Phenological Correlations between Flowering Plants and Activity of Urban Landscape Pests in Kentucky

Seasonal appearance of 33 insect pests of urban landscapes together with flowering phenology of 34 species of common woody ornamental plants were systematically monitored for 3 yr in central Kentucky. Base temperatures and degree-day requirements corresponding to these events also were determined. Phenological sequences of plant flowering and insect activity were highly consistent between years. For example, crawlers of the oystershell scale, Lepidosaphes ulmi (L.), hatched 1st in each year, followed by those of pine needle scale, Chionaspis pinifoliae (Fitch); euonymus scale, Unaspis euonymi (Comstock); juniper scale, Carulaspis juniperi (Bouché); calico scale, Eulecanium cerasorum (Cockerell); walnut scale, Quadraspidiotus juglansregiae (Comstock); a cottony maple leaf scale, Pulvinaria acericola (Walsh & Riley); and obscure scale, Melanaspis obscura (Comstock). Similar consistency occurred with clearwing borers (Lepidoptera: Sesiidae), leafminers, and other pests. Plant phenology was generally a better predictor of insect activity than was calender date. Comparison of the temporal deviation between plant-insect correlations in Kentucky and Michigan suggests that some phenological predictors are consistent across geographic regions, whereas others are not. A phenology calender was developed that facilitates prediction of pest activity and timing of control actions by horticultural professionals and lay persons.