INSECT CONTROL FOR TREES
Controlling and Preventing Damaging Tree Insects
Boulder and Fort Collins Tree Care Services
Insects That Attack Trees in Colorado
Every year, many trees in Colorado are attacked by various insects. These damaging tree pests include aphids, curl aphids, mealybugs, leafminers, bronze birch borers, elm leaf beetles, elm scales, honeylocust plant bugs, juniper scales, kermes scales, cottony maple scales, spider mites, oystershell scales, ash sawflies, emerald ash borers, and numerous other insects. While most of these pests do not kill trees, they can inflict severe stress, which reduces the tree’s ability to withstand biotic and environmental challenges such as heat and drought.
Effects of Insect Pressure on Trees
A tree experiencing insect pressure often grows significantly slower than a healthy tree. In fact, insect pressure can reduce a tree’s growth rate by as much as 70%. Although it is uncommon, untreated trees can eventually die from severe insect infestations over several years.
Aphid Pressure on a Tree
Tree Insects of the Front Range of Colorado
Aphids on a Tree
Aphids on Trees
Sap Suckers
Aphids are tiny, soft-bodied, pear-shaped insects that can vary in color, appearing in shades of green, blue, or black. They feed on trees by sucking moisture and sugars from the foliage and shoots through a slender mouthpart known as a proboscis. Typically, aphids gather in large clusters on the underside of leaves, preferring tender young shoots and buds. As they feed, they excrete a sticky substance called honeydew, which is shiny and tacky. When there are enough aphids on a tree, this honeydew can start to drip from the leaves. If you’ve ever parked under a tree in the summer and later found a sticky residue on your windshield, that was likely honeydew.
Aphid Treatment
Aphids can be found on almost all types of trees. Safari is a wonderful reactive treatment and Criterion is a wonderful preventative treatment for aphids on trees.
Black Locust Borer
Black Locust Borer
Very Damaging Pest
This adult beetle is a mostly black beetle with yellow cross bands on the thorax and “W” shaped bands on the wing covers. The black locust adults are about 18-22 mm in length and are most commonly noticed when they are visiting flowers in late summer and early fall. This is an introduced species to Colorado and is widely established. This insect is abundant and very damaging to black locust trees. In recent years it has been particularly damaging to the popular cultivar “Purple Robe” locust.
Black Locust Treatment
Controlling this insect after an attack is challenging. They tend to target trees that are stressed due to drought. To help prevent black locust borer infestations, following the 1-2-3-2-1 lawn watering technique has proven to be exceptionally effective. While preventative treatments with products like Criterion or Safari can be effective, reactive treatments are often difficult and usually ineffective. Given the destructive nature of this insect, it is highly recommended to apply annual preventative treatments to protect black locust trees and prevent them from dying.
Bronze Birch Borer
Bronze Birch Borer
Attach Birch Trees
The bronze birch borer is a serious pest that primarily attacks white, paper, and cut-leaf weeping birches. The adult bronze birch borer is a slender, dark, iridescent beetle that can sometimes appear greenish-bronze, measuring between 7 to 12 mm in length.
D-Shaped Holes
In late April or early May, the larvae transition into the pupal resting stage. By early June, the adults chewed their way out of the bark, leaving behind a characteristic “D”-shaped hole in the trunk of the birch tree.
Wilting and Limb Decline
The first sign of an infestation is wilting and the decline of the upper crown of the tree. A closer examination may reveal ridges and bumps on the limbs and branches, as well as the “D”-shaped emergence holes in the bark.
Bronze Birch Borer Treatment
Birch trees thrive in cool, moist, and shaded environments. They do not grow well in sunny or exposed areas. Bronze birch borers tend to lay their eggs on trees that are growing in full sunlight. Preventative treatments, such as Criterion or Safari, can be effective, but reactive treatments are often difficult and usually not effective.
