Invasive Species Watch: What Lodi Residents Need to Know

Lodi411 Resident Field Guide · June, 2026

Invasive Species Watch: What Lodi Residents Need to Know

By LodiEye Staff

Lodi sits in the heart of one of California's most important winegrape regions, surrounded by orchards, gardens, a maturing urban tree canopy, and the Sacramento–San Joaquin Delta. That same agricultural and ecological richness makes the area a target for invasive pests. This guide profiles the invasive species every Lodi household should be able to recognize — insects, a tree, a rodent, and a mollusk — and explains exactly how and where to report each one.

This guide covers the species Lodi residents are most likely to encounter or to be asked about: the insects threatening vineyards and orchards, the weed tree fueling future infestations, the invaders now established in the Delta and Mokelumne corridor, and a short watch list for the urban canopy. The connections matter. The glassy-winged sharpshooter spreads a disease that can kill grapevines and is already active in nearby counties. The spotted lanternfly is not yet established in California, but its favorite food is the tree of heaven — an aggressive weed tree already growing along Lodi's alleys and fence lines. The brown marmorated stink bug uses that same tree, and the Asian citrus psyllid threatens every backyard citrus in town. Out on the water, the golden mussel and nutria are reshaping the Delta. Knowing what you're looking at, and where to report it, is the resident's job.

Active Local Alert

Grape plants sold at local Costco stores may carry the glassy-winged sharpshooter

In late May 2026, the San Joaquin County Agricultural Commissioner's Office reported that inspectors found the glassy-winged sharpshooter on grape plants sold at Costco stores in Stockton, Lodi, Manteca, and Tracy. The plants were supplied by a wholesale nursery in Fresno County. Officials noted the food supply is not affected and that Costco was not at fault, because the problem originated with the nursery supplier.

If you bought a grape plant from one of those Costco locations between April 21 and May 19, 2026: do not plant, move, return, or throw the plant away. Isolate it and contact the County Agricultural Commissioner's Office at (209) 953-6000 or StocktonAg2@sjgov.org to arrange an inspection. An inspector will examine the plant and nearby vegetation and, if the pest is found, will remove and dispose of it safely. Monitoring traps may also be placed on the property.

The Insects

Glassy-Winged Sharpshooter

Homalodisca vitripennis

Status — Present in the region

The glassy-winged sharpshooter is the one to worry about most right now. It is the primary carrier of the bacterium Xylella fastidiosa, which causes Pierce's disease — a death sentence for grapevines and a direct threat to Lodi's signature crop. It also damages almond, citrus, and ornamental plants and feeds on more than 250 plant species. The insect has been in California since about 1990, and breeding infestations have been confirmed as far north as El Dorado, Solano, and Stanislaus counties.

An adult is about half an inch long, with a dark brown-to-black body speckled with ivory dots, a pale yellowish underside, and clear ("glassy") wings veined with red.

Photo: public domain via Wikimedia Commons.

🔗 Learn more: UC IPM — Glassy-Winged Sharpshooter Pest Notes

How to identify it

Size & shape

Large leafhopper, roughly half an inch (12–13 mm) head to wingtip — noticeably bigger than most leafhoppers, with a bullet-shaped, wedge profile.

Color

Dark brown to black body finely speckled with ivory or yellowish dots; underside is yellowish, sometimes with black markings; eyes can appear yellow.

Wings

Mostly transparent forewings with reddish veining (the red fades and darkens as the adult ages) — the trait that gives the "glassy-winged" name.

Tell-tale signs

Heavy "honeydew" and a whitewash-like spotting on leaves and fruit from feeding; chalky white egg-mass patches on the undersides of leaves.

Why it matters to Lodi: a single infected sharpshooter feeding on a vine can introduce Pierce's disease. Once a vineyard or backyard vine is infected, there is no cure. Early detection is the only practical defense, which is why the recent Costco grape-plant finding (above) is being treated so seriously.

If you see one

1. Take a clear photo and note the exact location.
2. Do not move any grape plants, nursery stock, or plant debris off the property.
3. Report it to the San Joaquin County Agricultural Commissioner or the CDFA Pest Hotline (contacts below).
4. Follow any inspection or treatment instructions the agency provides.

