Glassy-Winged Sharpshooter

Pest Notes, Publication 7492 Revised April 2019

Integrated Pest Management for Home Gardeners and Landscape Professionals Glassy-winged Sharpshooter

he glassy-winged sharpshooter, Homalodisca Tvitripennis (formerly H. coagulata) (Figure 1), is an insect that was introduced into California in the late 1980s. This insect is native to the southeastern United States and was most likely brought into southern California accidentally as egg masses in ornamental or agricultural plant foliage.

BACKGROUND The glassy-winged sharpshooter is a large leafhopper that obtains its nutrients by feeding on plant fluids in the xylem, the water-conducting tissues of a plant. Feeding on plants rarely causes significant plant damage, although the insects do excrete copious amounts of liquid that can make leaves and fruit appear whitewashed when dry. The excrement, Figure 1. Female glassy-winged sharpshooter, which is not necessarily damaging, can be a cosmetic nui- Homalodisca vitripennis. sance when shade trees are heavily infested, because cars parked under the trees tend to become spotted. Additionally, during hot weath- The main problem associated with the elm, maple, oak), citrus variegated er, large populations of glassy-winged glassy-winged sharpshooter is that chlorosis, coffee leaf scorch, and sharpshooters feeding on small plants it can transmit the plant-pathogenic olive quick decline disease, but these may cause them to wilt. bacterium Xylella fastidiosa from diseases have not been confirmed one plant to another. This bacterium in California. It should be noted that has a broad host range, able to infect the strain of X. fastidiosa that causes Authors: hundreds of plant species in dozens of oleander leaf scorch will not cause plant families. Although infection by Pierce’s disease in grapes and the Lucia G. Varela, UC Statewide IPM X. fastidiosa does not lead to disease in strain of X. fastidiosa that causes Program/UC Cooperative Extension, many of these host plants, it does cause mulberry leaf scorch does not cause Sonoma County. several important, often fatal, plant disease in oleanders or grapes. At Cheryl A. Wilen, UC Statewide IPM diseases in California. This includes this time there is no cure for any of Program/UC Cooperative Extension, Pierce’s disease of grape, alfalfa dwarf, these diseases. For more information San Diego County. almond leaf scorch, and mulberry on oleander leaf scorch, see the Pest leaf scorch. Other diseases caused by Notes: Oleander Leaf Scorch. Matthew P. Daugherty, Entomology, this bacterium in landscape plants UC Riverside. include oleander leaf scorch, sweet When a glassy-winged sharpshooter gum dieback, and cherry plum leaf feeds on a plant that is infected with David E. Haviland, UC Cooperative X. fastidiosa, it may acquire the bacte- Extension, Kern County. scorch. Other strains of X. fastidiosa cause phony peach disease, plum ria, which attaches to and multiplies leaf scald, bacterial leaf scorch in a within specific portions of the insect’s wide range of shade trees (sycamore, mouthparts. The sharpshooter then Pest Notes: Glassy-winged Sharpshooter Page 2 of 5