Brownheaded Ash Sawfly
Brownheaded Ash Sawfly
Some Years are Worse Than Others
The brownheaded ash sawfly is a pest that varies in severity from year to year along the Front Range. In some years, it can be a significant problem, while in others, it goes largely unnoticed. The larvae damage ash trees by chewing their leaves, typically during late May and early June. These larvae are pale green “worms” with light banding. During severe outbreaks, they can completely defoliate a tree within just a few days, causing considerable stress, especially if this occurs repeatedly.
Weather Plays a Role in Infestations
Weather plays a critical role in controlling their population; late spring frosts and strong winds can kill many larvae. The larvae are delicate, and strong winds can easily dislodge them from the trees. Once they are dislodged, it is rare for them to re-establish on the same tree.
Brownheaded Ash Sawfly Treatment
Ash sawflies can be effectively controlled using insecticidal soaps, and many can also be removed with a strong water jet from a hose. Criterion and Safari are both very effective insecticides for managing ash sawfly populations.
Cooley Spruce Gall
Cooley Spruce Gall
These are Not Cones
Cooley spruce galls are commonly found on the new growth of spruce trees. These galls are caused by an insect known as the Cooley spruce gall adelgid, which is a type of woolly aphid. During late spring, the galls appear light green but begin to dry out and turn brown starting in mid-July. People often mistake these galls for seed cones. They are particularly noticeable on blue spruce trees; however, they generally do little or no harm to the tree.
Damage New Growth
In spring, female adelgids mature and lay several hundred eggs near developing buds. The eggs hatch around the time of bud break, and young nymphs migrate to the new spring growth, where they feed at the base of the growing needles. The saliva introduced into the plant during feeding causes changes in plant development, resulting in the formation of galls.
Cooley Spruce Gall Treatment
Control of Cooley spruce gall is typically optional, as it does not harm the tree. However, insect control may be considered to prevent aesthetic injuries that could detract from the tree’s appearance. If control is needed, it should be applied in the fall using either Criterion or Safari, as spring applications will occur after the damage has already been done.
Elm Leaf Beetle
Elm Leaf Beetle
Can Cause Serious Visual Damage
Elm leaf beetles are common insects that cause damage to the leaves of elm trees by chewing holes in them. The larvae, which resemble dark grubs, feed on the underside of the leaves while avoiding the larger leaf veins. This results in a distinctive injury pattern known as skeletonizing, where the leaves appear lacy. Damaged leaves may turn brown and can drop prematurely from the tree. The elm leaf beetle prefers English and Siberian elms. Additionally, these beetles can become a nuisance in homes, as they often seek shelter indoors during the autumn months. Fortunately, elm leaf beetles are harmless inside, as they do not feed on or damage anything within a home.
Elm Leaf Beetle Treatment
The most effective way to control the elm leaf beetle is by using Criterion or Safari. These systemic insecticides can be applied to the soil, and they will move into the leaves where the elm leaf beetles feed.
Emerald Ash Borer
Emerald Ash Borer
Will Kill Ash Trees Fast
The Emerald Ash Borer (EAB) is one of the most well-known insects in Colorado. First identified in Michigan in 2002, it has since spread to 22 states, including Colorado. The EAB was introduced from East Asia, likely through infested shipping or packing materials. The most probable way it arrived in Colorado was through firewood or nursery stock.
Do Not Wait to Treat – Must be Proactive!
EAB is particularly dangerous because it kills ash trees, making it essential to protect high-value specimens. The larvae feed beneath the bark, eventually girdling the tree and cutting off its nutrients. Ash trees can die within 2 to 4 years after the initial symptoms appear, even if they were previously healthy. This pest can attack trees of all sizes, ranging from half-inch saplings to mature specimens.
Difficult to Detect
Detecting the EAB can be quite challenging since it resides under the bark, and the adult insects are only present from May to September. Due to the destructive nature of the EAB, we have created an informational page dedicated to this pest.
Proactive Treatment is a Must-Do!
