Insect and Borer Control

By Don Williams, the Tree Wizard

[Updated article coming soon.]

In the 1980s time frame I would do on site demonstrations showing the effects of tree trunk injection treatments for insects and borers. My goal was to get tree spraying companies to cease spraying trees because of chemical trespass issues with the remaining chemical residual danger to children and pets. Other companies were still spraying trees (and still do) with chemical being blown by the winds throughout the neighborhood. This is called chemical trespass and is illegal. It is incomprehensible to me why tree sprayers still spray trees. Using a hand sprayer with low pressure with large droplets on crepe myrtles, hedges, shrubs is acceptable as mist is controlled. ​

There are always some types of trees with more difficult to treat issues. We solved those problems. Several examples to follow are American elm, live oaks, ash trees. ​

American elm trees get elm bark beetles that will annually defoliate their leaves if not treated. These are hard shelled, small and black and, upon hatching, will almost cover the tree trunk with small dark beetles. During those years many would attempt insect control with high pressure sprayers where the nozzle would be pointed upwards towards the top of tree. This would kill a few, but many of the beetles where in the tops of trees where sprays couldn’t reach and/or under the very thick tree bark, unreachable by the spray. ​

I was the only tree man of that time using trunk treatment micro injection to kill insects. The treatment was available to all, but some relied on the old spraying method they were using. Most likely, it was because a different license was required which I had and others did not take the time to get. I have recently changed all my licenses to TDA (Texas Department of Agriculture) as I don’t need the same usage license from two different Texas agencies. ​

We use micro trunk treatment injections with an 11/64 inch diameter drill bit, drilled half inch deep at the base of tree, with treatment units usually 8-9 inches apart. The chemical travels throughout the sap stream, killing what is under the bark and what eats on the leaves. Insects that are not eating on the leaves or passing through the sapwood are desirable insects and not affected. Tree treatment trunk injections kills targeted insects not desirable insects. The trunk injection treatment will last for several months even killing most/all of the second crop of insects that year. We set up our operations on tree treatments this way to make sure we solve your tree issues. American elms have large leaves and the sap flows faster in these types of trees. Most treatments take a few hours or over night for results because of sap flow difference in smaller leaf trees. ​

One of the more difficult insects or beetles to control was the American Elm Bark Beetle. One example was a very large American Elm tree in the front yard covering the roof and the concrete driveway below. I believe it took about 14 micro units to treat. Ten to fifteen minutes after treatment, it appeared black rain was falling and you could hear thousands of hard shell beetles dropping onto the concrete driveway below. The treatment killed all the beetles plus the eggs when they hatched weeks later and they did not come back the following year. If American elm trees were concentrated and some left untreated within an area there would be a new infestation annually. ​

As some American elms in this area may be some blocks or miles apart the beetles may not return to that tree in the near future. American elms are great trees. They grow large and fast.

The fibers in elms are stronger than most trees. With most trees, they need to be pruned regularly to maintain the proper structure within this fast growing tree. When they are extremely large, some cables and/or bolts may need to be installed to prevent improperly pruned limbs from splitting off the tree, which can happen with many trees. ​

America elms in other parts of the country had a similar vascular disease as oak wilt, which is called Dutch elm disease. The exact trunk treatment injection we used since 1974 was originally used to control the same elm bark beetles spreading the disease. They did control the spread of this disease on golf courses and other selected valuable areas by controlling the elm bark beetle. It did take an annual treatment for control, but was worth keeping the trees in desirable areas. Similar treatments are used to assist for defense against oak wilt by controlling the insect that spreads the disease. There are many vectors concerning oak wilt which will be discuss in other articles. NOTE: In the forest the borers will kill the trees. The dead trees fuel the forest fires and kills the infestation which created the cycle. The forest regrows over time to repeat the cycle. ​

This elm bark beetle issue concerning the dutch elm disease is similar to the imported long horn beetle in the north eastern forest. They can control selected important areas and residential areas, but the other millions of trees needing control were allowed to die most likely because of budgetary issues. ​


Aphids are the small soft insects on the back of tree leaves. The leaves are sticky and this drops onto cars and driveways. It’s a mess and difficult to wash off. This sticky substance is actually aphid poop. The same micro trunk injection treatment described earlier will kill the aphids now and their eggs when they hatch. On trees with smaller leaves the insects will die a little more slowly as sap moves slower. I usually tell customers I can treat a tree at 5 pm and they will mostly be dead by 10 am the following day. I have noticed one or two still slowly moving. They must have just hatched or more recently eaten the leaves than the aphids that already died. ​