two generations per year. It overwin- ters as an adult feeding on citrus and other non-deciduous plants, moving to deciduous plants in January and February where adults feed on the sap from the leafless twigs before returning to the non-deciduous plants during cooler evening hours. These over- wintering adults begin laying eggs in February but lay most of their eggs in late March and April. At this time, first generation eggs are easily found on the non-deciduous hosts. Eggs hatch in 10 to 14 days and the nymphs feed on the leaf petioles or young succulent stems while they progress through five imma- ture stages. In the summer, first gen- eration adults begin to appear in May Figure 2. Detail of head of glassy-winged sharpshooter (left) and smoke-tree through July. Egg laying for the second sharpshooter (right). generation occurs between mid-June and October. The nymphs emerging from these egg masses typically devel- may inoculate the bacteria to another head of the smoke-tree sharpshooter is op into overwintering adults. plant when it feeds. Once acquired, covered with wavy, light-colored lines, The glassy-winged sharpshooter is sharpshooter adults are infective while the glassy-winged sharpshooter found in many habitats, including immediately, and they remain so for head is covered with spots. In profile, agricultural crops, urban landscapes, the remainder of their life. Immature the immature stages (nymphs) of the native woodlands, and riparian veg- sharpshooters are only infective until glassy-winged sharpshooter look sim- etation. It feeds on hundreds of plant they molt, at which time they shed the ilar to that of the adult, except they are species across dozens of plant families. bacteria as they pass to the next stage smaller, wingless, uniform olive-gray Hosts include numerous common of development. For more information in color, and have prominent bulging woody plants as well as annual and about X. fastidiosa and its transmission eyes. perennial herbaceous plants. It is by sharpshooters and other vectors see common to find this insect on acacia, the websites listed in the Suggested Before laying eggs, the female secretes avocado, eucalyptus, citrus, crepe myr- Reading section below. a chalky white substance that she transfers to the upper wings forming tle, heavenly bamboo, grape, photinia, white spots. After laying the eggs, she pittosporum, hibiscus, periwinkle, IDENTIFICATION AND covers them with this chalky material xylosma, some roses, and many others. BIOLOGY by transferring it from the wings. Thus, the white spots on the wings are only The glassy-winged sharpshooter is a visible on females shortly before laying large insect compared to other leaf- a batch of eggs and are not present hoppers. Adults are approximately ½ on males. Females lay egg masses, in inch long and are generally dark brown groups of 8 to 12 eggs arranged side-by- to black when viewed from the top or side, under the epidermis of the lower side. Wings are clear with red venation leaf surface of young, fully developed that fades as they age, but they appear leaves (Figure 3). When it is first laid, dark brown due to the body coloration each individual egg appears as a green- beneath them. The abdomen is whitish ish blister beneath the epidermis of the or yellow. The head is brown to black leaf. Shortly after the eggs hatch, the and covered with numerous ivory leaf tissue surrounding the egg mass to yellowish spots. These spots help begins to turn brown and remains as a distinguish glassy-winged sharpshoot- permanent brown scar. er from a close relative, smoke-tree Figure 3. Glassy-winged sharpshooter (Homalodisca liturata), In Southern California and in the sharpshooter female next to an egg which is native to the desert region San Joaquin Valley, the glassy- mass laid under the epidermis of the of Southern California (Figure 2). The winged sharpshooter typically has lower leaf surface (on left). Pest Notes: Glassy-winged Sharpshooter Page 3 of 5

Host preference changes throughout the year, depending on the availability and nutritional value of host plants. Some hosts are preferred for feeding while others are preferred for repro- duction. Irrigation level and fertilizer additions can also impact the attrac- tiveness of hosts for sharpshooters. Glassy-winged sharpshooter is estab- lished in residential and agricultural settings throughout most of southern California. In the San Joaquin Valley, it is abundant in much of Kern County and is locally abundant in certain parts of Tulare and Fresno Counties. Other localized infestations have occurred in parts of San Luis Obispo, Santa Clara, Contra Costa, Solano, Sacramento and Butte Counties, but were successfully eradicated. Nonetheless, there contin- ues to be great concern that this insect may eventually invade most California counties, leading to certain restrictions on the shipment of host plants from areas where the glassy-winged sharp- shooter is established. The map (Figure 4) shows the areas in California where this sharpshooter has been found and counties where it is feared that the pest may establish if introduced. For the most recent information, see the Figure 4. Distribution of glassy-winged sharpshooter in California Department of Food and California as of December 2017. Infested areas are blue and Agriculture website listed in Suggested at risk areas are green. Reading.

disease. Management of glassy-winged hosts such as trees and grape arbors, MANAGEMENT sharpshooters in a residential setting the presence of small droplets of liquid For areas where the glassy-winged relies on biological control in the sur- falling as a mist from the canopy or sharpshooter is not established, it rounding environment and, in some whitish, powdery coating on leaves or continues to be important to identify cases, chemical control. fruit indicated that sharpshooters are new infestations as soon as possible. present overhead. Yellow sticky cards This requires careful monitoring and Detection and Monitoring are the preferred monitoring method detection. If you find glassy-winged for government agencies that track sharpshooter in an area not currently Even though this insect is large enough glassy-winged sharpshooter popula- known to have this pest, immediately to be seen with the naked eye, it is tions. If you find one of these cards on call the California Department of Food inconspicuous in nature. The brown your property, direct any questions or & Agriculture pest hotline at 1-800-491- coloration of the insect blends in with inquiries to the phone number indicat- 1899, or contact your local agricultural the color of the twigs where it is usually ed on the trap. commissioner’s office. found, and it hides by moving to the other side of the twig or branch when In areas where the glassy-winged it detects movement or is otherwise Cultural Control sharpshooter is established, the prin- disturbed. When inspecting host plants Once glassy-winged sharpshooter is cipal reason for controlling the glassy- for glassy-winged sharpshooters, focus established in an area, there are no winged sharpshooter is to prevent the your attention about 6 inches to 1 foot cultural controls available to manage spread of X. fastidiosa to susceptible from the tips of new shoots. This is them. However, preventing transport of plants. Plants cannot be cured of the where they prefer to feed. For taller infested plant material to areas where Pest Notes: Glassy-winged Sharpshooter Page 4 of 5

