CHANGES IN FEEDING HABIT AS CATERPILLARS GROW

1. 200 of 1137 species of British microlepidoptera make a single marked change in feeding habit as they grow. 2. Most numerous are species that change from leaf mining to one of case bearing, spinning, tying and rolling or concealed feeding, and species that change from concealed feeding to case bearing or spinning, tying and rolling. 3. Although in some instances numbers of closely related species make similar changes in behaviour, most changes observed are scattered among subfamilies. 4. Leaf miners have considerably smaller adults than concealed feeders, which themselves are smaller than external feeders and spinners, tiers and rollers. When case bearers are excluded from the analyses, species that remain as leaf miners or concealed feeders throughout larval development are on average smaller as adults than those that start out with these feeding habits but later change. 5. We suggest a number of reasons why larvae might make such fundamental switches.