Insects love eating trees and shrubs, especially when the plants are weak or in poor health.
This is why good health is a plant’s strongest line of defense against attacking insects. A healthy tree or shrub is usually able to naturally defend itself against pests. The opposite is true for those that are under stress or in decline.
So what can you do if your plants are under attack?
- Identify the insect.
- Is the insect causing severe damage? It is normal to have some level of feeding activity on your trees and shrubs. But if the attack is severe to the point where it is threatening the very existence of your plants, that is a problem.
- Why did this attack happen in the first place? What are the underlying health issues that have prohibited your tree or shrub from defending itself?
- Fix the underlying health issues. This is critical for preventing future attacks.
- Apply treatments to reduce or eliminate the pest, assuming this is possible.
- When choosing a product, pick an organic or environmentally-responsible option, such as naturally-derived oils, beneficial insect release, or specialized bacterium that targets specific pests. Insect treatments should not come at the expense of harming the surrounding ecosystem.
- Continue to maintain the ongoing health of your trees and shrubs once you have addressed the underlying health issues and reduced the insect activity back to a reasonable level.
When it is necessary to use chemicals, deliver the product in the smallest, most targeted dosage possible.
Be very careful to minimize disturbance to the rest of the ecosystem. After all, the majority of insects found within an ecosystem are positive contributors to its health and vitality. You want to leave them unharmed.
In case you are interested, here is some information on the common insects in this area:
Emerald Ash Borer:The Emerald Ash Borer, or EAB, is a wood-boring beetle that originated in Asia. Since being imported, this beetle is responsible for killing close to 10 million ash trees in the United States. If trends continue, the Emerald Ash Borer will infest all unprotected ash trees in North America within the next 20 to 25 years.
Pine Bark Beetles:(Southern Pine Beetle, Turpentine Beetle, Ips Engraver) These small bark beetles are very destructive insects. Pine bark beetles are attracted to various species of pine trees that are sick, damaged, or are stressed due to drought and other factors. Healthy trees can also fall prey to attack from pine bark beetles if they attack in great numbers. Pine trees usually die once bark beetle populations reach elevated heights.
Ambrosia Beetles:(Shothole Borer, Black Stem Borer, Asian/Granulate Ambrosia Beetle, European Shothole Borer) The Ambrosia Beetle is a wood-boring insect that belongs to a broad group of beetles. There are hundreds of different species throughout the world. The beetle gets its name from the Ambrosia Fungus with which it shares a symbiotic relationship. Native Ambrosia Beetles prefer to attack stressed and weakened trees, while non-native species attack both stressed and healthy trees. Ambrosia Beetles are very damaging and often kill trees. It is possible for a tree to survive, but this will depend on the severity of the attack and what is done to aid the tree in recovery.
Scale Insects:(Tea Scale, Gloomy Scale, Lecanium Scale, Euonymus Scale, Obscure Scale, Wax Scale, Cottony Scale, Japanese Maple Scale, Juniper Scale, White Peach Scale) Scale insects are named as such due to the waxy covering that they use for protection. Scale insects can be divided into two main categories: armored and soft. Scales are piercing, sucking insects that insert their straw-like mouth parts into stems or leaves for feeding. Where the scales feed depends on the species. They suck out fluids from their host plant and can cause significant damage, especially when the plant is already stressed due to other health issues.
Japanese Beetles:The Japanese Beetle is easily recognized by its green, copper color. As the name suggests, the Japanese Beetle is native to Japan. It is not a serious threat in Japan since natural predators keep the populations in check. It is, however, a very destructive pest in the southern half of the United States.
Evergreen Bagworms:The bagworm is a type of clear-winged moth. This insect is named for the silken bag it constructs as it matures. The bagworm larvae are what actually damage the plant. Evergreen Bagworms are the most common bagworm in the Southeast. The Evergreen Bagworm feeds on many species of trees, but typically favors coniferous evergreens such as the Leyland Cypress.
Aphids:(Green Peach Aphid, Crape Myrtle Aphid, Woolly Aphid, Rose Aphid) Aphids are small insects that feed on tender leaves, stems, and flower buds to extract plant fluids. There are close to 4000 known species and at least 250 that are serious pests to trees, fruits, vegetables, and ornamental plants. Aphids are found in most countries throughout the world. They are identifiable by the sooty mold that grows on aphid honeydew exudation.
