An exploration into Spotted Lanternfly Nymph Biophysics, Theodore Bien '22

Over the summer I worked with Spotted Lanternflies in their nymphal stages. Spotted lanternflies are generally quite slow and immobile except when jumping or dropping from a height. Thus, we wanted to know what would prompt these dropping and jumping behaviors. We suspected that these behaviors would only be used in dire situations considering that they are extremely energy inefficient. After dropping or jumping the lanternfly has to expend a significant amount of energy to climb back to its previous location. We initially thought that we would get this response when stimulating the lanternflies by approaching them with looming objects or stimulating birds trying to feed on lanternflies. Both of these methods had little success, partially because birds are not a natural predator of the Spotted Lanternfly. We then tried a couple different methods and eventually discovered two that were quite successful. The Spotted Lanternflies responded to cyclical humid breath as well as the approaches of insect models (attached to a rod). We hypothesize that this is because the Spotted Lanternfly has insect predators and that there is a natural response to cyclical humid breath because it imitates a herbivore trying to eat the plant the lanternfly is on.

While doing these experiments we also observed that these spotted lanternflies frequently land upright. After doing some more experiments, we observed that they are able to do this consistently from heights as low as 10 cm. Thus, we started to analyze their self-righting properties. To do this we dropped them from a funnel or with tweezers and recorded the lanternfly in the air with a high-speed camera. From looking at these videos we saw that the spotted lanternflies were spinning along the horizontal and vertical planes. This spinning helps to stabilize the lanternfly in the air. These lanternflies also adopt a "stereotypical" falling posture of legs spread in all directions. This increases the lanternfly's surface area, increasing its air resistance and slowing its descent. Furthermore, we saw that when they were dropping off an object, they would alter their release in such a way to ensure that they landed upright. Another important aspect of the lanternflies self-righting behavior actually occurs when they hit the ground. In a lot of cases, when the lanternfly hits the ground it lands on its body and bounces upwards. This bounce provides the lanternfly with some time and momentum to self-right to an optimal landing position. It is through a combination of these different techniques that the Spotted Lanternfly is able to self-right so consistently.