This is a newsletter with practical suggestions. It will be updated often. Please revisit it.

Black vine weevils

June 25, 2003

Black vine weevils are black beetles, about ½ inch in length. They cannot fly, allowing them to migrate only by walking. Black vine weevils infest greenhouses by climbing wallsand entering through cracks..  They infest ornamentals in gardens by walking in.  Black vine weevils avoid grass, preferring to be on or around cemented areas. They are nocturnal insects, feeding on foliage at night, leaving notches in the leaves of the plants.

The larvae are about 3/8 inch long, white, legless insects with a light brown head, in the shape of a "C". Larvae primarily feed on roots. Outdoors they damage the roots of plants like rhododendrons, azaleas, hemlocks, and berries. They are commonly known as pests of ornamentals indoors, damaging the roots of plants like begonias, ferns, carnations, orchids, and especially cyclamens.

	Black vine weevil http://www.forestry.ubc.ca/fetch21/ FRST308/lab3/otiorhynchus_sulcatus/vine.html		Black vine weevil larvae showing damage to roots http://www.forestry.ubc.ca/fetch21/ FRST308/lab3/otiorhynchus_sulcatus/vine.html

Strawberry root weevils look like smaller black vine weevils. They are about ¼ inch in length and are more of a brown color with a protruding snout. They also, are unable to fly. The grubs are about 3/8 inch long, white, legless insects with a light brown head.

	Leaf notches shown as damage from adult weevils http://www.uga.edu/

Often gardeners never see weevils, only symptoms of their damage.  Symptoms of black vine weevil damage start with notched leaves, but may include leave wiltdue to root damage, despite  moist soil. Potted plants may become loose in the pot, caused by root disintegration. Infested plants should be thrown out because plants are past saving. Symptoms of strawberry root weevil damage include stunted plants, leaves bunched tightly together, and roots or crowns eaten off.

Root weevils are very difficult to control, considering they have few predators. To prevent greenhouses from becoming infested with black vine weevils, tightly seal walls, floors, roofs, and doors to prevent entrance of insects. Sticky tapes can be applied to legs of table to prevent weevils from climbing up the tables. Outdoors tanglefoot around ornamental  trunks can stop adult climbing.  To prevent strawberry root weevil damage, destroy old beds, rotating fields annually. If weevils are already present, try to isolate infested plants from healthy ones. Chemicals such as orthein or isotox can be sprayed as a soil drench to control adult populations in the soil. Merrit (imidacloprid) can be used as a soil drench or in combination with beneficial nematodes. Insect eating nematodes, such as Steinernema feltiae or beter still Heterohabditis bacteriophora can be used as a biological control to kill black vine weevils and strawberry root weevils. Nematodes are easily mixed with potting soil or peat moss for application in greenhouses or houseplants, or as a topdressing around shrubs and outdoor plants.

Text copyright ©2003 by BioLogic Company

Others are welcome to link to this site or copy intact versions with all links.