Tree bugs like Emerald Ash Borer can cost Texans nearly $19 billion over two decades, including tree treatment, removal, debris processing, and lost ecosystem services. Tree-killing insects represent only a small percentage of tree pests, but are responsible for a large percentage of tree and shrub damage in Texas. The majority of insect species do not affect the overall health of a tree, or may even be good for tree health. However, there are several species of insects that will kill a tree within 2-3 years without treatment.
Our guide covers the 8 most destructive tree pests in Texas and includes important identification characteristics as well as effective prevention methods.
Discover the top tree pests in Texas and how to keep your trees pest-free with Mighty Tree Care.
- Learn about bark borers, sap suckers and defoliators by the damage they create
- Prune and water to keep trees healthy and better able to resist pests
- Practice 5 prevention measures to help your trees better resist pests
- Identify 4 key times to call a certified arborist for help
The 8 Most Common Tree Pests
Ranking from most destructive to least destructive using kill rate and rate of spread.
1. Emerald Ash Borer
Emerald Ash Borer is a green jewel beetle and is one of the most destructive tree pests in Texas. An Emerald Ash Borer will kill an ash tree within 2-3 years.
How to Spot the Problem:
- Tiny D-shaped exit holes in the bark (about the size of a pencil eraser)
- Wavy S-shaped galleries beneath the bark (visible when the bark is peeled back)
- Dead twigs, usually at the top of the tree, growing downward
- A large number of woodpeckers pecking at the trunk or branches.
Which trees can get sick: All ash trees can be affected by this insect.
Control: If you see signs of the Emerald Ash Borer on an ash tree, contact us immediately.
2. Southern Pine Beetle (SPB)
Native to Texas, the Southern Pine Beetle (SPB) attacks pine trees and can kill entire stands of pine trees, particularly during drought years.
How to Identify:
- Popcorn-looking pitch tubes (hardened blobs of resin) on the trunk of the tree
- Reddish brown boring dust in bark crevices
- Needles change from green to yellow to red-brown
- Sounds hollow when knocking on the bark
Species affected: Loblolly and Shortleaf pines are the most susceptible but any pine species is at risk.
SPB attacks are mass attacks – meaning that the beetles attack tree after tree as they move through the pine stand. Quick detection and rapid response are necessary to save the rest of the stand.
3. Twig Girdlers
Twig Girdlers are long-horned beetles and the females make circular cuts on twigs to drop their eggs.
Identifying signs:
- Branches and twigs cut cleanly as if they were pruned
- Brown dead twigs on or under trees
- Most active from late summer to fall
Species at risk: Pecan, Oak, Elm, Mesquite, Hackberry and 15+ more.
Twig girdlers are unsightly but will not damage the health of mature trees. We recommend gathering and disposing of fallen twigs that contain larvae before they hatch in the spring.
4. Aphids
Green or black pear-shaped sap-sucking insects that gather on new growth and the undersides of leaves.
Look for:
- Yellow or curling leaves
- Sticky, translucent honeydew covering leaves and surfaces below
- Black sooty mold on honeydew deposits
- Clusters of aphids on new growth
Susceptible varieties: Aphids will feed on almost all tree and shrub species.
Tree health is rarely affected by aphids, but they can damage young trees or cause cosmetic damage to established trees. Sooty mold can decrease photosynthesis when it extensively covers leaf surfaces.
5. Scale Insects
Scale insects look like small bumps on branches, leaves, and bark that do not move and are often mistaken for disease or abnormal growth.
What to look for:
- Tiny brown, gray, white, or pink bumps that don’t move when touched
- Cottony or waxy patches on branches and bark
- Stunted growth and yellowing leaves
- Honeydew and sooty mold
Common hosts: Crape Myrtle Bark Scale feeds on Crepe Myrtles, while general scale insects target Oak, Pecan, Elm, and 20+ other species.
6. Bagworms
Bagworms are the baby form of a moth and construct a portable silk case (bag) made from silk and leaves, which is carried around as they feed.
Signs and Identification
- Small pinecone-shaped bags that are 1-2 inches long
- Bags made of silk and fragments of the host plant
- Trees rapidly losing large numbers of leaves
Favorite Host Plants: Bagworms have a strong preference for Junipers, Arborvitae, and Cedar trees but will feed on other species as well.
Controlling and Management: Bagworms can be physically removed by hand and disposed of when less than 1 inch in length.
7. Fall Webworms
Fall webworms feed in large, noticeable nests of silk webbing that cover the ends of branches.
