Saturday, July 11, 2009

Landscape - Black Vine Weevil

Black vine weevil will be laying eggs soon in the landscape. The following is more information of this pest which is a big problem on Rhododendrons in DE.

Black vine weevil adults [87-3644 (1259 peak) GDD base 50] feed on over 100 plants such as Taxus, hemlocks, euonymus, mountain laurel and rhododendrons. Magnolia x soulangiana in full bloom signals the beginning of adult activity. This flightless weevil feeds during the night and rests at the base of plants during the day. Adults are gray to brownish black. Larvae are c-shaped, legless, and creamy colored with brownish heads. Larvae feed in early spring and emerge from pupae in late-May to June. Adults (all female) feed for 21-45 days before egg laying in July when each female oviposits about 200 eggs in the soil or leaf litter around the plant. Adult feeding appears as notches on leaves. Larvae prefer to feed on young roots, but scarce roots and moist soil results in stem feeding that can eventually girdle plants. Larvae feed until soil temperatures force them to dig deeper to overwinter.

Black vine weevil adult. Photo by Mike Reding & Betsy Anderson, USDA Agricultural Research Service, Bugwood.org

Adult black vine weevil feeding appears as notches on leaves. Photo by Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org

Black vine weevil larvae. Photo by Mike Reding & Betsy Anderson, USDA Agricultural Research Service, Bugwood.org

Information from Brian Kunkel, Ornamental IPM Specialist, UD

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