We recommend using TREE-age for preventative and reactive tree treatments. For trees that have been treated with TREE-age and have not exceeded three years since the last application, we can perform a yearly preventative treatment using either Criterion or Safari.
Honeylocust Plant Bug
Honeylocust Plant Bug
Attacks Occur Late Springtime
Honeylocust plant bugs typically begin to attack honeylocust trees in late spring, around the end of May. This species of plant bug is quite damaging and is generally green in color. In its immature stage, it resembles an aphid; however, unlike aphids, it can jump long distances, often landing on people.
Symptoms of Damage
When honeylocust foliage is injured, it may turn yellow or brown, and the leaves can become twisted. Heavy infestations can lead to twig dieback. Additionally, significant midge infestations may collapse when new growth halts, making the trees less attractive to the egg-laying adult midges.
Honeylocust Plant Bug Treatment
Honeylocust plant bugs can be effectively managed using Safari as a reactive treatment or Criterion as a preventative measure. Honeylocust trees are vulnerable to various insect pressures, and both Safari and Criterion can help prevent most of these attacks. However, it’s important to note that neither Safari nor Criterion will prevent spider mites (which also attack honeylocust trees) from infesting a honeylocust tree.
Ips Bark Beetle
Ips Bark Beetle
Damages Pine and Spruce Trees
Ips beetles, also known as “engraver beetles,” are a type of bark beetle that damages pine and spruce trees. These small beetles measure between 1/8 and 3/8 inch in length and range in color from reddish-brown to black. They develop under the bark and create girdling tunnels, which can lead to tree dieback and, in some cases, death. In Colorado, there are 11 different species of Ips beetles.
Proper Lawn Watering Reduces Risk
Prolonged drought stress increases a tree’s vulnerability to Ips beetle attacks, while using the 1-2-3-2-1 lawn watering technique can significantly reduce the risk. Woodpeckers are common predators of Ips beetles; their presence can also indicate bark beetle activity, as they often remove tree bark to access this food source.
Ips Bark Beetle Treatment
To prevent Ips beetle attacks, promote vigorous tree growth through practices such as deep root fertilization and proper watering using the 1-2-3-2-1 lawn watering technique. Ips beetles can be treated proactively with a soil drench of Safari or reactively with a trunk injection of TREE-age.
Leafminers
Leafminers
Aerial Sprays Do Not Work
Leafminers are insects that feed on the inner tissues of leaves or needles. Their feeding creates tunnel-like injuries that can make the leaf tissue appear semi-transparent. Several types of insects have developed this feeding strategy, including the larvae of moths, beetles, sawflies, and flies. Most of these insects feed from inside the leaf throughout their entire larval stage. In Colorado, elm leafminers are the most problematic species and are found in numerous cities along the Front Range. These leafminers specifically target American, English, and Siberian elms.
Leafminer Treatment
Leafminers typically do not pose a serious threat to the health of trees or shrubs. The damage they cause is mostly cosmetic, so treatment decisions are often based on the plant’s appearance. To minimize the aesthetic impact of leafminer insects, products like Safari or Criterion can be used for control.
Lilac / Ash Borer
Lilac / Ash Borer
Can Cause Severe Damage
The lilac borer, also known as the ash borer, poses a significant threat to ash trees in Colorado. The larvae of these borers feed beneath the bark and into the wood, which weakens the tree and can eventually lead to its death. In the spring, adult moths emerge, mate, and lay their eggs on or near the trees. Once the eggs hatch, the larvae bore into the trunks of the trees, creating galleries underneath the bark that cause considerable damage.
Drought Stressed Trees are More Susceptible
The impact of the ash borer is more severe under stressful conditions, such as high heat and drought. To help limit infestations, proper care of the trees—including deep root fertilization and proper lawn watering—is essential. Additionally, freshly pruned wounds on the tree are particularly attractive to egg-laying moths, so it is crucial to avoid pruning before the moths are active.
