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Flight mechanics of the smallest insects
Microinsects with body sizes below 2 millimetres evolved from larger ancestors through natural selection to occupy specialized ecological niches. During miniaturization, many retained their major organs and functions, including the ability to fly. Moreover, microinsects from different orders convergently evolved morphological adaptations to the physical constraints that matter at such small scales.
In this talk, I will focus on flight and examine the insect flight apparatus from an engineering perspective, considering the mechanical factors that determine performance as well as the objectives and constraints that shape possible optimal designs. In particular, microinsect wings are notable because they operate near the lower limit of inertial scaling for aerodynamic forces. The Reynolds number, which measures the ratio of inertial to viscous forces in the airflow, is approximately 10. At this Reynolds number (which can be termed as intermediate) neither inertial nor viscous effects dominate.
I will show how microinsect geometrical and kinematic parameters are finely tuned to the flow regime set by their size. The first part of the talk will give a brief overview of current microinsect flight research. The second part will contain illustrative examples from our recent work on the beetle Paratuposa placentis and the waspsTrichogramma cacoeciae and Megaphragma viggianii, highlighting their distinct kinematic and morphological traits. The third part will focus on theoretical analyses of aerodynamic mechanisms.