Mature larvae drop from fruit and pupate in the soil to complete development. They emerge as adults in late June through August and remain in the orchard until harvest. Adults prefer the dense shade of the tree’s inner canopy. In Michigan, this summer generation does not lay eggs until the following spring. 

Early-season varieties are considered most susceptible to both feeding and oviposition damage. As fruit mature, older oviposition scars take on a broad, fanlike appearance.

Monitoring: Traps can be used early in the season to capture curculios as they move into and around the orchard. After fruit is present, visually inspect several fruit per tree for signs of feeding or egg laying. Concentrate sampling on trees adjacent to hedgerows and woodlands, especially where damage has occurred in the past. 

Beating trays can be used to determine the presence of plum curculio.