Countless insects live on, in, and around trees - many are harmless, while others can cause fatal damage. Below is a general description of the three main types of insect that affect trees.

• Chewing Insects

• Boring Insects

• Sucking Insects

Chewing Insects

Description

Defoliating insects migrate to the foliage of a tree and feed on the leaves. Other chewing insects attack the fruit. Caterpillars and beetles make up the largest proportion of chewing insects. Generally, trees can bounce back from an attack of these defoliators, though repeat infestation will weaken a tree and can eventually kill it by starving it of energy.

Examples

Spring and Fall Cankerworm, Tent Caterpillar, Gypsy Moth, Leafminers, Bagworm, Japanese Beetle, Apple Maggot, Cherry Maggot

Control

Healthier trees are less likely to become infested, so maintaining the strength and vitality of your tree is an important prevention step. Once chewing insects are present, controlling movement up and down the stem with physical barriers can interrupt the lifecycles of many caterpillars. Insecticides can be used to kill the insects.

Recommended Products

Prevention
TreeHelp Bug Bands are an effective tool to help control the movement of caterpillars from tree to tree as well as those that migrate up and down a tree trunk.
TreeHelp Annual Care Kits are helpful in promoting the overall health of a tree so that it can withstand the impact of an insect attack.

Treatment
If a tree has been attacked by chewing insects there are a number of effective sprays and controls that can be utilized to control the insects.

Safer's Trounce Yard & Garden Insecticide is a combination of insecticidal soap and natural pyrethrins.
BTK Biological Insecticide is made from a natural fungus that disrupts the insect's digestive system when it tries to eat leaves that have been sprayed. BTK needs to be reapplied every 7 to 10 days.
Garden Insect Spray with Spinosad is a new insecticide that is similar to BTK and also made from a natural soil fungus. Spinosad, however, is less sensitive to UV breakdown than BTK and therefore only needs to be reapplied every 3 to 4 weeks. Spinosad is approved for organic gardening.
Bug Buster is a stronger spray made from a synthetic pyrethrin. Bug Buster is recommended when a tree is under attack by a variety of chewing and sucking insects and is an effective treatment against a wide range of insects.

In some cases, due to the size of the tree, spraying is not an option. In these cases, there are two effective options:
Multi-Insect Killer Tree Injection Kit is injected directly into the tree's trunk and gets throughout the tree in about 72 hours.
Once-A-Year Insecticidal Soil Drench w/Merit is applied by watering the treatment right on to th tree's roots. The insecticide is then taken up through the tree's roots and dispersed throughout the tree. This normally takes about 3 weeks and provide protection for the tree for a full year.

Traps can also be used to reduce the local population of the attacking insect:
Gypsy Moth Trap (for gypsy moth only)
Safer's Japanese Beetle Trap (for Japanese Beetle only)
Apple Maggot Trap (for apples, pears, plums & cherries

Boring Insects

Description

Boring insects are often the most harmful to trees and if left intreated can cause death. Boring, or tunneling, insects cause damage by boring into the stem, roots, or twigs of a tree. Some lay eggs which then hatch and the larvae burrow more deeply into the wood blocking off the water-conducting tissues of the tree.  Boring insects generally feed on the vascular tissues of the tree. If the infestation is serious, the upper leaves are starved of nutrients and moisture and the tree can die. Signs of borer infestation include entry/exit holes in the bark, small mounds of sawdust at the base, and sections of the crown wilting and dying. It is important to regularly monitor a tree's trunk for signs of boring insects to enable early identification and quick treatment.

Examples

Asian Longhorned Beetle, Bronze Birch Borer, Dogwood Borer, Elm Bark Beetle, Ash Borer, Giant Palm Weevil

Control

The key is to prevent infestation by keeping the tree as healthy as possible. This includes proper pruning, watering, mulching and fertilization. Pruning should be done in late fall or winter to avoid attracting insects to open wounds. Dead or fallen wood should be removed immediately. Once borers are present, control becomes extremely difficult, but steps should be taken to prevent further damage and to stop the spread to surrounding trees.

Recommended Products

Multi-Insect Killer Tree Injection Kit is applied directly into a tree's trunk. The injection enables rapid release (about 72 hours) of the insecticide (based on Merit) within the trees thus slowing further damage as well as preventing other borers from entering and attacking the tree.
Once-A-Year Insecticidal Soil Drench w/Merit is ideally applied in the fall or early spring to provide protection against boring insects throughout the growing season.
Borer-Miner Killer Spray can be used jointly with the Multi-Insect Killer or Once-A-Year Soil Drench. The spray is applied regularly to the outer bark of the tree to create a barrier against the entry of the boring insects. The spray is also helpful in preventing spread to nearby trees.
TreeHelp Annual Care Kit is an effective tool to promote the overall health of the tree to assist it in repairing the damage done by boring insects. A strong and healthy tree is also less of a target for boring insects.
Pruning Sealer can help protect open wounds and reduce the attraction for boring insects.

Sucking Insects

Description

These insects do their damage by sucking out the liquid from leaves and twigs. Many sucking insects (e.g. scale insects) are relatively immobile, living on the outside of a branch and forming a hard protective outer coating while they feed on the plant juices in the twig. Quite often they will excrete a sweet, sticky substance known as honeydew which contains unprocessed plant material. Honeydew can cause sooty mold to form on leaves and can become a nuisance for homeowners. Signs of infestation include scaly formations on branches, dieback of leaves, and honeydew production.

Examples

Scale Insects, Aphids, Leafhoppers, Spider Mites, Thrips

Control

As with other insect infestations, prevention is the best approach. This means maintaining a strong and healthy tree. Once they mature on the tree, sucking insects generally must be killed on contact to prevent reproduction and achieve effective control.

Recommended Products

Prevention
TreeHelp Annual Care Kits help to maintain the overal health of the tree.
Aphid Chaser acts as a natural repellent against aphids. Can be used in the garden or indoors on houseplants.
Lady Bug Houses are refuges that give beneficial ladybugs a safe and secure place to stay in your garden. The House has a special pheromone to attract ladybugs who in turn eat many pathogenic insects such as aphids.

Treatment
Horticultural Oil can be used as a control for scale insects during the growing season or as a preventative treatment during the dormant winter season, preventing insects from overwintering.
Insecticidal Soap is a safe and effective control against many sucking insects. Since it is so safe, it is normally used as a first response against insect attacks.
End All II is made from insecticidal soap, but also contains naturally derived pyrethrins which enhance its effectiveness.
Bug Buster is a stronger spray made from a synthetic pyrethrin. Bug Buster is recommended when a tree is under attack by a variety of chewing and sucking insects and is an effective treatment against a wide range of insects. Bug Buster is also a good treatment when an insect problem is present, but the type of insect cannot be confirmed.

In some cases, due to the size of the tree, spraying is not an option. In these cases, there are two effective options:
Multi-Insect Killer Tree Injection Kit is injected directly into the tree's trunk and gets throughout the tree in about 72 hours.
Once-A-Year Insecticidal Soil Drench w/Merit is applied by watering the treatment right on to th tree's roots. The insecticide is then taken up through the tree's roots and dispersed throughout the tree. This normally takes about 3 weeks and provide protection for the tree for a full year. This is a good treatment when a tree has been repeatedly attacked by sucking insects over several years and a stronger treatment is required.

For information on specific insects, click here.