Spotted Lanternfly

Lycorma delicatula

Status — Not yet established in California (watch closely)

The spotted lanternfly is a striking planthopper native to Asia, first found in the United States in Pennsylvania in 2014 and now present in roughly twenty states. Live, breeding populations have not been found in the California environment, but dead specimens, a few live adults, and egg masses have been intercepted in shipments and at border stations — including lanternfly egg masses on firewood stopped at the Truckee inspection station. California has had an exterior quarantine in place since 2021 to keep it out. If it ever establishes here, it would threaten winegrapes, fruit, hops, and hardwood trees.

At rest the adult shows gray, black-spotted forewings; in flight it flashes red, black, and white hindwings. Egg masses look like a smear of gray-brown mud on bark or any smooth surface.

Photo: CC0 / public domain dedication via Wikimedia Commons.

🔗 Learn more: CDFA — Spotted Lanternfly Pest Profile

How to identify it

Adult

About one inch long at rest; folded forewings are gray with distinct black spots, with a tan tip marked by a black "brick" pattern; hindwings (seen in flight) are vivid red and black with a white band.

Early nymphs

Small, wingless, glossy black with bright white spots — often mistaken for ticks or beetles.

Late nymphs

Larger and bright red with black markings and white spots before they reach adulthood.

Egg masses

Inch-long patches that look like dried gray-brown mud or putty, laid in fall on tree bark, stone, vehicles, trailers, firewood, and outdoor furniture; by spring the coating cracks to reveal rows of seed-like eggs.

The hitchhiker problem: spotted lanternfly spreads mainly by laying eggs on portable surfaces. Most new introductions arrive on vehicles, firewood, and outdoor gear moved from infested states — which is why inspecting what you bring home matters.

If you see one

1. Take a clear photo and note the location, then call the CDFA Pest Hotline at 1-800-491-1899.
2. If safe to do so, kill the insect; adults and nymphs can be squished.
3. Scrape any egg masses into a bag or container of rubbing alcohol or soapy water to destroy them.
4. Do not move firewood, plants, or outdoor items that could be carrying eggs.

Brown Marmorated Stink Bug

Halyomorpha halys

Status — Established and spreading in California

The brown marmorated stink bug is the other major pest that loves tree of heaven, and it is already widely established — present in roughly 16 California counties and detected in more than 20 additional ones. It feeds on more than 170 plants, including most of what Lodi grows in the field and the backyard: grape, pear, apple, stone fruit, citrus, almond, hazelnut, and a long list of vegetables and ornamentals. In late fall it also becomes the household nuisance pest people complain about, crowding into homes by the dozens to overwinter.

A classic shield-shaped stink bug, about five-eighths of an inch long, mottled brown ("marmorated" means marbled). The fastest ID is the antennae: the last two segments each carry a clear white band.

Photo: USDA, public domain via Wikimedia Commons.

🔗 Learn more: UC IPM — Brown Marmorated Stink Bug Pest Notes

How to identify it

Size & shape

About five-eighths of an inch (14–17 mm) long, classic shield-shape with a small triangle in the middle of the back.

Color

Mottled, marbled brown across the back; underside paler.

Antennae (the key tell)

The last two segments of each antenna are clearly banded white — the single most reliable identification feature.

Abdomen edge

The edge that shows above the wings is striped with alternating light and dark bands.

Shoulders

Smooth and rounded — not toothed or pointed like several native look-alikes.

Smell

A strong, herbal-skunky odor when crushed or alarmed — the source of the common name.

The fall invasion you may already know: in October and November this is the bug that gathers in warm sunny spots on south- and west-facing walls, then squeezes inside through gaps around windows, vents, and eaves. Indoors they don't bite, breed, or damage anything — but they do stink when disturbed.

If you find them

1. In the garden or orchard: photograph and report unusual concentrations to the San Joaquin County Agricultural Commissioner; this helps track the local population.
2. Indoors: vacuum them up (a shop vac or a sock-lined hose attachment keeps the smell out of the machine) and empty the bag outside.
3. Don't squish them indoors — the odor lingers.
4. Before fall, seal gaps around windows, vents, and utility penetrations to keep them out.

