Pecan Nut Casebearer: Appearance, Territory, Damage and Life Cycle

Latin Name: Acrobasis Nuxvorella Appearance: The pecan nut casebearer is one of the most serious nut-infesting insect pests of pecan. It may be found in all pecan-growing districts of Texas as well as in south-eastern New Mexico. The adult casebearer is a 13-inch-long gray to practically black moth. The forewings are characterized by a ridge of black scales followed by a band of lighter hue. Moths are only active at night to mate and deposit eggs on pecan nuts. During her 5- to 8-day existence, each female produces 50 to 150 eggs. Eggs are round, flat, and small, hardly visible with the naked eye. When eggs are first deposited, they are greenish-white or white. Before hatching, little red dots emerge on the egg, giving it a pink appearance. Casebearer larvae are olive-gray to jade green in color and grow to reach approximately one-half inch long. Hosts Plants: Acrobasis Nuxvorella: This species is found solely on pecan trees. Other, closely related species have similar larvae on hickory and walnut. Territory: The pecan nut casebearer, Acrobasis Nuxvorella, is a Pyralidae moth. It is found in eastern New Mexico, Texas, Oklahoma, Louisiana, Missouri, southern Illinois, Mississippi, Alabama, Florida, Georgia, South Carolina, and North Carolina in the United States. Damage Insect Cause: The largest economic loss is generally attributed to first-generation larvae. Due to the tiny size of the nutlets thus early in the season, a single larval can kill a whole nut cluster. Later generations will usually only need to eat one nut to complete growth. As a result, control is focused exclusively on spring generation. Life History and Habits: The pecan nut casebearer hibernates as a little larva at the base of a pecan blossom in a cocoon-like hibernaculum. These larvae emerge at budbreak, feed on the buds, then pupate in the fragile shoots. Adults emerge in late May, mate, and deposit eggs on the maturing nuts’ tips. Casebearer larvae burrow into nutlets quickly after pollination, frequently devouring the entire cluster of nutlets. A well-timed pesticide treatment to the tree to eliminate newly born juveniles before they penetrate the young nutlets is the most reliable way of management. Treatment, on the other hand, is a best-guess decision based on moth catch, egg scouting, and pecan crop load. As a result, a portion of this equation is dependent on correctly recognizing adult male moths trapped in orchard traps.