1. Argentine Ant – Linepithema humile
The Argentine ant is often regarded as the Genghis Khan of the ant world. This species has a diverse diet and produces a large number of industrious and aggressive worker ants. Once adapted and thriving in a favorable habitat, they tend to exclude all other ant species, both native and invasive.
Argentine Ant (Photo: msstate)
2. Asian Longhorned Beetle – Anoplophora glabripennis
The shiny black Asian longhorned beetle with white spots poses a severe threat to hardwood trees in its native regions of China, Korea, and Japan. This beetle has found refuge in hardwood packaging in the U.S. and the U.K., with reports of infestation in New York in 1996 and Chicago in 1998.
Asian Longhorned Beetle (Photo: insecte.uef)
3. Asian Tiger Mosquito – Aedes albopictus
The Asian tiger mosquito was introduced to the U.S. and many other countries through imported used tires. This mosquito species is associated with the transmission of dengue fever, eastern equine encephalitis, heartworm, and possibly St. Louis and LaCrosse encephalitis viruses.
Common name: Dengue mosquito
Asian Tiger Mosquito – Aedes albopictus (Photo: ento.okstate)
4. Big-headed Ant – Pheidole megacephala
Originating from Africa, the big-headed ant is a wandering species that has spread globally through human trade. This aggressive ant species preys on many native organisms such as ants, beetles, moths, and spiders.
Big-headed Ant – Pheidole megacephala (Photo: hear.org)
5. Anopheles Mosquito – Anopheles quadrimaculatus
This relatively large mosquito is the primary vector for malaria. It mainly breeds in stagnant freshwater bodies and bites humans and livestock at night.
Common name: Malaria mosquito
Anopheles Mosquito (Photo: k12education)
6. Common Wasp – Vespula vulgaris
Common wasps build nests underground and in tree cavities. Besides delivering painful stings to humans, they compete with birds and other insects for food sources and scavenge for fruits around trash bins and campsites.
Common Wasp – Vespula vulgaris (Photo: cometpc)
7. Little Fire Ant – Wasmannia auropunctata
The little fire ant is considered a contributor to species diversity decline, reducing populations of winged insects, wood borers, and decimating spider populations. In the Galapagos Islands, they have been known to prey on hatchling tortoises and sting the eyes and nostrils of adult tortoises.
Little Fire Ant – Wasmannia auropunctata (Photo: sbs.utexas)
8. Cypress Aphid – Cinara cupressi
The cypress aphid causes severe damage to cypress and juniper species across many countries. This highly aggressive insect feeds on various parts of the plant, including tender shoots and woody stems. Damage can range from localized infestations to the death of entire trees.
Cypress Aphid – Cinara cupressi (Photo: j-alemany)
9. Crazy Ant (Yellow Crazy Ant) – Anoplolepis gracilipes
Known for their aggressive behavior, crazy ants have invaded native ecosystems and caused environmental damage in areas such as Hawaii, Christmas Island, Seychelles, and Zanzibar.
Crazy Ant (Yellow Crazy Ant) – Anoplolepis gracilipes (Photo: lamarabunta)
10. Snail Eater – Platydemus manokwari
The snail eater was introduced to many islands in the Pacific and Indian Oceans to control African snail populations. It has become a significant threat to native terrestrial mollusks. In Guam, it also threatens species in the Partulidae family and other endemic organisms.
Snail Eater – Platydemus manokwari (Photo: bishopmuseum)
11. Formosan Subterranean Termite – Coptotermes formosanus
This termite species causes significant damage to trees, homes, telephone poles, power lines, and underground telephone systems. In Hawaii, costs to prevent and/or control infestations and repair damage caused by this termite can exceed $60 million annually.
Formosan Subterranean Termite – Coptotermes formosanus (Photo: comp.uark)
12. Giant African Snail – Achatina fulica
The giant African snail has been widely introduced to many countries in Asia, Pacific islands, and the Indian Ocean, and more recently to the West Indies. It poses a dangerous threat to agriculture and acts as a vector for several pathogens and nematodes.
Giant African Snail – Achatina fulica (Photo: achatina.unnat)
13. Golden Apple Snail – Pomacea canaliculata
The golden apple snail is an omnivorous freshwater snail that feeds on various aquatic plants such as lotus, taro, water chestnut, and rice. This pest poses a significant threat to crops in Southeast Asia and Hawaii, causing severe damage to many wetland areas worldwide by altering habitats and competing with native species.
Golden Apple Snail – Pomacea canaliculata (Photo: applesnail)
14. Gypsy Moth – Lymantria dispar
The gypsy moth is one of the most dangerous pests for fruit orchards and ornamental plants across the Northern Hemisphere. It is also a significant threat to hardwood forests, as its feeding can defoliate trees, reducing growth rates and overall vitality.
Gypsy Moth – Lymantria dispar (Photo: agspsrv34.agric)
15. Khapra Beetle – Trogoderma granarium
The khapra beetle is one of the most dangerous pests for storage facilities worldwide and is subject to international quarantine regulations. They can survive in storage with very low densities and can remain viable for extended periods in a dormant state.
Khapra Beetle – Trogoderma granarium (Photo: ipm.uiuc)
16. Red Imported Fire Ant – Solenopsis invicta
The red imported fire ant is an aggressive carnivorous insect that reproduces rapidly and dominates most food sources. With their venom, they can overpower prey and drive larger vertebrate competitors away from their resources. Their diet consists of invertebrates, vertebrates, and plant material.
Red Imported Fire Ant – Solenopsis invicta (Image: creatures)
17. Rosy Wolf Snail – Euglandina rosea
This carnivorous species of wolf snail was introduced to islands in the Pacific and Indian Oceans as a biological control agent against another invasive species, the African Giant Snail (Achatina fulica). This introduction has led to the extinction of the Partulid snail species in French Polynesia.
Rosy Wolf Snail – Euglandina rosea (Image: biology)
18. Sweet Potato Whitefly – Bemisia tabaci
This sweet potato pest is a significant threat to food crops and fiber-producing plants worldwide. Damage occurs as larvae burrow into and suck sap from the leaves of plants, serving as a vector for transmitting plant disease-causing viruses and producing honeydew, which fosters the growth of sooty mold on leaves.
Sweet Potato Whitefly – Bemisia tabaci (Image: science.uva)
(The absence of species from this list does not imply they are less dangerous)
