Laurel plants are large plants that add dark green leaves and attractive flowers to the garden. This type of plant produces flowers annually. While the laurel is attractive to people, it can also become attractive to harmful insects that weaken it and spread disease to the laurel. Controlling black vine weevils is key to a healthy plant.
Black vine weevils
Black vine weevils are small black insects that feed on the leaves of many plants, from trees such as the yew to shrubs and flowering plants such as the laurel. Black vine weevils are about 9.5mm / 3/8 of an inch long and have blackish or brown bumpy bodies. These weevils feed on a host plant throughout their life cycle, from the time they hatch as grub-like larvae.
Black vine weevil larvae feed on the roots and stems of plants such as the laurel, weakening the plant's growth and preventing it from receiving the nutrients it takes in from the soil. Large infestations of black vine weevils have the potential to kill off a laurel plant by girdling and killing its roots. Adult black vine weevils feed on the leaves of laurel plants, stopping the laurel from photosynthesising and making it more susceptible to diseases.
Apply spray pesticides to the laurel plant and the soil around it to kill adult black vine weevils; during the day, the beetles may leave the plant and begin attacking it again after the pesticides wear off. Spray pesticides according to the directions on the package for the best results. Pesticides applied as a drench to the laurel and the soil help kill off eggs and larvae, according to the North Carolina State University Extension.
Cultural and Biological Controls
Prune the laurel plant each spring to remove weak or dead limbs from the plant. Weaker portions of the plant attract harmful insects to the laurel. Keep the ground around the laurel free of dead leaves where the black vine weevils can take shelter. Parasitic nematodes have been shown to be effective for controlling the presence of black vine weevils on various garden plants, according to the North Carolina State University Extension website.