The Country’s Most Dangerous Beetles

Invasive beetles of various colors and sizes have infiltrated U.S. forests, despite efforts by government experts

Colorado potato beetle
Scott Bauer / USDA


Asian longhorned beetle
(Maura McCarthy)

Native to: China, Korea and Japan
Attacks: Hardwood tree species, including maple, birch, poplar and elm
First discovered in the United States: In August 1996 in Brooklyn, New York
Currently found in: Worcester, Massachusetts; New York City; New Jersey
Has been eradicated from: Chicago, Illinois

Emerald ash borer (Agrilus planipennis)

Emerald ash borer
(Maura McCarthy)

Native to: Eastern Russia, northern China, Korea and Japan
Attacks: Ash trees of the Fraxinus genus
First discovered in the United States: Near Detroit, Michigan in summer 2002
Currently found in: Michigan, Illinois, Indiana, Ohio, Maryland, Pennsylvania, West Virginia, Wisconsin, Missouri, Virginia, Minnesota, New York and Ontario, Canada Strange symptom of infection: Increased damage by woodpeckers that eat the insect larvae


Mountain pine beetle
(Maura McCarthy)

Native to: Western areas of the United States and Canada
Attacks: Lodgepole, knobcone, ponderosa, sugar, white and whitebark pines
Recent outbreaks are more severe than in the past due to: Drought, a warming climate and decades of fire suppression
Level of damage: In northwestern Colorado alone, the beetles have killed 3.5 million acres of lodgepole pine forests


Citrus longhorned beetle
(Maura McCarthy)

Native to: China, Korea, Japan, Taiwan, the Philippines, Indonesia, Malaysia, Myanmar and Vietnam
Attacks: More than 40 hardwood species, including fruit trees and ornamentals
Has shown up in: Georgia, Wisconsin and Washington State
Why we don’t have to worry yet: Government managers have caught the beetle each time and prevented it from becoming established in this country

Goldenhaired (or red-haired) pine bark beetle (Hylurgus ligniperda)

Goldenhaired pine bark beetle
(Maura McCarthy)

Native to: The Mediterranean and Africa
Attacks: Several species of pine trees
Already spread to: South America, Australia, New Zealand and parts of Asia
First appeared in the United States: In 2000 at a Christmas tree plantation in Rochester, New York
Associates with: Two species of Leptographium fungi, including black stain root disease


Granulate ambrosia beetle
(Maura McCarthy)

Native to: Tropical and subtropical Asia
Attacks: Several ornamental and fruit tree species, including Bradford pear, pecan, dogwood and willow
Already spread to: Africa and the South Pacific
First appeared in the United States: Near Charleston, South Carolina in the 1970s
Currently found in: Hawaii and the southeastern United States
Strange behavior: The beetles infuse the trees they attack with an ambrosia fungus for the bettle’s offspring to feed on


Banded cucumber beetle
(Maura McCarthy)

Native to: Southern Arizona and Texas, Mexico and Central America
Attacks: Vegetable plants including cucumber, squash, beans, peas, sweet potato, corn, lettuce and soybeans
Current U.S. range: The southern half of the country, from North Carolina to California
Why it’s so dangerous: The adult beetle attacks all parts of the plant and is a known vector of virus diseases in beans


Colorado potato beetle
(Maura McCarthy)

Native to: Southwestern North America
Formerly ate: The buffalo bur, a weed in the foothills of the Rocky Mountains
Became a problem when: People started migrating west in the 1840s bringing a new food for the beetle—potatoes
Now attacks: Potato, pepper and tomato plants, eggplants
Has spread to: Much of North America, Europe and Asia

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