They pupate in early autumn and metamorphose into adults in about three weeks. These adults remain in the soil until the following August. The complete life cycle requires two to three years. The beak of the male is half the length of the body, and the beak of the female is slightly longer than the body. The pecan weevil is considered to be the most serious late-season pecan pest.
Pecan varieties differ widely in their susceptibility to attack.
Early ripening varieties that enter the gel stage in early August are most commonly infested. Consequently, certain trees may be infested year after year while other adjacent trees of the same variety may not be attacked. You can spray pecan trees that have a history of pecan weevil damage with an insecticide at gel stage and then spray again 10 to 14 days later. Cone-shaped emergence traps are the best way to detect first emergence of pecan weevil adults. The economic threshold is five pecan weevil per trap when the nuts have reached the gel stage.