THE ECOLOGY AND CONSERVATION OF THE HEATH FRITILLARY BUTTERFLY, <em>MELLICTA ATHALIA</em>. I. HOST SELECTION AND PHENOLOGY.

The heath fritillary butterfly, Mellicta athalia, is an endangered species in Britain and has been the subject of a detailed study in 1980–85. M. athalia is found in three types of habitat in which it uses a range of different host-plants: (i) newly cleared woodland where its sole host is Melampyrum pratense; (ii) rough, unimproved grassland where its main, primary hosts are Plantago lanceolata and Veronica chamaedrys; (iii) sheltered heathland where its main, primary host is Melampyrum pratense. Eggs are laid in large batches on plants close to the ground, chiefly in open, sunny situations. In woodland habitats some eggs are laid in fairly shady situations, but always close to sunny clearings. A large range of host-plants was observed in the field, but the range used by adult females was rather narrower than that of the larvae. One secondary host, Digitalis purpurea, which was commonly used by post-diapause larvae in heathland habitats, was apparently never used by egg-laying females. In captivity, pre-diapause larvae failed to survive on this plant but post-diapause larvae grew as quickly on it as on other hosts. Considerable variation was observed in the phenology of M. athalia between both years and regions. In the predominantly grassland habitats in Cornwall, the adult population peaked 2–3 weeks earlier than in the woodland habitats in Kent. In both regions a close relationship was found between the date of the peak flight period and the temperature during April and May when the post-diapause larvae were developing. The regional difference in phenology was therefore thought to be caused by climatic differences, but a habitat effect could not be ruled out. The host selection and phenology of M. athalia in the different habitats and regions are discussed. [ABSTRACT FROM AUTHOR]