Scientists have discovered that two species are more to blame for economic damage caused by invading pests than any other.
Since 1986, the American bullfrog and brown tree snake have cost the world a combined $16.3 billion (£13.4 billion) in damages.
In addition to doing environmental damage, the invasive pair has destroyed farm crops and cost-prohibitive power disruptions.
Researchers are hoping that their findings will lead to increased investment in efforts to prevent invasive species in the future.
The experts estimated that the brown tree snake was alone to blame for $10.3 billion in damages.
In Guam, the reptile was unintentionally introduced by US troops a century ago.
The sheer number of snakes in existence today results in widespread power outages because they crawl over electrical wires and cause significant damage.
The tiny Pacific island is home to more than two million brown tree snakes, with one estimate placing their density as high as 20 per acre in the jungle of Guam.
It is believed that island ecosystems are more susceptible to invasive species because they offer a higher threat to the extinction of native fauna and flora.