Asian Citrus Psyllid

Diaphorina citri

Status — Psyllid present in San Joaquin County; HLB disease not yet confirmed locally

The Asian citrus psyllid is a tiny sap-feeding insect, but its consequence is enormous: it spreads huanglongbing (HLB, also called citrus greening), the most serious disease of citrus in the world. There is no cure. The psyllid itself is already partially established in San Joaquin County. HLB has so far been confirmed in Los Angeles, Orange, Riverside, San Bernardino, San Diego, and Ventura counties, and keeping it out of the Central Valley depends on residents catching infected trees early. If you have a lemon, orange, mandarin, lime, kumquat, or any citrus relative in your yard, this section is for you.

Adults are tiny — only about 3–4 mm — but their feeding pose is unmistakable: head down, body tilted up at a sharp angle to the leaf, like a tiny diving board. They're almost always on new, tender citrus growth.

Photo: USDA, public domain via Wikimedia Commons.

🔗 Learn more: UC IPM — Asian Citrus Psyllid & Huanglongbing

How to identify it

Adult

3–4 mm long, brown with mottled wings held roof-like over the body. The body is tilted up at roughly 45 degrees while feeding — the diagnostic posture.

Nymphs

Yellow to orange, on new growth; they produce distinctive curly, white, waxy tubules that look like tiny springs — a second highly reliable tell.

Eggs

Tiny, almond-shaped, yellow-orange; laid on the tips of brand-new ("flush") citrus growth.

HLB symptoms in the tree

Blotchy, mottled yellowing on leaves that is asymmetric across the leaf midrib (not the symmetric yellowing of a nutrient deficiency); lopsided, hard, bitter fruit that stays partly green; twig and branch dieback; premature fruit drop. Only a laboratory test can confirm HLB.

Keep it out of Lodi: don't move citrus plants, cuttings, leaves, or homegrown fruit out of your yard. Buy citrus trees only from licensed nurseries with a CDFA certification tag — never from sidewalk sellers or social-media listings. Inspect tender new growth every few weeks in spring and summer, when both psyllid and tree are most active.

If you see psyllids or suspect HLB

1. Photograph the insects on the new growth, ideally from the side to show the tilted feeding angle.
2. Photograph any suspicious leaves and fruit; note the exact tree location.
3. Call the CDFA Pest Hotline at 1-800-491-1899 or contact the San Joaquin County Agricultural Commissioner.
4. Don't prune, move, or destroy the tree before an inspector responds — the agency needs the evidence in place.

The Plant

Tree of Heaven

Ailanthus altissima

Status — Already widespread in California

Despite the pleasant name, tree of heaven is an aggressive invasive tree on California's noxious weed list. Brought from China in the 1700s as an ornamental, it now grows along roadsides, alleys, vacant lots, fence lines, and riverbanks throughout the state. It spreads by both windblown seed and dense root suckers, a mature tree can produce hundreds of thousands of seeds a year, and its roots damage sewers, sidewalks, and foundations. Critically, it is the preferred host of the spotted lanternfly (and a favorite of the brown marmorated stink bug), so removing it is a frontline defense against future infestations.

A single leaf is one to four feet long with 11–41 leaflets. The clue that separates it from look-alikes is a small "thumb"-like glandular tooth at the base of each leaflet — and a strong, foul odor when leaves or twigs are crushed. (Shown here with its hanging clusters of winged seeds.)

Photo: CC0 / public domain dedication by Jebulon via Wikimedia Commons.

🔗 Learn more: CDFA — Tree of Heaven (Ailanthus) Weed Profile

How to identify it

Leaves

Large, feather-like (pinnately compound), 1–4 feet long, with 11 to 41 lance-shaped leaflets. Leaflet edges are otherwise smooth.

The key clue

One or two bumps ("glandular teeth") protrude at the base of each leaflet, each with a small gland underneath. No common look-alike has this.

