An insect known for killing citrus trees has been found in San Francisco’s Marina district, prompting state agricultural officials to declare a quarantine in the entire city Thursday to stop the bug from spreading to nearby areas.

The Asian citrus psyllid threatens all citrus trees and other plants such as curry leaf trees by feeding on the leaves and stems and spreading bacteria that causes the Huanglongbing disease. Once trees are infected, they produce “bitter misshapen fruit, and eventually die,” public health officials said in a statement Thursday.

Officials did not say where in the Marina district the insect was detected. They have placed traps throughout the area to determine if there are others.

“Even though San Francisco County is not a commercial citrus-producing area, we all play a role in limiting the spread of this insect,” said Cree Morgan, San Francisco agricultural commissioner.

“Officials plan to treat citrus host plants within 50 meters of the site where the insect was trapped,” officials said in a statement.

Residents living in the area where the insect was found will likely be invited to participate in a “community outreach meeting” with local and state agricultural officials in the future, officials said.

Asian citrus psyllids are no more than one-eighth-inch long. They are brown and yellowish orange winged insects that produce a white, waxy substance while feeding on citrus leaves and stems, officials said.

Their bacteria pose no threat to humans, but the disease it causes in trees and plants is incurable. In recent years, the invasive pest made its way from Southern California to the Bay Area, prompting temporary widespread quarantines spreading more than 100 square miles of quarantined land in the Bay Area in January 2016.

The Huanglongbing disease can kill a citrus tree in five years, according to the UC Division of Agriculture and Natural Resources. Officials with the UC Davis College of Agricultural and Environmental Sciences said in a 2017 publication that Florida citrus groves have been “decimated” by the disease in recent years.

Officials hope the San Francisco quarantine will prevent the tiny pests from hitching a ride on leaves, stems or potted citrus trees.

Under the quarantine rules, retail nurseries are required to sell only citrus plants in San Francisco that have been treated for Asian citrus psyllids and must prominently tag treated plants with blue “quarantine” tree tags, officials said. Citrus fruits can be sold at farmers’ markets, flea markets and swap meets as long as the stems and leaves were plucked from the fruits before getting transported to markets for sale.

Citrus fruit vendors in San Francisco are required to obtain a compliance agreement from the California Department of Food and Agriculture.

San Francisco residents with citrus trees on their properties are prohibited from transporting citrus fruit or leaves, potted citrus trees or curry leaves outside of the county, officials said.

City public health officials advise residents to follow some steps while handling citrus plants:

• Look for blotchy, yellowed leaves and other symptoms of disease while watering, spraying, pruning or tending to trees.

• Do not transport citrus plants, leaves, stems or fruit out of the area.

• Dry out citrus tree clippings or double-bag them before removing them from property.

• Only use registered budwood — such as budwood offered from the Citrus Clonal Protection Program — when grafting citrus trees.

Anyone who sees any Asian citrus psyllid insects or symptoms of Huanglongbing disease on citrus trees may call the San Francisco County agricultural commissioner at 415-252-3830 or the California Department of Food and Agriculture Pest Hotline at 800-491-1899.

Lauren Hernández is a San Francisco Chronicle staff writer. Email: lauren.hernandez@sfchronicle.com Twitter: @LaurenPorFavor