Photo: Louis-Michel Nageleisen, Département de la Santé des Forêts, Bugwood.org
The Nun Moth, Lymantria monacha, is one Tussock Moth native to Europe that has not made its way to North America. That's a good thing, because in its native range it has reaped havoc on forests. Nun Moths tend to chew the base of needles on coniferous trees, allowing the rest of the untouched needle to fall to the ground. This habit results in extraordinary needle loss when caterpillar populations are high.
Unlike many other Tussock Moths, both males and females are active fliers in this species. Their mobility allows them to mate and lay eggs over wider ranges of forest, spreading the defoliation. Females deposit eggs in masses of up to 300; the insect then overwinters in the egg stage. The larvae emerge in spring, just when tender new growth appears on the host trees. This single generation devours foliage as it matures through as many as 7 instars.