Journal: Ecological Entomology
Location: ?, Canada

The Elm Spanworm hatching boom is 2 weeks after the Sycamore Maple budburst. 85% more eggs were laid on the lower trunk than the crown (although those in later stages of development moved up towards the crown) and it had nothing to do with avoiding parasites (only one pupa was parasitised) or getting better quality leaves, although feeding on older leaves (three leaves expanded per bud) significantly improved the caterpillars’ chance of surviving to adulthood (90%, or 45% higher than when feeding on on younger leaves). Sycamore Maple leaves mature acropetally (from the base up).

Elm Spanworm – Ennomos subsignaria
Sycamore Maple – Acer pseudoplatanus

Fry HRC, Quiring DT, Ryall KL, Dixon PL, 2009. “Influence of intra-tree variation in phenology and oviposition site on the distribution and performance of Ennomos subsignaria on mature sycamore maple.” Ecological Entomology, DOI: 10.1111/j.1365-2311.2009.01091.x
Affiliations: University of New Brunswick, Canadian Forest Service, Agriculture and Agri-Food Canada (AAFC)