Diaprepes Root Weevil

In 1964 this weevil was accidentally introduced in the US, state of Florida, where it is presently a major pest of citrus. It was first discovered in southern California in 2005, where it is a pest of citrus, avocado, and nursery stock. In Texas it was found in the Rio Grande Valley in 2000, resulting in a 2001 quarantine, and then in 2009 around Houston. Another sighting in 2019 confirms that it is still in the area. In June of 2022, a new sighting also occurred in Pearland.

The adult citrus root weevil is somewhat variable in size but just over 1 cm (3⁄8 in) in length on average. Its elytra are glossy black with large stripes of tiny yellowish-orange scales, and its head and legs are black. It has adhesive pads on its legs which confer the ability to adhere to very smooth surfaces. The larva is a plump pale grub with a dark head, up to 2.5 cm (31⁄32 in) in length. A female weevil might lay 5,000 eggs, depositing them in clusters on leaves, then folding and gluing the leaves together. After a week the larvae emerge from the eggs, fall to the ground, and burrow down to the roots of the host plant. They feed on the roots for several months, which is very damaging to the plant. While the adult weevil does feed on the foliage of the plant, it is the larvae that do the most damage. They often eat the taproot of the plant, which can kill it by depriving it of water and nutrients or by making it vulnerable to infection by fungi, or water moulds such as Phytophthora. The weevil spreads mainly by "hitchhiking" when infested plants, soil, and containers are moved from site to site.