Denver is host to many insects that are attracted to your trees. All trees get bugs to some degree, and not all bugs are harmful to your trees. Some can just be a nuisance, cause minor damage, become deadly, or even benefit your trees. It’s important to have a trained professional inspect your trees since many different bugs cause similar damage, but may require different treatment methods. Here’s a list of the more common bugs and the corresponding trees they damage.
Leaf curling caused by aphids
Aphids - There’s over a dozen different species of aphids affecting plants and trees along the front range. Most damage and treatment is generally the same. They’re pretty common on any trees or shrubs in your yard. You might notice the honeydew around the area or even leaf curling on some branches. This damage is usually minimal, but occasionally will lead to branches dying off. This is more of a “bothersome” pest, so if the aphids are in an area of the yard that you don’t frequent, then you probably don’t notice them. If they happen to be over your patio area or along your normal walking path, then we should treat them before they become to bothersome. We do a foliar spray to reduce it’s population.
Emerald ash borer exit holes and severe tree decline
Emerald ash borer - You might've heard about this wood borer in the news recently. It's been around Boulder county since 2013. Thanks to proactive response from city forestry, this tree killer hasn't spread rapidly, but it is spreading. Look out for rapid and sever dieback on your ash trees. The "D" shaped exit holes is another telltale sign, but hard to spot. There is a lilac/ash bark borer that does similar damage, but requires a different treatment, so be sure to have a trained professional inspect your trees. A preventative injection treatment is the only option, but it is good for two years.
Beetle kill
Mountain pine beetle - This wood borer is still killing forests throughout Colorado. Mostly lodgepole and ponderosa pines. The 285 corridor has seen a resurgence in recent years, though not as bad as it was along I-70. Typically, you'll notice the top of you trees turn orange to brown, then the whole tree dies quickly. A preventative treatment is your only hope, because once you see the damage, it's too late. Treatment can be a trunk spray, or an injection treatment that is good for two years.
Ips beetle boring dust and larvae galleries
Ips beetle - Ips beetle damage is almost identical to mountain pine beetle. The tree will die from the top down. They're more associated with spruce trees in Denver, but will attack any pine species as well. The city forest department has urged contractors to prioritize dead spruce removals to try and reduce this beetle population in Denver. Preventative treatment is the only option, which is a trunk spray twice a year, or an injection that is good for two years.
Japanese beetles chewing away
Japanese beetle - These leaf chewers will devour your flower garden, vines, even trees and shrubs. They prefer more fragrant trees like fruit trees and lindens, but if you have roses or any fragrant flowers, they'll be all over them. We can spray for them, typically once a month through the summer.
Kermes scale on oak, European elm scale on elm, oyster shell scale on Aspen
Scale insects - There are many different scale insects in Colorado. Scales pierce the twigs, needles, or bark and suck nutrients right out of the tree. They're easily visible on Aspen and elm trees, but oak, pine, and spruce are hard to see with an untrained eye. You probably have scale on your oak tree if you see yellowjackets flying around it regularly. The damage starts minimal, but can kill off branches or weaken the tree making it easier for other bugs to do more damage. The key is treatment before it gets out of control. Different scales have different timing when it comes to spray, but an injection is possible as well.
Elm leaf beetle damage
Elm leaf beetle - Large elm trees have been devastated by these leaf chewing bugs in recent years. Usually they're more of a nuisance, but if they defoliate a tree too severely, it can die. We can spray, or do an injection to control this bug.
