Black Vine Weevil
Otiorhynchus sulcatus
📖 Description
The black vine weevil is one of the most important pests of ornamental horticulture worldwide, attacking over 100 species of woody and herbaceous plants. It is particularly devastating in container nursery production and landscape plantings of rhododendrons and yews. While adults cause distinctive notching of leaf margins, the real damage comes from the root-feeding larvae, which can completely destroy the root system of container-grown plants. The species is entirely parthenogenetic — every individual is a female capable of reproducing without mating, meaning a single beetle can start an infestation. They are flightless and spread primarily through movement of infested plant material.
⚠️ Symptoms to watch for
- C-shaped notches chewed from leaf margins by adults,Yellowing and wilting of container-grown plants,White C-shaped grubs found in the root ball,Root destruction causing plant instability and collapse,Severe decline and death of heavily infested container plants
🩹 Treatment
- Apply beneficial nematodes (Heterorhabditis bacteriophora) to moist soil for larval control (organic),Hand-pick adults at night and drop into soapy water (organic),Use acetamiprid or thiamethoxam soil drench for larval control (chemical),Apply bifenthrin or cyfluthrin as a foliar spray for adult control (chemical)
🌿 Organic treatments
- Apply beneficial nematodes (Heterorhabditis bacteriophora) to moist soil for larval control,Hand-pick adults at night and drop into soapy water
🧪 Chemical treatments
- Use acetamiprid or thiamethoxam soil drench for larval control,Apply bifenthrin or cyfluthrin as a foliar spray for adult control
🛡️ Prevention
- Inspect nursery stock carefully for larval infestation before planting,Use sterile potting mix and clean containers for potted plants,Apply nematodes preventively to container-grown plants in late summer,Place burlap bands around plant bases to trap daytime-roosting adults
🪴 Affected plants
- Rhododendron,Yew,Strawberries,Grapevines
🦋 Natural predators
- Beneficial Nematodes,Ground Beetles,Birds,Frogs
🌱 Host plants
- Rhododendron spp.,Taxus spp.,Fragaria × ananassa,Vitis vinifera
🔄 Lifecycle
- Black vine weevils produce one generation per year.
- They overwinter as larvae in the soil or as adults in protected locations.
- Larvae resume feeding on roots in spring and pupate in late spring to early summer.
- Adults emerge from June through August and feed on foliage at night, hiding in soil crevices and debris during the day.
- Females begin laying eggs about 2-3 weeks after emergence and continue for several months, producing 200-800 eggs each.
- Eggs are dropped loosely into the soil near host plants.
📅 Season
- Summer (adults); Year-round in soil (larvae)
🔎 Appearance
- Black vine weevil adults are large, dark brownish-black snout beetles with a distinctive oval body, fused wing covers that render them flightless, and a covering of fine golden-yellow hairs that give them a slightly dusty appearance.
- Their wing covers have distinct rows of small pits and their antennae are elbowed with a clubbed tip.
- Larvae are plump, creamy white, C-shaped grubs with a brown head capsule and no legs, reaching up to 10 mm in length, found in the root zone of host plants.
- The species is parthenogenetic — all individuals are female.
💥 Damage level
- High
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- North America
- Europe
- Asia
- Australia
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