Evasive behaviour in the cave‐cricket, Troglophilus cavicola

. Cave crickets of the genus Troglophilus occur in caves of the Alps and Dinarides generally in wintertime. Most hibernation sites in caves were inclined at more than 60° to the horizontal. The crickets show a striking escape behaviour which is strongly influenced by the inclination of the surface on which they are standing: stimulated adequately, they readily jump from horizontal surfaces, but only rarely from the side walls or roofs of caves. An arena with a tiltable floor was used to quantify this and other behavioural effects in relation to the degree of inclination of the floor, and gave the following results, (a) From 0° to 60° the rate of evasive jumping was inversely related to the steepness of the floor; above 60° jumping was almost completely inhibited. (b) Below 75° more than half the crickets showed a positive thigmotaxis to the arena walls, above 75° this thigmotaxis was much weaker, (c) The effect of blinding was to reduce these levels of thigmotaxis at inclinations lower than 60° and to increase the thigmotactic response at steeper inclinations, (d) Standing orientation was generally upwards at inclinations steeper than 60°; below 45°, the steeper the floor, the greater this upward orientation tendency, (e) If the cricket was standing orientated downwards, evasive jumping was less inhibited on slopes between 15° and 60°.