Newly hatched larvae burrow directly into the fruit where they feed. Inside the fruit the larvae continue to grow, passing through three instars each of 11 days duration. Periods of drought during periods of adult emergence or larval entry into soil will reduce populations. Infested cherries become shrunken, misshapen and undersized. The fruit turns reddish and ripens earlier than uninfested fruit.
Larval tunnels extend throughout the infested fruit.
Small larvae in the fruit may be detected more easily by boiling a suspect sample in water for one minute. The larvae then tend to sink to the bottom of the container. Use an action threshold of three flies per trap per week. See factsheets from New York , Michigan , Kentucky , Washington State .