ABSTRACT
Although insect flight, and the stimuli which induce it, have been studied extensively, the way in which insects land has received little attention. The majority of insects fly with the pro- and meso- and in some cases the metathoracic legs folded up beneath the body and the legs must be lowered before the insect makes contact with the landing surface. This paper describes a detailed examination of the movements of the legs of the fly Lucilia sericata and other insects and an attempt to determine the stimuli which result in Lucilia lowering its legs on approaching a suitable landing surface. There are several possible stimuli which may cause the legs to be lowered ; the object which the fly is approaching will appear to increase in size and this stimulus will of necessity be accompanied by a change in the light intensity falling on certain of the ommatidia. If the insect has a reasonable field of binocular vision, the lowering of the legs may be based upon an appreciation of its distance from the landing surface, together with its rate of approach to that surface. Alternatively, it may always lower the legs when the image of the approaching object falls simultaneously on corresponding ommatidia of the two eyes.