Lilac / Ash Borer Treatment
To eliminate and prevent the return of the lilac borer, we recommend following the 1-2-3-2-1 lawn watering technique. Additionally, consider having one of our tree care experts perform a tree trunk injection using a product called TREE-age. Proper lawn watering is the most effective way to prevent the lilac borer from attacking ash trees, as a healthy tree is very unlikely to be attacked.
Mealybugs
Mealybugs
Similar to Scales
Mealybugs are pests that can cause significant stress to trees in Colorado. These white, soft-bodied insects feed on plant juices and are related to scale insects. They get their name from the white, powdery, meal-like wax that covers the bodies of adult females. Like aphids, mealybugs can reproduce without mating, leading to rapid population growth if not controlled. While some species feed on plant roots, most mealybugs damage the parts of the plant above the soil line.
Moisture Sucking Insect
Mealybugs damage trees by sucking moisture and sugars from the plant’s stems and leaves. As a result, affected trees may exhibit wilted, curled, and discolored leaves. A lack of moisture can also lead to premature leaf drop. In severe infestations, twigs and small branches may die back.
Honeydew is a Clue
Additionally, mealybugs excrete a sweet substance known as honeydew, which can lead to the development of black sooty mold. Ants, which are attracted to honeydew, often accompany mealybug infestations.
Mealybug Treatment
Much of the mealybug’s life is spent on the bark of trees, while only the young, or the nymph stage feeds on the leaves. This makes controlling the mealybug with foliar insecticides challenging. Systemic insecticides, such as Criterion and Safari, are very effective in managing this pest. Additionally, natural predators like three species of lady beetles and green lacewing larvae can help control mealybug populations.
Piñon Pitch Mass Borer
Piñon Pitch Mass Borer
Pinyon Pitch Mass Borer
The piñon pitch mass borer is a significant pest that affects piñon trees in landscapes across much of Colorado. While piñon trees are the primary host, ponderosa pines and sometimes other types of pines can also be attacked. Like most borer pests, the piñon pitch mass borer targets trees that are stressed or weakened. Overwatering and overcrowding are major stress factors for piñon pines. It is crucial to adjust irrigation schedules to follow the 1-2-3-2-1 lawn watering technique to help prevent borer infestations. Damage caused by borers can disfigure large branches and severely weaken the tree. In cases of heavy infestation, branches may even break off completely.
Pinion Pitch Mass Borer Treatment
Piñon pines require less water compared to other tree species. They are highly resistant to heat and drought and prefer soils that dry out between watering sessions. It’s important to follow the 1-2-3-2-1 lawn watering technique for optimal results. If an infestation occurs, we recommend using a trunk injection control product called TREE-age.
Scales on Conifers
Scales on Conifers
Scales are a Real Problem
Scales are among the most problematic pests affecting conifer trees in Colorado. They feed on the bark and needles of the trees, removing sap and potentially damaging the plant’s cells. This can lead to needle drop, reduced vigor, and dieback. Trees that are stressed from insect pressure become more susceptible to other insects and diseases. Additionally, some scales excrete a sticky substance called honeydew, which further detracts from the plant’s appearance and attracts nuisance bees and wasps. Several types of scales can affect conifers, including black pineleaf scale, juniper scale, spruce bud scale, pine tortoise scale, pine needle scale, pinion pine scale, and striped pine scale.
Scales on Conifers Treatment
The best way to control scales on conifers is to apply annual soil drenches with Safari. If a tree is experiencing scale pressure, it may take two seasons of Safari applications to completely manage the scale population.
Scales on Ornamental Trees and Shrubs
Scales on Ornamental Trees and Shrubs
Notoriously Difficult
Scales are notoriously difficult to manage. These sap-sucking insects can infest a wide variety of trees and plants. While some species can cause significant damage to the foliage they feed on, others are relatively harmless. Scales often resemble small bumps on twigs and branches, making them easy to overlook since they do not resemble typical insects. In Colorado, several types of scales on deciduous trees pose problems. Oystershell scales are commonly found on shrubs and trees such as aspen, ash, cotoneaster, poplar, willow, and lilac. Kermes scale is a serious pest of pin and red oaks, while European elm scale poses a significant threat to large-leaf elms.
