This species belongs to the beetle group but, as with all weevils, possesses a longer snout on their heads than other beetles.
Damage. The larva stage is the most damaging, eating away roots of crops such as cyclamen and begonias in greenhouses, primulas, strawberries, young conifers and vines outdoors, causing above-ground symptoms similar to root diseases such as vascular wilt. Close inspection of the plant's root zone will, however, quickly show the unmistakable white grubs (see Figure 14.18). The adults may eat out neat holes or leaf edges of the foliage of hosts such as rhododendron, raspberry and grapes, and many herbaceous perennials (see Figure 14.18). Several related species, e.g. the clay-coloured weevil (Otiorhyncus singularis) cause similar damage to that of the vine weevil.
Life cycle. The adult is 9 mm long, black in colour, with a rough textured cuticle (see Figure 14.19). The forewings are fused together, the pest being incapable of flight. No males are known. The female lays eggs (mainly in August and September) in soil or compost, next to the roots of a preferred plant species. Over a period of a few years, she may lay a thousand eggs as she visits many plants. The emerging larvae are white, legless and with a characteristic chestnut-brown head. They reach 1 cm in length in December when they pupate in the soil before developing into the adult.
Spread is achieved by the female adult crawling around at night, or by the movement of pots containing grubs.
Control. Amateur gardeners sometimes use traps of corrugated paper placed near infested crops. Inspection of plants at night by torchlight may reveal the feeding adult.
Professional growers have residual chemicals, imidacloprid or chlorpyrifos incorporated or drenched into compost or soil.
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