Filbert Weevil: Appearance, Territory, Damage and Life Cycle

Latin Name: Curculio Occidentis

Appearance: Curculio Occidentis, sometimes known as the filbert weevil, is a kind of weevil in the genus Curculio. Because of the harm they inflict to acorns, weevils are considered a pest by many kinds of oak trees. He’s barely 1/4 inch long and 1/8 inch wide when he’s dressed in “fur,” with huge black eyes, a long narrow nose, and elbowed antennae.

Hosts Plants: Oak Trees

Territory: Curculio Occidentis is indigenous to western North America. It is found in British Columbia, Canada, California, Arizona, New Mexico, and Utah in the United States, as well as Mexico.

Damage Insect Cause: Filbertworm and filbert weevil larvae devour nut kernels and can cause up to 50% damage if left untreated. Both species produce harm in the same way. The shells of infested nuts have holes, and the kernels have been damaged by feeding and are polluted with excrement.

Life History and Habits: In a growing acorn, the female Curculio Occidentis lays little batches of two to four eggs. The larvae that form feed on the kernel and, when fully formed, tunnel out of the nut, fall to the ground, and excavate a little chamber for themselves. They may not pupate for one or two years. Acorns from Garry oak trees were gathered in 1996, 1997, and 1998 to study pest damage. It was concluded that infection levels did not change with crown level during low crop years but did during high crop years. During the high crop year, affected acorns were more prevalent in the lower portion of the tree than in the upper portion of the tree.

The filbert weevil eats the acorns of a variety of oak trees, as well as the Filbertworm moth’s larva (Cydia Latiferreana). These larvae infected up to 66 percent of Garry oak (Quercus Garryana) acorns in British Columbia. Although these acorns can still germinate, they do so at a slower pace than uninfected nuts.