Trends of Populations of Aphid Predators in South Dakota Cereal Crops—1963–65

Populations of aphid predators in cereal crops were monitored over an extensive area of South Dakota during the 1963–65 crop seasons. In all 3 seasons the population tended to peak early in May, decline in early June, and rise toward a second peak later in June. Populations were highest in 1964. Reproduction was not detected in cereals before June in any of the 3 seasons and at all times appeared to be negligible. No correlation existed between number of adult predators present at a given location and number of immature forms subsequently taken in samples. Thus, increases in populations in cereal crops appeared primarily dependent on movement from other crops.