Hickory Nut Curculio: Appearance, Territory, Damage and Life Cycle

Latin Name: Conotrachelus Hioriae

Appearance: If you spend any time at all in the fall picking up hickory nuts or acorns, you’ve probably spotted acorns and nuts with a tidy, little circular hole through the side. This is the hole made by the chubby, white, wrinkled, legless grub that grew within the nut. Insects of many types can be found living within nuts and acorns. The most prevalent are a group of closely related weevils known as “nut weevils.” Nut weevils are dangerous pests of both native and non-native nut plants. While the nuts are still on the tree, these harmful insects begin to damage the kernels in the growing nuts. However, issues are frequently overlooked until the nuts are collected and cracked.

Hosts Plants: Nuts of the Hickory Tree

Territory: The hickory nut curculio is native to North America and may be found in the southern United States. It feeds on hickory tree nuts (genus Carya, which includes pecan trees).

Damage Insect Cause: Adult punctures and larval feeding from within the nut both cause damage. Adults’ punctures (either for feeding or egg-laying) are plainly visible. Larval eating within the nut may cause sap to leak from the puncture holes, resulting in sticky brown deposits on the nut’s surface. After being penetrated, these nuts normally abort and fall off the tree two weeks later. While feeding, these snout beetles pierce the nuts, causing them to abort and fall from the tree. Many households are noticing this summer decline and are unaware that it is caused by an insect. When the adults mate, the females gnaw a hole in the nut’s shell and lay an egg on the inside. The egg will then hatch, resulting in the development of a grub that will feed on the growing kernel. Following eating, the grub cuts a nice spherical hole in the shell, climbs out, and falls to the ground.

Life History and Habits: Adults spend the winter under the soil or litter, emerging in late spring (mid-June to mid-July) and eating on immature nuts via nose punctures. Following mating, female adults use their snouts to produce punctures in which the eggs are placed. After around five days, the eggs hatch, and the larvae eat and develop within the nuts for three to four weeks (late July to late August). However, because hickory nut curculio seldom causes serious economic damage, it is not regarded a major pecan pest, and no population requirements for treatment are set. Insecticides can be used to control their numbers, and they are frequently used during pesticide treatments for the Pecan weevil or third-generation Hickory shuck worm.