Colorado is home for a myriad of insects which may be either beneficial or harmful to the landscape.
Beneficial insects in the landscape environment include pollinators and predatory insects and any insecticidal treatments should be applied and timed to limit any harm to these insects. Elk Creek will inspect first to diagnose the problem and then treat it accordingly. All applications are made in accordance with Colorado Dept. of Agriculture guidelines and laws.
With the Front Range climate being semi-arid, there are fewer insects overall than what can be found in humid, hot areas of the country. But this does not make them any less damaging and some species of insects can cause damage throughout wide areas of the United States, for example the Emerald Ash Borer has now been found in 35 states and Canada. There is no single way to control all insects in the landscape however; an integrated pest management program will ensure that the proper plants are treated with the necessary control at the right time.
Elk Creek Lawn and Tree Care will always use the appropriate treatment needed to control a specific insect problem. Treatment options include, systemic sprays or injections, preventative sprays, foliar or trunk sprays, or at times the best option would be no to treatment as to allow for a beneficial population of predatory insects to do what nature intended. Once again, the best defense against an insect is a healthy plant so remember to water during the winter and times of drought. Tree fertilizations will also help to boost your trees natural defenses.
Below, we will highlight on some of the most common and damaging insects in our area and will continue to add the list. If you cannot find information on the tree or insect that you are concerned about, please contact us and we will do our best to answer any question you may have.
The IPS Beetle, also known as the Engraver Beetle, is another destructive bark beetle in Colorado and there are a variety of IPS species that attack pines and spruces although, it is most damaging to spruces and pinyon pines in our area. Bore holes from this beetle will be smaller than the Mountain Pine Beetle and damage will usually begin at the top of the tree and may be hard to identify. This beetle will bore into branches as well as the trunk so a preventative spray will need to be applied to the entirety of the bark.
Preventative bark sprays will also help to control the following borers and moths for our region: Zimmerman Pine Moth, Tussuck Moth, Pine Tip Moth, Pinyon Pitch Mass Borer, Western Spruce Webworm and Sawfly larvae.
Cooley Spruce Gall affects most species of spruces in our area. Eggs are deposited on the underneath of spruce tips by the adult Spruce Gall Adelgid. Upon hatching the larvae will bore into the tip of the spruce branch growing and feeding throughout the summer. Spruce tips will become enlarged as the larvae grow and will turn brown and dry after the insect has emerged. In most instances this is a cosmetic problem and the tree will generally not be harmed. Aesthetically unpleasing the damaged tip will take a couple of years before they are pushed out by new growth. Two foliar sprays applied to the spruce tips and branches, one applied in spring as the eggs begin to hatch and one in the fall as adult females return to lay their eggs, is our recommended control for this pest.
Systemic insecticides and preventative sprays will also help to control theses boring insects in our region: Ash Bark Beetle, Clear Winged Borer, Bronze Birch Borer, Peach Tree Borer, the Round Headed Apple Borer and the European Elm Bark Beetle, just to name a few.
The Walnut Twig Beetle has been causing the decline of Black Walnut trees from Boulder to the north western suburbs. As the Walnut Twig Beetle enters the branch it also introduces a fungus to the tree wound and causes a disease known as Thousand Cankers Disease. The fungus will kill an area under the branch causing a dead area known as a canker. When numerous, these cankers can girdle a branch, restricting nutrient flow which may kill the limb. There currently is not an effective treatment for this fungus. The best control is a preventative or systemic treatment to control the twig beetle.
Leaf Feeding Insects
The Japanese Beetle has been a prominent pest of the eastern U.S. during the last century. Just recently, several communities along the Front Range have seen permanent, reproducing populations of this beetle become established. Adult beetles can rapidly defoliate flowers and the leaves on many landscape plants including garden fruits and vegetables. On leaves, a characteristic feeding pattern, known as skeletonizing in which the softer tissue is removed in between the larger leaf veins, will help to identify the damage inflicted by this beetle. Adult beetles may be treated with several different insecticides depending on the affected plant and landscape setting. Due to the broad spectrum nature of these insecticides, treatments cannot be applied to flowers or while plants are flowering when honeybees or other pollinators are likely to be present. The best control of the Japanese beetle on flowers or small plants is to simply handpick the beetles from the plant. Treatment of the beetle larvae if present in the lawn will also help to disrupt the life cycle of this insect.
