Ash Bark Beetles

Ash trees don’t have an easy time of it in Colorado. Among the problematic ash borers that are in the state are three species of ash bark beetles. They’re members of the snout beetles/weevil family and have been spotted throughout Colorado.

Like all opportunistic insects, ash bark beetles prey on stressed or weakened trees. Ash trees that have been recently transplanted are often at most risk of infestation. Improperly pruned trees that have multiple shaded branches or broken branches are a bark beetle’s favorite entryway into a tree. They cut egg nurseries (also known as galleries) under the bark. The easier it is to cut into a

tree, the more infestation a tree is likely to have. It’s not unusual for an entire tree to be infested.

Small holes that are called ventilation holes are a sign of an egg gallery immediately below. A gallery can spread quite widely around a borehole with a central chamber and two narrower corridors running across the wood grain. When eggs hatch, larvae tunnel in a line around their gallery. Branches can be killed if the tunnels separate the branch from a supply of nutrients.

Ash bark beetles larvae often leave obvious signs of infestation. Fungi usually develops in the larvae’s feeding tunnels. Wood is stained a warm brown color by the fungi. Another sign of infestation is oozing sap from twig wounds.

Untreated larvae overwinter in trees and become active in mid- to late spring. Mating season is usually a brief three to four weeks and by mid-summer, the life cycle begins anew.

Ash Bark Beetles Treatment

Preventive treatment can reduce or eliminate the risk of bark beetles. Proper locating, pruning, watering and fertilization can strengthen a tree so that it can withstand insect invasion. Chemical treatment is often the only option for an already infested tree. Because specific chemicals are used for each life cycle of ash bark beetles, professional application is recommended.

If ash trees are part of your landscaping, they may be at risk for bark beetle infestation. Contact SprayTech, Colorado commercial and residential insect treatment specialists, at 720-248-0000 to discuss preventive measures and treatment.