Spongy Moth Research Continues News | August 5, 2025 | 0 | by Morgan McCarthy The Wisconsin Department of Natural Resources is asking residents to watch out for spongy moths. The worm-like bug is known to cause drought and defoliation. Anyone seeing signs of decline in their trees should email a report. Spongy moth outbreaks usually last two to three years, and happen every ten to twelve years. CLICK HERE FOR MORE.