Like all widely cultivated plants, palm tree plants have problems specific to each individual species. Gardeners who grow palm trees should always be on the lookout for bugs, as infestations may quickly go from a simple nuisance to a major problem. Despite bug problems, palm plants are still enjoyed across the globe, and many gardeners feel that the exotic, stately trees are worth the effort.
Many palm bugs feed exclusively on a few different species of palms, so it's helpful to know what kind of bugs are attracted to the palm tree. Some of the most common palm bugs include the cabbage palm caterpillar (Litoprosopus futilis), a black and brown caterpillar that nibbles on the cabbage palm (sabal palmetto); the royal palm bug (Xylastodoris luteolus Barber), a yellowish-green, oval-shaped bug that feeds on royal palms (Roystonea regia); and the giant palm borer (Dinapate wrighti), a large beetle that prefers Washingtonia and Phoenix varieties of palms.
Cabbage palm caterpillars feed on the flowers of the palm, leaving an unsightly mess and an overall weakening of the tree. The reddish-brown larvae of the caterpillar leaves unattractive stains across the tree. An infestation of thrips (Order Thysanoptera), which are small-winged insects, may lead to discolored or wilting leaves, or even unsightly trails of black droppings. Young palm leaves that wilt and die early may be the result of the palmetto weevil (Rhynchophorus cruentatus), a black- or red-winged insect.
Some bugs may cause the death of a palm, while others may just maim or reduce the attractiveness of a palm. A palmetto weevil infestation spells almost certain death for a palm, as the entire crown of the palm tree may weaken and break. The palm budworm (Litoprosopus coachella), a pinkish beetle larvae that feeds on the flowers of a variety of fan palm plants, is not a cause for alarm. It can generally be removed before lasting harm is done to the tree. Thrips are also a less serious problem.
Treatment varies depending on infestation. Many insecticides treat bug infestations of all kinds. Heavily infected leaves can often be pruned and destroyed without major harm to the plant. Sometimes, a spray with water and soap suffices. Serious infestations like those caused by the palm weevil are best taken care of by destroying the tree to prevent the problem from spreading to nearby healthy trees. Taking steps to ensure a palm plant is healthy is the best way to keep insects from attacking in the first place.
Sometimes a disease may be mistaken for an insect infestation, as they may share similar symptoms. An infection of phytoplasma called "Lethal Yellowing" causes a yellowing of palm foliage and a weakening of the entire plant that virtually ensures the death of the palm within six months of the first symptoms. Fusarium wilt (Fusarium oxysproum) is a fungus that causes leaf wilting and death. You can help to prevent diseases from spreading by cleaning and sterilizing palm tools such as handsaws.