Abstract
An earlier model of hostplant exploitation by insects (Courtney 1982b) fails to take account of differences between strategists in search efficiencies. Modifications which accommodate such differences are presented which increase the explanatory power of the model. Some novel deductions for insect-host coevolution arise. Hostplants may be under selection for chemical crypsis when the insect identifies the host by a positive chemical stimulus; by crypsis, a hostplant may increase the ‘handling time’ of females searching for oviposition sites. Contrary to earlier predictions, the evolution of a monophagous relationship is possible even when alternative hosts are present.