March 16, 2021
This story was originally titled “Lighting up with Lanterns: A new invasive pest insect is providing summer fishing.” It appeared in the Feb-Mar 2021 issue of Fly Fisherman.
When the reliable spring mayfly hatches are complete, and fly fishers anxiously await the fall mayflies to start their dances, we focus on insects that captivate the attention of trout in the summer months. This often means terrestrials.
In the heavily forested Mid-Atlantic and Northeast regions, cicadas and other terrestrials provide sporadic success. When periodic cicadas hatch, it can be some of the best dry-fly fishing in the world. However, cicadas are highly localized and can be hit or miss.
Where I live in Pennsylvania, 2020 was a poor year for cicadas, and the fish had low interest. In those kinds of years, East Coast fly fishers turn envious eyes toward our Western counterparts, who seem to enjoy endless and dependable terrestrial fishing with hoppers, beetles, and ants.
But those Eastern terrestrial dry spells may be a thing of the past, as a new invasive pest insect has been lighting up East Coast states, and the trout have quickly developed an appetite for them.
Long before we heard of coronavirus, the spotted lanternfly (Lycorma delicatula) was causing quarantines of its own. These insects were first detected in Berks County in Pennsylvania in 2014, and shortly afterward more than a dozen counties were quarantined to try to control its spread, but the pests soon spread to New Jersey, New York, Maryland, Connecticut, Delaware, and Virginia. It is now prolific in the Delaware Valley, and the Susquehanna and Potomac watersheds.
The spotted lanternfly is a planthopper native to China, Vietnam, Bangladesh, and Taiwan. In China it is closely associated with the host plant Ailanthus altissima or the tree of heaven. This noxious invasive plant species came to Philadelphia in 1784. By 1840 the Chinese plant was widely available in nurseries, and was planted in decorative gardens and along city streets and railways. It came to California in the 1890s during the Gold Rush and is widely distributed across the U.S. More recently, Ailanthus altissima was used to revegetate areas where acid mine drainage has occurred, because it’s almost impossible to kill and can tolerate pH levels as low as 4.1. Gardeners and conservationists today sometimes call this plant “the tree of hell.” Its suckering ability makes it almost impossible to eradicate.
In China, it was believed that spotted lanternflies needed this host plant to propagate, but in the U.S., lanternflies have adapted to other plant species and now use at least 70 species of native plants in the United States as hosts. They love grapevines, fruit trees, hops, soybeans, and many hardwood trees such as black walnuts and maples.
A recent The New York Times headline read “Lanternflies Eat Everything in Sight. The U.S. Is Looking Delicious.” They are worrisome and prolific insects. In some forested river valleys in 2020, their numbers were akin to a locust plague of Biblical proportions.
Although adult lanternflies sport two large beautiful wings, they are clumsy fliers, and therefore resort to jumping and hopping along the ground, from plant to plant, and from tree to tree using their wings to assist, much like grasshoppers.
Promotional campaigns in recent years encouraged East Coasters to stomp on lanternflies, but if you take this advice too seriously you’d be out there all day stomping them.
It’s not hard to see how they end up in rivers, and trout, bass, and sunfish have quickly learned to take advantage of this new food source. The large adult flies have black heads, and gray-brown forewings sporting large black spots.
They don’t actually produce light. Their name comes from two bright crimson hindwings that lie underneath the forewings, producing a lantern-like appearance. If the bug itself was rare, it might be cherished for its ornamentation, but because of its ferocious ability to reproduce it is more of a curse than a wonder.
Lanternflies have a life cycle that might sound familiar to fly fishers. They begin as a barely visible egg mass that typically resembles a pale gray lichen. These egg clumps are nearly impossible to spot. Eggs pose the greatest risk of spread, as egg masses have been found on surfaces such as stone, firewood, and even trucks, boats, and RVs. In 2014, several items were banned for transport from certain locations including lawn mowers, firewood, and outdoor furniture.
After overwintering, eggs begin to hatch in late April to early May. Much like aquatic insects, lanternflies proceed through four immature nymph stages called instars. All these stages are wingless, but the bugs are capable of hopping about. The first, second, and third instars, occurring from May through July, produce a black and white spotted bug that gets progressively bigger in each stage.
In the fourth instar, the lanternfly gets some color. It acquires a red body with both white and black spots.
