Black Vine Weevils

(Otiorhynchus sulcatus)

Description

While both the Vine Weevil and its larvae will feed on African Violets, it is the larvae which are most damaging. The adult Vine Weevil is a dark gray beetle about 3/8 inch in length. It feeds by night, eating large, irregular-shaped holes in the leaves which start from the edge. All Vine Weevils are female, so all have the capacity for laying eggs. Its larvae are white with brown heads. The larvae generally measure about 1/2 inch in length and have no legs. These larvae will burrow in the soil and feed on the roots of African Violets until they work their way up to the main stalk. If left untreated, the larvae will be fatal, while the adult Vine Weevils will strip your Violet of its leaves.

Distinguishing Symptoms

• Visible insects or other pests. The adult Vine Weevil is a dark gray beetle which measures about 3/8 inch in length. Its larvae are white with brown heads. These generally measure about 1/2 inch in length and have no legs. Look for larvae burrowed among the roots.

If your African Violet has this symptom, it probably has Black Vine Weevils.

Other Symptoms

• Leaves are damaged. This damage is caused by the adult Vine Weevil as it feeds on the foliage.
• Leaves have holes in them. They may appear to have been eaten. Vine Weevils chew large, irregular-shaped holes in the leaves, starting from the edge.
• Leaves wilt. They may appear translucent brown with a soft, jelly-like consistency. If Vine Weevils are at work, this will most likely be a symptom of its larvae as they eat their way through the roots.
• Leaves darken. They appear brown or black in color. This is probably a symptom of the larvae.
• Plant growth is slow.

Treatment

If the infestation is not too heavy, you may be able to remove both the Vine Weevil and its larvae by hand. Look for the adult Vine Weevil among the leaves or among the leaf and flower debris which have settled on the surface of the soil. Look for its larvae among the roots.

If the infestation is too heavy to handle in this way, spray with Diazinon (as directed on the label). When treating for adult Vine Weevils, spray again, in one month, in order to get any emerging larvae.

Prevention

Remove any leaf and flower debris which has dropped into the soil. This is where Vine Weevils typically find shelter.

Important Note on the Use of Pesticides

Please note that almost all pesticides are formulated for specific uses and conditions. When applied incorrectly, pesticides can cause ill health or damage to plants. Therefore, when using any kind of pesticide or chemical treatment, always apply as indicated on the product label.

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