Scales on Ornamental Trees and Shrubs
The most effective method for controlling scales on conifers is to apply annual soil drenches with Safari. Please note that if a tree is experiencing significant scale pressure, it may take two seasons of Safari applications to fully reduce the scale population. European elm scale has developed resistance to Safari, so the best treatment for this specific issue is a direct trunk injection using TREE-age or a special trunk injection called Lalguard.
Spider Mites on Trees
Spider Mites on Trees
Close Relatives to Spiders
Surprisingly, spider mites, which are incredibly tiny creatures, can have a significant negative impact on trees. Even the largest tree can suffer serious damage. Spider mites are among the most commonly found pests on trees and shrubs. They belong to the Tetranychidae family, which means they are more closely related to spiders and ticks than to insects. There are hundreds of different species classified as spider mites.
Sucking Moisture and Nutrients
These tiny pests damage plants by sucking the nutrients from their tissues, primarily from the leaves. Mites often cluster on the undersides of leaves. Each adult female can lay around 100 eggs, and in warm weather, they can produce up to 30 generations in a single year.
Spider Mite Treatment on Trees
Spider mites are not classified as insects, which means that insecticides like Safari and Criterion are ineffective against them. For controlling spider mites on deciduous trees, we recommend using a product called Orthene. For fruit and coniferous trees (up to 20 feet tall), our organic insect control product, Ecotrol, has proven to be highly effective. Please note that Eriophyid mites cannot be controlled with either of these products.
Tussock Moth Caterpillar
Tussock Moth Caterpillar
A 7 – 10 Year Cycle
The Douglas fir tussock moth caterpillar is a native pest that feeds on spruce, Douglas fir, and true fir trees. It rarely affects Colorado blue spruce trees that are planted in urban areas. Outbreaks of this moth typically develop quickly and then decline just as suddenly, primarily due to a virus that spreads through each isolated population. In Colorado, these outbreaks tend to be cyclical, occurring roughly every seven to ten years.
Needle Defoliation
The most visible sign of a Douglas fir tussock moth infestation is needle defoliation, which can strip trees of all their foliage in a single season. This defoliation usually starts at the top of the tree and progresses downward. Besides causing damage to the trees, the hairs of the tussock moth caterpillar can irritate human skin and lead to painful rashes upon contact.
Tussock Moth Caterpillar Treatment
Tussock moths can be controlled both preventatively and reactively by applying a soil drench of Safari.
Walnut Twig Beetle
Walnut Twig Beetle
Thousand Cankers Disease
Thousand cankers disease is a recently identified illness that was first discovered in Boulder, Colorado, in 2008. It primarily affects black walnut trees and is caused by a fungus that is transmitted by the walnut twig beetle. Over the past decade, thousand cankers disease has led to the widespread death of walnut trees in numerous western states.
A Fungus on The Beetle’s Back
This disease kills trees through the cumulative effects of multiple coalescing cankers and tunneling that develop around the entry wounds created by the walnut twig beetles. As a result, the affected tree loses its ability to transport fluids up and down its trunk.
Thousand Cankers Disease Treatment
Using soil injection systemic insecticides such as Criterion (imidacloprid) and Safari (dinotefuran) is the most effective way to prevent bark beetle attacks. However, it is important to note that these treatments are not always 100% effective. If the beetles attack in large numbers, they can still kill the tree, even if it has been treated. Additionally, treatments applied after symptoms have begun to appear are ineffective.
