Flight Activity in the Blowfly Calliphora Erythrocephala, in Relation to Light and Radiant Heat, with Special Reference to Adaptation

Abstract

1. The spontaneous flight activity of a population of the blowfly Calliphora erythrocephala has been studied in relation to light and radiant heat in a small wind tunnel. 2. Flight activity occurs at a low level in the dark under these conditions, and is practically independent of light up to 10 lux. Activity increases sharply with light between 10 and 2600 lux, before heating effects become important. 3. Population activity shows adaptation to light intensity, and a method of analysis is described. The rate of increase of activity following an increase of light is much slower than is the reverse change; the state of low activity at low light intensities tends to persist. Complete adaptation would take at least a number of hours. 4. Heating, which accompanies strong light intensities, causes initially a momentary decrease in activity, usually followed by an increase. Similar reactions occur when the heat is applied in several different ways.