Several species of scale Insects develop on conifers in Colorado, sometimes causing serious damage as they feed on plant sap. The most vulnerable stage of the scale insect's life cycle is the crawler stage, an active unarmored stage that occurs after egg hatch. If insecticide applications are made for control, proper timing is important in their success.
Scales are some of the most important insect pests affecting conifer trees and shrubs in Colorado.
As scales feed on bark and needles, they remove sap and may damage cells. This can lead to decreased vigor, needle drop and dieback, and increased susceptibility to other Insects or disease. Some scales also excrete sticky honeydew, which further detracts from plant appearance and attracts nuisance bees and wasps. There are several important scale insect pests in urban Colorado. Pine-needle scale has long been the most damaging species.