Practical Black Vine Weevil Management

Black vine weevil, Otiorhynchus sulcatus F, is the most obviously injurious insect pest of rhododendrons. Rhododendron enthusiasts are disheartened when purchasing precious species or hybrid plants, if they then find that the plant came with unwanted weevils hitchhiking in the roots. If the plant is small, feeding by black vine weevil larvae may cause sufficient root loss to kill the plant, or the larvae may girdle the main stem, with the same result. Larger plants can be affected in other ways. Root feeding can lead to nutrient deficiencies, because poorly functioning roots cannot translocate minerals available in the soil to the foliage. Finally, adult black weevils give plants a ragged appearance by notching the edges of leaves while feeding. This article is an update to my earlier review of black vine weevil biology (Cowles, 1995), and suggests practical approaches for managing this pest in nursery and landscape settings.