Spruce seed midge

The spruce seed midge (Plemeliella abietina) is a small dipteran insect belonging to the Cecidomyiidae family. It is a highly specialized pest that primarily targets the seed production of Norway spruce, significantly impacting forestry and seed yield potential.

The damage caused by this insect is restricted to the seeds located within the female spruce cones. During the female flower development phase, the adult female midges lay eggs inside the ovules. Once the larvae hatch, they consume the internal tissues of the developing seed, ultimately destroying the embryo.

The biology of Plemeliella abietina is characterized by a flexible life cycle. While most individuals complete their development in one year, a portion of the population can remain in a state of diapause inside the seed for several years, which acts as a survival strategy against poor cone crop years.

In terms of economic impact, the spruce seed midge is considered one of the most destructive pests for spruce seed production. High infestation rates can lead to a drastic reduction in seed viability, causing severe losses for forest nurseries and commercial seed orchards that rely on healthy cone harvests.

Effective management and protection strategies include several key approaches:

• Implementing regular monitoring of adult midge flights during the peak flowering season.
• Applying silvicultural practices such as thinning infected stands to reduce the population.
• Utilizing seed processing methods that effectively separate infested seeds from healthy ones.
• Promoting the natural presence of parasitoids that feed on midge larvae within the cones.