In 1869, a French entomologist trying to breed a hardier silkworm let a batch of moth larvae escape his Massachusetts yard. Twenty years later they had defoliated 360 square miles nearby, and the spec

Key Points:

• In 1869, Étienne Léopold Trouvelot, an amateur naturalist in Massachusetts, accidentally released European gypsy moth caterpillars while experimenting with silk production, leading to a major invasive pest problem in North America.
• The gypsy moth population remained low and unnoticed for about 20 years before erupting into a large-scale outbreak in 1889, defoliating hundreds of square miles of trees around Medford, Massachusetts.
• The moth spread steadily over the next century, damaging over 81 million acres of forest by 2013 and feeding on more than 300 tree and shrub species, causing significant ecological and economic harm.
• Efforts to eradicate the moth failed, and current management focuses on containment through the federal Slow the Spread program, which uses traps, mating disruption, chemical treatments, and a naturally occurring fungus to control populations.
• This case highlights the challenge of slow-developing biological invasions, where a small initial event can lead to extensive long-term consequences that are difficult to predict or reverse.