Overwintering of adult Stethorus punctum punctum (LeConte) was investigated in apple orchards in south-central Pennsylvania. A separation technique was developed to remove adults from soil samples. Density of overwintering adults in the autumn was greatest in the area around the trunks of the apple trees, but because of the relatively small area of the ground cover in the trunk zone, more adults were located in the remainder of the herbicide strip and in the border between the herbicide strip and drive row. In the spring, however, >70% of the adults were located in the trunk zone. Adults were associated with fallen leaves and apple root suckers. Density of adults in orchard ground cover peaked in midautumn and declined to relatively low levels in the spring. Methods to conserve this predator while managing tufted apple bud moth, Platynota idaeusalis (Walker), are discussed.
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Felland et al. (1996) studied this question.