Alder lace bug

The Alder lace bug, scientifically identified as Corythucha pergandei, is a member of the Tingidae family, commonly known as lace bugs. These insects are distinguished by their intricate, lace-like wing covers and thorax. They are specialized plant feeders that primarily target trees belonging to the Alnus genus.

While alder trees are the preferred hosts, this species can also be found on birch, linden, and elm trees in specific ecological settings. The distribution of Corythucha pergandei is largely determined by the availability of host plants and favorable humidity levels. They are typically found in temperate regions where these tree species flourish.

The life cycle consists of the egg stage, five nymphal instars, and the adult stage. Eggs are laid in clusters on the undersides of leaves and are covered with a brownish secretion. The nymphs are gregarious, feeding in large groups on the underside of leaves. Depending on regional temperatures, the insect can complete multiple generations per season, significantly increasing the population density.

Feeding damage is characterized by a stippled appearance on the upper surface of the leaves. As the bugs extract sap, the chlorophyll is destroyed, resulting in yellow or pale white spots. If the infestation is severe, the entire leaf turns brown and falls prematurely, which stresses the tree and leads to reduced annual growth and a decline in overall tree health.

To manage and control populations, the following practices are recommended:

• Regular monitoring of foliage during late spring and early summer.
• Application of horticultural oils or insecticidal soaps on the underside of leaves where nymphs reside.
• Systemic insecticide treatments for heavily infested high-value landscape trees.
• Maintaining healthy soil conditions and proper irrigation to help trees recover from feeding stress.