Q. I am having a problem with a bug infesting my trees. I
haven’t identified the pest but I wanted to first ask how did this infestation
happen or if it’s common in the Vegas Valley and second how is the cycle of
reproduction of this bug?
haven’t identified the pest but I wanted to first ask how did this infestation
happen or if it’s common in the Vegas Valley and second how is the cycle of
reproduction of this bug?
 |
| Flat headed borer taken from tree |
A. Thanks for sending the pictures. You have taken the
larva or “worms” of a beetle from this tree. These larva or worms are called
borers. You can notice the flattened head of this worm so it is commonly called
a flat-headed borer.
larva or “worms” of a beetle from this tree. These larva or worms are called
borers. You can notice the flattened head of this worm so it is commonly called
a flat-headed borer.
I think it is either the Flatheaded Apple Tree Borer or
Pacific Flat Headed Borer. I have been following this insect and its damage for
many years in this valley. The adult of this “worm” is a beetle about ½ inch
long.
Pacific Flat Headed Borer. I have been following this insect and its damage for
many years in this valley. The adult of this “worm” is a beetle about ½ inch
long.
 |
| Borer damage on Apple when first seen |
The adult female beetle flies around searching for a mate
so that it can lay its eggs. It finds a male by “smelling” the male’s pheromone
it releases. Most likely this happens any time from about April through August.
Once the female mates and prepares to lay eggs, she searches for suitable woody
plants that are injured or unhealthy.
so that it can lay its eggs. It finds a male by “smelling” the male’s pheromone
it releases. Most likely this happens any time from about April through August.
Once the female mates and prepares to lay eggs, she searches for suitable woody
plants that are injured or unhealthy.
 |
| Extensive borer damage to Locust |
This insect is part of an “ecological recycling cycle”
helping plants that are on the decline continue in a downward spiral toward death.
However, I have found this insect in trees that appear to be very healthy as
well. The female laden with fertilized eggs searches for suitable plants
through her sense of “smell”. One of the “smells” she identifies is damage of plants
from sunburn.
helping plants that are on the decline continue in a downward spiral toward death.
However, I have found this insect in trees that appear to be very healthy as
well. The female laden with fertilized eggs searches for suitable plants
through her sense of “smell”. One of the “smells” she identifies is damage of plants
from sunburn.
 |
| Discoloration and canker to scaffold limb because of sunburn |
High light intensity of our desert sun shining directly
on the bark of trees that are thin and don’t provide much insulation become
damaged and frequently die in the damaged area. Death in localized areas of the
branches and trunk of woody plants leaves behind a “canker” in the surface.
on the bark of trees that are thin and don’t provide much insulation become
damaged and frequently die in the damaged area. Death in localized areas of the
branches and trunk of woody plants leaves behind a “canker” in the surface.
 |
| Sunburn damage to Japanese blueberry |
The smells and aromas of damaged plants attract the egg-laying
of flat headed borers. She lays her eggs in the general vicinity of the damage
but on top of healthy tissue. The very tiny worm or larva “hatches” from this
egg and tunnels inside the plant just under the bark.
of flat headed borers. She lays her eggs in the general vicinity of the damage
but on top of healthy tissue. The very tiny worm or larva “hatches” from this
egg and tunnels inside the plant just under the bark.
 |
| Borer damage to flowering plum |
The wood just under the bark is laden with wet, sugary
juices from the plant which the flatheaded borer feeds upon. As this flat
headed borer feeds, it inches slowly forward just under the bark making a convoluted
tunnel. At the beginning of this tunnel is the flattened head and it leaves a
trail of sawdust and feces behind it as it feeds, moves and creates the tunnel.
I can sometimes push on the bark covering the surface of these tunnels and feel
a difference in the “hardness” of the stem.
juices from the plant which the flatheaded borer feeds upon. As this flat
headed borer feeds, it inches slowly forward just under the bark making a convoluted
tunnel. At the beginning of this tunnel is the flattened head and it leaves a
trail of sawdust and feces behind it as it feeds, moves and creates the tunnel.
I can sometimes push on the bark covering the surface of these tunnels and feel
a difference in the “hardness” of the stem.
 |
| Borer feeding under the bark inside peach tree limb |
This borer matures (pupates or turn into an adult) inside
the tree, exits the tree as a winged adult and searches for a mate to repeat the
lifecycle. Sometimes, if it is late in the season, this borer will tunnel into
the center of a limb to survive the winter and exit as an adult the following
spring.
the tree, exits the tree as a winged adult and searches for a mate to repeat the
lifecycle. Sometimes, if it is late in the season, this borer will tunnel into
the center of a limb to survive the winter and exit as an adult the following
spring.
 |
| Borer feeding just under the bark of peach tree limb |
Borers attack dozens of different trees and shrubs, many
in the Rose family. This includes many of our fruit trees, landscape plants in
the Rose family like Pyracantha and flowering plum and numerous others as well.
in the Rose family. This includes many of our fruit trees, landscape plants in
the Rose family like Pyracantha and flowering plum and numerous others as well.
What to do?
Dig it out. Using
a sharp and sanitized knife and laying it almost parallel with the branch, I
will cut away the surface of the branch to expose the tunneling. I will remove
all of the surface bark where there is damage. I will clean the surface bark all
away until I have nothing but fresh wood remaining. In this way, I expose the
tunneling and the source of protection for the boring insect. This exposes the
hiding place to predators of this soft bodied “worm”.
a sharp and sanitized knife and laying it almost parallel with the branch, I
will cut away the surface of the branch to expose the tunneling. I will remove
all of the surface bark where there is damage. I will clean the surface bark all
away until I have nothing but fresh wood remaining. In this way, I expose the
tunneling and the source of protection for the boring insect. This exposes the
hiding place to predators of this soft bodied “worm”.
 |
| Borer control using a sharp, sanitized knife |
Prune it out. If
the damage is more than 50% of the branch, I will remove the branch. If
removing the branch seems excessive, I will not remove it and give it a chance
to heal.
the damage is more than 50% of the branch, I will remove the branch. If
removing the branch seems excessive, I will not remove it and give it a chance
to heal.
Using insecticide.
In a last ditch effort I will use is a soil applied systemic insecticide. I never
use these on fruit bearing trees but on ornamentals only. I will use these on non-flowering
ornamentals because it is suspected that this systemic may impact bees visiting
the flowers. If the tree produces flowers, I time the application of the
insecticide just after the time of flowering.
In a last ditch effort I will use is a soil applied systemic insecticide. I never
use these on fruit bearing trees but on ornamentals only. I will use these on non-flowering
ornamentals because it is suspected that this systemic may impact bees visiting
the flowers. If the tree produces flowers, I time the application of the
insecticide just after the time of flowering.
 |
| One of the insecticides containing imidicloprid systemic for borer control |
Whitewash to
prevent. Whitewashing the upper surfaces of limbs, scaffold limbs and the
trunk reduces sunburn which should also reduce problems from borers. I make the
whitewash by mixing white latex paint 1:1 with water. You can also buy
commercial whitewash. In the old days, it was made from lime.
prevent. Whitewashing the upper surfaces of limbs, scaffold limbs and the
trunk reduces sunburn which should also reduce problems from borers. I make the
whitewash by mixing white latex paint 1:1 with water. You can also buy
commercial whitewash. In the old days, it was made from lime.
 |
| Whitewashing fruit trees in the winter to help prevent sunburn |