The presence of holes in your pecans is most commonly a sign of pecan weevil infestation, a pervasive pest that damages nuts from the inside out.
Understanding Pecan Weevil Damage
Pecan weevils ( Curculio caryae ) are a primary culprit behind holes in pecan shells. These insects undergo a specific life cycle that directly leads to the characteristic damage you observe:
- Internal Development: Adult female weevils lay eggs inside developing nuts during the summer. Once hatched, the legless, white larvae develop and feed within the individual pecan, consuming the kernel. This internal feeding remains unseen until the larvae are mature.
- Exit Holes: After the larvae mature, they chew their way out of the pecan. They exit through distinct, BB-sized holes in the shell. These holes are the most obvious indication of their presence and departure.
- Pupation: Upon exiting the nut, the mature larvae drop to the ground and burrow into the soil, where they pupate. They typically spend one to two years in the soil before emerging as adult weevils, ready to infest new crops.
This process results in pecans that appear normal externally until the larvae emerge, leaving behind the tell-tale holes and often a hollow or damaged kernel.
Identifying Pecan Weevil Infestation
Beyond the visible holes, other signs can indicate a pecan weevil problem:
- Premature Nut Drop: Infested nuts may drop from the tree earlier than uninfested nuts.
- Damaged Kernels: Even without visible exit holes, opening a suspect nut might reveal a shriveled, discolored, or completely consumed kernel.
- Frass: While less common for weevils, sometimes powdery residue (frass) might be present inside heavily damaged nuts.
Management and Prevention Strategies
Effective management of pecan weevils involves a combination of cultural practices and, if necessary, chemical controls.
- Sanitation:
- Collect Fallen Nuts: Regularly gather and destroy fallen nuts, especially those dropping prematurely. This helps remove weevil larvae before they can burrow into the soil and continue their life cycle.
- Tillage: Light tillage around pecan trees in late fall or early spring can expose overwintering larvae and pupae to predators and harsh weather, reducing populations.
- Monitoring:
- Pheromone Traps: For commercial growers, monitoring adult weevil populations with traps can help determine the timing of insecticide applications.
- Jarring Method: For individual trees, placing a light-colored sheet under the tree and gently jarring branches can dislodge adult weevils, making them visible for collection and destruction.
- Chemical Control (If Necessary):
- Timing is Key: Insecticide applications are most effective when adult weevils are active and before they lay eggs in the nuts. This typically occurs from late July through August, depending on your region.
- Consult Local Extension: Always consult your local agricultural extension office for the most current recommendations on approved insecticides and application timings for pecan weevils in your area. They can provide specific guidance tailored to your climate and tree type.
- Examples of Resources: For detailed information on pecan weevil management, resources from university extension services, such as the University of Georgia Extension or the Texas A&M AgriLife Extension, often provide comprehensive guides.
Table: Stages of Pecan Weevil Damage
| Stage of Damage | Characteristics | Hole Presence? |
|---|---|---|
| Larval Development | Larvae feed inside the nut, unseen externally. | No |
| Larval Exit | Mature larvae chew out of the nut. | Yes |
| Post-Exit Damage | Nut often hollow or with shriveled kernel inside. | Yes |
By understanding the life cycle of the pecan weevil and implementing appropriate control measures, you can significantly reduce the incidence of holes in your pecans and protect your harvest.
