Trees and Shrubs (Woody Ornamental Plants)

Find answers to your questions regarding diagnosis and effective management of arthropod (insect and mite) pests of trees and shrubs in Pennsylvania. This section is designed to assist you with easier access to information on key arthropod pests of woody ornamental plants.

Most people do not differentiate one insect from another and consider many insect and mite species to be harmful. Here are some facts to keep in mind when confronting insect issues:

  1. Insect identification can be confusing.
  2. Most insects do not cause economic or aesthetic damage to woody ornamental plants.
  3. Mistaken identity can result in overuse of chemical spraying and can be harmful to beneficial insects.
  4. Learning how insects live and eat can lead to effective control measures.


The omnivorous leafroller has recently been detected and confirmed in a greenhouse in Pennsylvania. Your assistance is needed in monitoring for this pest both indoors and outdoors in Pennsylvania.

The goal of ornamental entomology is to provide facts so that informed decisions are made when attempting to effectively manage key insect and mite pests of woody ornamental plants.

The emerald ash borer has killed more than 40 million ash trees in Michigan, Ohio, Indiana, Illinois, Maryland, Virginia, Pennsylvania, West Virginia, Missouri, Wisconsin, Minnesota, Kentucky, New York, Tennessee, Iowa, Kansas, Connecticut, Massachusetts, New Hampshire, North Carolina, Georgia, Colorado, New Jersey, Arkansas, Louisiana, Texas, Nebraska, and Delaware.

Adapted from Johnson, W.T. and H.H. Lyon. 1991. Insects that feed on trees and shrubs. 2nd ed., Cornell Univ. Press, Ithaca, New York, 560 pp.