arthropods that eat sharpshooters effective than in the past when used (such as spiders, assassin bugs, praying against glassy-winged sharpshooters in mantids, and lacewings). agricultural fields in Kern and Tulare Counties. Therefore, urban landscapes Chemical Control close to these agricultural areas may experience less effective control with In the event of glassy-winged sharp- imidacloprid products. shooter spread to new areas, residential insecticide treatments may be neces- In instances where the white excre- sary as part of localized eradication ment produced by this pest causes efforts by state and federal regulatory residues on cars or other surfaces, agencies. Otherwise, in most parts of other insecticides can be applied to California, insecticide applications for infested foliage to provide immediate the control of glassy-winged sharp- relief. The least toxic and least disrup- shooter are typically not recommended tive to biological control are insecti- around homes and urban landscapes. cidal soaps and oils. Insecticidal soaps This is because populations are gen- and oils are only effective in killing Figure 5. Glassy-winged erally low and under good biological the soft-bodied nymphs of the glassy- sharpshooter egg mass with control, and there is a relatively low winged sharpshooter and must directly parasitoid emergence holes. prevalence of Xylella diseases in urban contact the insect to kill it, so thorough settings. The exceptions are cases coverage of the plant or tree foliage is where residents notice large sharp- essential. Applications of these materi- glassy-winged sharpshooter is not es- shooter populations on particularly als need to be repeated at 7- to 10-day tablished is an essential step in slowing favored hosts, such as some varieties of intervals. Other insecticides (includ- further spread in California. Nurseries citrus, or rare instances where popula- ing Bioadvanced Insect, Disease and shipping plants out of an infested area tions in ornamental plantings are high Mite Control, Ortho Insect, Mite and must follow rigorous treatment pro- enough that white residues from excre- Disease 3-in-1, or Sevin Insect Killer) grams and have the plants inspected ment production become a significant are available for foliar applications that before they are shipped and again after nuisance. are more effective for longer periods they arrive at their destination. of time. However, these materials may The most common insecticides used be more harmful to the parasitic wasps for glassy-winged sharpshooter contain Biological Control and predatory insects that provide the active ingredient imidacloprid. biological control, and they can be Following the invasion of glassy- Some retail imidacloprid products toxic to pollinators. For all insecticide winged sharpshooters in California, available to residents include Bayer applications, it is important to follow multiple species of small wasps in BioAdvanced 12 Month Tree and application instructions on the label the genus Cosmocomoidea (formerly Shrub and Bayer Advanced Fruit, to minimize harm to pollinators and Gonatocerus) were introduced for its Citrus and Vegetable Insect Control. other beneficial insects. control. These parasitoids, which attack Applications are made by calculat- and complete their entire life cycle ing the amount of product needed ••• within a glassy-winged sharpshooter (depending on the size of the tree or egg, are now established in all regions shrub), diluting the product with water, of California where glassy-winged and pouring the mixture around the sharpshooters exist. Eggs parasitized by base of the plant where it soaks into these tiny wasps are easily identified by the soil. With appropriate watering, pinpoint holes found at one end of the the active ingredient is absorbed by egg (Figure 5). Parasitoid populations the roots and moved throughout the are typically low early in the year, pro- plant in sufficient quantities to protect viding modest parasitism (10 to 50%). against sharpshooters. Typically, the However, by the late summer or early plant becomes protected within a few fall these wasps can cause upwards of weeks. Imidacloprid treatments may 90% mortality of glassy-winged sharp- have a secondary benefit by helping to shooter eggs. It is important to support control other common sucking insect biological control by avoiding the use pests, such as some scales, aphids, or of broad-spectrum insecticides that whiteflies. Recent research has sug- may kill parasitoids and beneficial gested that imidacloprid may be less Pest Notes: Glassy-winged Sharpshooter Page 5 of 5