Zimmerman Moth
Zimmerman Moth
Austrian, Scotch and Ponderosa Pines
The Zimmerman pine moth has become well established along the Front Range of Colorado, primarily infesting Austrian pines. Scotch and ponderosa pines can also serve as hosts for this pest. The larvae of the Zimmerman moth damage the branches of pine trees, often causing them to break at the crotch where they connect to the trunk. Symptoms of infestation include dead and dying branches, particularly in the upper half of the tree, as well as popcorn-like pitch masses at the wound sites. These pitch masses can grow to the size of a golf ball and may ultimately resemble clusters of small, pale grapes.
Zimmerman Moth Treatment
The Zimmerman moth only attacks trees that are stressed from overwatering. If your tree shows signs of Zimmerman moth damage, we recommend conducting a sprinkler audit to ensure that the lawn is being watered according to the 1-2-3-2-1 lawn watering technique. Once the watering is corrected, we will apply a trunk injection using an insecticide called TREE-age.
Tree Insect Experts of Colorado
Do You Need Help Treating Your Trees for Insects?
Boulder (303) 499-2000 or Fort Collins (970) 225-9425.
Insect Control for Trees FAQs
How to Keep Insects From Attacking Trees?
Depends on the Type of Tree
Each tree species is unique, with different types of insects attacking them at various times of the year. We utilize three main insect control methods to kill and prevent these pests from harming trees. The choice of insecticide depends on the type of tree and the specific insects we aim to manage. Our primary insect controls are:
- Criterion – a preventative soil drench insecticide and will protect a tree for one full year.
- Safari – a soil drench insecticide that serves both preventative and reactive purposes and will protect a tree for 6-12 months.
- TREE-age -a trunk injection insecticide specifically designed for trunk-boring insects.
By using one of these three insecticides, we can effectively control about 99% of the insects that pose a threat to urban trees in Colorado. For personalized assistance, please call and speak with one of our tree care experts. They can help you develop a tree care program tailored to your property.
Are Tree Insect Controls for Trees Safe for Bees?
Criterion and Safari belong to the neonicotinoid family of pesticides, which if applied aerially are highly toxic to bees. At Organo-Lawn, we DO NOT DO ANY AERIAL APPLICATIONS using Safari or Criterion. We are deeply committed to the safety of honeybees.
Extensive Research When Used as a Soil Drench
Our research on using Criterion and Safari as soil injections shows no evidence that honeybees come into contact with the insecticides Imidacloprid or Dinotefuran. We feel confident using these insecticides because the active ingredients cannot penetrate the abscission layer of the tree, meaning they cannot reach the flower or pollen. If we discover scientific evidence suggesting otherwise, we will discontinue the use of these insecticides.
Additional Tree Insecticide FAQs
Imidacloprid is a systemic insecticide that targets various pests by affecting their nervous system. It is commonly used for lawn, tree, and agricultural pest control, as well as in flea treatments for pets.
It is absorbed by plants through the roots when applied as a soil drench. When insects feed on treated plants, they ingest the toxin, leading to paralysis and death.
If applied as a soil drench, Criterion and Safari can remain active in plants for around one year. Soil drenches provide longer protection, while foliar sprays break down more quickly.
When applied as a soil drench, Criterion and Safari have a lower risk of harming beneficial insects like pollinators and predators (e.g., ladybugs, and lacewings) compared to foliar sprays. However, it can still impact soil-dwelling beneficial insects, such as earthworms and certain predatory beetles, depending on soil conditions and application rates.
When applied as a soil drench, imidacloprid absorption time depends on tree size, soil conditions, and environmental factors. However, general estimates are:
Small trees (1-5 inches in diameter): 1-2 weeks for uptake and systemic movement.
Medium-sized trees (5-10 inches in diameter): 3-4 weeks for full absorption.
Large trees (over 10 inches in diameter): 4-8 weeks for the insecticide to fully distribute throughout the canopy.
Factors Affecting Uptake Speed:
Soil Moisture: Proper watering before and after application speeds up absorption. Dry soil slows uptake.
Soil Type: Sandy soils allow faster absorption, while clay-heavy soils slow movement.
