Black Vine Weevils
Identification and Control of Weevils
Remove mulch and other plant debris to eliminate hiding places from around plants. If they are a voracious problem cut down on watering, water only when necessary as they prefer moist damp conditions. Hand removal of weevils is somewhat effective in small plantings or container gardens. Remember they are nocturnal and won't be seen much in daylight.
For ornamental plants place burlap, or even plywood around the tree and shrub bases to trap weevils that hide under it during the day. Remove the burlap periodically and slaughter the little buggers. Another trap is known as a pit fall trap, which is easily made by placing a paper or plastic cup in the ground, leaving the rim at soil level. Bend a piece of paper to a cone shape near the top and insects will slide down into the cup filled with water and drown.
Milky Spore is another weapon in the war against weevils , it is not harmful to beneficial insects, birds, bees, pets or man. The product is approved and registered with the EPA, Milky Spore will not affect wells, ponds or streams. As larvae and grubs burrow through the soil, feeding -they ingest the spores . The spores germinate inside the grubs, and multiply rapidly in their blood. When the bacteria become very numerous in the blood they again form spores, completing the bacterial cycle. Infected grubs survive for 7-21 after their blood has become loaded with spores, particularly in low temperatures. As the grub carcass decomposes, it releases billions of new spores. It is only effective against newly hatched larvae within the soil, not once they enter the plant.
Bacillius thuringiensis [Bt] is somewhat effective against the larvae stages it should be applied as soon as the presence of adults is evident, to head off the imminent egg laying and hatched larvae.
In severe infestations, there are a number of broad spectrum pesticides registered for use against weevil, sold under varying trade names. Acephate is one I would recommend. Bonide 941 and 951, Orthene 97.4% Acephate and Agrisel are a few brands readily available to home gardeners.