Asian Citrus Psyllid and Huanglongbing

A tiny insect no bigger than a grain of rice may go unnoticed on your citrus trees, but it could have devastating consequences for California citrus if not stopped. The Asian citrus psyllid feeds on citrus leaves and stems, and can infect citrus trees with a bacteria that causes a serious plant disease called Huanglongbing, also known as HLB or citrus greening disease. While not harmful to humans, the disease kills citrus trees and has no cure.

The best way to protect citrus trees from HLB is to stop the Asian citrus psyllid. Once a tree is infected with HLB, it will die. Diseased trees need to be removed in order to protect other citrus trees on the property, neighbors’ trees and the community’s citrus.

Click through the photo slideshow below to see photos and learn how to detect the Asian citrus psyllid and Huanglongbing on your citrus tree. If you think you have spotted the pest or disease, call the free statewide pest hotline at 800-491-1899.

  • Photo of Asian citrus psyllid adults and nymphs

    Asian citrus psyllids feed on citrus leaves and stems, and can infect trees with deadly Huanglongbing disease. Seen here are adults and young nymphs.

  • How to find the Asian citrus psyllid on citrus leaves

    Inspect for Asian citrus psyllids monthly. Look for small, brown pests that feed on citrus leaves with their body at a 45-degree angle.

  • Inspect citrus tree flush for the Asian citrus psyllid pest

    Check new flush, the smallest, tender new leaves sprouting on your citrus tree, for the Asian citrus psyllid. This is a favorite spot for the pest to feed and lay eggs.

  • Asian citrus psyllid nymphs produce a white secretion on tree leaves

    Young Asian citrus psyllids, called nymphs, produce a white, waxy substance to direct honeydew away from their bodies.

  • Adult Asian citrus psyllid photo

    Asian citrus psyllids are small – no more than 1/8th of an inch long – brown, winged insects that feed on citrus tree leaves and stems.

  • Citrus tree sooty mold from Asian citrus psyllid

    Asian citrus psyllids can cause a sooty mold to form on citrus tree leaves.

  • Twisted leaf damage on citrus trees

    When Asian citrus psyllids feed on citrus tree leaves, they can cause a twisting damage to the leaf.

  • Ants and Asian citrus psyllid on tree leaf

    Ants actually protect Asian citrus psyllid nymphs, therefore it is important to apply ant bait around your tree.

  • Asymmetrical yellowing from Huanglongbing disease

    A symptom of Huanglongbing is yellow discoloration on leaves that is asymmetrical, meaning not the same on both sides of the leaf.

  • Huanglongbing causing yellow leaves on citrus tree

    Huanglongbing causes uneven yellowing in citrus tree leaves because nutrients are being restricted.

  • Citrus tree leaves turning yellow from Huanglongbing disease

    This blotchy yellowing of citrus tree leaves is an early sign of Huanglongbing and will worsen as the disease develops in the tree.

  • Pomello tree infected with Huanglongbing

    Huanglongbing seen here in a pomello tree. All varieties of citrus are at risk of contracting and dying from the disease.

  • Citrus greening disease shown on fruit

    Huanglongbing is also known as citrus greening disease because it causes fruit to stay green and not fully ripen.

  • Yellow shoots on citrus trees

    In Asia, Huanglongbing is sometimes known as yellow dragon disease due to the symptoms of entire shoots turning yellow.

  • Misshapen citrus fruit due to Huanglongbing

    Citrus fruit from trees infected with Huanglongbing may be misshapen and lose their symmetrical appearance.

  • Corky vein symptom of Huanglongbing

    Corky veins on citrus tree leaves is another symptom of Huanglongbing.

  • Citrus greening disease in Florida groves

    Huanglongbing, also known as citrus greening disease, has decimated citrus groves in Florida. We must protect California citrus trees from this threat.

  • Grafting citrus tree

    When grafting citrus fruit varieties, it is important to get registered budwood from a reputable source to avoid grafting plant material infected with Huanglongbing to your healthy tree.

  • Removing citrus tree infected with Huanglongbing

    It is important to remove diseased trees to prevent Huanglongbing from spreading to healthy citrus trees nearby.

  • Yellow pest traps placed in citrus trees

    Agriculture officials track the presence of pests like the Asian citrus psyllid by placing yellow sticky traps in citrus trees throughout the state. When you allow these traps on your property, you help protect California citrus.

California Areas at Risk

The California Department of Food and Agriculture tracks the presence of the pest and disease, and establishes quarantines to help protect California citrus trees. It is important to remember that it is illegal to bring citrus fruit or plant material into California from other states or countries, and to move it out of quarantine areas. Learn what you can do to protect California citrus.

View more detailed maps and quarantine information on the CDFA website.

Global Spread of Huanglongbing

As their names indicate, the Asian citrus psyllid and Huanglongbing are not native to the United States. The pest and disease were first discovered in Asia. Throughout the world, the disease has many names, including Huanglongbing, HLB, citrus greening disease, yellow shoot disease and yellow dragon disease. Globalization and people moving citrus plants from one place to another have spread this devastating disease. Do not transport citrus plants, budwood or plant material like leaves out of your area, and only buy your citrus plants locally from reputable sources.

Visit the United States Department of Agriculture’s website, SaveOurCitrus.org, to learn more about the presence of Huanglongbing throughout the world and elsewhere in the U.S.