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Tree and Shrub Pests


The number one insect adversary in the rose garden is the rose aphid (often referred to as greenfly), a small, green, soft-bodied insect (about 1/16 inch long). It is often found in large colonies, particularly on the first lush spring growth, sucking the sap from stems. Control by washing off the stems with water or spraying with an insecticide containing acephate or malathion. Herbi-Systems recommends that professional lawn care companies apply an approved insecticide.


Bagworms are caterpillars that make distinctive spindle-shaped bags on a variety of trees and shrubs. They attack both deciduous trees and evergreens, but are especially damaging to juniper, arborvitae, spruce, pine and cedar. Large populations of bagworms can quickly strip plants of their foliage and eventually cause them to die. Infestations often go unnoticed because people mistake the protective bags for pine cones or other plant structures. If only a few small trees or shrubs are infested, picking the bags off by hand and disposing of them may offer satisfactory control. This approach is most effective during fall, winter or early spring before the eggs have hatched. When many small bagworms are infesting evergreens, an insecticide may be needed to prevent serious damage.


An insect or insect larva, that bores into the stems and trunks of plants and trees.

Crape Myrtle Bark Scale

The Crape Myrtle Bark Scale steals nutrients from the tree’s bark, and leaves a black moldy residue on the bark and anything under the tree. The pest may be fatal for the tree. Some homeowner treatment is possible.

Japanese Beetle

Japanese Beetle’s will indiscriminately eat parts of the foliage and sometimes the flowers. Pick beetles off the by hand or spray foliage and flowers with an approved insecticide.

Lace Bugs

Lace bugs are usually detected when injury to the leaves on the host plant becomes evident. The young bugs and adults live on the lower leaf surface and suck up the plant cell contents through slender, piercing mouthparts. This feeding produces numerous yellow or whitish spots on the upper leaf surface. As the insects feed, they deposit their hard, black, varnish-like excrement on the leaf, commonly referred to as “tar spots.” Lace bugs have several generations a season as long as the host plant supports them, so when numbers become high and feeding extensive, leaves will turn brown and drop. To manage lace bugs, periodically inspect plants that have been attacked in the past or are known hosts of lace bugs, and treat as soon as plant injury is apparent. Plants under stress are more susceptible to severe infestations, so evaluate the site and culture for infested plants. In fact, azaleas are less likely to become infested with azalea lace bugs if they are grown in their preferred site—morning sun and afternoon shade.


Scale insects feed by piercing plant tissues and feeding on the sugary sap. Excess sap, ‘honey dew,’ is excreted, and falls on foliage below the insects’ feeding site. Sometimes shiny spots of honey dew are visible on plant leaves. These feel sticky when touched. Often it is a sooty, black mold, growing on the sugary drips, which is the first symptom noticed. Scale insects are easily mistaken for brown ‘flecks,’ especially when they are young and among variegated foliage. Search on both sides of the leaves, particularly along main veins. ‘Flecks’ which can be moved with a fingernail are adult scales. In severe cases, stems and veins of plants will be plastered with scales overlapping each other.

Armored Scale

Waxed Scale

Spider Mite

The spider mite establishes huge colonies underneath leaves, giving the appearance of salt-and-pepper particles. As mite numbers increase, these white speckles will increase in number, the leaf will take on a bleached appearance and die. If the problem is detected early enough, you can control it with an EPA approved insecticide; direct the spray to the underside of the leaves. If you prefer, apply a fine misting of water to the undersides of the foliage to wash the mites to ground level; they are unable to fly, so they will die on the soil surface.


Whiteflies are small winged insects which look more like moths than flies. They have a powdery wax which both protects them and is key to identification. They are active in all parts of the world and will thrive year-round in the South but go dormant during the winter in northern states. Whiteflies are a problem because they have piercing mouth parts which allow them to suck plant sap. This behavior is what they do to feed and host plants are prone to many problems during such feeding. There are many problems that feeding whiteflies cause including: 1) Leaf damage. 2) Sap drainage. 3) Whiteflies excrete honey dew which lures other nuisance insects onto the host plant.

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