New Jersey forest and environmental officials are in a constant battle with native and invasive bugs that seriously threaten the Garden State's forests and leafy neighborhoods.

Here are the three bugs that are of particular concern this year.

Emerald ash borer

Emerald ash borer (NJ Dept. of Environmental Protection)
Emerald ash borer (NJ Dept. of Environmental Protection)

The emerald ash borer is not native to North America, which means the beetles do not have any natural predators to keep their populations in check. And trees here, meanwhile, have not evolved with the emerald ash borer, so they have no natural defenses.

"Emerald ash borer can kill an ash tree in as quick as three years, and when their populations reach high enough levels, they can really cause widespread tree deaths in ash," said Rosa Yoo, regional forester with the NJ Forest Service.

The ash-eating beetle was discovered in New Jersey in 2014, but the state has been monitoring for emerald ash borer for the last 7 years to try to detect it as early as possible, Yoo pointed out.

The emerald ash borer was first detected in the midwest in 2002 and has been progressively moving eastward and southward through the years.

"It was either through infested firewood, people unknowingly moving firewood far distances; or infested nursery stock, like ash trees, that they were purchasing from other states," Yoo said.

New Jersey has nearly 25 million ash in forested areas, mainly in the northern part of the state, which Yoo noted does not include the countless ash that are planted in yards, along streets and in parks statewide.

"Our greatest threat we could assume is the northern half, because that's where our ash forests are, but we can't discount all the ash that are planted in these residential or private areas," said Yoo.

Don't transport firewood!

It's difficult to see the impacts of emerald ash borer immediately because a lot of times trees are infested and the trees takes some time before they start to die, explained Yoo.

Most of the emerald ash borer activity has been in the central part of the state — in Somerset, Mercer, Middlesex, Monmouth and Burlington counties — as well as in Bergen County.

Yoo says the emerald ash borer is difficult to control.

"All we're trying to do is slow the continual expansion of the emerald ash borer within the state," she said, stressing the message is always" "don't move firewood to new locations."

Instead, Yoo suggested, "if you want to go camping, buy firewood locally or purchase firewood that is certified, which means its heat-treated, there's no living organisms in it."

Pesticide treatments also can be done on individual trees, but Yoo noted it's not effective for large areas. A Biocontrol Program is more effective in forested areas, she said.

"There are several options. We cannot eradicate emerald ash borer. It's just a matter of trying to contain the populations that we know of, and prevent it from spreading further, faster," said Yoo.

Southern pine beetles

A forester with the New York Department of Environmental Conservation points out a tiny southern pine beetle at the tip of his finger on the bark of a tree
A tiny southern pine beetle (AP Photo/Frank Eltman)

The other destructive insect of concern to New Jersey is the southern pine beetle, which has mostly been an issue in the southern half of the state, where most of the pine forests exist.

"The southern pine beetle is kind of unique because it is a native insect to North America, and so there are natural predators and things like that, but (they) can reach epidemic levels. Their populations can reach very high levels where they begin to infest healthy pine trees, and that's when it becomes an issue," Yoo said.

Southern pine beetle generally attacks trees under stress, and they cannot successfully infest health trees.

Southern pine beetle larvae eat the trees from within. The bugs also spread a fungus that accelerates the destruction of the tree.

A southern pine beetle infestation can be kept at bay by cutting out the infested trees and a buffer of uninfested trees to try to disperse the beetle, so that their movement is disrupted from spreading, according to Yoo.

Gypsy moth

Gypsy Moths
A gypsy moth caterpillar walks along partially eaten leaves of a tree in Trenton. (AP Images)

The gypsy moth, which is not native to the continent, is another serious forest threat in New Jersey, where its population started peaking last year.

Gypsy moths often get confused with native tent caterpillars and do not create any kind of nest, Yoo pointed out.

"The pupa of the gypsy moth is like a brown shell and is typically either along the trunk of the tree or in the soil," she said.

Gypsy moths do not cause immediate tree mortality, but after repeat defoliation or leaf eating, they can cause widespread tree deaths.

"We typically see tree mortality caused by gypsy moths after two, three, four years of heavy defoliation. They generally prefer oak trees, but they will feed on hundreds of different species of trees and plants when their populations reach these very high levels," Yoo said.

Last year, most of the gypsy moth activity was in the northern part of the state with a small out layer in southern portion of the state, in Cape May County, according to Yoo. "But typically when the populations reach high levels, it is pretty much statewide," she said.

"The state works cooperatively with the New Jersey Department of Agriculture to spray target areas where the populations are high, using a natural pesticide called Bt," said Yoo.

There are other forest health threats that the state is always concerned about, noted Yoo, including hemlock woolly adelgid and beech bark disease.

"We also continue to monitor for insects and diseases that are impacting neighboring states, but that we have not detected here, such as winter moth or sirex wodwasp, spotted lanternfly, or thousand cankers disease," Yoo added.

The state is advising homeowners and municipal public works departments to keep abreast of developments with the two beetle species, especially, and to report anything that looks suspicious to either the NJ Forest Service or the state Department of Agriculture for further assistance.

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