10 Most Unwanted Arizona Invasive Species: Plants & Animals

1. Quagga Mussel

Origin: Eastern Europe and Ukraine
Prolific populator; Removes food/nutrients from water column, clogs pipes and water conveyance infrastructure, damages boat motors and marinas; Management/eradication costs can be enormous for power and water supply agencies. Dispersal by boats and equipment, pipes, canals, live wells.

2. Buffelgrass

Origin: Africa
Pervasive grass introduced for soil stabilization and livestock feed; Potential to severely alter Arizona’s desert landscape due to fire-carrying capability; Regrows quickly and outcompetes to replace native plants in disturbed areas. Dispersal by windblown seeds and rapid spread along roadways into the desert and rangelands/pastures.

3. New Zealand Mudsnail

Origin: New Zealand
Out-competes native Arizona snails for available food resources/territory; Very prolific and spreads quickly by floating and attaching to vegetation to rapidly increase its range. Dispersal by boaters and anglers (waders, boating gear, fishing equipment, etc.)

4. Red Imported Fire Ants

Origin: South America
Caused severe, irreparable damages to economy/ecology in southeastern states and parts of New Mexico and California; Damages include total crop losses, nursery infestations, livestock depletion and harm to human health (stings/allergic reactions). Dispersal by plant trade and vehicular travel.

5. Asian tiger mosquito

Origin: Asia
Widely established in southeast and
midwest U.S.; Aggressive biter carries diseases harmful to humans, e.g., West Nile virus, yellow fever and dengue fever; Detected in Arizona in 2000 and 2006 on imported, non-native plants. Dispersal by exotic plant trade (egg dispersal), back-yard containers, and transporting old tires.

6. Northern Crayfish

Origin: Canada, south to Texas,
west to Utah, north to Montana.
Popularly used as bait and for aquatic weed control; Populations have exploded in Arizona due to no natural predators; Arizona has no native crayfish; Voracious appetite for larval fish, plants, and insects can severely harm ecosystems. Dispersal by bait buckets and aquarium discard.

7. Yellow Starthistle

Origin: Eurasia, southern Europe
Displaces native and agricultural plants
in rangelands/pastures; Grows and spreads in dense, impenetrable stands; Toxic to horses; Introduced to southwest as contaminant in grain seed. Dispersal by livestock, roadways, contaminated seed, and vehicular travel.

8. Red Bromegrass

Origin: Eurasia, Mediterranean region
Weedy annual now common throughout southwest U.S.; Grows prolifically with winter rainfall; Substantially increases fine fuels on rangelands; Increases occurance and severity of wildfires. Dispersal by seeds spreading to disturbed areas along
roadways, rangelands, agricultural
fields and urban landscapes.

9. Silver carp

Origin: China
Introduced into U.S. for algae control and as a food fish; Currently well established in the Mississippi drainage; Can grow up to 4 feet long and weigh over 60 pounds; Adults outcompete juvenile sportfish (e.g., bass, bluegill) for planktonic food. Dispersal by bait buckets and illegal commercial transport.

10. Giant Salvinia

Origin: South America
Pervasive aquatic fern that can greatly alter aquatic ecosystems; Forms very thick surface mats and completely blocks light and oxygen penetration; Impedes water flow, clogs water conveyance, and eliminates all other plant/fish species. Dispersal by boats, equipment, and natural downstream flow.

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