The bay laurel (Laurus nobilis) is a hardy herb plant that serves as a popular ornamental in mild and warm climates. In addition to growing outdoors, they may be grown in a greenhouse in colder temperatures. Parts of the plants, especially the leaves, are used to season food, while the oil is used in massage therapy and is a common treatment for poison ivy rashes. Once established, the tree is very hardy, though it is susceptible to a few insects and pests.
The bay sucker, also called jumping plant lice, is fairly common among bay trees. If left unchecked, the bay sucker, which feeds on sap, will destroy foliage and may kill a tree. An early symptom of infestation is yellowing leaves and a thickening of the leaf tissue. As the bay suckers begin to multiply, leaves will turn brown before dropping. Growers should look for a pale brown insect about 2 millimeters in size. To control the insects, which will thrive in the soil before moving onto the plant, it is important to remove infected leaves and stems and burn them. This will reduce the chance of further infection or the bugs transferring to other plants. The remainder of the plant, particularly the undersides of the leaves, should be sprayed with an insecticidal soap. More serious infestations may be treated with thiacloprid, which works well against the bay sucker.
There are approximately 8,000 species of scale bugs, pests that are generally between one-eighth and a quarter of an inch in size and tend to cluster together on leaves and twigs. Because of its diversity and small size, identifying scale may prove difficult. The bugs may be soft bodied or armored and may be black, brown, yellow or white. Like the bay sucker, scale rips open leaves and eats the liquid inside, creating unsightly holes, but the bugs are not generally fatal if left unchecked. Growers may fight the problem by introducing natural enemies — ladybugs are favorites — or a good dose of insecticidal soap may also do the trick. A number of pesticides, including poisons and insect growth regulators, are available to treat the problem.
Aphids are common garden pests found in just about every region of the country. They feed on most plant types, and more than 4,000 species cause rapid defoliation and eventual death of the plant. They are visible to the naked eye, and their colors — including green, yellow, black and red — change depending on the species of the plant being eaten. Growers may control aphid populations by introducing natural predators, including ladybugs, wasps or lacewings, or spraying infected plants with an insecticidal soap or insecticide. To prevent problems, growers should remove weeds, fallen leaves and other debris, as these provide a hiding place.
Beetles and Borers
Brown beetles, including the Asiatic garden beetle, are among the most common pests of laurel trees. The bugs are approximately half an inch long and dark brown in color. These pests tend to live on twigs, and they create unsightly holes by feeding on the leaves. They also cause leaves to wilt and turn brown. The severity of the damage may vary depending on the specific species, but it may prove fatal if left untreated. A number of borer species are also damaging to the bay laurel. They most often drill into new growth, causing death. The size and coloring of borers will vary depending on the species, but growers should remove affected stems and branches as soon as a problem becomes evident. Insecticidal soaps are rarely effective, and most pesticides will not kill beetles or borers at all stages of life, so a targeted spray may be required.