Guide to Insect Pests & Diseases of Trees in New Jersey

New Jersey is home to many pests and diseases that want to attack your trees and plants. Effective prevention and treatment of pests and disease starts with identification.

Which Tree Pests and Diseases Do We Have in Northern New Jersey?

Want to know which creatures are after your trees and plants? Check out our extensive information below and check back for updates as new pest knowledge becomes available.

Call Aspen Tree for Identification & Treatment of Insect Pests & Diseases!

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Tree & Shrub Diseases in Northern New Jersey

OPC pest disease anthracnose


(Colletotrichum lindemuthianum)

Anthracnose is a fungal condition caused by various fungi species of the Colletotrichum genus. Symptoms include leaf spotting and the development of cankers.

OPC pest disease bacterial leaf scorch

Bacterial Leaf Scorch

(Xylella fastidiosa)

The bacteria responsible for BLS invades the xylem tissue of plants, restricting water flow from the roots to the crown. Symptoms include premature leaf browning and early leaf drop.

OPC pest disease boxwood blight

Boxwood Blight

(Calonectria pseudonaviculata)

Boxwood blight is a condition resulting from infection by Calonectria pseudonaviculata fungus. Symptoms of boxwood blight include leaf spots and blotches, defoliation, and lesions on plant stems.

OPC pest disease cedar apple rust

Cedar-Apple Rust / Hawthorn Apple Rust

(Gymnosporangium juniperi)

Another fungal disease, cedar apple rust, also known as hawthorn apple rust, most commonly affects species of apple and crabapple trees. Symptoms include green-yellow leaf spots that enlarge and turn brown and orange jelly-like galls.

OPC pest disease diplodia tip blight

Diplodia Tip Blight

(Sphaeropsis sapinea)

Diplodia tip blight is a fungal disease that attacks stressed landscape pine trees. Symptoms include browning of the pine needles on branch tips. Branch die-off is common and repeated infections can result in the death of the tree.

OPC pest disease dothistroma needle blight

Dothistroma Needle Blight

(Dothistroma septosporum)

This fungal disease is slow moving with a lifecycle that takes a full year to complete. Symptoms include the browning of needles with repeated infections severely damaging the tree canopy.

OPC pest diseasefire blight


(condition caused by Erwinia amylovora)

The highly contageuous Erwinia amylovora bacteria causes dying branch tips in apple, pear, and crab apple trees. It also attacks shoots, leaves, branches, fruits, and roots of infected trees.

OPC pest disease rhizosphaera needlecast

Rhizosphaera Needlecast

(Rhizosphaera kalkhoffi)

Spruce trees suffering from heat stress and poor planting are especially at risk from this fungal disease. Symptoms include needle death and premature needle drop.

Insect Pests of Trees & Shrubs in Northern NJ

OPC pest disease apple maggot larva

Apple Maggot

(Rhagoletis pomonella)

Also called the apple maggot fly or railroad worm, this insect is a pest of cultivated apples and is native to North America.

OPC pest disease bagworm


(Thyridopteryx ephemeraeformis)

A native pest, the bagworm is a defoliating caterpillar that causes most of its damage in urban and suburban areas. The extent of the damage ranges from the weakening of affected plants to plant death.

OPC pest disease boxwood leafminer

Boxwood Leafminer

(Monarthropalpus flavus)

An invasive pest from Europe, this small fly lays eggs in the underside of leaves. Upon hatching, the leafminer maggots begin mining the insides of the leaves as they feed.

OPC pest disease boxwood psyllid 1

Boxwood Psyllid

(Psylla buxi)

This sap-sucking insect pest feeds primarily on the common box (Buxus sempervirens), but all boxwood species are susceptible.

OPC pest disease cankerworm 1

Canker Worm

(Alsophila pometaria & Paleacrita vernata)

The larval form of the adult moth, the fall (A. pometaria) and the spring (P. vernata) canker worms are both found in North America and are known to feed on multiple shrub species of the Acer, Ulmus, Betula, and Prunus species.

OPC pest disease codling moth 1

Codling Moth

(Cydia pomonella)

Believed to have been introduced from Europe, this moth is a common orchard pest whose larvae feed on fruits including apples, peaches, and pears.

OPC pest disease cottony cushion scale 1

Cottony Cushion Scale

(Icerya purchasi Maskell)

Introduced to California from Australia, this insect pest affects a number of host plants including apple, boxwood, cypress, hackberry, locust, maple, oaks, peaches and plums (Prunus), pecan, pears, pine, rose, verbena, walnut, willow and other woody ornamentals.

OPC pest disease cottony maple scale 1

Cottony Maple Scale

(Pulvinaria innumerabilis)

Native to North America, this insect pest can kill trees in high enough numbers and has a number of hosts including honey locust, black locust, white ash, euonymus, oak, boxelder, dogwood, hackberry, sycamore, linden, beech, elm, willow, basswood, poplar, rose and sumac.

OPC pest disease eastern tent caterpillar

Eastern Tent Caterpillar

(Malacosoma Americanum)

Native to North America, these leaf-eating caterpillars can easily defoliate an entire tree. Outbreaks occur every few years as the populations of this pest fluctuate.