A friend named Frank who we fished with in Corpus Christi had so many grackles on his ash trees that it was impossible to park under. Every morning the entire car and windows would be 1/2 inch thick in Grackle poop. At about 3 pm we treated the ash trees for aphids so they would not have anything to eat on. The next morning the grackles were completely gone and have not returned in 16 years. This broke their psychological habit of roosting there. His two ash trees did not have any more grackles, but the neighbors’ trees did. This was not a grackle targeted treatment. The grackle control apparently was the side benefit of the aphid treatment. ​


Web worms are difficult to treat with high pressure spraying and you have the risk of chemical trespass. The webbing is thick and strong and the spray sometimes does not penetrate the webs. Micro trunk injection puts the chemical into the sap stream and will kill web worms when they eat the leaves and will be effective for months. ​ BORERS ASH TREE BORERS, INCLUDING THE EMERALD ASH BORER, ARE CONTROLLABLE IF TREATED ANNUALLY AND TREATMENT STARTS WHILE TREE DAMAGE IS MINOR THE CHEMICAL DOESN’T CARE IF IT IS AN ASH TREE BORER OR AN EMERALD ASH BORER, IT WILL KILL THEM. FOR ALL INSECTS AND BORERS, WE REFER TO MICRO TRUNK TREATMENT INJECTION AS THE EIGHTH WONDER OF THE WORLD. ALL IT TAKES FOR SUCCESS IS FOR THEM TO EAT THE LEAVES OR ENTER INTO THE SAP STREAM. ​ Ash trees have been dying for years from borers only because people do not know treatment is available. There are thousands of mature 24-50 inch trunk diameter ash trees that just need treatment to continue to live. If you have an older large ash tree, treat it annually or lose it. Ash trees are good trees that need some care. Some think ash trees have a 25 year life span. If you take care of it, I know they will live past 75 years. A tree does not die of old age. Annually it grows a new ring of cambium, which enlarges the tree with a new layer of wood. This annual process creates a new tree outwardly. It is the borers eating on the new cambium layer that cause destruction of the new tree growth. The issues trees have determine their lifetime. Improper pruning creates openings in trees allowing bacteria to enter and this is the beginning of inner rot. ​


When President Bill Clinton mentioned they did not know how to control the imported long horn beetle that was destroying the forest trees in the northeast, I wrote to him explaining the process. In a few months I read in the newspaper that they had decided to use the same brand micro trunk injection treatment which I had advised. ​ He was also advised to treat the trees and check them every six months. When they stated in newspaper what they would use, they printed the same exact statement I had made to him, saying they would treat now and check every six months. Since 1974, we were locally using the same brand micro trunk injection treatment as was used in the Northeastern forest. Over 50 of their county agents approved. ​


The Emerald Ash Borer is just another borer, but new to Central Texas areas. This has been talked about for years and a few of them have arrived in this area. The stories are scary when they describe how they destroy all ash trees. These will kill ash trees by eating the area just under the bark. They are not a super borer with chemical immunity. ​ Ash trees already have a natural enemy in borers that eat under the bark causing the bark to fall off a couple of years later. This is usually the time when you realized you had borers. They have been eating a couple of years doing unseen damage and now you call me. I treat the ash tree with micro trunk injection treatment and all borers will be dead in a day or two.

The damage done can be extensive and may have long lasting effects on trees, causing it to struggle to maybe survive and/or to later die or to die shortly after discovery of the damage. If you have an Ash tree the sooner you call the better results you will have. Treatment to prevent is best. All trees also need deep water in dry hot summers or they will decline. Ash borers are common and completely controllable. Tree owners will watch an ash tree or any tree decline for years hoping it recovers, but it won’t. The years-long procrastinating only allows the borers to cause more extensive, avoidable damage. I actually like Arizona ash trees. They grow reasonably large and fast and, if receiving proper care, they will have a good appearance and exceed a 75 year life span. They have a reputation of living 25 years and this is true if the tree is not cared for properly, as is the case for other trees. These trees do have some preventable issues and they do need proper pruning more often as they grow fast. (Never top an ash tree, or any tree). They are susceptible to all kinds of borers. If you have a nice big Arizona ash tree it should be treated with an annual borer treatment which will prevent any borer damage including the Emerald Ash Borer. At this time most 30-40 year old ash trees look bad with pieces of bark falling off from borer damage. ​

We have treated ash tree borers for over 30 years. It’s easy, simple and effective. Tree owners need to call if they have one so we can look at it and keep it healthy. Ash trees are not the only tree we treat for borers, but ash trees seem to always have borers to some degree. There is no safe number of borers as borer damage is progressive. ​ When using this treatment for either insects or borers it kills both in the process. If you are treating for insects you also get borer protection. If you are treating for borers you also have insect protection. Treat all your large ash trees annually before they become damaged and you should eliminate the main problem which kills them. ​


The method of treatment is the same as others. It is best to pretreat or treat at first signs of damage. Usually damage is fast so pretreat yearly and this covers all insects and borers as described elsewhere. ​


One of the worst things to happen to a live oak tree is when the massive insect hatch corresponds with leaf bud break. Nature intends for buds to break out and leaves to mature and toughen a little before the massive insect hatch occurs. If the massive insect hatch appears when buds are opening and the leaves are tender, then the insects will destroy the buds and new leaves. We have to treat the tree to break this cycle so leaves can develop. A declining or weak tree may have a late bud break and this corresponds to the time of insect hatch. This is very damaging to live oaks. ​ In the early 1980’s many live oaks were not leafing out in March and April.

