Tree Insect Calendar

Important Annoucement - DLC Arbor Services is no longer recommending treating pines and spruce trees for Mountain Pine Beetle and IPS Beetles. The populations of both insects have returned to their pre-outbreak population levels. Do not waste your money on spraying or injecting your trees for these tree insects. It is a total waste of money.

japanese beetle speading in denver

Japanese Beetle - Spring to Fall

This insect is now radiating out of Cherry Hills Village into the entire Metro Area. It is a lawn insect in the grub stage, and as an adult in summer damages foliar plants from trees and vines to potted flowers. Control options vary depending on the species of plant.

emerald ash borer is not in the Colorado Front Range

Emerald Ash Borer - Spring to Fall

The time to treat for emerald ash borer is now. Since its discovery in Boulder in 2014, it is now present in all of Boulder and is expected to move into the entire NW Colorado area in the next decade. DLC's Arborist can provide you with treatment options. For more information, click here.

Ash/Lilac Borer common ash tree pest

Ash/Lilac Borer - Spring to Summer)

This very common parasitic wasp has plagued ash trees with trunks less than 12' in diameter. It can be difficult to find an ash tree without it. Although fatal if left untreated, it can be controlled with a combination of insecticide and fertilizer.

out door funiture sticky? Got tree aphids

Aphids - Throughout Growing Season

Aphids are soft bodied insects that suck sap from the leaves. They are found on almost any type of plant. Their damage ranges from the nuisance of a sticky substance called honeydew and the curling of leaves to branch dieback and and in rare cases, the death of entire trees. Control can be achieved through a variety of methods depending on the plant species.

ips beetles aggressivey attack pine and spruce trees

Ips Beetle - Spring and Late Summer

The ips beetle, also known as the engraver beetle, is a native insect that develops under the bark and tunnels through the tree, attacking spruce and piñon pines. Prevention is the only treatment since death is inevitable once infested. Treatment requires two bark sprays per year since the insect can fly and attack new trees when the temperature is above 65 degrees for at least 3 hours.

kermes scale attacks oak trees in Denver

Kermes Scale - May to September

Kermes scale is a large scale insect that attacks the twigs of certain oak trees. Symptoms of infestation are most obvious when branch tips fall off in in great numbers during May and September, often confused with squirrel damage. DLC has great success treating this tenacious insect with a combination of systemic insecticides.

oystershell scales treatment for aspen trees

Oystershell Scale - Growing Season

Oystershell scale are tiny insects that live under a protective cover on the leaves or bark of their host plant. This insect can infest a variety of plants and is common on aspen. It’s not rare to find them on only one stem of a tree and not on the adjacent aspens. They can eventually kill the tree. Their shell (scale) protects them from insecticide sprays so they are best controlled with systemic insecticide injections or difficult-to-time trunk sprays during their "crawler stage" from May into June.

treat American elms for leaf beetle

Elm Leaf Insects - Spring to Early Summer

The over-planted elm is plagued by a variety of leaf feeding insects including elm leaf beetle, elm leaf miner and aphids. These insects are so common that treatment is required annually. Damage includes "shot holes,” interveinal skeletonization and dripping honeydew. Some trees can be defoliated or the leaves made useless. Control is best achieved through soil injection of insecticides in spring.

tree american elms for tree scale

European Elm Scale - Spring

The European elm scale is a very common insect plaguing American elms that is now resistant to the typical insecticide used to control it - neonicotinoids. This soft scale pest secretes honeydew that covers cars parked beneath the infested trees, and causes black "sooty mold" that turns the bark black. Branch die-back is typical. There are new treatment options available.

zimmerman moths attack pines trees found in the front range colorado

Pine Borers - Spring

Pine borers include mountain pine beetle, Zimmerman pine moth, piñon pitch mass borer and turpentine beetle. They all dig tunnels into the tree and can cause damage from limb breakage to tree death. Most cause pitch to ooze from the hole and are treatable if detected early.

treating common pest to peach and other fruit trees

Peach (Fruit) Tree Borer - Spring

The peach tree borer is the most damaging pest of peach, cherry, plum and stone fruits. It can weaken or kill trees and control is strongly advised. Adults bore holes in the base of the tree and roots. Symptoms include a jelly-like ooze at the base of the trunk. Control is best achieved in spring and does not affect the fruit.

treating boxelder bugs in Denver

Boxelder Bugs - Spring to Summer

If you have a boxelder tree, you have boxelder bugs. In the fall, this species congregates in large numbers on the south side of trees, buildings, and rocks exposed to the sun. It is during this period that homeowners become aware of the insects. Adult boxelder bugs will frequently attempt to enter cracks and crevices in the walls in an attempt to secure an over-wintering site in homes. Since they eat boxelder seed they can be controlled (or at least reduced) with a spring systemic insecticide application.

oystershell scale attacks several hardwood tree species in Denver

Ladybugs - The More the Better

Ladybugs are good for your yard and trees. We love them so much, in fact, they’re our mascot—look for them on our trucks. In the spring, buy several packages of live ladybugs and let them loose in your yard.