Predatory Nematode
You use this approach a year after you have struggled with weevils on one or more landscape plants. They will have laid their eggs in the soil directly below the plant. Applying predatory nematodes is one of the best techniques for dealing with weevils which are always tough to control using a spray insecticide. Predatory nematodes will go down into the soil seeking out the larvae of the weevil, thus knocking them out before they even become adults able to eat the leaves of the landscape plant. Release them early in the season when the soil has warmed up; around planting time for tomato seedlings. .
For detailed information see the file Using Predatory Nematodes
Diatomaceous Earth (D.E.)
Diatomaceous earth (D.E.) is a fine powder that is made of crushed microsopic sea shells, creating very sharp edges that don’t hurt us, but do serious damage to the shell of the weevil. Dust D.E. around the base of the plant to create a barrier for the pest, or dust the whole plant with D.E. Dusting should progress upward from the ground, covering all stems and leaves, especially the undersides of leaves. Apply D.E. in late evening or at night, and predator insect destruction will be low.
For detailed information see the file Using Diatomaceous Earth