Green spruce sawfly

The green spruce sawfly (Pikonema dimmockii) belongs to the Tenthredinidae family within the order Hymenoptera. It is a specialized defoliator that poses a significant threat to spruce species, often causing widespread needle loss in both forest stands and ornamental nursery settings.

This pest primarily attacks various types of spruce trees. While they can be found on mature trees, they are particularly damaging to younger specimens in plantations. The presence of these insects can lead to stunted growth and structural decline of the host tree if the infestation is not managed correctly.

The biological cycle of this sawfly is synchronized with the growing season of the host plant. Female sawflies deposit eggs into the needles. Upon hatching, the larvae begin feeding voraciously. They undergo several instars before descending to the soil, where they create cocoons to overwinter safely in the forest floor litter.

The damage caused by Pikonema dimmockii is primarily defoliation. Early-stage larvae often feed on new needles, whereas older larvae may consume older growth. This loss of foliage reduces the tree's ability to photosynthesize, eventually leading to reduced vigor and making the trees highly susceptible to drought and secondary pathogens.

Effective management strategies combine cultural and chemical control measures. Regular monitoring during the egg-laying and larval emergence stages is critical. Chemical intervention using systemic insecticides during the early larval stage is often the most effective way to prevent extensive damage. Biological controls, such as naturally occurring parasitoids, also play a role in regulating populations.

• Perform visual inspections of needles for signs of larval feeding.
• Apply targeted insecticides when early-instar larvae are active.
• Encourage beneficial insect populations to naturally manage numbers.
• Maintain tree health through proper irrigation and fertilization practices.