Mites:(Southern Red Mite, Two-Spotted Mite, Boxwood Mite, etc.) Spider mites are common pests that feed on many different species of plants. Spider mites are part of the arachnid family and closely related to spiders. There are at least 1200 species of spider mites, though we are only concerned with 4 to 5 species here in the Southeast. These pests are very damaging if left untreated. They have the ability to multiply rapidly and thus cause exponential damage.
Fall Webworm:The Fall Webworm is a native moth species in North America. It feeds on approximately 100 species of trees and shrubs. The Fall Webworm is named as such because of the communal nests they build at the ends of branches, which offer protection from birds and predatory wasps. In the Southeast, the Fall Webworms prefer deciduous hardwood trees.
Eastern Tent Caterpillar:The Eastern Tent Caterpillar is a species of moth that is found throughout eastern North America. Eastern Tent Caterpillars build tent-like nests in the crotch of branches located in the host tree, which is where this insect receives its name. Eastern Tent Caterpillars often feed on crabapple, plum, apple, and cherry trees.
Azalea Lace Bugs:Lace bugs belong to a group of insects found throughout the world. The lace bug originated in Japan and was first introduced into North America in 1915. There are at least 170 species of lace bug that affect plants in North America. Each species of lace bug is usually host specific, meaning it only feeds on one kind of plant. The species of lace bug that is most harmful in the Southeast is the Azalea Lace Bug. They are very damaging to Azaleas.
Whitefly:Whiteflies look like tiny moths, but they are neither moths nor flies. They are closely related to scale insects and mealy bugs. The Whitefly originated in Asia and is now widely distributed throughout North America and other parts of the world. Whiteflies are a common pest on gardenias. The species that causes the majority of the damage in our area is the Citrus Whitefly.
Cankerworm:The Cankerworm is a moth also known as Spanworm or Inchworm. It is a native insect that has shown increased numbers in our area for several years. The Cankerworm larvae cause damage to trees during feeding. Though it will feed on many species, it seems to prefer Willow Oaks here in North Carolina.
Boxwood Leafminer:The adult Boxwood Leafminer is a very small, orange colored fly that resembles a tiny mosquito. You will see the adult swarming around boxwood plants in spring. But it is the Boxwood Leafminer larvae that cause the serious damage to the plant by boring through the leaves. As the name suggests, the Boxwood Leafminer is a serious pest to the American Boxwood. It does not typically affect the English and Asian variety of boxwoods.
Orangestriped Oakworm:The Orangestriped Oakworm is a caterpillar that feeds on oak trees, especially species of the Red Oak family, in late summer. Though oaks are the preferred host trees, these caterpillars may occasionally feed on hickory and maple trees. Orangestriped Oakworms are native to North America and are more abundant in northern states. This moth species is considered cyclical in the Southeast, which means that populations change in severity from year to year.
Peachtree Borer/Lesser Peachtree Borer:Peachtree Borer and Lesser Peachtree Borer are closely related. Both belong to a group of borers known as Clearwing Borer. They resemble wasps but are actually moths. Both borers are widely distributed throughout North Carolina and are a native species to the United States. You will find Peachtree Borer and Lesser Peachtree Borer on fruit trees and Prunus species such as cherry, apricot, cherry laurel, “Schip” Laurel, “Otto Luyken” Laurel, peach, and plum.
Leafhoppers:Leafhoppers feed on a wide variety of vascular plants including conifers, grasses, many types of broad-leafed woody, and herbaceous plants. Leafhoppers deposit their eggs in the host plant’s tissue, which also injures the plant. But that being said, feeding and egg deposits are not what kill the plant. Leafhoppers transmit various plant pathogens such as bacteria and viruses during feeding. In particular, they spread Bacterial Leaf Scorch, which has devastating affects on species such as sycamore, elm, and maple.
Weevils:(Pales Weevil, Black Vine Weevil, etc.) Weevils are damaging to plants in two ways. First, the larvae of the weevil eat the roots. Second, the adult will feed on the foliage of the plant. Excessive damage to the roots is usually why plants die, especially during periods of drought, too much soil moisture, or if there are any harmful soil-borne pathogens that invade the root system.
Dogwood Borer:The Dogwood borer is one of the most damaging pests of the flowering dogwood. This species of borer is native to North America and is a member of the clearwinged moth family. Feeding damage eventually causes limb and stem girdling, branch dieback, structural weakness, and decline. Death of the plant usually occurs depending on the extent of infestation.