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Black Vine Weevil

Black Vine Weevil

Otiorhynchus sulcatus

Insectalso: Vine weevil, Root weevil, Strawberry root weevil, Taxus weevil

The black vine weevil, known in Britain simply as the vine weevil, is a flightless, night-feeding beetle whose adults notch the edges of leaves while their grubs, hidden in the soil and potting mix, chew the roots and crown - by far the more serious damage. It attacks a very wide range of plants, with rhododendron, azalea, yew, hydrangea, and strawberry among its favorites, and container-grown plants suffer worst, where a heavy grub population can wilt or kill a plant before the weevil is ever seen.

🔎 How to spot it

The adult is a slate-gray to dull-black, hard-shelled weevil about three-eighths of an inch (9 mm) long, its wing cases often flecked with dirty-yellow specks, with a short broad snout. It cannot fly but climbs well and feeds only at night. The clearest adult sign is neat, crescent-shaped notches chewed along the leaf margins. The grub is a plump, white, legless, C-shaped larva up to about three-eighths of an inch long with a pale brown head, found in the soil and root ball. A plant that wilts or declines despite good care, with notched leaves above, often has grubs eating its roots below.

🥀 Damage it causes

Adult leaf-margin notching is mostly cosmetic and rarely affects a plant's vigor, but it is the warning sign of the real threat below. The grubs chew the roots and strip bark from the crown and lower stem, which can girdle and kill the plant - container-grown plants, azaleas, rhododendrons, yew, and strawberries are hit hardest. Grubs can also bore into the tubers of cyclamen and begonia and into the stem bases of cacti and succulents. Most plant losses happen from fall into early spring, when the grubs are reaching full size.

🛡️ Prevent it

Inspect new nursery and container plants for notched leaves and reject infested stock, since that is how these flightless weevils usually spread. Keep plants vigorous so they better tolerate some root feeding, and check the most susceptible pot plants regularly. Sticky barriers around pot rims and greenhouse benches trap the climbing adults, and encouraging natural predators - birds, frogs, toads, and hedgehogs - helps keep numbers down.

🧯 If it is already here

Target the grubs, the most damaging stage, with beneficial nematodes (such as Steinernema kraussei or Heterorhabditis species) watered into moist soil in late summer to early fall, while the soil is still warm enough for them to work. For the adults, go out after dark and shake or beat the foliage over a sheet to dislodge and collect them, or trap them by day under boards and burlap. Repot badly affected container plants, washing the grubs from the roots and into fresh mix, and remove plants killed by heavy feeding.

💡 Good to know

Vine weevils are unusual in that all adults are female and reproduce without mating, each laying several hundred eggs through spring and summer, so a single weevil can seed a serious infestation. There is one generation a year: adults emerge from late spring, feed for a few weeks before laying, and the grubs feed through fall and overwinter in the soil. Because the adults are flightless and feed only at night, the crescent-notched leaves usually show up long before you ever spot the weevil - treat that notching as your cue to check the roots.

🌱 Plants it attacks

225 plants in the library can be attacked by this pest

African MarigoldAgapanthusAgeratum🍓Albion StrawberryAlice du Pont MandevillaAmethyst Falls WisteriaAnemoneAngelique TulipAngeloniaAnnabelle Smooth HydrangeaAnnual VincaApeldoorn TulipApril Tryst CamelliaArizona Sun Blanket FlowerArkin CarambolaAroniaAugust Beauty GardeniaAutumn Joy SedumBachelor's ButtonBalsam FirBarbara Karst BougainvilleaBecky Shasta DaisyBee BalmBenarys Giant ZinniaBengal Tiger CannaBilberryBlack CrowberryBlack CurrantBlack RaspberryBlack-Eyed PeaBlack-eyed Susan VineBlood OrangeBlue Bird DelphiniumBlue Bird Rose of SharonBlue FescueBluecrop BlueberryBoysenberryBrunneraBurning BushButterfly Blue Pincushion FlowerButterfly Marguerite DaisyButterfly WeedCafe au Lait DahliaCaladiumCalendulaCalibrachoaCalifornia Giant ZinniaCalifornia PoppyCampanulaCardinal FlowerCarolina GeraniumCarolina JessamineCatawba GrapeClimbing HydrangeaClimbing Prairie RoseCocktail Vodka BegoniaColeusConcord GrapeCoral Drift Groundcover RoseCosmosCranberryCreeping PhloxCupani Sweet PeaDavid Garden PhloxDelft Blue HyacinthDenim n Lace Russian SageDusty MillerDutch Master DaffodilEastern Red ColumbineEastern White PineElderberryEndless Summer HydrangeaEnglish LavenderEnglish Shelling PeaEvening PrimroseEvergreen HuckleberryFanal AstilbeFeather Reed GrassField PeaFireworks GoldenrodFlamingo Feather CelosiaFlower Record CrocusFountain GrassFoxgloveFreesiaFrench MarigoldGarden GladiolusGarden PrimroseGarden SageGarvinea Sweet Glow GerberaGateway Joe Pye WeedGauraGlobe AmaranthGlobemaster AlliumGlossy AbeliaGoji BerryGoldflame SpireaGoldsturm Black-Eyed SusanGooseberryGraham Thomas English Rose

For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.