The Adirondack Mountains are presented as a natural barrier to the westward spread of the gypsy moth. Their forests, composed of tree species the insect does not find attractive, helped limit its advance and illustrate how the composition of a landscape can shape the boundaries of a pest’s range.

Setting and Natural Barrier

The book describes the Adirondacks as a barrier in the northeastern United States, where the gypsy moth’s range had expanded through several routes. The New England hurricane of 1938 carried the moth into Pennsylvania and New York; the mountains, by contrast, generally checked its movement farther west. Their effect depended not simply on elevation or distance, but on the forest itself: its tree species did not appeal to the insect.

Role in Containing the Gypsy Moth

Efforts to confine the gypsy moth to the country’s northeastern corner had used a variety of methods. The Adirondacks were one part of that containment story, but a distinctive one: unlike an intervention, the range’s barrier function arose from the ecological character of its forests. The contrast makes containment more than a record of human action; the landscape could also resist the insect’s spread through the limits it placed on its habitat.