Northern walking stick

The Northern walking stick (Diapheromera femorata) belongs to the order Phasmatodea and the family Diapheromeridae. As a specialized phytophagous insect, it has evolved a remarkable camouflage strategy that allows it to blend in perfectly with twigs and branches. Measuring up to 9 centimeters in length, these insects are elusive, often going undetected until significant population outbreaks occur.

This species primarily targets a wide range of broadleaf deciduous trees. Key host plants include oak, basswood, cherry, hazel, and apple trees. In forested areas or landscapes adjacent to wild patches, the Northern walking stick can cause significant damage to foliage. While usually present in low numbers, they can occasionally reach infestation levels that require human intervention to prevent long-term tree health issues.

The life cycle of the Northern walking stick is univoltine, meaning there is one generation per year. Eggs overwinter in the leaf litter on the forest floor, demonstrating impressive cold hardiness. Hatching typically occurs in late spring, around May or June. Nymphs pass through several developmental stages, feeding continuously throughout the summer months before reaching adulthood and laying eggs in late summer or autumn.

The feeding damage is characterized by ragged or complete consumption of leaf blades. When large populations congregate on a single tree, the extensive defoliation prevents the plant from producing the necessary nutrients through photosynthesis. Consecutive years of such attacks can severely stress trees, leading to stunted growth, dieback of the upper crown, and increased vulnerability to wood-boring insects and fungal diseases.

Management strategies focus on monitoring and targeted control. Because they are often hidden, landowners should inspect foliage during the early summer when nymphs are most active. Control measures include:

• Using biological insecticides (e.g., Bacillus thuringiensis) for younger stages.
• Applying registered contact insecticides if infestation levels cross economic thresholds.
• Preserving habitat for natural predators like birds, spiders, and parasitic wasps.
• Maintaining healthy soil and tree vigor through appropriate fertilization and watering.

Integrated Pest Management (IPM) is the most effective way to handle these insects. By combining cultural practices, such as maintaining diverse plantings, with timely and careful use of suppressive measures, growers can mitigate the impact of the Northern walking stick on their forest resources and ornamental tree populations.