Highly destructive and medically hazardous outbreaks of gypsy moth-caterpillars have occurred several times within urban and residential regions of Massachusetts during the last two decades. Considering the scope of these well publicized outbreaks, most residents of the state have likely heard the story about this pest species’ unfortunate introduction into the state. To make a long story short, a French artist transported the larval insects into the state during the 1860s in order to encourage the gypsy moth species to interbreed with native silkworm species, as the ambitious artist had hoped to find a more efficient method of producing commercially valuable silk. Unfortunately, the aspiring entrepreneur’s plan did not go well, as his abundant collection of non-native caterpillars escaped from his property where they quickly established an invasive habitat within a nearby forested region. Twelve years later, massive numbers of these caterpillars emerged from the forest where they proceeded to infest an entire neighborhood.

This enormous caterpillar population rapidly covered lawns, gardens, fences, houses, sidewalks, and even people, but worst of all, the newly introduced pests defoliated every tree in the area. The caterpillars had also damaged lawns and completely destroyed gardens, and the species’ furry-looking and venomous spines caused allergic reactions in the form of tremendously itchy rashes that irritated numerous residents for days, and sometimes weeks. By 1889 the caterpillars had established a 360 square mile habitat where dense populations continued to terrorize residents. Most affected homeowners had taken it upon themselves to regularly collect the pests and their eggs from trees and lawns by hand before burning them, but the pests continued to proliferate. Due to the public outcry over these seemingly uncontrollable infestations, the state of Massachusetts dedicated a substantial amount of money to the formation of one of the first large-scale pest control programs in American history. However, the eradication methods employed were far from ideal, as government officials and residents found that the application of arsenic poisons often killed the trees that they had been hoping to save from the caterpillar pests, and burning the caterpillars and their eggs with the help of crude petroleum naturally caused more damage to lawns, as well as residential and forested tree species. Rural and urban areas where trees and vegetation were once abundant became barren “wastelands” as a result of these ill-conceived pest control methods, which resulted in an even greater degree of public discontent. Unfortunately, by this point, the state of Massachusetts had already wasted a considerable amount of money on the failed caterpillar elimination program.

In the following years, gypsy moth-caterpillars continued to expand their territory, forcing the state to spend an additional 200,000 dollars (4 million dollars today) on more ecologically-friendly control methods, such as caterpillar survey counts and lead-creosote treatments. This approach successfully reduced the caterpillar populations, until the pests established a widespread habitat in Rhode Island, which prompted the USDA to invest in a biological caterpillar control program that entailed the importation of nine species of the caterpillar’s natural wasp predators. Despite this novel method, the next several decades saw the caterpillars spread despite numerous costly federal programs that made use of insecticide solutions, pheromone traps, predatory beetles and many other experimental control measures. Luckily, in 1989, the accidental introduction of a pathogenic fungus from Asia was found to kill gypsy moth caterpillars more efficiently than any of the previous experimental control measures. This fungal species, E. maimaiga, was imported into the US from Asia where it is still used to control gypsy moth-caterpillars to this day.

Has a Gyspy moth-caterpillar outbreak ever occurred in your hometown?