Look for:
- Clumps of white silk webbing covering the entire ends of branches
- Webs appearing in late summer and into fall
- Skeletonized leaves inside the webs
- Multiple (50-200+) webs on a single tree
Common hosts: Pecan, Oak, Elm, Mulberry, and most other deciduous trees.
Fall webworms are a cosmetic issue in most cases and rarely endanger the health of mature trees despite massive defoliation. Severely affected branches can be pruned out for cosmetic reasons. Never burn webs on a tree – the fire damage is much worse than webworm damage.
8. Texas Leaf Cutting Ants
Large, reddish-brown ants (1/8 to ½ inch long) that carry semicircular leaf pieces back to underground nests where they farm fungus gardens.
Look for:
- Ant trails carrying semicircular leaf fragments
- Large underground nest mounds a few feet across
- Rapid defoliation of several plant species
- Large reddish-brown worker ants
Common hosts: Trees, shrubs, roses, and many garden plants of all species.
Leaf cutting ants defoliate young trees quickly. Mature trees are not killed but instead are gradually weakened by repeated cutting of many species each year. The ants are only interested in the fungus they farm, not the leaves themselves.
Signs of Infestation: What to Look For
- Holes and tunnels: Insects bore round or D-shaped holes through bark and tunnels underneath it
- Sticky honeydew: Many insects excrete a sweet, sticky honeydew that drips onto leaves and soil beneath the tree.
- Odd growths: Fuzzy, waxy, or hard growths on branches and bark are most likely scale insects (small bugs).
- Webs or sacks: Silky webs or small sacks on trees are evidence of webworms or bagworms, respectively.
- Wood dust: Small piles of wood dust at the base of a tree indicate boring insects are tunneling inside.
- Premature leaf drop: If leaves fall off or change color before the usual time, it may indicate insects are damaging the tree.
5 Ways to Prevent Tree Pest Problems
The best way to prevent bugs from attacking your trees is to keep your trees healthy. Below are some tips for tree health.
Water properly in dry conditions: Here in Texas we go a while without rain. We don’t recommend sprinkling a little bit of water every day. Try to water your trees heavily 1-2 times per month. More often, it hasn’t rained in a while.
Use a light hand with fertilizer: Excessive fertilization promotes soft, succulent growth that is more susceptible to insect attack. Soil test before fertilizing to learn exactly what the tree needs.
Protect the trunk: Your tree can take a beating from lawn mowers and weed wackers. These tools can wound your tree and make it easy for insects to harm them. Another tip is to lay mulch 3-4 inches away from the trunk of your tree.
Prune correctly: Remove dead or diseased branches at the best time of year for that tree. Avoid Oak pruning in the spring and early summer (Oak wilt risk) and Elm pruning when beetles are flying.
Apply dormant oil sprays: oil kills overwintering eggs when applied in the late fall or early spring. Oils can also reduce populations of aphids and scale insects by as much as 90%.
When to Call a Certified Arborist to Treat Your Tree for Bugs
Contact certified arborists when:
Suspect borer infestation: EAB and SPB kill trees quickly. Treatment needs to be done at a very specific time to be effective and is best left to professionals.
Visible decline: Visible symptoms suggest the pest has had time to spread, and now there’s a serious problem. Don’t wait until it’s too late. Professional treatment may save the tree.
If you have a lot of trees that need treatment: A tree doctor will be able to spot the issue quickly and will have the equipment on hand to handle your tree with care.
If you’re not sure what insect it is: The wrong tree bug treatment will not help. A tree doctor can identify what pest is causing the issue so you don’t waste time and money on a treatment that isn’t going to work.
Protect Your Texas Trees with Mighty Tree Care
There are 3 main types of pests that affect trees in Texas: borers, sap suckers and defoliators. Borers (considered urgent) tunnel into and threaten the structure of the tree. Sap suckers (annoying but rarely lethal) drain tree sap from leaves and stems. Leaf-eating bugs (ugly but usually not deadly): Some insects will defoliate trees, leaving them leafless and unsightly, but generally not dead.
To catch these problems earlier, we recommend inspecting your trees regularly. A healthy tree can defend itself if it’s taken care of, but it’s vulnerable to pests if they’re neglected.
Contact Mighty Tree Care immediately if you spot boring insects in your tree or if your tree appears to be rapidly becoming diseased. Our tree doctors will come out and examine your trees, diagnose the problem, and provide a solution to nip the issue in the bud before it becomes a major one. Remember, early detection is the key to saving your trees before it’s too late!