COINCIDENCE BETWEEN CONSUMER AND HOST OCCURRENCE - MACROLEPIDOPTERA IN BRITAIN

1. The interspecific relationship between the distributions of consume rs and resources is examined, using data for macrolepidoptera (moths) in Britain. 2. Monophagous moth species feeding on host plants with sm all geographical ranges also have small ranges, whilst those feeding o n host plants with large ranges may have small or large ranges themsel ves. Likewise, there is an approximately triangular relationship betwe en the proportion of the range of its host that a monophagous moth occ upies and the size of the host range. 3. Most monophagous moths occupy a small proportion of the range of their host, and only feed on hosts that have relatively large geographical ranges. 4. Factors determinin g both the range size of a monophage and the proportion of the host pl ant's range that it occupies are independent of taxonomy. 5. Monophage s tend to have smaller geographical ranges than congeneric polyphages, but do not occupy a smaller proportion of the ranges of the plants th at they consume.