Life cycle (Summer fruit tortrix moth)

  • There are two generations per annum in the UK.
  • Larval development has five instar stages.
  • The pest overwinters as a second or third instar larva in a silken hibernaculum in crevices in the bark etc.
  • There is often considerable winter mortality which is sometimes an important limiting factor in population development.
  • After emergence in spring shortly after bud-burst, individual larvae feed amongst the buds, characteristically tying them and the rosette leaves together with webbing.
  • On early apple varieties and on pears, larval feeding produces cavities in the receptacle, which later heal to form corky scars characteristic of early caterpillar feeding.
  • Larvae pupate when fully fed, normally around blossom time of Cox.
  • First generation adult moths emerge in June.
  • Eggs are laid in batches on the foliage. These hatch in 7-10 days depending on temperature (see ‘Forecasting’).
  • Cool and wet weather conditions at the time of moth flight and/or during egg-hatch limit population increase.
  • Many larvae migrate to the growing points in shoots where they form leaf rolls.
  • In July and August more mature larvae feed on fruits before pupation in August.
  • A second generation of adults occurs in August and September, depositing eggs on leaves and also directly onto fruits.
  • These hatch and the young larvae feed beneath silken webs spun on the under-surfaces of leaves, often at a junction between the main and a side vein.
  • In late September and October, larvae have reached the second or third instar stage and migrate to crevices in the bark to overwinter.