Curculio occidentis

Casey, T.L., 1897

filbert weevil, California Acorn Weevil

Curculio occidentis, the filbert weevil, is a weevil native to western North America. It is primarily known as a seed of oak acorns, with documented on Garry oak (Quercus garryana), coast live oak (Quercus agrifolia), and other oak species. The species has also been recorded feeding on hazelnuts (Corylus avellana), though it generally prefers oak species and rarely causes economic damage to commercial hazelnut crops. Females lay small batches of 2-4 in developing acorns; larvae feed on kernels and exit in autumn to pupate in soil, potentially remaining for 1-2 years before .

1916. Curculionidae. Balaninus sp. Larvae in Quercus californica acorns. (36063345802) by R6, State & Private Forestry, Forest Health Protection. Used under a Public domain license.

Kaldari Curculio occidentis 01 by Ryan Kaldari. Used under a CC0 license.

Pronunciation

How to pronounce Curculio occidentis: /kʊərˈkjuːlɪ.oʊ ˌɒksɪˈdɛntɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

possess the characteristically elongated rostrum typical of Curculio weevils, with jaws at the tip used for drilling into acorns. Larvae are creamy white, legless that develop within acorn kernels. Specific diagnostic features distinguishing C. occidentis from other North American Curculio are not documented in available sources.

Images

Habitat

Oak woodlands and forests; specifically associated with acorn-bearing oak trees. Within-tree distribution varies with acorn crop abundance: during low crop years, occur uniformly throughout the crown; during high crop years, infestations concentrate in lower crown levels.

Distribution

Native to western North America. Range includes British Columbia (Canada), California, Arizona, New Mexico, Utah (United States), and Mexico.

Seasonality

activity coincides with oak acorn development. Larvae exit acorns in autumn when acorns fall. Adults emerge from soil chambers in spring, synchronized with oak leaf-out and new acorn production. Extended of 1-2 years in soil has been observed.

Diet

Developing kernels of acorns, primarily of oak (Quercus spp.). Documented include Garry oak (Quercus garryana) and coast live oak (Quercus agrifolia). Also feeds on hazelnuts (Corylus avellana), though with lower economic impact.

Host Associations

Quercus garryana - primary Garry oak; up to 66% acorn recorded in British Columbia
Quercus agrifolia - Coast live oak; higher rates in lower crown
Corylus avellana - secondary European hazelnut; rarely causes economic damage

Life Cycle

Complete . laid in developing acorns hatch into larvae that feed on kernels. Fully developed larvae tunnel out of acorns in autumn, fall to ground, and excavate soil chambers. occurs after 1-2 years of dormancy. emerge in spring and climb to tree to feed and reproduce.

Behavior

Females drill holes in acorn husks using rostrum jaws to deposit small batches of 2-4 . Within-tree distribution patterns shift based on resource availability: uniform crown distribution during low acorn production years; preferential use of lower crown acorns during high production years.

Ecological Role

Seed of oaks. Reduces acorn germination success: heavily damaged acorns fail to germinate; lightly to moderately damaged acorns show reduced germination but unaffected seedling growth if germination occurs. rates have reached 80.7% in some Garry oak .

Human Relevance

Considered a pest of oak trees due to acorn damage. Minor relevance to hazelnut production; generally prefers oak over commercial hazelnuts. Management research limited compared to other Curculio species.

Similar Taxa

Curculio obtususHazelnut weevil; eastern North American counterpart with similar and appearance
Curculio nucumEuropean hazelnut weevil; similar ecological role in European hazelnut production
Cydia latiferreanaFilbertworm moth; co-occurs on oak acorns and causes similar damage, though Lepidopteran rather than Coleopteran
Curculio glandiumAcorn weevil; similar acorn-feeding in European and eastern North American oaks