Mesquite Borer: All You Need to Know in a Nutshell

Mesquite Borer is a type of beetle known to infest mesquite trees, which are common in the southwestern United States and Mexico. As the beetles burrow into the bark and wood, they weaken the structural integrity of the tree.

These beetles can cause significant damage if infestations are not addressed early on. In this article, we will explore the characteristics and life cycle of the Mesquite Borer, as well as offer tips for detecting infestations and managing the issue.

The key to mitigating damage from Mesquite Borers is early detection. Familiarize yourself with the signs of infestation, such as sawdust-like frass or holes in the bark. Stay vigilant and take preventative measures to protect your mesquite trees from these invasive pests.

Mesquite Borer Basics

Classification and Taxonomy

The Mesquite Borer, belonging to the order Coleoptera and family Cerambycidae, is a species of longhorn beetle. Its scientific name is Placosternus difficilis.

Physical Characteristics

Mesquite Borer exhibits the following features:

• Adults are typically 3/8 to 5/8 inches long
• Body color ranges from reddish-brown to black
• Distinctive light-colored bands on the elytra (wing covers)

Distribution and Range

The Mesquite Borer can be found in:

• Texas
• Arizona
• Other parts of the United States
• North America
• Honduras

This species primarily inhabits regions containing mesquite trees, its primary host.

Mesquite Trees and Borer Interactions

Signs of Infestation

Mesquite trees can be infested by wood-boring insects like borer beetles. Signs of infestation include:

• Small holes in the bark
• Sawdust-like material around the tree base
• Slime flux, a foul-smelling liquid oozing from the tree

Impact on Mesquite Trees

Borer infestations can have negative effects on mesquite trees:

• Weakened tree structure
• Increased susceptibility to diseases and pests
• Potential tree death if not treated

Prevention and Control

To prevent and control borer infestations in mesquite trees, use:

• Appropriate irrigation and pruning to keep trees healthy
• Insecticides like neem oil for natural prevention
• Chemical insecticides for severe cases

Pros and Cons of Neem Oil:

To sum it up, maintaining healthy and well-cared-for mesquite trees is crucial to prevent borer infestations. Monitor your trees regularly to ensure their health, keeping an eye out for any signs of infestation. When necessary, apply neem oil or a more potent insecticide to control the pests.

The Borer Life Cycle

Larvae

Mesquite borer larvae are typically found in the bark of trees, causing damage as they feed on the wood. They are:

• Creamy white in color
• Cylindrical in shape
• Grow up to 2 inches long

During the rainy season, these larvae are more active, feeding on trees that have absorbed enough water to soften the wood.

Adults

Adult mesquite borers emerge during the warm season, usually in late spring or early summer. Some key features of the adults include:

• 1 to 1.5 inches long
• Dark brown or black color
• Long antennae

They are strong fliers and are attracted to lights at night. The adults serve an essential role in reproduction, with females laying eggs in tree bark during the summer months.

Reproduction

The life cycle of the mesquite borer typically revolves around two main seasons—reproduction during the warm season followed by the rainy season when larvae are most active. A brief overview of the reproduction process:

1. Adult females lay eggs in bark during summer months
2. Eggs hatch into larvae
3. Larvae feed on wood, causing damage
4. Larvae pupate and develop into adults during spring
5. Cycle repeats

While the life cycle of mesquite borers varies, they generally align with seasonal changes in rainfall and temperature. This benefits their development as it connects the larvae’s feeding patterns with the natural growth of their host trees.

Ecological Aspects

Borer Food Sources

Mesquite borers feed on:

• Mesquite trees
• Dead branches
• Leaves
• Bark tissue

A variety of fungi, bacteria, and insects also live in these environments.

Attracted to Freshly Cut Wood

Mesquite borers are attracted to freshly cut wood because:

• It offers easy access to food.
• Freshly cut wood releases odors that attract borers.

Cutting branches or trimming trees may inadvertently attract these pests.

Pests and Enemies

Mesquite borers are not the only pests that affect trees. Some other common tree pests include:

• Emerald ash borer
• Mealybugs
• Bark beetles

Possible enemies of mesquite borers:

• Woodpeckers
• Parasitic wasps

These predators help control mesquite borer populations.

By understanding the ecological aspects of mesquite borers, we can better protect our mesquite trees and maintain a healthy ecosystem.

Potential Threats and Management

Invasive Species Concerns

• Emerald ash borer: A serious threat to ash trees (not currently established in Oklahoma) source
• Red oak borer: Attacks oak and maple trees; can be a serious pest in nurseries source

Invasive species can damage trees, leading to potential borer beetle infestations. Healthy trees generally resist borer beetles well, but stressed trees are more susceptible to pests source.

Fungal Diseases Associated with Borers

Fungal diseases may weaken trees, making them more prone to borer infestations. Some examples include:

• Dutch elm disease: Affects elm trees
• Oak wilt: Infects oak trees

Stressed trees are more likely to attract borers. To keep trees healthy, it’s important to check for and manage any fungal diseases.