Smell

Crushed leaves, twigs, or bark give off a strong, unpleasant odor — commonly described as rancid peanut butter, burnt peanut butter, cat urine, or sweaty gym socks.

Bark

Smooth and gray-green when young; older trunks turn gray-brown with shallow diamond-shaped fissures and a texture like cantaloupe skin.

Twigs

Stout, greenish to brown, with large V- or heart-shaped leaf scars; snapped twigs reveal a spongy brown center (pith).

Seeds

On female trees, hanging clusters of single-seeded winged "samaras," 1–2 inches long, that turn from green to tan, yellow, or reddish.

Don't confuse it with: black walnut, butternut, the sumacs (staghorn and winged), and ash trees all have similar feather-shaped leaves. The combination of the glandular teeth at the leaflet bases plus the foul crushed-leaf odor reliably separates tree of heaven from all of them.

If you find it on your property

1. Note the location and rough size; report large stands to the County Agricultural Commissioner.
2. Do not simply cut it down — cutting alone triggers aggressive root sprouting that makes the problem worse.
3. Effective removal usually requires a targeted herbicide treatment (cut-stump or basal-bark application). Consider consulting a licensed professional for established trees.
4. Replace removed trees with native or non-invasive species.

In the Delta and Wetlands

Lodi's water story runs through the Mokelumne River, Lodi Lake, and the Sacramento–San Joaquin Delta. Two recent invaders are reshaping all three. One is a fingertip-size mollusk that arrived in 2024 and is already triggering local emergency declarations. The other is a forty-pound rodent that has been quietly chewing through Delta marshes since 2017.

Golden Mussel

Limnoperna fortunei

Status — Local emergency declared; spreading in the Delta and connected waterways

The golden mussel was first found in North America near the Port of Stockton in October 2024 — almost certainly arriving in a freighter's ballast water from Asia. State officials believe the population had probably been there for a couple of years already. In April 2026 the San Joaquin County Board of Supervisors proclaimed a local emergency over the threat. The mussel has since been detected in roughly thirty locations across the Delta and in reservoirs that receive Delta water, and East Bay Municipal Utility District has restricted boat access at Camanche and Pardee on the Mokelumne to slow the spread. Experts now consider full eradication unlikely; the goal is to keep it out of as many uninfested waters as possible.

Fingertip-size, with a yellow to golden-brown shell and a distinctive lopsided "D" shape (one end pointed, the other rounded). They attach in dense clusters to almost any hard underwater surface.

Photo: CC0 / public domain dedication, Naturalis Biodiversity Center via Wikimedia Commons.

🔗 Learn more: CDFW — California's Invaders: Golden Mussel

How to identify it

Size

Adults are roughly half an inch to one inch — the size of a fingertip. Juveniles are much smaller and easy to miss.

Shell

Yellow, gold, or light brown; smooth surface; asymmetric "D-shape" with a pointed front end and a rounded back. A dark stripe often runs along the hinge line.

How they attach

Sticky "byssal threads" anchor them to docks, ropes, boat hulls, intake pipes, settlement plates, and rocks — usually in dense clusters. Native freshwater clams are not anchored.

Where

Fresh and brackish water (up to about 3 parts per thousand salinity); tolerates temperatures from roughly 41 to 95 degrees Fahrenheit — well within Delta and Mokelumne range.

Don't confuse with

Quagga and zebra mussels (smaller, different banding), Asian clams (lighter shell, not anchored), and native freshwater mussels (larger, unanchored, with a different shape).

Why this one matters: golden mussels clog water-intake pipes, fish screens, pumps, and irrigation infrastructure; they foul boat hulls and outboard motors; and they spread between waterbodies in any standing water a boat or trailer carries away. In California it is illegal to import, transport, or possess them.

If you boat, fish, or paddle locally

1. Clean, drain, and dry your boat, trailer, paddleboard, and gear between every waterbody — every time.
2. Check launch requirements before you go; many local reservoirs now require inspection, quarantine periods, or tamper-proof bands.
3. If you see mussels attached to a dock, boat, or other surface, photograph them with a hand or coin for scale and report immediately to CDFW.
4. Report sightings to the CDFW Invasive Species Program at (866) 440-9530 or invasives@wildlife.ca.gov.

