Mesquite Twig Girdler (Oncideres rhodosticta) Incision
Velcro bug, el Torrito, Mesquite Twig Girdler, or Oncideres rhodosticta: the most abundant beetle in Arizona after the monsoon
You can see the perfectly circular cut made by the beetle at the tip of our naturalist Anne's finger. The cut prevents sap from flowing beyond that cut. The beetle lays it's eggs below the surface of the twig just beyond the cut so flowing sap does not encase the eggs in sap. The twig beyond the cut dies. This doesn't harm the tree which receives "a gentle pruning," in the words of Anne, our naturalist on this Sabino Canyon Nature Walk.
This is my sixth nature walk. The environment changes each week. Some things are pointed out each time. That is wonderful for me because it helps me to become more familiar with the habitat and its inhabitants. I try to read more about what we have seen, in addition to entry in the Naturalist's Guide To Sabino Canyon.
For example, here is more information on the Mesquite Twig Girdler Beetle:
Margarethe Brummermann writes:
"Like most adult longhorn beetles, adult O. rhodosticta feed on plant material. The chew leaf buds and the green bark of fresh mesquite twigs. Sometimes the nightly feeding frenzy of the beetles leaves the ground under a tree littered with chewed-off leaf-matter and twigs.
"Life cycle of the Mesquite Twig Girdler Oncideres rhodosticta :
Adult twig girdlers eclose from late August to early November.
Towards the end of our summer monsoons, the female beetles create the most well-recognized sign of O. rhodosticta 'infestation' when they prepare a nursery for their off-spring:
Dead or dying finger-thick mesquite (or sometimes Acacia) branches that stay connected to the tree and usually carry the wilted, bleached leaves like flags into the winter months.
The common name, Mesquite Twig Girdler, hints at the story: Before she lays her eggs, the female chews a precise, complete circle around a finger-thick twigs. This task can take up to two days. She bites all the way through the Xylem and Phloem of the bark and thus disconnects the branch from its water source. Then she chews a separate shallow grove for each of about 8 eggs in the distal, dying part of the branch. The larvae will hatch and live in the wood until they are grown, pupate, go through their metamorphosis and hatch as adult beetles by the end of the next monsoon season to restart the cycle.
Most wood boring insects attack sick, injured or dead wood rather than a living tree. This is partly because of the ability of healthy trees to fight intruders by ‘gumming’ them up, that is by drowning and encapsulating them in sticky resin rich tree sap. So the female Mesquite Girdler protects her eggs by cutting off the tree’s defense lines. A glob of fresh tree sap often hangs from the girdling cut: the trees attempt to fight the parasite which didn't reach its target. The nursery that the longhorn beetle creates is so attractive that several other insect species infest the girdled branches. I have raised more wasps, buprestids, anobiids, bostrichids and dermestids from collected girdled branches than O. rhodosticta adults.
Of course, the pruning-activity of the beetles comes as a cost to the trees. They lose the carbohydrates stored in the girdled twigs and a part of their photosynthesis-machinery. However, a study of Texas Tech. University showed no conclusive results concerning the use of the beetles to control the mesquite tree overpopulation of the grass lands. Natural girdler infestation can cause an over 30% reduction of the canopy, which does not seem to harm the mesquite trees but instead to induce healthy re-growth in the following season."
arizonabeetlesbugsbirdsandmore.blogspot.com/2010/09/velcr...
Also see:
___________________________________________
As an avid gardner, I'm always looking for gardening hints…;)) I have mesquite trees in my gardens. Here's an interesting and useful article:
When Can You Trim a New Mesquite Tree?
www.ehow.com/info_12312122_can-trim-new-mesquite-tree.html
And
Desert Harvesters Guide to Pruning Native Sonoran-Desert Multi-Trunk Trees:
www.desertharvesters.org/native-tree-information/a-guide-...
IMG_2073 - Version 2
Mesquite Twig Girdler (Oncideres rhodosticta) Incision
Velcro bug, el Torrito, Mesquite Twig Girdler, or Oncideres rhodosticta: the most abundant beetle in Arizona after the monsoon
You can see the perfectly circular cut made by the beetle at the tip of our naturalist Anne's finger. The cut prevents sap from flowing beyond that cut. The beetle lays it's eggs below the surface of the twig just beyond the cut so flowing sap does not encase the eggs in sap. The twig beyond the cut dies. This doesn't harm the tree which receives "a gentle pruning," in the words of Anne, our naturalist on this Sabino Canyon Nature Walk.
This is my sixth nature walk. The environment changes each week. Some things are pointed out each time. That is wonderful for me because it helps me to become more familiar with the habitat and its inhabitants. I try to read more about what we have seen, in addition to entry in the Naturalist's Guide To Sabino Canyon.
For example, here is more information on the Mesquite Twig Girdler Beetle:
Margarethe Brummermann writes:
"Like most adult longhorn beetles, adult O. rhodosticta feed on plant material. The chew leaf buds and the green bark of fresh mesquite twigs. Sometimes the nightly feeding frenzy of the beetles leaves the ground under a tree littered with chewed-off leaf-matter and twigs.
"Life cycle of the Mesquite Twig Girdler Oncideres rhodosticta :
Adult twig girdlers eclose from late August to early November.
Towards the end of our summer monsoons, the female beetles create the most well-recognized sign of O. rhodosticta 'infestation' when they prepare a nursery for their off-spring:
Dead or dying finger-thick mesquite (or sometimes Acacia) branches that stay connected to the tree and usually carry the wilted, bleached leaves like flags into the winter months.
The common name, Mesquite Twig Girdler, hints at the story: Before she lays her eggs, the female chews a precise, complete circle around a finger-thick twigs. This task can take up to two days. She bites all the way through the Xylem and Phloem of the bark and thus disconnects the branch from its water source. Then she chews a separate shallow grove for each of about 8 eggs in the distal, dying part of the branch. The larvae will hatch and live in the wood until they are grown, pupate, go through their metamorphosis and hatch as adult beetles by the end of the next monsoon season to restart the cycle.
Most wood boring insects attack sick, injured or dead wood rather than a living tree. This is partly because of the ability of healthy trees to fight intruders by ‘gumming’ them up, that is by drowning and encapsulating them in sticky resin rich tree sap. So the female Mesquite Girdler protects her eggs by cutting off the tree’s defense lines. A glob of fresh tree sap often hangs from the girdling cut: the trees attempt to fight the parasite which didn't reach its target. The nursery that the longhorn beetle creates is so attractive that several other insect species infest the girdled branches. I have raised more wasps, buprestids, anobiids, bostrichids and dermestids from collected girdled branches than O. rhodosticta adults.
Of course, the pruning-activity of the beetles comes as a cost to the trees. They lose the carbohydrates stored in the girdled twigs and a part of their photosynthesis-machinery. However, a study of Texas Tech. University showed no conclusive results concerning the use of the beetles to control the mesquite tree overpopulation of the grass lands. Natural girdler infestation can cause an over 30% reduction of the canopy, which does not seem to harm the mesquite trees but instead to induce healthy re-growth in the following season."
arizonabeetlesbugsbirdsandmore.blogspot.com/2010/09/velcr...
Also see:
___________________________________________
As an avid gardner, I'm always looking for gardening hints…;)) I have mesquite trees in my gardens. Here's an interesting and useful article:
When Can You Trim a New Mesquite Tree?
www.ehow.com/info_12312122_can-trim-new-mesquite-tree.html
And
Desert Harvesters Guide to Pruning Native Sonoran-Desert Multi-Trunk Trees:
www.desertharvesters.org/native-tree-information/a-guide-...
IMG_2073 - Version 2