Curculio caryae

Distinguished from other Curculio species by its obligate association with Carya nuts and specific morphological proportions. Adults can be identified by the combination of medium-brown coloration and proboscis length approximately equal to body length. Larval exit holes in pecan shells are clean, round, and BB-sized—diagnostic of pecan weevil infestation when found on fallen nuts. Monitoring using pyramid traps, wire cone traps, or circle traps placed on tree trunks can confirm adult presence.

Adults are medium-brown beetles approximately 9.5 mm (3/8 inch) long with a proboscis of equal length to the body; mouthparts are located at the distal end of the proboscis. Larvae are legless, creamy-white grubs with reddish-brown head capsules, reaching up to 15 mm (3/5 inch) at full growth.

Pecan orchards and native stands of hickory and pecan (Carya species). Adults are found in tree canopies during the nut development period; larvae develop within nuts. Immature stages occur underground in soil cells where larvae burrow 4–12 inches deep to pupate and overwinter.

Native to North America; present throughout most of Texas and pecan-growing regions of the United States and Canada, including Ontario and Québec. Distribution corresponds closely with commercial and native ranges of Carya illinoinensis and other Carya species.

Adults emerge from soil from mid-August through early September, with peak emergence from late August through early September; emergence may be delayed by drought conditions. Adult activity continues through fall. Larvae emerge from nuts beginning in late September and continuing as late as December.

Obligate feeder on nuts of North American hickories and pecans (Carya species). Adults feed on developing pecan nuts. Larvae feed exclusively inside nuts, consuming the kernel. Has been observed to infest Persian walnut (Juglans regia), though this is not a primary host.

• Carya illinoinensis - primary hostpecan; economically most important host
• Carya species - primary hosthickories
• Juglans regia - secondary hostPersian walnut; observed but not primary

Complete metamorphosis with an extended life cycle typically requiring two years, though approximately 10% of individuals require three years. Adults emerge from soil, feed on nuts, and oviposit into developing kernels. Eggs hatch into larvae that feed inside nuts for about 42 days. Full-grown larvae exit nuts through chewed holes, drop to ground, and burrow 4–12 inches into soil to construct cells where they remain 8–10 months. Most pupate and transform to adults within weeks, but adults remain in cells until the following summer. Some larvae delay pupation for an additional year.

Adults are relatively sedentary, with mean movement distance less than 30 meters over 2–3 week periods, though some individuals disperse greater than 100 meters. More adults crawl to tree trunks than fly; a proportion flies directly from orchard floor into canopy. Majority of movement occurs at dusk. Vertical distribution within canopy is generally uniform, though more individuals are captured near tree tops when flying between trees.

Specialized herbivore of Carya nuts; significant pest in agroecosystems. Limited adult dispersal may constrain natural spread between orchards. Population dynamics influenced by soil conditions affecting emergence timing.

Major economic pest of pecan production, causing crop loss through adult feeding and oviposition that causes nut drop, and larval feeding that destroys edible kernels. Infestations are often localized and vary within orchards. Management relies on monitoring emergence with traps and applying foliar insecticides when adults are present and nuts reach gel stage. Early harvest before larval exit can reduce infestations. Transport of infested nuts can spread weevils to uninfested areas.

• Conotrachelus nenupharplum curculio; also a curculionid nut/fruit pest with elongated rostrum, but attacks rosaceous fruits (stone and pome fruits) rather than Carya nuts, and has different host associations and geographic range
• Sitona hispidulusclover root curculio; another curculionid agricultural pest, but feeds on alfalfa and clover roots rather than tree nuts, and has different life history and habitat

• agricultural pest
• nut pest
• Curculionidae
• Coleoptera
• North America native
• biennial life cycle
• economic pest
• pecan
• hickory

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Insects that feed on the pecan nut - AgriLife Extension Entomology
• Insects and mites that feed on leaves - AgriLife Extension Entomology
• Managing Insect and Mite Pests of Commercial Pecans in Texas - AgriLife Extension Entomology
• Bug Eric: February 2009
• Clover Root Curculio: Historic Perspectives Guide Modern Management
• Plum Curculio: New Guide Gathers IPM Recommendations for North American Fruit Pest
• Movement of adult pecan weevils Curculio caryae within pecan orchards