OPC pest disease elm bark beetle 3

Elm Bark Beetle

(Hylurgopinus rufipes)

The larvae are small, white, and grub-like and are found under the bark of dying or dead elms. This bark beetle is native to North America and is best known as a vector of Dutch elm disease.

OPC pest disease elm leaf beetle 2

Elm Leaf Beetle

(Xanthogaleruca luteola)

This invasive beetle from Europe is widespread in North America. Adults and larvae feed on and skeletonize leaves of multiple elm species including the English elm, American elm, white elm, Siberian elm, and Chinese elm.

OPC pest disease fiorinia scale 2

Elongate Hemlock Scale

(Fiorinia externa)

Also known as fiorinia scale, this Japanese native pest affects forest and ornamental hemlock trees in New Jersey.

OPC pest disease eab

Emerald Ash Borer

(Agrilus planipennis)

An invasive pest from Asia, this beetle species attacks ash trees across the country. Once infested with EAB, ash trees die quickly.

OPC pest disease euonymus scale 2

Euonymus Scale

(Unaspis euonymi)

Native to China and Japan, this pest affects several Euonymus species, Pachysandra species, and Celastrus species. Vine-type euonymus are especially susceptible to this scale insect.

OPC pest disease fall webworm 1

Fall Webworm

(Hyphantria cunea)

The larvae of this moth is a pest of various shrubs, ornamentals and trees. Native to the United States, this webworm was introduced to Yugoslavia from where it spread to much of Europe.

OPC pest disease japanese beetle

Japanese Beetle

(Popillia japonica)

An extremely destructive pest, these invasive beetles quickly devour leaves, giving them a lace-like appearance. They are non-specialist and are known to attack over 300 tree and plant species.

OPC pest disease leaf roller 2

Leaf Roller

(family Tortricidae)

A large group of larvae in the Tortricidae family, the leaf-roller or bell moth are among the most destructive North American tree and shrub pests. They are named for the leaf rolling habit of the larvae.

OPC pest disease oak leaf skeltontizer 2

Oak Leaf Skeletonizer

(Bucculatrix ainsliella)

With two generations per year, the North American native oak leaf skeletonizer is a prolific pest, named for its feeding pattern of skeletonizing oak leaves.

OPC pest disease false webworm 2

Pine False Webworm

(Acantholyda erythrocephala)

The invasive pine false webworm was first identified in North America in 1961. While initially affecting only immature white and red pines, larger scale infections on mature pines have been identified since 1993.

OPC pest disease pine sawfly 1

Pine Sawfly

(Neodiprion sertifer)

This conifer pest is known for defoliating pines in localized or regional outbreaks lasting one or more years. The European pine sawfly, introduced to the US in 1925, is the most common pine sawfly in New Jersey.

OPC pest disease plum curculio 2 larva

Plum Curculio

(Conotrachelus nenuphar)

This snout beetle species is native to North America. Adults feed on trees before females lay eggs on apples, peaches, and other fruits which the larvae then feed on until pupating underground in the fall.

OPC pest disease san jose scale

San Jose Scale

(Quadraspidiotus perniciosus)

Originally from China, this invasive scale insect was first identified in California and later accidently transported to Virginia and later New Jersey. Heavy infestations by these sucking pests can result in tree death.

OPC pest disease scale insect

Scale Insects

(superfamily Coccoidea)

This diverse insect group uses their piercing mouthparts to suck sap from trees resulting in yellowing leaves, stunted growth, and even death of the host.

OPC pest disease spider mite

Spider Mites

(Tetranychus urticae)

These tiny sap-sucking pests are more closely related to spiders than insects. They are identifiable by the silk webbing they leave on the underside of leaves.

OPC pest disease spongy moth

Spongy Moth / Gypsy Moth

(Lymantria dispar)

An invasive European moth, the spongy moth (formerly the gypsy moth) is a defoliator that interferes with a trees ability to perform photosynthesis.

OPC pest disease SLF

Spotted Lanternfly

(Lycorma delicatula)

This Chinese native feeds on a wide variety of ornamental, fruit, and woody trees. They feed by using their piercing mouthparts to suck sap from their host, weakening the plant.

OPC pest disease white peach scale 2

White Peach Scale

(Pseudaulacaspis pentagona)

Originating from either Japan or China, this scale pest has decimated peach orchards throughout New Jersey. Though most prevalent in the southern US, the pest has spread through the northern US as far as Maine.

OPC pest disease white prunicola scale 1

White Prunicola Scale

(Pseudaulacaspis prunicola)

Another invasive species, white prunicola scale have several host species including the cherry laurel and other Prunus species. Light infestations result in leaf yellowing and shedding with heavier infestations causing branch death.

OPC pest disease woolly adelgid

Woolly Adelgid

(Adelges tsugae)

Also know as hemlock woolly adelgid, this invasive insect pest threatens ornamental hemlocks throughout eastern North America. As part of their complex life cycle, immature nymphs settle at the base of hemlock needles and use their sucking mouthparts to feed.