Alder flat-headed borer

Systematic position: The alder flat-headed borer (Dicerca alni) is a member of the order Coleoptera and the family Buprestidae. These beetles are primarily associated with stressed or weakened deciduous trees, serving as secondary pests that often complete the decline of a host plant.

Host plants: The primary host for this species is the alder (Alnus). However, it is also known to attack birch and other deciduous trees when environmental factors lead to a reduction in tree vigor. It is frequently found in both natural forests and landscape plantings.

Biology and life cycle: The life cycle of Dicerca alni typically spans one to two years. Adults are active during the warmer months, feeding on leaves and searching for suitable oviposition sites in bark crevices. Once the eggs hatch, the larvae bore into the inner bark and cambium, creating extensive feeding galleries.

Damage and harmfulness: The primary damage is caused by the larval stage. As the larvae feed, they create meandering, flat galleries between the bark and the wood. This boring activity disrupts the vascular system of the tree, impeding the transport of water and nutrients. Over time, this leads to crown dieback and eventual tree mortality.

Control measures: Management of this pest focuses on silvicultural practices rather than direct chemical control:

• Maintaining tree health through proper irrigation and soil management to prevent infestation.
• Sanitation, which involves the prompt removal and destruction of infested and dead trees to prevent the spread of the next generation of beetles.
• Applying systemic insecticides on the trunks during the peak adult flight period if the infestation is caught early.
• Preserving local populations of natural enemies, such as woodpeckers and parasitic wasps, which exert significant control over larval populations.