Spotted lanternfly nymphs use multiple righting behaviors during landing

Abstract Many small animals use aerial righting to mitigate the risks associated with falling, such as predation, starvation, and desiccation. Spotted lanternflies (Lycorma delicatula) (SLFs) are invasive insect pests that often fall from host plants in response to predators or abiotic factors (e.g., wind). We used high-speed video to study whether immature SLFs (nymphs) impact surfaces, and subsequently land upright, more often than expected by chance, and, if so, whether they do so via active or passive mechanisms. SLF nymphs were found to adopt a stereotypical falling posture proposed to promote passive righting, and similar to those assumed by falling insects, spiders, geckos, frogs and skydivers. Live SLF nymphs landed upright in more trials when releasing voluntarily (100%) or when dropped from tweezers (56%) than did dead specimens (33-35%), with differences being highly statistically significant, even when the dead specimens were posed in the falling posture. These results support a role for active aerial righting. The fraction landing upright also did not depend significantly either on orientation during release or at first impact. We found that significantly more live SLFs reoriented to upright after impacting in a non-upright orientation via bouncing in combination with adhering to the substrate with one or more feet. Videos of nymphs landing on leaves confirmed that these insects can use similar tactics to land upright on host plants. These findings indicate the important role post-impact righting plays in determining final orientation, and highlight the importance of studies that include ecologically-relevant substrates and naturalistic conditions. Summary statement High-speed video revealed the unexpected complexity of landing behaviors used by highly-invasive spotted lanternfly nymphs, providing new insights into a key step in understanding their dispersal and control.