Protect Your Garden: Eradicating Cottonwood Borer Infestation

folder_openColeoptera, Insecta
comment10 Comments

Cottonwood borers are a common pest that can cause significant damage to trees such as cottonwood, poplar, and willow. These large black and white longhorned beetles lay their eggs at the base of host plants, and when the larvae hatch, they tunnel around the crown and buttress roots of the trees, causing serious harm.

Getting rid of cottonwood borers is crucial for the health and longevity of your trees. In this article, we’ll discuss methods to control and prevent these pests, ensuring your trees remain vigorous and pest-free. Stay tuned for practical tips and solutions to tackle this gardening challenge.

Understanding Cottonwood Borer

Life Cycle

The cottonwood borer (Plectrodera scalator) is a member of the longhorned beetle family, Cerambycidae. Its life cycle consists of four stages:

  • Eggs: Females lay eggs in niches they cut into the bark at the tree base.
  • Larvae: Creamy white grub-like larvae tunnel around the crown and roots.
  • Pupa: The larva develops into a pupa inside the tree.
  • Adult: Mature beetles emerge in late spring or early summer.


Cottonwood borers mainly infest cottonwood, poplar, and willow trees. Their feeding and tunneling activity usually occurs at or below the soil line.

Physical Characteristics

Here are some physical characteristics of the cottonwood borer:

  • Size: Adults typically measure 1.25 to 1.5 inches in length.
  • Color: They have a distinctive black and white pattern on their bodies.
  • Antennae: Long, black antennae are a notable feature of this beetle.

Comparison Table: Cottonwood Borer vs. Other Longhorned Beetles

Feature Cottonwood Borer (Plectrodera scalator) Locust Borer (Megacyllene robiniae) Red-Headed Ash Borer (Neoclytus acuminatus)
Length 1.25 – 1.5 inches 0.75 – 1 inch 0.5 – 0.75 inch
Primary Color Black and white Black and yellow Reddish-brown
Key Host Trees Cottonwood, poplar, willow Black locust Ash, oak, hickory
Antennae Length Nearly as long as body Body length Shorter than body length
Larval Appearance Creamy white, grub-like White, legless Creamy white, cylindrical

Pros of the cottonwood borer:

  • Occupies a specific ecological niche within its host trees.

Cons of the cottonwood borer:

  • Weakens and damages the structural integrity of the host trees.
  • Can cause decline or death of young or infested trees.

Identifying Infestations

Signs of Infestation

One common sign of a cottonwood borer infestation is the presence of frass, a mixture of chewed wood and insect excrement, around the base of the tree or near trunk and branches. Adult borers may leave tiny holes on the trunks and branches, while larvae can create galleries or tunnels within the tree, weakening its structure.

Flagging, or wilting of leaves, is another sign of a potential infestation as it indicates the disruption of water and nutrient transportation within the tree due to larvae damage.

Commonly Affected Trees

Cottonwood borers often target trees like:

  • Cottonwood1
  • Poplar2
  • Willow3

Here’s a comparison table of the trees affected by cottonwood borers:

Tree Type Susceptibility to Infestation Additional Info
Cottonwood High Most commonly targeted by cottonwood borers
Poplar Moderate Second most common target
Willow Moderate Less susceptible than cottonwood & poplar

To prevent infestations, adopt proper tree care practices like regular pruning, watering, and mulching. Keeping trees healthy minimizes the chances of cottonwood borer infestations.

Effective Treatment Methods

Chemical Treatments

There are a few insecticides that can help treat cottonwood borer infestations. Two common examples are:

These insecticides are available as contact insecticides and systemic insecticides. Contact insecticides kill borers on contact, while systemic insecticides are absorbed by the plant and kill borers when they eat the plant tissue.


  • Effective in reducing borer populations
  • Can protect valuable landscape trees


  • May harm non-target organisms
  • May require multiple applications

Comparison table:

Insecticide Type Pros Cons
Permethrin Contact Rapidly kills borers on contact May harm beneficial insects
Carbaryl Contact/Systemic Can protect trees for up to a year May require multiple applications

Cultural Practices

Cultural practices involve non-chemical methods to prevent and manage cottonwood borer infestations. Some examples include:

  • Protect young tree trunks with physical barriers like tree wraps, which can help to prevent egg-laying
  • Prune and remove infested branches to reduce borer populations and prevent the spread of infestations
  • Encourage natural predators such as birds, which can feed on adult cottonwood borers
  • Burn infested wood to destroy larvae and prevent further infestations of wood borers

These practices, when combined with attentive monitoring and timely treatments, can help to keep borers in check and maintain the health of your trees.

Prevention and Maintenance

Proper Fertilization and Watering

A healthy tree is more resistant to pests like the cottonwood borer. To maintain healthy trees:

  • Apply the right amount of fertilizer to support tree growth.
  • Provide supplemental water during dry periods.

