Pecan Weevil
Curculio caryae
A brown snout weevil that is one of the most serious late-season pests of pecan and hickory, attacking the nuts in two ways. Adults feed on the nuts before the shell hardens and cause them to drop, while the grubs feed inside hardened nuts and destroy the kernel.
🔎 How to spot it
The adult is a brownish weevil about three eighths of an inch long with a very long, slender snout that in females is nearly as long as the body. The grub is a creamy white, legless larva with a reddish brown head that feeds inside the nut. Round emergence and exit holes about an eighth of an inch across in the shell are a telltale sign.
🥀 Damage it causes
Before the shell hardens, adults puncture and feed on the nuts, which causes them to stain and drop. After the shell hardens, females lay eggs inside, and the grubs eat out the kernel, leaving the shell packed with frass, with one to several grubs destroying the nutmeat. Both kinds of injury can cause heavy crop loss in a bad year.
🛡️ Prevent it
Monitor from late July with trunk-mounted Circle traps or pyramid traps and by jarring limbs to detect emerging adults, since timing control to emergence is essential. Gather and destroy dropped and infested nuts to kill the grubs before they leave to enter the soil. Because larvae burrow several inches down and the cycle spans years, sanitation steadily lowers the local population.
🧯 If it is already here
Treat the canopy when monitoring shows weevils emerging, generally with carbaryl or a labeled pyrethroid, repeating at roughly seven to ten day intervals through the emergence period, especially after rains that bring more adults out. Before shell hardening, treat if nut drop from adult feeding is high; after shell hardening, treat as adults emerge to prevent egg laying. Backyard control is difficult on large trees, so trapping and sanitation are important partners to any spray.
💡 Good to know
The pecan weevil takes two to three years to complete one generation, emerging from the soil mainly from August into September after rain softens the ground, with peak emergence often between mid-August and late September. After feeding inside the nut, grubs drop and burrow several inches into the soil, where they remain for one to two years before pupating. Hosts are pecan and hickory, the two nuts whose kernels the grubs develop in.
🌱 Plants it attacks
3 plants in the library can be attacked by this pest
For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.