Days before harvest after last application of insecticides or fungicides. Some Important Fruit Tree Insects in Nebraska Apple maggots are the larval stage of a small fly. The damage is caused by maggots burrowing into the fruit, leaving brown trails that cause deterioration of the fruit. Adults emerge from pupae that overwinter in the soil in early to mid-June and may be active through July. Flies deposit eggs under the skin of apples.
Egg laying punctures cause the fruit to have a dimpled appearance.
It is very important to have insecticide sprays on trees during the egg laying period to kill the flies because control is impossible after the eggs are deposited. Checking for first adult activity can be done with special pheromone traps that can be purchased by commercial growers, or by using a red sphere about the size of an apple. Cover the sphere with a light coating of Tanglefoot and suspend it in apple trees the first of June. Flies are attracted to the red sphere and become trapped in the sticky substances. If Tanglefoot is not available, use a thin layer of petroleum jelly.