Studies on insect infestations in the machinery of three English flour mills in relation to seasonal temperature changes

Abstract

Temperatures in three flour mills near London, England, were influenced by heat production during milling and by seasonal weather conditions. When a mill was operating, temperatures within a centrifugal rose to 32–36°C in summer and 18–20°C in winter. When milling ceased these temperatures dropped to 18–20°C and 7–9°C respectively. During milling, mill air temperatures were 6–7°C lower than those in the centrifugal, and about 8–10°C higher than temperatures recorded at a nearby meteorological station. Insect infestations in the milling section were studied for periods of 3–5 years. After fumigation in summer, there was a negligible increase in populations of Anagasta kuehniella (Zell.), Gnathocerus cornutus (F.) or Cryptolestes turcicus (Grouv.) until February to April in the following year. There were differences in the intensities of the infestations developing in different years, but these could not be related to climatic factors. The cold-tolerance of insects infesting milling machines in temperature regions is discussed.