I am not aware that anyone has published actual observations on the method of oviposition by this insect. On the 13th of June, 1889, I was fortunate enough to see a female perform the entire operation which was as follows: First a cavity was eaten in the apple as deep as the beak was long, the bottom being much enlarged and sub-triangular in outline. The walls of the cavity converged to the opening which was only large enough to admit the slender beak.
Proceedings of the Iowa Academy of Sciences
©1890 Iowa Academy of Science, Inc.
Gillette, C. P.
"Egg-Laying of the Apple Curculio (Anthonomus quadrigibus Say),"
Proceedings of the Iowa Academy of Science, 1(Pt. 2), 109-110.
Available at: https://scholarworks.uni.edu/pias/vol1/iss2/45