# Acorn weevil (Curculio glandium) > A small, long-snouted beetle whose larvae develop inside acorns, often reducing seed viability but posing no danger to people. Source: https://insectscanner.com/species/acorn-weevil/ (updated 2026-10-10) ## Is it dangerous? **Non-toxic.** Acorn weevils do not sting or bite people and are not considered medically significant. Handle gently if needed; the tiny rostrum and mandibles are not dangerous. **Pets:** The weevils are not toxic to pets, and a pet that eats a larva is unlikely to be harmed. Acorns themselves, however, can upset a dog's stomach or cause a blockage if eaten in quantity, so discourage pets from chewing fallen acorns. ## Quick facts - Scientific name: Curculio glandium - Also called: Oak acorn weevil - Order: Coleoptera (Beetles) - Family: Curculionidae (Weevils) - Size: 4-8 mm body length (rostrum adds additional length) - Colours: Brown, Grey-brown, Cream (larva) - Habitat: Oak woodlands, parks and hedgerows where oaks (Quercus species) produce acorns - Range: Primarily Europe and parts of western Asia where host oak species occur - Active: Adults active in late spring to summer when acorns are developing; larvae present inside acorns in summer and autumn, then overwinter in the soil before pupating - Lifespan: Adults live for weeks to a few months; the full life cycle usually takes one to two years because larvae can stay in the soil for more than one winter - Effect on plants: Seed predator - Pest: no ## Overview The acorn weevil Curculio glandium is a small beetle in the true weevil family (Curculionidae) that specializes on oak acorns. Adult females use a long rostrum (snout) to drill a hole in developing acorns and deposit single eggs. The legless white larvae (grubs) consume the acorn kernel, exit in autumn, and overwinter in the soil, where they later pupate. Populations are generally univoltine (one generation per year) and are most noticeable where oak trees produce many acorns. ## How to identify it Adults are compact, oval beetles with a pronounced curved rostrum. They are typically 4-8 mm long (body not including rostrum). The body surface is covered with fine scales or hairs giving a mottled brown to grey appearance that helps camouflage them on bark and leaf litter. Legs and antennae are short; the antennae arise partway along the rostrum as is typical for weevils. Larvae are creamy-white, C-shaped grubs without legs, with a brown head capsule. - Look for a small (4-8 mm) oval beetle with a distinct long rostrum (snout) pointing forward. - Mottled brown-grey scale-like patterning on the elytra and body helps camouflage the beetle on bark and leaf litter. - Find evidence in acorns: small neat exit holes or a legless grub inside usually indicates Curculio species. - Timing: adults are most often seen on or near oak trees in late spring and summer during acorn formation. ## Lookalikes - **Hazelnut weevil** (Curculio nucum): Prefers hazelnuts (Corylus) rather than acorns; slightly different host and often a different body shape/size on close inspection. - **Chestnut weevil** (Curculio elephas): Attacks chestnuts and has different host preference and regional distribution; look at the host nut and local species lists to separate them. ## Life cycle - **Egg:** Females chew a hole in a developing acorn with their rostrum and deposit a single egg under the shell. - **Larva (grub):** A white, legless grub that feeds on the acorn kernel. When mature it chews an exit hole and drops to the ground in late summer or autumn. - **Pupa:** After dropping from the acorn the larva burrows into the soil and overwinters there, often for one or more years, before pupating in the following summer. - **Adult:** Adults emerge from the soil, climb host trees, and feed and mate while females bore into developing acorns to lay eggs. ## Diet and predators - Young eat: Acorn kernel (oak seeds) - Adults eat: Adult weevils feed on oak foliage and acorn surfaces; some species feed little as adults and concentrate on reproduction - Predators of the young: Birds, small mammals (that open acorns), and parasitic wasps and flies that can attack larvae or eggs - Predators of adults: Birds, predatory insects, and spiders ## Effect on plants and gardens Larvae consume the seed inside acorns and can greatly reduce the number of viable acorns produced by infested trees; usually not a major threat to mature oak health but can reduce natural oak regeneration and seed crop quality. ## Where and when to find it Look on oak trees (leaves, branches and developing acorns) in late spring and summer; inspect fallen acorns in summer and autumn for exit holes or grubs. - Best time: Late spring to autumn; daytime for adults on trees, autumn for finding fallen infested acorns. - Tips: Carefully open suspect acorns to check for a grub; photograph adults on acorns or bark from a short distance to capture the rostrum and body pattern. ## Fun facts - Female acorn weevils use their long snout both to find a suitable spot and to drill a hole in the acorn for egg-laying. - Females usually lay one egg per drilled hole, so many infested acorns hold a single larva, although one acorn can contain several. - Acorn weevil infestations can influence oak regeneration and affect animals that rely on acorns by reducing the number of sound seeds available. ## Frequently asked questions ### Are acorn weevils dangerous to people? No. They do not bite or sting and are not poisonous. They are harmless to people. ### Do acorn weevils ruin acorns? Yes. Larvae consume the acorn kernel and make the seed non-viable; infested acorns often have an exit hole or one or more grubs inside. ### Why are acorn weevils in my yard? If you have oak trees producing acorns, acorn weevils are attracted to the developing nuts to lay eggs. You will notice them more in years with heavy acorn crops. ### How do I get rid of acorn weevils? Collect and destroy or remove fallen acorns in autumn before larvae burrow into the soil. Netting small trees during acorn development can reduce egg-laying. Widespread chemical control is rarely needed or practical. ### Can acorn weevils kill my oak tree? Unlikely. They reduce seed viability but do not normally harm mature oak trees. Heavy, repeated infestations could affect natural regeneration of young oaks. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/148145), [Wikipedia](https://en.wikipedia.org/wiki/Curculio_glandium). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.