The following are pests that are currently active in Delaware landscapes.
Tuliptree scale and magnolia scale crawlers are active. Horticultural oil and Distance provide good control.
Magnolia scale. Photo by Brian Kunkel, UD Extension
Tuliptree scales. Photo by Gerald J. Lenhard, Louisiana State Univ, Bugwood.org
European Hornets/German Wasps and Yellowjackets are very active. They are predatory natural enemies of other insects but may need control, especially where food or food crops are present.
Late season leafhooper and lace bug damage is showing up. On evergreen plants, (Azalea and Andromeda), a fall horticultural oil application may reduce lacebugs and their eggs that would potentially overwinter on leaves.
Information from the September 18, 2009 edition of the Ornamentals Hotline newsletter from University of Delaware Cooperative Extension.