Experimental analysis of the locomotor behaviour of Schistocerca gregaria induced by odour

The locomotor behaviour of the desert locust in response to volatile chemicals released from grass as a food plant was investigated in a wind tunnel. When bruised grass was at the windward end of the tunnel the insects responded by moving upwind towards the grass. The response was maximal for locusts starved for 4 hr or longer. Feeding just prior to an experiment inhibited the response; the degree of inhibition of the response, as estimated by the proportion of larvae responding, increased with the duration of the feeding period. All the larval instars and adults reacted in essentially the same way, but the response varied in the course of any one instar, there being more response in the first half of the instar—that is, the period preceding peak food intake—than later.