The primary hosts are pecan and hickory and the larvae feed mostly in the nut shucks, especially after shell hardening. The first generation larvae commonly feed and develop in phylloxera galls.
First generation larvae may destroy a few pecan nutlets but this damage is usually not heavy enough to be serious. Second generation larvae feed in the nuts causing them to drop from the trees. Third generation larvae mine the shucks, reducing nut fill and causing the shucks to adhere to the shell. This reduces nut quality and yield. Damage to phylloxera galls can be considered _ beneficial; however, serious shuckworm problems often follow a heavy infestation of phylloxera.
Shuckworms overwinter as pupae in old pecan shucks on the tree or scattered about on the orchard floor. Adults emerge from mid-April to mid-May, mate, and lay eggs. First generation eggs may be laid on hickory nuts, small pecan nutlets, or phylloxera galls. Larvae in pecan nutlets die when the nuts fall from the trees as the nuts are to small to allow development. Larvae in hickory and phylloxera galls develop in May and June and first generation adults emerge in late June and July. These adults lay eggs on pecan nuts and cover them with a gelatin-like material produced by the female. This material becomes creamy white and is a distinctive characteristic of shuckworm egg sites. The larvae feed in the nuts during July and August. Nuts damaged by this generation usually drop from the tree. Second generation adults emerge in late August and early September and give rise to a third generation of larvae. They feed in the pecan shucks during the fall, pupate, and overwinter. There are three generations per year in Oklahoma.
The adult is a small, dark brown to smoky black moth about 1/3 inch long. There is a series of dark and white marks on the outer edge of each front wing near the outer end. The larvae are white or cream colored with brown heads and are about 112 inch long at maturity.
Please contact your local county extension office for current information.