Iowa crews take flight to stop spread of gypsy moths

Hooking up became substantially more difficult for gypsy moths in three tracts of northeast Iowa timber Monday following the aerial spraying of pheromone flakes.

The flakes confound male gypsy moths, which are attracted to their mates by the powerful scent released by the flightless female moths.

'The males get off track and can't find the females, which disrupts natural reproduction,” said Mike Kintner, gypsy moth and emerald ash borer coordinator for the Iowa Department of Agriculture and Land Stewardship.

Low flying airplanes released the flakes Monday in wooded areas of Allamakee and Jackson counties to slow the spread of gypsy moths, a pest that can destroy trees and shrubs.

The treatment covered 13,520 acres in three blocs, all on the leading edge of gypsy moth expansion. Two blocs, measuring 11,749 acres and 742 acres, are in Allamakee County. The third, a 1,029-acre area, is in Jackson County.

Kintner said the treatment could delay or prevent the classification of Iowa as a gypsy moth-infested state.

Similar treatments were conducted in Iowa in 2011 and 2013, according to Kintner. Follow-up testing with pheromone traps indicated those birth-control treatments were successful, he said.

The density of moths captured in those same traps, set out in a grid pattern, also helps to determine areas to be treated, he said.

The plastic pheromone flakes, which are specific to gypsy moths, are applied at a rate of about 1 cup per acre.

Because female gypsy moths cannot fly, they spread along 'a slow-moving front,” at about the pace the wind can transport treetop larvae, according to Kintner.

Gypsy moth larvae feed on more than 300 different species of trees and shrubs, with oaks a favored species. Each larva can grow up to 2 inches long and can consume up to 11 square feet of foliage from early May through June.

The larvae and their droppings can become so dense as to constitute a nuisance in parks and other wooded areas frequented by people.

Although healthy trees can survive defoliation, repeated removal of leaves can kill a tree. Older, less vigorous trees suffering from drought can be killed by a single defoliation.

Many animal species - and especially insects - communicate through pheromones. The ability of ants or bees to converge quickly upon a source of food, for example, is attributed to pheromone trails. Commercial Japanese beetle traps are baited with pheromones.

The northeast Iowa treatment is being conducted through a partnership among Iowa's agriculture and natural resources departments and the U.S. Department of Agriculture Gypsy Moth Slow the Spread Foundation.

In other states, where large infestations have occurred, spot treatment with insecticides has been used to kill gypsy moths and their larvae. That has not yet become necessary in Iowa, Kintner said.