The adhesive substance on the sticky band is surprisingly thin, but even insects as large as spotted lanternfly find escape difficult. It should be noted, however, that adult spotted lanternfly have repeatedly been observed escaping the band with a strong jump; perhaps this is why the only lanternflies this band has successfully trapped are stuck legs-up.

Collateral Mortality of Spotted Lanternfly Trapping

Contributed by Luke Hearon, The John J Willaman & Martha Haas Valentine Plant Protection Intern

Our sticky banding system, replete with cage, catch, and bycatch. Note the spotted lanternflies loitering just below the band; at this time of year, a slim fraction of the spotted lanternfly on a given tree actually encounter the band.

Though introduced to Berks County, PA, in 2014, spotted lanternfly (Lycorma delicatula, SLF) have been slow to invade Morris Arboretum. It seemed that significantly more SLF were on our trees this year than any previous year, but the populations were still small compared to those seen on favored trees (such as tree-of-heaven) in the heavily infested areas of Pennsylvania. While a nuisance, the presence of SLF at the Arboretum does at least allow us to contribute to the crucial research of SLF control.

The current insecticides able to control SLF are dissatisfactory for homeowners. Organic options offer mediocre and brief control, and though synthetic pesticides such as pyrethroids and neonicotinoids are much more lethal, they are often reserved as a last resort due to ecological concerns. It is no surprise, then, that the process of sticky banding is frequently recommended to homeowners for control of SLF. In this process, a band with an adhesive surface is placed around the trunk of an infested tree, trapping SLF when they attempt to traverse the band. The affordability and simplicity of sticky banding, coupled with its appeal as a chemical-free means of control (and, of course, the strong visual feedback of a few dozen SLF stuck to the band) has made this practice a popular choice for homeowners. 

Bristletails (Order Archaeognatha) are an ancient lineage, having arisen in the Middle Devonian period, and remaining generally unchanged in appearance for hundreds of millions of years since. Each bristletail offers a glimpse into some of the earliest days of insect existence.

Unfortunately, the sticky band method is not without its drawbacks. Its control is untargeted; any creature traversing the banded tree trunk will encounter the sticky band. If the creature is not able to free itself (few arthropods can), it becomes ensnared and dies of starvation and exposure. The bycatch of large and charismatic taxa (e.g. squirrels, woodpeckers, and bats) quickly rallied outrage and criticism of the sticky banding method for control of SLF. However, these vertebrates are easily protected by the construction of a cage over top of the sticky band, allowing large animals to pass over the band while smaller creatures walk underneath the cage. We are not currently aware of any cases where a large animal has forced its way underneath a properly constructed cage.

While the candy-striped leafhopper (Graphocephala coccinea or G. teliformis) feeds on plants and can even vector bacteria leading to leaf scorch, it is not considered to be a damaging pest. Present in all of North America, their beauty often goes unnoticed due to their diminutive size.

While large vertebrate bycatch can be avoided, the catch of non-target arthropods is inevitable. A chicken wire or hardware cloth cage cannot both permit SLF entrance and prevent beneficial insects from becoming trapped. While a different trapping method that reduces bycatch may be possible, such as one using chemical attractants specific to SLF, none are currently on the market and many homeowners would likely still prefer the more cost-effective DIY method. The severity of the collateral mortality of sticky banding has so far evaded scrutiny. Before the process can be recommended as an eco-friendly procedure to control SLF, its efficacy must be weighed against its damage. Some amount of collateral damage can and must be tolerated; the question is not one of the presence or absence of bycatch, but of its scale and its kind. In brief, what are the species being caught and how many are being caught? Even still, the raw number of individuals caught is not itself a reliable metric of ecological damage. It would be foolish to give equal weight to one instance of bycatch of five monarch butterflies, another of five European honey bees, and a third of five brown marmorated stink bugs. Every species should be considered individually for its ecological value and local abundance.

Though often a painful pest around humans, Eastern Yellowjacket (Vespula maculifrons) are important predators that keep the populations of herbivores like caterpillars in check. Yellowjackets have been among the most frequently observed bycatch, likely because they are attracted to the sweet honeydew that spotted lanternfly excretes.

As the John J. Willaman & Martha Haas Valentine Plant Protection Intern, I decided to orient my research project to address this issue. Beginning mid-August sticky bands were applied for 72 hour periods, once per week on two Tetradium daniellii (bee-bee tree; Korean evodia) at the Arboretum and five Ailanthus altissima (tree-of-heaven) on property provided by the Wissahickon Valley Watershed Association in collaboration with the research project. While SLF feeds or lays eggs upon a great variety of trees over the course of its development, these two species proved good candidates as they serve as hosts for the majority of SLF’s life cycle. Banding will continue until mid-November, when Penn State Extension recommends that sticky banding ends. Each week, the bands are removed and the trapped insects are recovered and identified. Once all data collection is complete, we will examine patterns in time, location on band (top or bottom of band), tree species, and other phenomena which may prove significant. Our hope is not to condemn the use of sticky bands, but to facilitate effective, efficient, and responsible practices. Data analysis will be conducted over the winter with results expected in the spring of 2020, so keep an eye on our blog for further developments!