Woolly alder aphid

Systematic position: The woolly alder aphid (Prociphilus tessellatus) is classified within the order Hemiptera and the family Aphididae. It is a highly specialized species known for its distinct appearance and its complex life cycle that involves alternating between two different host plant species.

Host plants: The primary host for this pest is the silver maple (Acer saccharinum). During its seasonal life cycle, the aphid migrates to its secondary hosts, which are various species of alder (Alnus). The colonies are most noticeable on the bark and branches of the alder trees during the summer months.

Biology and life cycle: The lifecycle is characterized by a specific migration pattern. Spring generations develop on the maple, causing leaf deformation. As summer approaches, winged adults migrate to alder trees to establish colonies. They secrete a characteristic white, waxy, wool-like substance that covers the entire colony, providing them with effective protection against environmental stresses and predators.

Damage and pest impact: Damage is caused by the aphids extracting plant sap, which leads to tree stress and stunted growth. On maples, the leaves become curled and distorted. On alders, the heavy infestation of white woolly colonies is unsightly, and the associated honeydew production often leads to the growth of sooty mold, which impairs the plant's ability to photosynthesize effectively.

Protection measures: Controlling this pest typically involves the use of systemic insecticides during the early stages of infestation. Regular inspection of host trees is essential for early detection. For smaller infestations, high-pressure water sprays or insecticidal soaps can be effective in removing the waxy coating, thereby exposing the aphids to predators or causing them to dehydrate.