What type of pine needles do pine sawfly caterpillars primarily feed on?

Pine sawfly caterpillars primarily feed on young pine needles. This preference is significant because young needles are more tender and nutritious compared to older, tougher needles. The caterpillars utilize these fresh, new growths as their primary food source, allowing them to grow and develop effectively.

Old pine needles, while they may provide some sustenance, generally do not provide the same level of nutrients necessary for the caterpillars' growth. Additionally, the structure of older needles may not be suitable for younger caterpillars, which are more adapted to consuming the softer, more palatable young needles. Understanding this feeding behavior is crucial for managing pine sawfly populations and maintaining the health of pine forests, as an abundance of young needle consumption can lead to significant defoliation and stress on the trees.