The Behavior and Survival of Adult Cereal Leaf Beetles1,2

The adult cereal leaf beetle population was studied in an 1842-acre area in Kalamazoo County, Michigan from 1970-74. Adults were found to survive winter in highest densities at the edge of the woodlots. Other habitats include sparse woods, fence rows, dense woods, and croplands (in order of “preference”). Emergence from overwintering is temperature-dependent and, although cumulative emergence is quite regular on a degree- day scale, differences occur between years. Following emergence, the adult beetle population moves among wild grasses and grain fields as it decreases rapidly clue to mortality. The density within a field depends on the size of the regional population and the stage of development of the crop during this period of mobility. Generally early-planted winter grains and late-planted spring grains maintain lower populations than normal plantings of each. The cereal leaf beetle population in the study area declined between 1970 and 1974 and several factors were investigated as possible causes. This decline was apparently not caused by spring mortality rates, planting dates, or relative acreages of crops, however a shift of the majority of the population from oats to wheat was associated with the declining densities and may be a factor in population regulation.