The developmental dynamics of Tipula paludosa and the relation of climate to its growth pattern, flight season and geographical distribution.

The model of Meats (1974a) is tested against Laughlin's (1967a) data on growth in the field. A good measure of agreement is found. The model is then used to investigate the consequences of the univoltine T. paludosa starting its life cycle (flight season) at various dates in the range quoted by Coulson (1962)-i.e. from July to October. Similarly the influence of increased or decreased monthly temperatures is also investigated. The model indicates that growth will be poorer the later the life cycle starts or the lower the mean monthly temperature.Populations at Moor House (high Pennines) are probably obliged to start their cycle earlier by shortening the prepupal/pupal period because the relatively colder average temperatures would otherwise prevent the attainment of a suitably sized adult. Lowland populations from Canada, England, Germany and Poland differ in developmental schedule depending on prevailing temperatures but usually achieve sufficient growth despite a relatively prolonged prepupal/pupal period and late flight season. Dry conditions (which, like low temperatures, can slow growth) are not associated with advanced flight seasons. In areas where low temperatures are critical, successful growth may be restricted to wet soils. The relation of climate to prepupal diapause is discussed and developmental dynamics is related to potential geographical range.