Ecologists have found a new pattern in the gypsy moth invasion
across the Northeastern United States that might be useful in
battling the moths. The gypsy moth invasion is arguably the most
intensively studied species invasion in history. Since the
moths' accidental release near Boston in 1869, the species has
swarmed across more than 1 million square miles of the United
States, defoliating up to 12 million acres of forest each year.
By analyzing more than four decades' worth of data, Derek
Johnson and colleagues at the University of Louisiana at
Lafayette discovered the moths' spread occurs in pulses roughly
four years apart. That, say the scientists, is probably because
moths that spread far beyond the current frontier cannot
establish breeding populations unless they colonize in
sufficient numbers. Thus, says Johnson, moths can spread only at
times when their populations are high and so targeting large
groups of moths near the edges of the current distribution could
help to slow their advance. The study ap