Get Educated on the many Borer Beetles of Colorado

The Front Range has a wide variety of Borer Beetles. Find out their preferred hosts and how to identify infected trees.

Mountain Pine Beetle

For being so small they sure can do some damage in large numbers. Watch Berry explain some things about this native beetle.

Emerald Ash Borer

The Emerald Ash Borer, Agrilus planipennis, is a metallic green, wood-boring beetle native to China, Japan, Korea, and parts of Russia. Adults are about half an inch long with a coppery-red abdomen and feed on ash tree leaves, while the larvae cause the most damage by feeding on the inner bark and phloem, disrupting nutrient and water transport within the tree. Larvae create distinctive S-shaped tunnels under the bark, which are a key sign of infestation.

Spread and Impact

EAB was first detected in Michigan in 2002 and has since spread to 37 U.S. states, the District of Columbia, and parts of Canada. It spreads naturally as adults fly and through human activities, such as moving infested firewood, logs, or nursery stock. The beetle can attack healthy ash trees in forests, urban, suburban, and rural areas, leading to widespread tree mortality. The economic impact in the U.S. has exceeded $10 billion, affecting communities, forestry, and ecosystems.

Life Cycle

The EAB life cycle can take one to two years depending on tree health, temperature, and timing of egg-laying. Eggs are laid in bark crevices, larvae feed under the bark, pupate in winter, and adults emerge in late spring to early summer, leaving D-shaped exit holes. Adults live about three weeks and are most active during warm, sunny days.

Detection and Symptoms

Signs of infestation include canopy thinning, dying branches, vertical bark cracks, and increased woodpecker activity as they feed on larvae. Early detection is difficult because larvae feed beneath the bark, hiding damage until tree decline becomes noticeable.

Management and Prevention

Management strategies include monitoring, insecticide treatments, biological control using natural predators, and public awareness campaigns such as “Don’t Move Firewood” to prevent human-assisted spread. Diversifying tree species in urban and forested areas also helps reduce vulnerability to EAB infestations.

Ecological Significance

EAB is considered one of the most destructive invasive species in North America, often referred to as the “wildfires of the East” due to its rapid and extensive damage to ash trees. All ash species in affected regions, including White, Green, and Black Ash, are susceptible.

Ips Beetle - AKA Engraver Beetle

When Adult Ips beetles enter pine/spruce trees and tunnel a yellowish- or reddish-brown boring dust is produced and accumulates in bark crevices or around the base of the tree. Affected parts of the tree will become discolored and eventually die. The small round holes in the bark of infested trees indicate the adult beetles have exited and moved to another part of the same tree or to neighboring trees.

Locust Borer

The adult locust borer is a black beetle with bright yellow markings, including a distinctive W-shaped band across the wing covers (elytra). Adults are typically 0.75 to 1 inch (19–25 mm) long, with reddish legs and long antennae characteristic of the Cerambycidae family. From a distance, they can be mistaken for wasps due to their coloration

Poplar Borer - Saperda calcarta

How to spot Poplar Borer in your Aspens - Willows and Cottonwoods

Oozing sap mixed with fine frass
Rust colored stains on bark
Large amounts of course frass at tunnel entrances

Linden Tree Borer

The linden tree borer (Saperda vestita) is a native long-horned beetle whose larvae tunnel under the bark of linden trees, causing significant damage and potentially killing weakened trees.

Early signs include loose or bulging bark, thinning canopy, and branch dieback. In severe infestations, trees may die, though large trees can show no symptoms for up to five years. Larval feeding produces broad, irregular sapwood mines often packed with sawdust and frass, which may accumulate at the base of the tree. Holes in leaves can also indicate larval activity, though other pests may cause similar damage.

More coming soon

Stay tuned for new Colorado Bark & Borer Beetle facts !!

Colorado has so many interesting Bark & Borer Beetles with fun facts about them all. Berry will be posting more as his journey continues.

Beat-the-Beetle-back

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