It is possible to grow almost pest-free apples without spraying the trees with insecticide several times over the course of the growing season. The most common pest of apple trees is the apple maggot fly. It bores into ripening fruit and lays its eggs. When the eggs hatch, the small white maggot burrows and tunnels into the flesh of the fruit, feeding on it and leaving telltale brown tracks or trails. Once the apples fall to the ground, the maggots leave the fruit and burrow into the soil. They remain and pupate there until the following summer, when they emerge as adult flies and begin the cycle again. To control their population without spraying, it is necessary to interrupt their life cycle by removing their habitat, by trapping them or by preventing them from reaching the ripening apples.
Practice Good Sanitation
Promptly pick up apples that fall to the ground. Doing so will greatly decrease the number of apple maggot pupae that overwinter in the ground and consequently will reduce the population the following year. Bury the fallen apples at least a foot deep. Enlist the cooperation of nearby neighbors with apple trees on their property for the most effective reduction of these pests.
Bag the Fruit
Place plastic bags over each apple to prevent the pests from reaching them. This should be done prior to July 1st for the best results. Loosely fasten the bag around the stem of the apple with string, twist ties or staples. Clip small holes in the bottom corners of the bags. This will allow any water to drain out and help prevent fungal diseases.
Use Sticky Traps
Sticky traps mimic the look of real apples and are coated with a sticky substance that is commercially available specifically for this purpose. The pests think they are real apples and when they land on them the bugs become trapped and die. For the most effective management of apple maggot flies, hang one trap for every 100 apples on your tree (approximately five traps for an average standard size apple tree). Install them before July 1st for best results. Check the traps every few days. Clean off and re-apply the sticky substance if the traps are covered with dead insects and debris or the traps will become ineffective.