Tree Health: Stressed or unhealthy trees may take longer to absorb the treatment.
Temperature: Warmer temperatures encourage root activity and faster uptake.
Best Practices for Fast & Effective Absorption:
- Water the soil before application to improve uptake.
- Apply in early spring or late summer for optimal root activity.
- Keep soil moist (not saturated) after application to help transport the insecticide.
- Avoid applying in extremely dry or cold conditions, as root absorption will be slower.
When Will the Insecticide Start Working?
- For root-feeding pests (like grubs): 1-2 weeks after uptake.
- For sap-sucking insects (like aphids and leafhoppers): 4-6 weeks after application.
- For wood-boring insects (like emerald ash borers): 6-8 weeks for full protection.
Safari (Dinotefuran) is a systemic insecticide that is absorbed through the tree’s roots and transported through the vascular system to protect against pests. It is known for its fast uptake and quick action compared to other insecticides like imidacloprid.
General Uptake Time by Tree Size:
- Small trees (1-5 inches in diameter): 1-3 days
- Medium trees (5-10 inches in diameter): 3-7 days
- Large trees (over 10 inches in diameter): 7-14 days
Factors That Influence Absorption Speed:
Faster than imidacloprid – Dinotefuran moves quickly through tree tissue, offering faster protection.
Soil Moisture – Adequate watering before and after application speeds up uptake.
Soil Type – Sandy soils allow for faster absorption, while clay-heavy soils slow movement.
Tree Health – Healthy trees absorb treatments faster; stressed or drought-affected trees may take longer.
Temperature – Warmer temperatures encourage root activity, leading to faster uptake.
How Soon Does Safari Start Working?
- Sap-sucking insects (aphids, scales, lace bugs): 24-48 hours after absorption.
- Leaf-feeding pests (leafhoppers, caterpillars, beetles): 3-5 days after absorption.
- Wood-boring pests (emerald ash borer, bark beetles): 7-14 days for full systemic protection.
Best Practices for Fast & Effective Absorption:
- Water the soil before and after application to improve uptake.
- Apply in spring or early summer when trees are actively growing.
- Keep soil consistently moist (not waterlogged) to aid movement.
- Avoid applying in extreme drought conditions, as root uptake will be slower.
Why Choose Safari (Dinotefuran)?
- Faster absorption than imidacloprid (weeks vs. days).
- Better movement through trees for quicker pest control.
- Highly effective against difficult pests like armored scales and borers.
Why Choose Criterion (Imidacloprid)?
- Less Expensive than Safari
- Just as effective as Safari on many insects – but must be applied 3-5 weeks before insect pressure.
We will determine which product to recommend based on the season and the specific insect species we aim to control. If the less expensive Criterion option is suitable, we will suggest it.
Criterion and Safari are effective in controlling a variety of tree insects, including aphids, ash sawflies, leafhoppers, leafminers, mealybugs, Japanese beetles, thrips, whiteflies, birch borers, and many others. It’s important to note that neither Criterion nor Safari controls spider mites. While both products help prevent emerald ash borers from affecting trees, they do not eliminate these pests if they are already inside the tree.
Comparison of Criterion (Imidacloprid) vs. Safari (Dinotefuran)
| Feature | Criterion (Imidacloprid) | Safari (Dinotefuran) |
|---|---|---|
| Absorption Speed | 4-8 weeks | 1-2 weeks |
| Duration of Protection | 12+ months | 6-12 months |
| Best For | Long-term pest control | Fast-acting pest control |
| Effectiveness Against Borers | Moderate (better if applied early) | High (rapid penetration) |
| Reapplication Needed? | Annually | Twice per year |
| Environmental Breakdown | Slower | Faster |
Soil drench applications of imidacloprid and dinotefuran offer superior effectiveness, safety, and environmental benefits compared to aerial sprays. Here’s why:
Better Absorption & Longer Protection
Systemic Action – The insecticide is absorbed through the roots and transported throughout the tree, protecting it from the inside out.
