Caribbean Root Weevils

According the The University of Florida IFAS, this root weevil which is native to the Caribbean was first reported in Florida in 1964 from a nursery near Apopka. It was presumably introduced in an ornamental plant shipment from Puerto Rico. Since 1964, Diaprepes abbreviatus or Root Weevil, has spread over a large area of central and southern Florida where it is damaging to citrus, ornamental plants, and some other crops. It is estimated that Diaprepes abbreviatus causes about 70 million dollars in damage annually in Florida. Estimates show the weevil infests more than 100,000 acres of citrus.

These adult Florida weevils vary in length from 0.95 to 1.90 cm (3/8 to 3/4 inch). They are black, and overlaid by minute white, red orange, and/or yellow scales on the elytra (wing covers). These scales are often rubbed off of the tops of ridges on the elytra giving the appearance of black stripes on a light colored background. Adults emerging from pupae in the soil are armed with a pair of deciduous mandibles which break off as they tunnel through the soil to get above ground. Scars at the site where the deciduous mandibles break off are visible under a microscope.

Life Cycle of the Caribbean Root Weevil

A single Diaprepes abbreviatus female can lay up to 5,000 eggs in her three to four month long life. Eggs are laid in clusters of 30 to 265 and enclosed within leaves that have been folded and glued together, or within two leaves glued together. In seven to eight days the neonate larvae emerge from eggs, leave the cluster and fall off of the leaves onto the ground. The larvae then enter the soil and search for and feed on the roots. After feeding for several months, the mature larvae pupate in the soil. Adults emerge from the soil, seek a host and mate as conspecifics gather on the host. The complete life cycle varies in time depending on nutritional and environmental factors.

Although adults can emerge year round, their primary emergence period is May through October and November in central Florida. It is suspected that their seasonality in South Florida is quite different because of the similarity with the Caribbean, where it can be found throughout the year.

Adults do not fly far from the spot where they emerged from the soil (estimated to be less than 300 m). Therefore, long distance dispersal is through the movement of contaminated soil and containerized plants containing potentially all life stages of the weevil. In addition, soil residues on vehicles may be contaminated with larvae.

Adults do not fly far from the spot where they emerged from the soil (estimated to be less than 300 m). Therefore, long distance dispersal is through the movement of contaminated soil and containerized plants containing potentially all life stages of the weevil. In addition, soil residues on vehicles may be contaminated with larvae.

Damage Caused

Notching along the margins of young leaves is a telltale symptom of the presence of Diaprepes abbreviatus adults, or other related root weevils. However, other pests such as grasshoppers and caterpillars may produce similar damage. Therefore, it is best to look for a sign, such as the pest doing the damage. Look for Diaprepes abbreviatus adults during the day on the foliage. Shaking the plant may aid in detection as adults fall off of the plant onto the ground. A light colored piece of canvas placed beneath the plant before shaking is useful. Do not look immediately after a heavy rain, which usually knocks weevils off of the plant.

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