targets, but also important native species such as the Black Cherry which is highly valued for its beauty, wildlife support, and lumber quality.
So, this small and seemingly unassuming insect is a potential major threat to a wide range of desirable plants. Interestingly, it does not cause damage by directly feeding on the plants. The small sips of sap that it takes are hardly enough to do anything and native cicadas have the potential to do far more damage. Instead, the diet of the Spotted Lanternfly is so rich in sugar that its waste is similarly sugar-rich. Black sooty mold will grow underneath Lanternfly colonies when they grow in large enough numbers. This mold will, in turn, grow thick enough to damage the plants it is growing on.
As an invasive species, they were introduced to the United States in Eastern Pennsylvania. Likely through some eggs stuck to a piece of lumber or some other cargo. They were first confirmed in 2014 but had likely been present for a few years before that point. Currently, most of their American population has been radiating outwards from the greater Philidelphia area, but a few scattered pockets have cropped up elsewhere. In all likelihood, a few individuals hitched a ride on a truck causing new isolated pockets of infestation.
Despite its name, the Spotted Lanternfly is not a True Fly. Instead, it is a member of Hemiptera, the True Bugs. One of the traits that can clearly be seen to distinguish the difference is the Spotted Lanternfly has two pairs of wings while True Flies only have one. Their hind pair of wings has instead evolved into a completely different structure.
The hind pair of wings is a characteristic bright red with black spots. The tips of the wings transition to solid black. Sometimes, a band of white can be seen marking the border between these two sections.
While this bright red hind wing can be seen in flight, typically the Spotted Lanternfly will have its wings folded when at rest. This leaves only the forewings visible. These wings are more of a drab gray with a hint of pink to them. However, just like the hind wings, they are covered in black spots and the tips of the wings transition to a more solid black. If you look closely, you may see the gray-pink color following the veins of the wing all the way to the tip.
Like most members of Hemiptera, the Spotted Lanternfly undergoes an incomplete metamorphosis rather than the complete metamorphosis made famous by butterflies. It does not have a pupa stage but instead grows as a small nymph that vaguely resembles the adult form. This nymph has no wings and is much smaller than the adult. It has a distinct black coloring with white spots. They can be surprisingly fast.
Near the end of their nymph stage, they grow to near the size of the adults and develop a red coloring in addition to their black and white pattern. This stage, sometimes called “late instar” is the closest the Spotted Lanternfly has to a pupa form. While in this stage, they are still quite nimble.
Typically, they emerge from their eggs in late spring, spend most of the summer as nymphs, and then become adults in the late summer. The adults can be seen through the fall as they breed and lay their eggs. The egg masses will wait over winter until they are ready to hatch in the spring. One generation takes exactly one year.
Unfortunately, I have not managed to personally get any decent photos of the egg masses. They are well camouflaged and often resemble a bit of lichen stuck to a tree’s bark. However, other photographers have managed to capture them such as here and here.
Efforts to control their spread are ongoing but have limited effect. A single gravid female can lay hundreds of eggs meaning that missing only one or two of them can quickly turn into a new infestation hot spot. It is thought that eventually, they will spread throughout the Eastern United States, but efforts to slow their spread will give other areas more time to prepare methods of dealing with them.
If you see any, please report their presence to your local Department of Agriculture or a similar organization. Authorities are very concerned about monitoring the spread and more data points are always helpful. Sightings in Pennsylvania can be reported here and sightings in Maryland (where I live) can be reported here. Other states have their own reporting systems, though I have not personally used them.
In addition to reporting, if you manage to catch them (they can be fast) please kill them. While it won’t stop the spread completely when dealing with invasive species every bit helps. Authorities can only do so much personally and it is up to action from the average person to make a real difference.