Drawing Open Access
Transverse orientation is the process by which insects can fly keeping a constant angle relative to a distant light source, such as the moon. This helps them to flight at a straight line. Unnatural sources of light, such as a bulb, are too close so that there are substantial changes in the angular relationship between the light source and the direction of flight. By instinctively trying to keep constant the angle of their direction of flight, insects would end up describing a spiral flight towards the light bulb. Here I present a drawing (in *.pdf, *.png, and *.svg formats) to illustrate this process. For a comprehensive discussion on this process of orientation in moths, see Franks (2006, Effects of artificial night lighting on moths, in: Rice and Longcore [eds] Ecological consequences of artificial night lighting ISSBN 1–55963–128–7).