Nutria

Myocastor coypus

Status — San Joaquin County is part of the active infestation area

The nutria is a large, semi-aquatic South American rodent that California thought it had eradicated by 1978. In 2017 a pregnant female was killed in Merced County, and the species has since spread through the southern Delta and the San Joaquin Valley — San Joaquin County was among the first counties to record the new infestation, in the marshes near the river. The state's eradication program has trapped thousands of animals, but new detections continue, including expansion into the northwestern Delta and the San Joaquin River corridor. A single female can produce up to 200 offspring in a year, and a colony's burrows can compromise levees that protect cities, farms, and the state's water supply — which is the larger reason the program exists.

Up to three feet long (plus a long, round, rat-like tail), brown to reddish-brown fur, white whiskers, and bright orange front teeth that are visible even at a distance.

Photo: U.S. Fish & Wildlife Service, public domain via Wikimedia Commons.

🔗 Learn more: CDFW — Nutria in California

How to identify it

Size

Big — body up to about 3 feet long, with a long tail adding roughly another foot; weight commonly 15 to 30+ pounds. Larger than any native rodent in California's wetlands.

Tail (the key tell)

Long and round, like an oversized rat tail. Beavers have a wide flat paddle tail; muskrats have a thin, side-flattened tail. Nutria tails are not flattened in any direction.

Teeth

Front incisors are bright orange to yellow-orange — visible even from a distance. Distinctive enough that biologists call it the "nacho-cheese teeth" tell.

Whiskers and feet

White or pale whiskers; hind feet are webbed between four of the five toes.

Signs to look for

Burrow openings in levees and streambanks (often 6–9 inches across); flattened "haul-out" platforms at the water's edge; chewed vegetation at the waterline; floating feeding mats.

Don't confuse with

Beaver (flat paddle tail, larger), muskrat (much smaller, about 2 pounds, with a thin flattened tail), or river otter (sleek, no orange teeth, very different shape).

Why this one matters for Lodi: the immediate threat is the levee system. Nutria burrow into earthen banks, and a colony's tunnels can weaken the very levees that protect Delta cities, farmland, and the pumps that send water to two-thirds of the state. Wetland damage and crop loss are real, but levee compromise is the worst case.

If you see one

1. Photograph the animal — the program asks specifically for views of the tail, the hind foot, and the whiskers, with a size reference if you can manage it.
2. Do not approach, capture, or harm the animal yourself.
3. Report immediately to the CDFW Invasive Species Program at (866) 440-9530 or invasives@wildlife.ca.gov.
4. Landowners near the river or marshes can grant CDFW survey teams written permission to enter; this materially helps the eradication effort.

Urban Canopy Watch List

Three tree-boring beetles are spreading in California and threaten the species Lodi's urban canopy depends on. None has been confirmed established in San Joaquin County, but residents and arborists should know the names, the signs, and the firewood rule.

Mediterranean oak borer (Xyleborus monographus)A tiny ambrosia beetle (about an eighth of an inch) that infests white oaks — valley oak, blue oak, and Oregon white oak. It carries a symbiotic fungus that blocks the tree's vascular system. The beetle is established and spreading in Lake, Napa, Sonoma, Mendocino, Marin and other Northern California counties, with detections moving south and east. The signature symptom is unexplained branch dieback in mature oaks.

Invasive shothole borers (Euwallacea spp.)Sesame-seed-sized beetles that carry a Fusarium fungus and cause Fusarium dieback. They can reproduce in more than 65 California tree species, including California sycamore, several oaks, cottonwoods, and box elder. They have killed thousands of trees in Southern California and have been confirmed killing trees in San Jose-area riparian forests. The tell is a peppering of tiny entry holes ("shot hole" pattern) sometimes with weeping sap, sawdust strings, or sugary exudate.

Goldspotted oak borer (Agrilus auroguttatus)A wood-boring beetle native to Arizona, now killing coast live oaks and other oaks primarily in Southern California and spreading north. Its main vector is firewood — which is the firewood rule's whole point: don't move it.

