Spatial Distribution of Lycorma delicatula (Hemiptera: Fulgoridae) Egg Masses on Tree-of-Heaven, Black Walnut, and Siberian Elm in North America

Abstract

Abstract The spatial distribution of Lycorma delicatula (White) egg masses on three species of trees were studied in Pennsylvania. Five tree-of-heaven, five black walnut, and one Siberian elm trees were felled in early spring 2019 to sample for egg masses. Each egg mass was marked for its cardinal direction, position in the tree, height above ground, and spread from the bole. A total of 214 egg masses were found on tree-of-heaven and black walnut, with 38.3, 29.4, 22.0, and 10.3% on the north, west, south, and east quadrant, respectively. No significant difference in cardinal direction was found for either species. Equal number of egg masses were found on branches and boles on tree-of-heaven. However, significantly more egg masses were found on branches (96.5%) compared to boles (3.5%) on black walnut. Egg masses were laid at 0.30–12.92 and 0.70–17.00 m above ground, with most on boles/higher branches and middle/lower branches for tree-of-heaven and black walnut, respectively. Significant effect of height above ground was found for black walnut, with more egg masses found at 4–6 m compared to 0–2, 12–14, and 14–16 m. Significant effect of spread from the bole was found for tree-of-heaven, with more egg masses found at 0–2 m compared to 2–4 and 4–6 m. The 24 egg masses on the Siberian elm were mostly found on east quadrant branches 0–2 m above ground and within 2 m from the bole. Variation in tree branching patterns and difference in egg mass distribution of other forest pests were discussed.