(Taken from an article written by Jessica Strickland, Extension Agent Wayne County, NC)

Time to Manage Pecan Weevils

August through September is the time of year to manage pecan weevils as they begin to emerge from the ground and into pecan trees. Large infestations of pecan weevils can cause significant losses of pecans, and homeowners should be aware of their identification and activity.

Identifying Pecan Weevil Damage

The pecan weevil causes two types of damage.

Adult Pecan Weevil Damage

The first type is when the adult weevils puncture the nuts in early August, resulting in premature drop and unfilled pecans. The adult pecan weevils are grey/reddish-brown beetles with long slender snouts and thin legs.

Larval Pecan Weevil Damage

The second type of damage is caused by larval feeding within the nut. Adult female weevils will lay eggs inside pecans, with the resulting larva feeding on the nut inside. Larvae will then chew a circular hole through the shell, exiting the nut, and burrowing into the soil to pupate until next year. Larvae can be distinguished as creamy white, legless grubs with reddish-brown heads.

Monitoring Pecan Weevil Activity

Weevils typically emerge from the soil during a two-month period from August through September, so monitoring for emergence can help with control. A simple way to monitor is by inspecting nuts that have dropped to the ground and looking for dark spots that resulted from feeding through the husk. Weevil feeding may also cause the shell to stick tightly to nuts creating difficulties at harvest.

Control Methods for Pecan Weevils

If you decide to use insecticide to control the pecan weevils, applications should be made every 7 to 10 days (depending on product label recommendations) from mid-August through mid-September using a carbaryl (Sevin) insecticide.

Chemical Control with Insecticides

In commercial orchards where control is important, specialized equipment such as air blast sprayers and aerial applications may be used. For homeowners, this equipment far exceeds reasonable expense and most homeowners cannot reach into the canopy to make an effective insecticide application.

Sanitation and Cultural Practices

An alternative control method is to gather and destroy weevil-infested nuts as soon as they fall to prevent the larvae from entering the ground and hanging around until the next growing season. After several seasons of such sanitation practices, you can reduce the potential population of weevils around your trees. However, since pecan weevils can fly, no control method can completely eliminate weevils from the environment.

Trapping Adult Pecan Weevils

To monitor and trap active adults, you can wrap burlap around the trunk of trees creating a fold of material. As insects crawl up the trunk they will be slowed by this fold and can be removed. The addition of tanglefoot gel to this burlap may also trap a few more insects, but will also trap more debris and other small insects. Do keep in mind that many pecan weevils can fly into trees, so traps have limited effect.

Additional Resources

If you would like more information on pecan weevils and their control you can contact Daniel Simpson at (252) 745-4121 or Daniel_simpson@ncsu.edu.