What residents and arborists should doDon't move firewood across counties. Inspect mature valley oaks, blue oaks, and sycamores annually for unexplained branch dieback, entry holes, and sap weeping. Report suspicious symptoms to the San Joaquin County Agricultural Commissioner, and consult a certified arborist before treating high-value trees.

🔗 Learn more: UC IPM — Invasive Shothole Borers · Goldspotted Oak Borer (GSOB.org)

How and where to report

Residents are the front line for early detection. When you report, include a clear photo and the exact location, and do not move the insect or plant material before an inspector responds.

CDFA Pest Hotline (statewide)

1-800-491-1899

California Department of Food and Agriculture — for spotted lanternfly, glassy-winged sharpshooter, and other invasive pest sightings.

Online: the CDFA "Report a Pest" tool at cdfa.ca.gov

San Joaquin County Agricultural Commissioner

(209) 953-6000

Email: StocktonAg2@sjgov.org

Main office: 2101 E. Earhart Ave., Suite 100, Stockton, CA 95206

Lodi office: 10 W. Locust Ave., Lodi, CA 95240 — (209) 331-7287

CDFW Invasive Species Program (aquatic and wildlife)

(866) 440-9530

Email: invasives@wildlife.ca.gov

California Department of Fish and Wildlife — for nutria, golden mussel, and other aquatic and wildlife invasives. Online sighting reports also accepted via the CDFW Invasive Species Program website.

How residents can help

• Inspect what you bring home. Check vehicles, trailers, firewood, and outdoor furniture for egg masses and hitchhiking insects, especially after travel to states where the spotted lanternfly is established.
• Buy plants from reputable sources. Inspect new nursery stock — particularly grapevines and citrus — and ask whether shipments came from a quarantine area. Buy citrus only from licensed nurseries with a CDFA certification tag.
• Don't move firewood across county or state lines. Firewood is a primary spreader for the spotted lanternfly, the goldspotted oak borer, and other tree pests.
• Boaters and paddlers: clean, drain, and dry. Every waterbody, every time. Comply with launch inspections and quarantine requirements at Camanche, Pardee, and other regional reservoirs — they are the best tool to keep the golden mussel out of new waters.
• Inspect backyard citrus for the Asian citrus psyllid on tender new growth, especially in spring and summer; don't move citrus plants, cuttings, leaves, or homegrown fruit out of your yard.
• Learn to recognize tree of heaven and remove it properly from your property — it is the spotted lanternfly's preferred host and a magnet for the brown marmorated stink bug.
• Watch the canopy. Annual inspection of mature valley oaks, blue oaks, and sycamores for unexplained dieback or entry holes is a small investment that catches borer infestations early.
• Report early. A photo and a phone call cost nothing; a missed infestation can cost the region's vineyards, gardens, levees, and waterways dearly.

About This Report

LodiEye is the investigative research and publishing arm of Lodi411.com. It is not a traditional newsroom, and its founder is not a journalist by training. Residents seeking original local reporting should turn to professional outlets including the Lodi News-Sentinel and Stocktonia, and to statewide coverage from the Sacramento Bee and CalMatters. This report synthesizes publicly available guidance from agricultural and regulatory agencies into a practical reference for Lodi households; it is offered as a civic resource, not as a substitute for the work of those newsrooms or for the official instructions of state and county agencies.

The report was assembled with the help of AI research tools across five capacities:

• Source Discovery — Claude and Perplexity located primary guidance from the California Department of Food and Agriculture, the California Department of Fish and Wildlife, USDA APHIS, University of California agricultural extension resources, and the San Joaquin County Agricultural Commissioner.
• Credibility Validation — claims were checked against official agency publications and current local reporting.
• Analysis and Synthesis — the material was organized into resident-facing identification and reporting guidance.
• Presentation — content was formatted for readability and accessibility.
• Final Review — the founder and editor reviewed and approved all content prior to publication and is responsible for it.

Corrections and additions are welcome at editor@lodi411.com.