Proper Storage of Firewood

Firewood may harbor wood-boring insects source. The following steps can help prevent their spread:

• Store firewood at least 20 feet away from your home
• Keep firewood off the ground by placing it on a raised platform
• Cover firewood with a tarp to keep it dry and prevent moisture buildup

Proper storage of firewood helps minimize the risk of spreading wood-boring insects to healthy trees.

Comparison Table: Invasive Species vs. Fungal Diseases

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Mesquite Borers

Beatle of some sort?
Location: San Antonio, Tx
January 23, 2012 7:55 pm
I sell wood for fireplaces, bbqs, etc. Recently I split some mesquite to let dry out and there are a million of these guys everywhere. I just leave them be not knowing what they are. They seem harmless. They run extremely slow and sometimes will just sit still when I move the wood pile around like they are trying to blend in. just wondering what they could be as I have a 2 yr old curious little boy and don’t want him harmed in anyway if they are dangerous.
Signature: Thank you for your input, Mike

Hi Mike,
You have Mesquite Borers, Placosternus difficilis, a native species that BugGuide reports from Arizona and Texas.  Mesquite Borers are Longhorned Borer Beetles in the family Cerambycidae.  The larvae are wood borers.  You should advise your customers to keep their firewood outside until they are ready to use it or they might find their homes invaded during an emergence of the adults from the wood.  Often warm indoor temperatures trigger an emergence in the home.  Since this is a native species, transporting the firewood shouldn’t be a problem, but with many invasive, exotic borer insects showing up in North America, people are warned about transporting firewood as this helps to spread an invasion..

Letter 2 – Mesquite Borer

Bug in Mesquite tree.
Recently part of a VERY large mesquite tree fell on my fathers house. He asked me to help clear the wood and so I did. Rather than waste the wood by merely disposing of it or using it in a fire place, I decide to keep the wood for use in making my famous Mesquite smoked Texas Bar-B-Q. I noticed an unusual bug in the wood as I loaded it up at my fathers, but now that It has been in place for several weeks in my back yard. I have noticed the pile of wood absolutely covered with these bugs. Can you please tell me what type of bug it is and also (if you can) whether or not they pose a threat to anything, or anyone. (please see attached photo of one of the bugs crawling on my house) Thank You,
Michael Chambers
Dallas TX

Hi Michael,
This is a new species for our site, the Mesquite Borer, Placosternus difficilis. The larvae of the Mesquite Borer bore into the wood of mesquite and some other plants. The active adults feed on nectar and pollen and are attracted to lights. See BugGuide for more information.

Letter 3 – Mesquite Borer

Unusual bug found in my house
I have never seen one of these before and really have no idea how to look it up on your database. I like its colors. Thanks for the info.
Steven Floyd
Corpus Christi, Texas

Hi Steven,
This is a Mesquite Borer, Placosternus difficilis, and you are right, it is a beautiful insect.

Letter 4 – Mesquite Borer

Subject: I’m not sure what type of bug this is
Location: Albuquerque NM
January 30, 2016 8:10 pm
Acouple of days ago I lift the door open while letting in some cool air, and I didn’t really pay attention and make sure no bugs came in. Then just recently I noticed this bug and I think it looks like a cockroach, it has antennas and has 3 legs on each side with patterns on the back.
Signature: Thanks for the help in advance

This is not a Cockroach.  It is a Mesquite Borer, Placosternus difficilis, a beetle in the Longhorned Borer Beetle family Cerambycidae.  According to BugGuide:  “Larval hosts: Prosopis, Acacia, Pithecellobium, Platanus, Citrus, Leucaena” and “Adults are active day and night, running rapidly along freshly cut branches of their host plants and feeding on the blossoms of Koeberlinia, Acacia, Baccharis, Bumelia, Clematis, and Solidago.”  BugGuide also notes:  “Adults come to lights and bait.”  So, we surmise that either you had firewood from one of the host plants in your house and this beetle emerged from the wood after metamorphosis, or you have at least one host plant growing in your yard or nearby and that the beetle was attracted to the light emanating from the open window.

Letter 5 – Mesquite Borers

Subject: What is this beetle
Location: Brady texas
August 14, 2017 8:10 pm
West Texas , cutting and stacking mesquite and oak wood and after being stacked for a couple hours, hundreds of these were all over the new wood we just cut.
Is this some form of blister beetle?
Signature: Tony

Dear Tony,
These are not Blister Beetles.  They are Longhorned Borer Beetles in the family Cerambycidae, and their larvae are wood borers.  Based on BugGuide imagery, and the fact that you cut mesquite, we are quite certain they are Mesquite Borers, Placosternus difficilis.  According to BugGuide:  “Adults are active day and night, running rapidly along freshly cut branches of their host plants.”