Longer-Lasting Protection – Soil drenches provide months to a full year of pest control, while aerial sprays often require multiple applications.
More Targeted Pest Control
Reaches Hidden Pests – Soil drenches protect against wood-boring insects (e.g., emerald ash borer, bark beetles) that aerial sprays can’t reach.
Kills Sap-Feeding Pests – Aphids, scale insects, and leafhoppers ingest the insecticide when feeding, eliminating them more effectively.
Safer for Pollinators & Beneficial Insects
Reduces Risk to Bees – Unlike aerial sprays, soil drenches do not coat flowers or foliage, minimizing exposure to pollinators.
Less Impact on Beneficial Insects – Since the insecticide moves internally, ladybugs, lacewings, and other beneficial insects are less affected.
Eliminates Spray Drift & Environmental Contamination
No Pesticide Drift – Aerial sprays can drift onto non-target plants, water sources, and surrounding landscapes; soil drenches stay in the root zone.
Lower Risk of Runoff – When applied properly, soil drenches bind to soil and roots, reducing contamination of nearby water bodies.
More Efficient & Cost-Effective
One Application for Season-Long Protection – A single soil drench can last 3-12 months, while aerial sprays require multiple treatments.
Less Waste – Aerial sprays lose effectiveness due to wind, evaporation, or poor coverage, while soil drenches ensure precise application.
A soil drench of imidacloprid or dinotefuran provides long-lasting, targeted pest control while reducing risks to pollinators, the environment, and beneficial insects. For the best tree protection, ditch the aerial spray and go with a soil drench!
We usually apply Criterion applications around the first few weeks of April. Proper soil moisture is essential for uptake, so water the tree before and after application to enhance absorption and effectiveness.
The best time to apply Criterion (imidacloprid) as a soil drench to a tree is in early spring, just before pests become active. This timing allows the tree to absorb the insecticide through its roots and distribute it throughout its vascular system before insect infestations peak. For sap-feeding pests like aphids, leafhoppers, and scale insects, applying imidacloprid before bud break ensures early-season protection. For root-feeding pests like grubs, applying in late spring to early summer targets newly hatched larvae. If treating wood-boring insects such as emerald ash borer, the application should be made in early to mid-spring to allow enough time for the insecticide to move throughout the tree before adult beetles begin laying eggs.
If a tree is under active insect attack and needs rapid treatment, Safari (dinotefuran) is the better choice for a soil drench application. Safari is absorbed by the tree’s roots and translocated through the vascular system much faster than Criterion (imidacloprid)—typically within 1-2 weeks, compared to 4-8 weeks for Criterion. This makes Safari ideal for urgent pest control, especially for sap-feeding insects like aphids, scale, and leafhoppers, as well as wood-boring pests like emerald ash borer. However, since Safari breaks down faster (lasting 6-12 months), it may require a follow-up treatment or be paired with Criterion for long-term protection.
We do not use any synthetic insecticides for controlling pests on fruit trees. If you have aphids or spider mites affecting a fruit tree, we recommend using Ecotrol. Ecotrol is an organic insect control product made from 10% Rosemary Oil, 2% Peppermint Oil, and 88% other ingredients, including Wintergreen Oil, Vanillin, Lecithin, and Butyl Lactate. It is an excellent organic option for managing aphids and spider mites on fruit trees.
According to the product labels for Criterion (imidacloprid) and Safari (dinotefuran) when applied as a soil drench, the recommendation is:Stay off the treated area until the soil drench has completely dried.
This typically takes 4-6 hours, but in cooler or more humid conditions, it may take longer.
For pets and children, waiting at least 24 hours is a good precautionary measure to allow full absorption into the soil.
While you don’t need to take any specific actions for the tree. We however, d strongly encourage you to water around the canopy of the tree; this will enhance its ability to absorb the insecticide effectively.