If your spruce aphid monitoring efforts reveal heavy spruce aphid populations you may want to consider control options to decrease populations and minimize the damage caused by the insect feeding. Several control options are available and may be applicable in differing situations.
Integrated Pest Management options for spruce aphid control
Cultural control
Maintain tree health
Keeping trees and forest stands healthy during increased spruce aphid activity is an important first step for management. Healthy trees are more resilient to the damage caused by these aphids.
- Water. Provide supplemental water during dry periods, especially in the spring when trees are breaking winter dormancy. This may not always be practical on a landscape scale but can be important for ornamental tree plantings.
- Avoid soil compaction. Avoid activities that compact the soil around the root zone of trees, such as driving or parking motorized vehicles, stacking firewood, or piling snow. Continual activity that compacts or hardens the soil decreases the space around the roots and limits access to water, nutrients, and oxygen passing through the soil. If construction is occurring, extra precautions for priority trees should also be considered, such as fencing off the bulk of the tree’s root zone.
- Avoid unnecessarily damaging trees. Avoid activities that could damage the trunk of trees. Keep mowers and string trimmers away from the base of trees. Provide mulch for the tree but keep it away from the bark to prevent trapping moisture and contributing to rot.
- Decrease competition. Competition for resources in landscapes usually comes from turf. While lawns are nice to look at, keeping a healthy lawn involves activities that can potentially damage trees such as mowing, trimming, fertilization and sometimes herbicide applications. Mowing over above-ground roots, knicking trunks with string trimmers, high nitrogen fertilizer, and competition with turf for water and other resources can stress trees making them more susceptible to insect damage. Consider a turf-free zone around the tree to avoid some of these common problems. Pulling back the turf and mulching the area can be a successful compromise for aesthetics and tree health.
- Avoid excess nitrogen in the soil. Use slow-release sources of nitrogen if choosing to fertilize. Fertilizers can be beneficial for trees in soils with known nutrient deficiencies. Trees are typically able to access the nutrients they need and practices such as mulching around trees can help maintain levels of nutrients available to tree roots. If fertilizers are deemed necessary, slow-release formulations are preferred. Adding too much nitrogen quickly can actually benefit spruce aphids.
Physical control
Aphids can be knocked off of trees with a strong jet of water. It can be difficult to remove all aphids and will likely need to be repeated through the season. This practice is best suited for individual small trees as it can be difficult to reach the canopy of larger trees.
Biological control
In general aphids have many natural enemies in the environment that can help to control their populations. Predatory insects such as lady beetles and lacewings will feed on aphids, but may not immediately exist in high enough numbers to make a dent in an outbreak-level population. Other common aphid predators would include spiders and some birds. We do have some parasitic wasps that will help control aphids, but again, often our populations of natural enemies have to “catch up” when we experience outbreaks of pests.
Natural enemies are important and naturally occurring parts of the environment. It is important to keep them in mind if you plan to use chemical control measures. If possible, avoid broad-spectrum sprays during times when beneficials are most active, generally late spring through late summer.
Chemical control
If spruce aphid pressure is high in an area, pesticide applications may be an option to consider. Due to several factors, pesticides are usually restricted to use on high-value ornamental trees.
Pesticide applications are effective when applied properly per the label recommendations. Pesticide failures are usually the result of improper timing, inadequate coverage, or poor product mixing.
Several products are available to treat for spruce aphid. As a group, aphids are fairly susceptible to insecticides, and many active ingredients can be used to control them. Application methods vary for different products and include sprays, soil drenches, and stem injections. The table below lists active ingredients and example products that may be used on spruce to control spruce aphid. Spruce aphids, like other aphids, can easily build up resistance to insecticides. If you are planning to use pesticides, make sure to understand the product(s) you choose and follow all label recommendations for limiting resistance build up in aphids.
| Active Ingredient | Common Product(s)* | Application Method(s) |
| Dinotefuran | Ortho® Tree and Shrub | Soil drench |
| Safari™ 20 SG | Soil drench, foliar spray, soil injection | |
| Transtect™ | Soil drench, soil injection, foliar spray, trunk spray | |
| Imidacloprid | BioAdvanced™ 12 Month Tree and Shrub Insect Control | Soil drench |
| Pointer® Insecticide | Trunk injection | |
| Acephate | Acecap® Systemic Insecticide Tree Implants | Trunk injection |
| Bonide® Systemic Insect Control | Spray | |
| Orthene® Turf, Tree, and Ornamental | Spray, soil injection | |
| Bifenthrin | Talstar® | Spray |
| UP-Star® Gold | Spray | |
| Abamectin | Avid® | Spray |
| Abacide™ 2 | Trunk injection | |
| Azadirachtin | AzaGuard® | Spray |
| AzaSol™ | Spray, soil drench, trunk injection | |
| Ornazin® | Spray, soil drench, trunk injection |
Timing of pesticide applications for spruce aphid can be difficult due to the timing of their damage and environmental conditions required for the use of many pesticide products. Typically, early spring damage occurs when temperatures are too low for spraying, soils are still frozen and cannot be drenched, and trees are dormant and therefore trunk injections cannot be made. If you decide pesticides are warranted for spruce aphid control, it may make sense to treat for possible fall feeding populations using a product that would have residual effects for approximately one year and would still be available for the following late winter/early spring aphid populations.
Chemical options can be applied in a variety of ways as listed in the table above, and some products are more suited to certain situations or application types. Taller trees (generally those greater than 25 feet tall), especially those with previous aphid feeding and crown damage, may benefit more from systemic products applied as soil drenches or injected directly into the tree. These products then travel within the tree to be available in needle tissue. Spray applications may be better suited for medium and smaller trees where reaching the canopy is easier. There are always pros and cons to different application types. Systemic products applied to the soil or injected into the base of the tree may take time to travel through the tree to the needle tissue, while foliar sprays may have limitations on applications near water bodies, flowering plants, or during certain weather conditions. For any product or application type, follow all recommendations on the product label to ensure the most effective and economical application with the least environmental effects.