Every staple Wisconsin tree is at risk of being attacked by bugs and insects. While many of them appear to be harmless, they contribute to problems that long-term could cost a tree’s life. Insect control is a crucial part in keeping your landscape both beautiful and healthy.
Below is a list of common pests that attack many of our Wisconsin trees. If you’ve noticed these pests throughout your property or have identified their signs, contact our experienced team of arborists today for an insect control consultation and plan.
Maple Tree Pests
Maple Gall Mites – less than 2mm long (cannot be seen without magnification), become very active in spring and cause strange swellings on Maple leaves.
Cottony Maple Scale – small, winged insects within 3-6mm long, recognized by the egg masses on twigs and branches and withdraw plant fluids that cause dieback.
Asian Longhorn Beetle – (found on several trees), range from 1.7 to 3.9 cm, hatch from eggs within bark and chew their way out as adults, feed off of leaves – destroying foliage.
Oak Tree Pests
Two-line Chestnut Borer – 5-12mm long, lay eggs on weakened oak trees, larvae feeds off of the nutrients in the bark, foliage turns brown and dieback occurs
Gypsy Moth – 20-35mm long, brown in color, feed on foliage and can weaken trees through defoliation – resulting in drought, disease and additional attacks
Honey Locust Leadhopper – small, light green insects, feed on the foliage through sucking out plant sap and causes dieback of branch ends.
Ash Tree Pests
Ash Plant Bug – 6-7mm long, green to light brown with yellow triangular spot on back, directly attack foliage that causes leaves to drop prematurely.
Emerald Ash Borer – 7-12mm long, bright green beetle, bore through tree bark as adults and heavily feed on foliage – resulting in defoliation, nutrient deficiency and fatality.
Ash Flower Gall – small mites (magnification required to see) that feed on tiny male ash flowers, signs include green tumor-like growths on flowers, creates long-term cosmetic damages
Birch Tree Pests
Bronze Birch Borer – 7-12mm long, dark greenish-bronze beetles that create D-shaped holes (similar to EAB) as they leave the bark, signs include wilting and dying of upper crown, ridges and bumps on limbs and branches.
Birch Leafminer – 3-6mm long, saw flies relating close to bees and wasps that feed off foliage, signs include brown scorched areas on foliage.
Elm Tree Pests
Elm Leafminer – 6-7mm long, black in color, feeds on the tissues in between outer layer of elm tree leaves, signs include browning and leaf drop.
Elm Leaf Beetle – 3-6mm long, olive-green beetle with black stripes, chew entirely through leaves, causing foliage to turn brown to whitish – resulting in complete defoliation.
Hackberry Tree Pests
Hackberry Psyllid – small insects that resemble smaller cicadas, creates growths on the backside of hackberry tree leaves, causes cosmetic damage.
Pine Tree Pests
Sawflies – 2-20mm in size, black/brown in color, cause defoliation of the oldest needles, can feed on tender bark, signs include deformed branches and tufted appearance.
Pine Weevils – 4-6mm in size, rust-colored and irregularly shaped scales on wings, larvae burrow and chew completely around stem, causing structural damage long-term
Shoot Moths – 25mm long, reddish brown and gray in color, signs include yellowing of needles near the tips of twigs, clear deposits of pitch near bud clusters.