Large evergreen shrubs, laurels grow well in hedgerows or screens. Grow different types of laurels, ranging from English laurel to the Mountain laurel to the Cherry laurel. A variety of pests, both annoying and serious, infest laurel shrubs. Control methods for insects vary, but before starting insect control measures, properly identify the pest.
Black Vine Weevil
As grubs, black vine weevils (Otiorhynchus sulcatus) feed on the root systems of shrubs, often girdling the plant and causing the leaves to yellow and then turn brown. Severely damaged plants can die. Adult black vine weevils feed nocturnally on laurel foliage, creating unsightly notching on the leaves. Black adult weevils grow about ½ inch long with segmented bodies and do not fly.
Bark beetles, particularly the shothole borer (Scolytus rugulosus), often overrun laurel shrubs. With their strong jaws for chewing, these borers eat into the inner wood of laurel trunks and branches. According to the University of California, a shrub infested with shothole borers excretes gum from woody parts. In addition, the presence of boring dust indicates bark beetles. Twigs may also die back.
Two different categories of scale, armoured and soft, also infest laurels. Armoured scales have a flat, hard covering over the actual insect. Unlike soft scales, these scales do not excrete the sticky substance called honeydew. Oleander and greedy scale feed on laurel. A large infestation causes some wilting and yellowing of leaves, as well as cracking in the bark.
Soft scales grow bigger than armoured scales and appear cottony or waxy. With no covering over their insect bodies, they expel honeydew as they feed on plant tissues. Soft scales on laurel include brown and frosted soft scale. While scales in general do not seriously harm laurels, high amounts of honeydew cause black soot fungus to form.
Control some insects by spraying insecticides. Others, like the black vine weevil and the shothole borer require different measures. To combat an infestation of black vine weevils, according to the Connecticut Agricultural Experiment Station, first treat the soil around the base of the laurel with insect pathogenic nematodes for larvae control and then use other insecticides if necessary.