Weevil numbers in the trees build up rapidly with the approach of petal fall, but it is about a week after petal fall that largest numbers occur. In unsprayed trees, curculio numbers remain high through June, before declining in July. Oviposition continues at a high rate through the first half of July, then declines. The earliest eggs are laid in apple varieties that sizeup first, such as Gravenstein. Periods of 70 degrees F or higher temperatures early in the egg-laying period greatly accelerate egg laying.
Egg laying occurs both day and night under suitable temperature conditions.
Both feeding and egg punctures are made in the fruit. An average of 4 eggs per day are deposited by each female. In about a week, the larva or grub hatches from the egg and tunnels toward the center of the fruit. If the infested apple drops, the larva becomes full grown in 2 to 3 weeks, then leaves the fruit and enters the soil to a depth of 2 to 3 inches to pupate. If the infested apple does not drop, the larva soon dies and the developing fruit will have a typical shield-shaped russet spot later on.