The winged adults begin to appear around July and quickly start their mating rituals. In 2020, huge numbers of adults were hopping around and clinging to trees past mid-October.
Why are lanternflies so bad? To put it figuratively, they suck the life out of every plant they land on, and too many of these little suckers can kill the host. They leave behind a clear, sticky, sugary waste—referred to as honeydew—that fosters the growth of a black fungus called sooty mold. Most people find this residue a simple annoyance on their property as it discolors siding, patio furniture, and more. But it can be a death sentence for the plants because it can block photosynthesis.
It seems that we’ve learned nothing from the Japanese beetle, emerald ash borer, and other invasive pests, or else maybe we’re incapable of stopping the spread of these pests in a global economy. I was truly astounded when a buddy of mine sent me a photo of a lanternfly trap he put on some of the trees outside his home in 2019. In a few hours he captured hundreds of lanternflies on a single tree. Without mitigation, lanternflies may reach farther into the United States, leaving a wake of agricultural destruction, and trout with full bellies.
It is striking how quickly fish can zero in on a new prey. Fly fishers have seen phenomena like this before with booming spruce moth populations in the Rockies, and Japanese beetles in the East. Lanternflies, however, are much larger food items, and in some watersheds they are much more prevalent. From a continental perspective, they are just getting started here in the U.S.
As soon as I saw these bugs emerging on the trees near my local stream, my first thought was to put on the biggest topwater fly I had in my box. It happened to be a cicada. Upon splashing down into the water, it was met with an explosion that I wasn’t ready for. I’ve since caught panfish, bass, many trout, and even a small pike using patterns that specifically imitate lanternflies.
In some lakes and ponds, I’ll admit that I’ve done some “scientific research” by throwing fistfuls of lanternflies into the water to see how they react. Sometimes it’s like feeding time at the zoo. Please don’t do this in rivers or streams, as you may contribute to the spread of lanternflies.
In terms of flies, matching the hatch isn’t all that important. Spotted lanternflies are large, a little more than an inch long in the winged adult phase, and slightly smaller in each previous instar phase. Many fly tiers in the Tri-State area (New Jersey, New York, and Pennsylvania) have realized these insects form a substantial food source and have started tying replicas.
My good friend Rob Gentry came up with a simple version using a large black foam body for the base. Great argus spotted back feathers replicate the forewings, and he follows this with a macaw feather for the red lantern underwings. Another local tier, Jayson Mumma, starts with JS Realistic Nymph Legs and a large foam body. For the underwing he uses red hen saddle hackle, followed by some rooster neck feathers. Both are highly effective and simple to tie.
The best part about fishing with lanternfly imitations is that the real insects are inept fliers, and they have substantial mass, just like stoneflies. Windy days are the best time to fish them when they are blown from the trees and cannonball into the water with a splash. What this means for presentation is that it may or may not matter. When I fish big flies like this, I normally try to make them splash down as loudly as possible. But in some waters—particularly in low water late in the year—this can spook off potential prospects. My advice is to start subtle with a natural drift, add some twitching, and then ramp up the chaotic splash casting before moving on to the next spot.
Since these flies are so meaty, I tend to use a setup similar to my go-to steelhead and bass rigs. A 9-foot, 7-weight rod with a fast action will do just fine. Pair this with a line weighted to throw large flies such as Scientific Anglers Amplitude Anadro series or Cortland Streamer series. These lines are built with aggressive short tapers to deliver large flies with ease. You are not finesse fishing here, so you want to use a heavy 9-foot leader tapered down to about 1X or 2X tippet.
A Positive Spin
If we try to look on the bright side of the spotted lanternfly appearance on the East Coast, it would have to be the fact that they don’t bite us, suck our blood, or give us diseases—an unusual change of pace considering how the rest of 2020 went. And on top of that, they make for great fishing during the summer and early fall, when the most important aquatic insect hatches have faded. Unfortunately, it appears that spotted lanternflies are here to stay, and they may soon be appearing on other rivers in other states. If you do happen to see a spotted lanternfly in an area where they have been previously unreported, squish it, report it to the local authorities, and begin tying large flies immediately.
Bobby Norgard is a student in the Cell and Molecular Biology Graduate Group at University of Pennsylvania, Philadelphia.