Tree & Shrub Pests Identification

Japanese Beatles

Japanese beetle identification Adult Japanese beetles are 7/16-inch long metallic green beetles with copper-brown wing covers. This tree pest has row of white tufts (spots) of hair project from under the wing covers on each side of the body. Adults emerge from the ground and begin feeding on plants in June. They usually feed in groups and begin at the top of the plant and work their way down. Since the beetles are most active on warm sunny days, activity is most intense over a 4 to 6 week period beginning in late June, after which the beetles gradually die off. Individual beetles live about 30 to 45 days. Japanese beetle control is very important to maintaining tree and shrub health.

Box Elders

This bug is about 1/2 inch long and 1/3 as wide. It is black with three red lines on the thorax, a red line along each side, and a red line on each wing. The adult bugs lay eggs on the host trees in the spring and the nymphs emerge in a few days. In the summer Box elder bugs normally feed on the leaves, flowers, and seed pods of the boxelder tree or silver maple. Activity of nearly fully grown nymphs is noticed in August and September when they gather in large numbers on the trunks of box elder trees. The migration of the adults begins at this time. Eggs are a rusty red color and are not often seen as they are deposited on boxelder trees.
Box Elder Bugs do not bite or cause any structural damage, but they find their way inside looking for a suitable place to live over the winter and their droppings can stain your interior furnishings.

When they gain entry to buildings through cracks or other openings they remain in wall cavities and will occasionally emerge inside the home in the spring. They will not breed indoors, so there is no danger of starting an “infestation”.

Bag Worms

Bag Worms Bagworms range in size from less than 1 cm to 15 cm. The bagworm is the larval stage of a moth that is reported to feed on over 100 different plants. On pine trees, its cone-shaped bags are often mistaken for cones, which go unnoticed until the infestation is severe.

Bagworms spread slowly because the female is unable to fly, however, bagworms can be windblown or crawl to other host plants and can also spread through infested nursery stock.

Spider Mites

Spider Mites are extremely hard to see by the naked eye. They may look like tiny, moving dots. An adult female is usually less than 1/20 inch long and are commonly found in landscapes and gardens. They feed on many fruit trees, vines, berries, vegetables, and ornamental plants. Spider mites live in colonies, mostly on the undersurfaces of leaves. Adult mites cause damage by sucking cell contents from leaves. At first, the damage may show up as light dots on the leaves and then the leaf begins to turn yellow or red, then drop off.

Leaf Beetles

Leaf Beetles Adults are 1/4″ to 3/8″ long, oval, yellow to olive-green, with long dark stripes running the length of the wing covers. There are three black spots behind the head. Larvae are worm-like, up to 1/2″ long when mature, and dull yellow with black stripes. Over the winter Beetles go to a protected location such as inside homes or underneath loose tree bark. As tree buds begin to expand in spring, beetles move from overwintering sites to begin feeding and egg laying on leaf undersides. About a week after the larvae have emerged from the egg they begin feeding on leaf undersides between the veins, leaving the upper leaf surface intact. This type of feeding gives the leaves a transparent appearance and is often called “window feeding.” As larvae mature, defoliation increases as feeding takes place on both upper and lower leaf surfaces. By eating all foliage except for the leaf veins the larvae “skeletonize” the leaves. Heavy feeding can give the tree an overall brown appearance and cause the trees to loose its leaves earlier than normal.

Aphids

Aphids Aphids are generally about 1/8” long. They are commonly green, yellow or black. They have piercing-sucking mouthparts and cause damage by sucking the plant juices. They are commonly found on the stems, undersides of leaves and on flower buds in colonies. The most distinguishing feature in the identification of aphids is the two short cornicles, or tubes, which extend from the end of their body which excretes large amounts of honeydew. This honeydew is a sugary liquid composed of unused plant sap and waste product. The honeydew is unsightly and interferes with photosynthesis and stops the growth of the plant. They are often referred to as “plant lice”.

Emerald Ash Borer

The adult emerald ash borer has a distinct metallic green color and they only grow to about 8.5 millimeters in length, shorter than the diameter of a penny.

The Emerald Ash Borer is an invasive species of beetle that has killed tens of millions of ash trees, from forests to neighborhoods.

Scale

Scale Insect Scale infestation can be devastating to some varieties of plants, and if left undetected can infest most plants in the landscape. Occasional inspection of plants is recommended so that scale can be detected in its early stages. Tree scale is relatively easy to detect. It appears as a small shell like nodules along the bark, or on the leaves, of affected plants. Inside each nodule is a small insect, which after hatching, hooks its beak into the sap stream of the plant, secretes a shell over itself, and lives on the sap within the plant. Spraying for scale should be done immediately after the eggs hatch. This generally takes place at the end of April or early May depending on the temperature. A second application ten days later is recommended.

Apple Scab

Apple scab is a fungal leaf disease.

The severity of the disease varies with the weather and the susceptibility of the hosts.

Although this disease is not fatal to a plant, continued infection and defoliation weakens the plant allowing other diseases and pests to take hold.