This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This Sawfly larva is very frequent in apples, and is often mistaken for the Codlin Maggot. It can be told from the latter by having more than four pairs of sucker feet, and by its eating out larger chambers in the young apples. A small hole is formed to the outside of the fruitlets, and through this is passed out a brownish liquid and excrement. The Sawfly appears when the Apples are in blossom. The female lays her eggs deep in the blossoms; as a rule, one only in each flower. The male and female both have four transparent wings and dark-and-yellow bodies, and are about the size of the Gooseberry Sawfly.
The larva will leave one fruitlet and eat its way into another, several fruitlets often being spoiled by one larva. By the middle of July the larvae are mature, and have fallen to the ground, which they enter to winter in. In the soil they form silken and earthen cocoons, and in spring they pupate.
All that can be done is to hand-pick the attacked fruitlets as soon as they show signs of invasion, and burn them. In this manner it can be cleared out of gardens and plantations, if done thoroughly.
Fig. 344. - Apple blossom Weevil (Anthonomus pomorum) nat. size and magnified.