Defoliated Trees Prompt Gypsy Moth Egg Study in Mahwah

A high amount of defoliation in Mahwah trees has prompted the state to study the township’s gypsy moth egg population, officials from the town and state said last week.

According to Jeff Beach of the state Department of Agriculture, aerial surveys of the entire state showed that about 273 acres of trees in Mahwah have fewer leaves on them than they should, a typical sign of gypsy moth activity. About 195 acres showed signs of moderate defoliation, and 78 showed heavy defoliation, according to state data.

Mahwah’s town council approved last Thursday the state’s request to perform an egg nest survey. The test will see DoA workers on the ground in Mahwah this fall searching for moth egg nests, Beach said. Defoliation is only a preliminary indicator of a large moth population, and the field-testing is one way to confirm a high number, Beach said.

Defoliation-prompted testing, something the state does each year, is relatively low this year, as the state is in a low point on the gypsy moth population cycle, Beach said. Mahwah and Oakland are the only two Bergen towns that showed significant defoliation during aerial tests, he said.

Township officials said the testing costs the town nothing, and contains no obligations to treat the moth population that is found.

However, the state will make treatment recommendations after the testing that could include spraying large areas of trees in an attempt to control the moth population.

If a high number of gypsy moth caterpillars hatch next spring, Beach said they would be a “serious nuisance,” to any nearby residents.

“That’s when we’d start getting calls about people going outside on their decks and slipping because there are so many caterpillars on the deck,” he said.

The caterpillars do not carry any serious diseases and are generally not dangerous for humans, he said. But, their nesting can depreciate local tree health, and three consecutive years of defoliation will kill trees, Beach said.

Across the state, the DoA found about 2,887 acres of defoliated land.