Formosan subterranean termite
> Year of swarm / US introduction: 1960s
One of the most destructive pests in the United States, Formosan subterranean termites cause over $1 billion in damage every year. Believed to be native to East Asia, they were first detected in the continental U.S. in the 1960s and are now established in at least nine Southern states and Hawaii. Colonies can contain several million termites and to date have been impossible to eradicate.
> Year of swarm / US introduction: 1980
With the floodwaters of Hurricane Allen creating perfect mosquito breeding grounds in August of 1980, Texas was overrun with billions of mosquitos. Swarms targeted local cattle and horse ranches, sucking so much blood of livestock that they killed 15 cattle in one night.
> Year of swarm / US introduction: 1981
In 1981, European gypsy moth caterpillars defoliated over 9 million acres of trees in the Northeastern United States, from Maryland to Maine. The larvae — not to be confused with tent caterpillars, which build large webs in trees — are known to eat over 300 different species of trees and shrubs.
> Year of swarm / US introduction: 1990
In the 1950s, a Brazilian apiary began crossbreeding African honey bees with local honey bees. Multiple swarms escaped and began moving northward, eventually reaching Texas in 1990. These Africanized bees attack intruders much more rapidly and in larger numbers than domestic honey bees, and they have even been known to chase humans for a quarter mile. Hordes of these bees have killed about 1,000 humans, earning them the name “killer bees.”
Asian longhorned beetle
> Year of swarm / US introduction: 1996
Native to China and Korea, the Asian longhorned beetle was first detected in 1996. The beetle is a threat to eastern hardwood forests as it can infest and feed on a dozen different species of hardwood trees, including maple, ash, and birch. These beetles are currently a threat in Massachusetts, New York, and Ohio, and have the potential to destroy millions of acres of hardwoods.
Signs of the beetle appear after 3 to 4 years after infestation. Trees are destroyed over the course of 10 to 15 years and do not recover or regenerate.