tunnels inside pecan shucks late in the growing season. However, an earlier generation flies in early July and lays eggs on young nuts. In the photo above, the red arrows point to oviposition scars created by female shuckworm moths to deposit eggs in the shuck.
Once she lays eggs inside the shuck, she scrapes some scales off her abdomen and places them over the hole in an effort to disguise the eggs from predators and parasites. The white halos around each scar are the scales left behind by the female moth.
At this time of year, it takes about three days after a nut is punctured for that nut to fall from the tree. Fortunately, the generation of hickory shuckworm that causes this kind of nut drop is usually quite small and does not cause enough damage to warrant insecticide treatments.