Animals, including insects, play a biological role in sustaining a healthy environment for trees. It is when they abnormally increase in population and disrupt nature’s balance that they become “pests.” If not controlled, pests can bring disease and damage our trees, homes, and wallets. Identifying common tree pests helps maintain the health and survival of our trees and their surrounding areas.
There are three categories of pests, listed by a study from the University of Nebraska-Lincoln:
- Continuous pests that are often present and warrant regular control
- Sporadic, migratory or cyclical pests that require occasional control
- Potential pests needing control in isolated cases
Common Tree Pests
1. The Asian long-horned beetle (Anoplophora glabripennis) is a black, white-spotted, and shiny insect that measures about an inch long. This insect originated in Asia and attacks healthy hardwood trees (e.g. maple, poplar, birch, willow, and elm), potentially killing them. Since the Asian long-horned beetle does not have a known natural enemy, the only way to control its spread is to remove infested trees and quarantine potentially-affected surrounding trees.
2. The emerald ash borer (Agrilus planipennis) is another beetle native to Asia. An adult beetle is coloured green and is approximately one-half inch long. It feeds on ash trees (particularly the green, white, black, blue, and pumpkin varieties). Trees infested with the emerald ash borer exhibit bark deformities and holes. They also have shoots growing out of their trunks, roots, and branches. Regulating man-made activity (such as transporting infected ash firewood and nursery stock) can control its spread.
3. Bark beetles are notorious for affecting (and eventually killing) pine trees and spreading the fungus that causes Dutch elm disease. Those usually affected by Dutch elm disease are American and rock varieties. Regularly watering the trees (recommended by the Yale School of Forestry and Environmental Studies) helps trees produce sufficient sap that naturally contains these pests.
4. Cankerworms are caterpillars that usually emerge in spring and fall (most commonly found on hardwood trees like oak, maple, and elm). A massive attack occurred in Mississauga during June 2017. Cankerworms consume buds and leaves, stripping trees bare and leaving them more susceptible to disease from other insects. Most mature trees affected by cankerworm infestations are more vulnerable to damage from extreme weather. One way of treating cankerworm infestation is to use a biological control agent (like a group of bacteria called Bacillus thuringiensis serotype kurstaki or BTK).
5. Scale insects are tiny, shell-shaped organisms that attack fruit trees, retard their growth, and cause fruit damage. To initially control them, these pests must be scraped off the infested limbs. If the infestation is severe, experts prune the most affected branches and/or remove large old trees that bore encrusted scales.
Effective pest control
- Any insect can be a pest. The first step to pest control is to accurately identify the problem. This step is the most crucial because we only control a pest when it starts causing more harm than what is reasonably acceptable. Unnecessarily regulating insects will only disturb nature’s self-regulating mechanism. If you are not sure what insect is harming your trees, a professional tree expert can help.
- Determine and control the factors that may influence an insect’s spread to prevent it from becoming a pest. Applying an oil spray to fruit trees, for example, might help repel scale insects.
- Seek professional assistance when doing pest control and/or tree removal. Have a trusted arborist or tree surgeon implement strategies that reduce pest population to a more acceptable level. Arborists have the expertise necessary to effectively isolate pest infestations and cause little harm to nearby plant life.
If you have any concerns on pests that may seriously hurt your trees, our tree experts can develop an integrated pest control program to suit your needs. For more details, please call Timberlane Tree Service at (905) 778-9438 or (416) 878-2108.