REFERENCES SUGGESTED READING Varela LG, Smith RJ, Phillips PA. For current information regarding glassy-winged sharpshooter see the California 2001. Pierce’s Disease. UC ANR Publ. Department of Food and Agriculture (CDFA) website, 21600. Oakland, CA. cdfa.ca.gov/pdcp/Glassy-winged_Sharpshooter.html. Wilen CA, Hartin JS, Henry JM, Costa For a map of infested sites in California see the CDFA website, HS, Blua M, Purcell AH. April 2008. cdfa.ca.gov/pdcp/map_index.html. Pest Notes: Oleander Leaf Scorch. UC For more information on plant diseases caused by Xylella fastidiosa, see the ANR Publ. 7480. Oakland, CA. University of California, Berkeley website, nature.berkeley.edu/xylella.

WARNING ON THE USE OF PESTICIDES Pesticides are poisonous. Some pesticides are more toxic than others and present higher risks to people, nontarget organisms, and the environment. A pesticide is any material (natural, organic, or synthetic) used to control, prevent, kill, suppress, or repel pests. “Pesticide” is a broad term that includes insecticides, herbicides (weed or plant killers), fungicides, rodenticides, miticides (mite control), molluscicides (for snails and slugs), and other materials like growth regulators or antimicrobial products such as bleach and sanitary wipes that kill bacteria. Always read and carefully follow all precautions and directions provided on the container label. The label is the law and failure to follow label instructions is an illegal use of the pesticide. Store all chemicals in the original labeled containers in a locked cabinet or shed, away from food or feeds, and out of the reach of children, unauthorized persons, and animals. Never place pesticides in food or drink containers. Consult the pesticide label to determine active ingredients, correct locations for use, signal words, and personal protective equipment you should wear to protect yourself from exposure when applying the material. Pesticides applied in your garden and landscape can move through water or with soil away from where they were applied, resulting in contamination of creeks, lakes, rivers, and the ocean. Confine pesticides to the property being treated and never allow them to get into drains or creeks. Avoid getting pesticide onto neighboring properties (called drift), especially onto gardens containing fruits or vegetables ready to be picked. Do not place containers with pesticide in the trash or pour pesticides down the sink, toilet, or outside drains. Either use all the pesticide according to the label until the container is empty or take unwanted pesticides to your local Household Hazardous Waste Collection site. Contact your county agricultural commissioner for additional information on safe container disposal and for the location of the Hazardous Waste Collection site nearest you. Follow label directions for disposal of empty containers. Never reuse or burn the containers or dispose of them in such a manner that they may contaminate water supplies or natural waterways.

Produced by the Statewide Integrated Pest Management For more information, contact the University of California Cooperative Program, University of California, 2801 Second Street, Davis, CA Extension office in your county. See your telephone directory for ad- 95618-7774. dresses and phone numbers, or visit: ucanr.edu/County_Offices. Technical Editor: K Windbiel-Rojas University of California scientists and other qualified professionals have anonymously peer reviewed this publication for technical accuracy. ANR Associate Editor: AM Sutherland The ANR Associate Editor for Urban Pest Management managed this process. Editor and Designer: B Messenger-Sikes To simplify information, trade names of products have been used. No ILLUSTRATIONS: Figures 1, 3 & 5: Jack Kelly Clark; Fig. 2: Jack endorsement of named products is intended, nor is criticism implied of Kelly Clark, adapted from Reyes Garcia III; Fig. 4: adapted from similar products that are not mentioned. Calif. Dept. Food & Agric. website. This material is partially based upon work supported by the Extension This and other Pest Notes are available at ipm.ucanr.edu. Service, U.S. Department of Agriculture, under special project Section 3(d), Integrated Pest Management.

ANR NONDISCRIMINATION AND AFFIRMATIVE ACTION POLICY STATEMENT It is the policy of the University of California (UC) and the UC Division of Agriculture & Natural Resources not to engage Suggested citation: Varela LG, Wilen CA, Daugherty MP, in discrimination against or harassment of any person in any of its programs or activities (Complete nondiscrimination policy statement can be found at ucanr.edu/sites/anrstaff/files/215244.pdf). Haviland DR. 2019. UC IPM Pest Notes: Glassy-winged Inquiries regarding ANR’s nondiscrimination policies may be directed to John Fox, Affirmative Action Contact, University of California, Agriculture and Natural Resources, 2801 Second Street, Davis, CA 95618, (530) 750-1397. Sharpshooter. UC ANR Publication 7492. Oakland, CA.