Sawflies are a group of non-stinging wasps with larvae that defoliate by feeding on the leaves or needles of plants. The larvae resemble caterpillars but are more closely related to bees and ants. Defoliation is usually seen in late spring, as sawflies are among the first insects to be found feeding on plants, and can last into early summer. Species of sawfly can be found on both conifers and deciduous plants and two prolific hosts for this pest are Ponderosa Pines and Ash trees. Contact insecticides will provide good control if applied during spring while larvae are small and if full coverage is attained. Adult Sawflies are not considered a landscape pest and are therefore cannot be treated.
Unlike boring beetles, leaf eating beetles will only feed on the foliage and will not bore into a tree damaging its vascular system. The larvae of these beetles will skeletonize the leaves with adults occasionally causing circular holes. Feeding will only cause cosmetic damage to the leaf though repeated infestations will add to the overall decline of the plant. The most common of this category of beetle in the Front Range is the Elm Leaf Beetle, and the Rabbit Brush Beetle has become problematic during recent years with very wet springs. A contact insecticide should be applied to control leaf eating beetles in most instances.
Leafminers refer to a large spectrum of insects which feed on the interior cell tissue of leaves. Damages from feeding may resemble tunnels in the leaf, cause patchy dead areas or the leaf may become skeletonized. Once the leaf damaged has occurred , the mostly cosmetic damage will remain throughout the growing season or until the leaf prematurely drops. Foliar sprays for this type of insect are not effective as the miners are protected inside the leaf tissue. Systemic insecticides are the recommended treatment for miners and need to be applied several weeks before populations become established to prevent leaf damage. Prominent Front Range species include the Sawfly Leafminer, Elm Leafminer, Aspen Leafminer and the Lilac Leafminer. Leaf Miners may also be classified by the damage that they inflict, Serpentine Leafminers and Tentiform Leafminers.
Needleminer is the term used for the larvae of several small moth species that develop and pupate in the needles of evergreen trees. The larvae bore into the needle causing needle die back, brown tips and the hollowing out of needles. System insecticides will provide the best control though a foliar spray with residual properties, applied during times of egg hatch can also be an effective control. The Front Range typically sees Ponderosa Pine Needleminers, Pinyon Needleminers, Spruce Neddleminers, Pine Sheath Needleminers and occasionally White Fir Needleminers.
There is a large variety of leaf eating caterpillars in Colorado which may affect either deciduous or evergreen plants. The caterpillars are the larvae of many different moths and feed on host specific plants causing complete defoliation during the worst outbreaks. Systemic, preventative and foliar sprays will all provide control though foliar sprays will need to be repeated as necessary. Common to this region are the Douglas-fir Tussock Moth, Tiger Moth, Fall Webworm and Juniper Webworm, Western Spruce Budworm and Pine Budworm, Bagworms, Cankerworms and several species of tent caterpillars, including the Western Tent Caterpillar.
Galls are abnormal growths of plant tissue caused by wounding, infection or the feeding and egg laying of insects, mites and parasitic wasps. Galls will be found on evergreens and deciduous plants. Although unattractive, galls rarely do serious damage and chemical controls are often not needed and are not used to treat the gall but rather the insect or mite responsible for the gall. Gall damage occurring on trunks or branches is largely irreversible though plants tips with gall will usually be pushed out by new growth within a couple years. Some of the more common galls and gall producers are Eriophyid Mites, Petiolegall Aphids, Hackberry Nipplegall, Cooley Spruce Gall, Poplar Twiggall, Pinyon Needlegalls, Gall Midges, Bulletgall Wasp, Rose Gall Wasp and Willow Blistergall.