Sunflower Moth Larval Distribution in Sunflower Heads 1

Abstract

The distribution and movement of sunflower moth, Homoeosoma electellum (Hulst), larvae in flowering sunflower heads was determined. Sampling was initiated 3 days after first bloom and was continued at 3-day intervals untill larval numbers substantially declined. Flowers were divided into eight sections and each section into five subsections before larvae were counted. Larval counts from adjacent eighth sections were combined to create quarters and halves. There were no statistical differences ( P < 0.05) In larval densities among eighth sections in 91% of the heads, quarter sections in 86% of the heads, and half sections in all heads sampled. Larval movement among subsections of a head was influenced by floret and seed maturation, and to a lesser degree by instar.