I. Larvae
The fruit damaged by larvae mostly feeds on calyx and depression, and insect dung is discharged from the holes of the damaged fruit in the early stage, and most of them do not feed in the later stage. Young insects eat the core of the fruit directly. Under the condition of high humidity, the surrounding of the hole often turns black and gradually decays, commonly known as "black plaster". Eating peaches, plums and apricots is mostly harmful to the pulp near the pit.
Second, the mold
It overwinters with mycelium hidden in necrotic tissue or diseased fruit or spores hidden in bud scales, and is spread by spores in the following year and invades the fruit core from calyx tube. The occurrence of diseases is most closely related to varieties, and all fruits with open calyx mouth and calyx tube connected with stone are prone to diseases. The rotten part of the fruit is easy to smell or see mildew. In wet and rainy environment, mold is more likely to breed.