The apple maggot passes the winter in a pupal stage in a brown oblong case about a quarter-inch long known as a puparium. These puparia can be within two inches of the soil surface. Adult flies begin emerging from the puparia late in June and continue to emerge through September and sometimes as late as early October. The flies mate, and the females begin to lay their eggs singly in tiny punctures that appear as pinpricks made in the skin of the apple. The eggs hatch, and the larvae begin to tunnel through the flesh of the fruit, leaving tarnished, irregular threadlike trails.
Maggots spend the winter in the puparia until the following summer.
However, it is not unusual for them to spend one to two years in the soils before emerging as mature flies. Some control can be achieved by pickup up and destroying dropped apples before the maggot leaves to enter the grass. Emergence of the flies can be monitored by using red sticky spheres. The red balls can be made by painting 2 to 3-inch balls red or using commercially available plastic or wood balls. These are covered with a petroleum jelly or a commercial sticky trap such as Tangle Trap.