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Abstract:
Combined field and laboratory investigations showed that C. villosa was univoltine in the Breitenbach, Germany. Speed and duration of embryogenesis were determined by temperature. Lowest values of accumulated temperature occurred at 6 and 8 degree C, when the duration of embryogenesis was shortest, and egg mortality was low. Egg masses exposed at upstream field sites needed similar time and accumulated temperatures for embryogenesis to those expected from laboratory experiments. At all field sites the emergence period of adults lasted from September until December. Size and weight of both sexes were significantly lower at the upstream site, not necessarily as a result of temperature, but possibly caused by differences in nutrition.