This was the same time period when the media spoke often about Oak Wilt. If an oak tree failed to leaf out it was treated for oak wilt. I received an oak wilt call where others were also called to consult. By that time the customer was price bidding for oak wilt treatment. We used a 10 power magnifying glass to view the buds and told him it was not Oak Wilt. Tree company owners and home owners have a false perception at times (they still do) and this is hard to overcome. ​

Sometimes when the live oak tree begins to bud but then fails to leaf out it may be an insect that eats the buds off the tree. The tree will not leaf out because the buds are being eaten off. In time the insects may pass by, but damage has already occurred with fewer leaves than normal. Use a 10 power magnifier to look at buds and you will see the chew marks. Simply use the same treatment discussed in this article and in six weeks the tree will develop new buds and leaves will soon appear. ​ We got the job to treat for the bud destroying insects and treated them. I took pictures when the tree was treated and had no leaves. Then I took pictures 6 weeks later when tree was full of leaves again. It was a long time ago and pictures were on a floppy disc. What happened to the other three clueless tree men who thought the tree had oak wilt? They are still giving estimates to treat trees for oak wilt. Many times it is not wilt as there are many issues an oak can have. I will try to cover some, but there are many more issues which I will describe later.

TO REVIEW, any tree can get insects or borers and we treat them the same way. Just too many trees to mention. ​


There are more than 700 species of gall-forming insects and nearly 80% form galls on oaks. Galls are growth deformities caused by the larvae living within. Live oaks are often attacked by a group of tiny flying wasp called gall makers. In the spring and summer tiny male and female wasps emerge from the galls. The female wasp then lay eggs on the larger under side vein of the leaf. They develop galls again from the larvae that hatch within and in the process they develop more encircling galls. ​

The wasp are/seldom seen and spraying will not control them. It may take one to three years for the larvae living in the woody twig galls to mature so you can treat anytime for control. This is why we use a trunk injection insecticide treatment to kill the larvae within the gall. Treatment last for months and will kill any insect, gall or borer with the treatment. The gall deformity visually does not go away for a few years, but the larvae inside are dead and cannot cause continuing injury or damage to tree. ​

For control of galls on your trees they must be treated annually. If not treated the infestation and damage multiples annually. The galls will eventually damage and can kill some smaller limbs. There are beneficial side results as the treatment will also control all leaf sucking or chewing insects and borers. Object of treatment is to kill the grub within the gall to cease the damage from that gall.

There is no treatment for the wasp that lays the egg. ​ The female wasp flies where she wants, gets blown about by the wind to all areas already infected, and areas yet to be infected. Each wasp can have many offspring over the years and within a few more years most/all live oaks will be infected. ​ We first saw this in the 1980 time frame in Temple. I received a call about a twelve inch diameter trunk live oak tree with dead, three foot long tips all around. I noticed where the limbs begin dying there was a gall that was growing around and into the limbs. Areas on the smaller limbs past the gall were dead. The gall encircles smaller limbs and eventually the growth will cut off the sap flow, killing the limb past the gall.

It was reported at the time that galls were imported to the area from nursery trees as it was usually only the young nursery trees that would have them. Later it was confirm this is where they originated. I would say they just originated somewhere, but concentrated around large areas of young tender oaks. Many live oaks being planted today are already infected with this gall. If your recently planted live oak has this issue, it would be best to refuse delivery. Even if you replaced the new live oak tree, it will also have this infestation in a few years because of the wasp. Over 40% of mature live oaks now have this gall. This must be treated annually as many live oaks presently have widespread infestation.

This issue will not go away and annually multiples. Damage can be extensive if not treated on an annual basis. The object of treatment is to minimize the numbers and damage caused by the galls on your personal trees, as you will not get rid of the wasp that lays the eggs. As a note, the small hard bb size galls that almost cover the entire back of live oak leaves are not a notable health issue. They hatch and fly away. The 3/4 to 1 inch round hard shell ball or gall with fuzz inside, that barely attaches to leaves and limbs, is not a notable health issue. They hatch and fly away. ​

More information to come.

Have any questions about this tree topic? Give Big Country Trees a call at (512)983-4148.