2. Quest for the Honey Mesquite Borer,Megacyllene robusta Linsley and Chemsak

                               Collection notes.                                                                                                                                                         UPDATED: Friday, October 19, 2012
Tues - Thurs, September 25-27, 2012. 7:00-9:30 pm
Locality #1. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4166 ft. elevation

(4) M. antennata - 1 male, 3 females
Remarks. Collected at 40w blacklight.
Apparently a common species in southeast Arizona where it is associated with dead Prosopis glandulosa (Honey Mesquite).

I have taken it as early as March, then sporadically through summer, into early fall. Although circumstantial, it seems to fly early in the evening.


Saturday, October 06, 2012. 6:00 pm
Locality #1. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4166 ft. elevation

(1) M. robusta - female
Remarks. Found at base of store front window/entrance. Specimen dead but still pliable.






Sunday, October 07, 2012.
Locality #1. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4166 ft. elevation

(3) M. robusta - 2 males, 1 female
Remarks. Beetles were found in two of five traps. Although evidence is circumstantial as to a bait preference, beetles were in traps baited with brown sugar/beer mix. Nothing in other traps baited with molasses/beer.

Two of the beetles were alive and active indicating they had flown that morning.

Also in the traps, Euphoria sepulchralis rufina (3), and Cotinus nitida (1, weird bluish color).

Monday, October 08, 2012. 2:30 pm
Locality #1. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4166 ft. elevation

(3) M. robusta - 1 male, 2 females
Remarks. Two females in brown sugar/beer trap. A third, male, flew in and alighted on a nearby Mesquite branch while I was filling the trap. Beetles were in, or near, same brown sugar/beer traps as on October 7th.

I moved one unproductive molasses trap, thus far anyway, closer to the more attractive brown sugar traps.

                     Also in the traps, Euphoria sepulchralis rufina (1).

Tuesday, October 09, 2012. 2:30 pm
Locality #1. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4166 ft. elevation

(4) M. robusta - 2 males, 2 females
Remarks. Beetles were in both brown sugar (3) and molasses (1) baited traps.

Also in a brown sugar trap, Euphoria sepulchralis rufina (1).

I ponder why one particular brown sugar/beer trap is the most productive, consistently attracting beetles?

Consider, it hangs on the south edge of a large stand of 10-14 foot mesquites and is exposed to full sun for most of the day - from early morning to late afternoon ( i.e., during peak hours of M. robusta activity). Is it possible that solar radiation heats the fermenting trap contents making them more aromatic and attractive? The other traps are, more or less, hung in filtered sunlight being placed within the mesquite canopy. Or, as Occam's Razor decrees: "All things being equal, the simplest solution tends to be the best one,"  ... the trap is fortuitously placed in a good location.

Thursday, October 11, 2012. 1:00 pm
Locality #2. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4185 ft. elevation

(20) M. robusta - will sort to gender upon curating.
Remarks. "I love the smell of fermenting brown sugar-beer in the morning.
It smells like ... victory."

I hadn't had an opportunity to check trap contents since their deployment on October 4. Three traps, still contained about an inch of bait mix.

Also in the traps, Megacyllene antennata (1), Euphoria sepulchralis rufina (3), Plionoma suturalis (4), Sphaenothecus bivittata (10), Chrysobothris octocola (3).

Friday, October 19, 2012. 1:00 pm
Locality #2. Cochise Co., Sulphur Springs Valley.
Upper Sonoran Mesquite/Grassland   4185 ft. elevation

( -- ) M. robusta
Remarks. Individual beetles and mating pairs were still active on smaller (± 2-6 inch diameter) limbs of Prosopis glandulosa. I had removed all the traps earlier in the week. This trip was for investigative purposes as I was hoping to document evidence of beetle emergence. I asked Fred Skillman, Longhorn Ranch, Dragoon Mountains, to join me.

(Above). Arrow indicates area of Propsopis limb where emergence holes were observed. There were several similar areas throughout this tree but these were the most convenient to photograph. I lack irrefutable evidence indicating that these are actual M. robusta emergence holes, however, adults were actively flying and crawling over this area while I was present.


(Left). Closeup of emergence holes (± 0.25 inch dia.) (arrows) that had just begun to exude sap indicating very recent emergence.

I cannot explain the other slight damage to this particular area.



(Below). Holes sealed by sap flow several days after beetle emergence.

Note diameter of limb.

                                                  © Delbert La Rue 2012. All Rights Reserved.