For example, a 10-10-10 fertilizer can promote robust tree health, making it less susceptible to infestation.

Pruning and Mulching

Regular pruning and mulching can further deter cottonwood borers:

  • Prune dead or damaged branches to reduce egg-laying sites.
  • Apply mulch around the tree base to retain moisture.

Following these practices, you can minimize the risk of cottonwood borers infesting your trees and keep them healthy and vibrant.

Prevention Method Pros Cons
Proper fertilization Supports healthy tree growth Needs regular upkeep
Supplemental watering Prevents tree stress Must monitor droughts
Pruning Reduces egg-laying sites Requires proper skills
Mulching Retains moisture Needs regular upkeep

Cottonwood Borer Distribution

North America

Cottonwood borers are found throughout North America, primarily infesting cottonwood, poplar, and willow trees1. These insects are common in areas where their host trees grow and can cause significant damage to young trees2.

Key Features:

  • Infest cottonwood, poplar, and willow trees
  • Widely distributed in North America

Rocky Mountains

The Rocky Mountains region also has a presence of cottonwood borers, due to its suitable habitat for cottonwood trees. These trees provide shade and produce yellow flowers, attracting the borers3. In this region, borers can be a notable concern for various tree species.

Examples of Trees at Risk:

  • Cottonwood
  • Poplar
  • Willow

Table 1: Comparison of Trees Susceptible to Cottonwood Borer Infestation

Tree Species Native to Rocky Mountains Provides Shade Yellow Flowers
Cottonwood Yes Yes Yes
Poplar Yes Yes No
Willow Yes Yes No

Additional Tips for Dealing with Tree Borers

Identifying Other Tree Borers

There are various types of tree borers that can infest your trees, such as bark beetles, longhorn beetles, and wood-boring beetles1. When dealing with an infestation, it’s essential to identify the specific type of tree borer you’re dealing with. Here are some common examples of tree borers:

  • Bark Beetles: Holes as thick as a pencil lead along the main trunk and major limbs2.
  • Longhorn Beetles: Adult borers are conspicuously colored black and white, measuring 1 1/4 to 1 1/2 inches3.
  • Wood-Boring Beetles: Reddish frass in bark crevices or around entry holes4.

To identify the specific type of tree borer, you can compare their physical appearance and the signs of damage caused by each. This will help you in determining the most effective method to tackle their infestation.

Enlisting Expert Help

If you’re unsure of the type of tree borer infesting your tree or need assistance with an infestation, consider enlisting the help of an expert. Professionals in the field of tree care and pest management can provide valuable advice and recommendations on how to deal with tree borers effectively. They can:

  • Accurately identify the specific type of tree borer
  • Provide tailored recommendations for treatment options
  • Help prevent future infestations

By working with an expert, you can save time, effort, and ensure the health of your trees in a more efficient manner.


  1. Cottonwood Borer – Texas A&M University 2 3
  2. Cottonwood Borer | Oklahoma State University – OSU Extension 2 3
  3. Shade Tree Borers | Oklahoma State University – OSU Extension 2 3


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts
Tags: Cottonwood Borer

Related Posts

10 Comments. Leave new

  • I’ve been looking for a site like yours for a bit now. I want to thank you for posting the picture of the cottonwood leaf beetle. I found one tonight just inside my window. It was very helpful knowing exactly what I’m looking at.
    I used to be very big into entomology but haven’t had out my pins in almost 15 years. Now the kids are excited about figuring out what the bugs are that they find and bring home to mom. This was helpful tonight. Thank you.

  • I just now found that bug. Thank you for the info!

  • Thanks found that yesterday and had no idea what it was

  • Mary Thomas
    July 22, 2019 9:16 pm

    Yes!! Just found this beetle hanging out on our back porch yesterday. Contacted AG department and collected specimen.

    • You didn’t mention your location, but the Cottonwood Borer is a native insect to the center of the country, with most of our sightings coming from Texas and Oklahoma. We don’t believe the agricultural department will have concerns regarding a native species.

  • I found one in front of my door in northern Oklahoma. Blackwell,ok to be exact Is it a harmful beetle does it bite or sting??

  • I just found one on my driveway. Never seen one before.

  • Just killed one on my patio in DFW. The thing was huge probably about 1-1/2 body length with 1-1/2 antennas. Intimidating looking bug for sure

  • Carless W Jones
    August 16, 2021 12:38 pm

    We have seen a few in our yard this year and we have cottonwood trees .
    Southeast Missouri


Leave a Reply

Your email address will not be published. Required fields are marked *

Fill out this field
Fill out this field
Please enter a valid email address.
You need to agree with the terms to proceed