Bionomics of the Destructive Prune Worm, Mineola scitulella, on Sour Cherry in Wisconsin1

Abstract

A study of the bionomics of the destructive prune worm, Mineola scitulella Hulst, on sour cherry in Wisconsin from 1960 through 1962 showed that the overwintering larvae left their hibernacula in early May just as the buds started swelling, penetrated the fruit buds primarily, and fed inside on the developing flower parts, injuring 32.8 and 7.4% of the fruit buds, and destroying 18.1 and 6.2% of the pistils by the petal-fall stage in 1961 and 1962, respectively. The larvae started leaving the buds during the early-bloom stage to construct nests in and feed on the expanding blossom and leaf clusters prior to pupating in the soil. Pupation began during early bloom and was usually completed by petal fall around the first of June. Adult emergence started ordinarily the last week in June and was over by the last week in July with peak emergence occurring during the first week in July. Newly emerged summer larvae often penetrated the ripening cherries, feeding just beneath the skin for a short time before emerging to construct their hibernacula in sheltered areas on the tree. Larval-infested fruit at harvest was 0.14% in 1961 and 1.5% in 1962. An earlier and shorter growing season in 1962 resulted in less injury to the fruit buds and pistils by the spring larvae, but a higher infestation of the fruit at harvest by the summer larvae. On an equal population basis, in 1961 the destructive prune worm was more injurious than the eye-spotted bud moth (Spilonota ocellana (Denis & Schiffermüller)) to the fruit buds and pistils.