Friday, September 28, 2012

Quest for the Honey Mesquite Borer,
Megacyllene robusta Linsley and Chemsak,
using Fermenting Bait Traps

Because of their distinctive elytral patterns in striking black and yellow ("aposematism") or muted earth tones ("crypsis"), species of the longhorned beetle genus Megacyllene Casey (Cerambycidae: Cerambycinae: Clytini) are popular with collectors.

In past Fall seasons, I have serendipitously encountered a few specimens of this beautiful species, Megacyllene robusta Linsley & Chemsak:

Megacyllene robusta
Linsley and Chemsak
Admittedly, collecting longhorned beetles (Cerambycidae) isn't exactly my milieu. Yet, I challenged myself to make an effort to collect more of a series of this and other local Megacyllene this Fall. Hopefully, along the way, educating myself a little about their bionomics and distribution.

From my field notes of prior specimens (3), M. robusta adults were collected in late morning to early afternoon in late October. One locality, where three were found, is a service station surrounded by Mesquite/Grassland at 4166 feet elevation. One beetle was found on a sunny white wall and two others around the gas pump islands. Anecdotally, other species of Cerambycidae are known to be attracted to petroleum distillates. One that immediately comes to mind is the Banded Alder Borer, Rosalia funebris Motschulsky, which is commonly attracted to volatiles of freshly painted buildings and creosote-treated utility poles. Agreed, my inference that M. robusta may be similarly attracted is pure speculation.

In southeast Arizona, there are two other temporally and geographically sympatric species: M. antennata (White), and M. snowi snowi  (Casey).

Megacyllene antennata (White)
Fermenting bait traps have long been employed to collect a wide variety of beetles, especially scarabs and longhorns. Often they will attract species otherwise difficult to obtain. There are probably as many "bait" variations as there are insects attracted to them. A veritable cornucopia of ingredients, and combinations of, have been used including cheap wine, stale beer, vinegar, brown sugar, molasses, rotting fruit, and denatured alcohol. Essentially, the bait is poured into a plastic container, usually a 1-gallon juice or water jug, modified by cutting out large openings on the sides. Beetles, and other insects, attracted to the fermenting cocktail, enter the trap and drown in the liquid. (Above, my collection of raw "bait" materials).

Megacyllene snowi snowi (Casey)

For my efforts, I follow recipes and deployment tips suggested by colleagues, Missouri entomologist, Ted MacRae, author of the highly recommended Beetles in the Bush, and Cerambycid cognescenti, Fred Skillman, Longhorn Ranch, Dragoon Mountains, Arizona ...

Bring 12 oz. dark molasses or 1 lb. brown sugar and 12 oz. beer, wine, or similar libation up to 1 gal. with water. Add a packet of active dry baker’s yeast to get the fermentation process started and mix well.

For best results, hang the trap in a tree or suitable shrub along the edge of forest borders. Traps placed inside forests or stands of vegetation usually yield smaller amounts of beetles but possibly different species.

Add 1-quart of fresh liquid. Generally, it will take 2-3 days for the liquid to start fermenting and become attractive. It will remain so for about another week.

Check traps every 2-3 days by pouring the liquid bait through a fine kitchen strainer into another container. Reuse or replace the liquid as necessary. A can of beer or other alcoholic beverage can be used to replenish the liquid to a suitable level.

Collected specimens should be washed in water to remove bait residue.

Here then, are my trap localities in the Sulphur Springs Valley, Cochise County ...

Above. Locality 1. This is the locality mentioned above at 4166 feet elevation . The area has been slightly impacted by automobile and diesel traffic and light construction. The original expanse of mesquite has been curtailed to just a few acres. Five traps were placed here.

Below. Locality 2.  Upper Sonoran mesquite/grassland at 4185 feet elevation. The area is being utilized as open range. Three traps were placed here among many large stands of old growth mesquite.

NOTE: All sites are on private property. I have been granted permission to conduct my trapping activities by the property owners with the caveat that I keep specific locality information discreet.

Internet Resources
Megacyllene antennata, M. snowi snowi photos courtesy of  A Photographic Catalog of the  Cerambycidae of the New World 

© Delbert La Rue 2012. All Rights Reserved.


  1. Glad to see you've got the blog up and running again.

    This post whets my appetite to start up the bait traps again this coming spring. Here we can get Purpuricenus spp., Sarosthes fulminans, and Plinthocoelium suaveolens (along with grunt genera such as Orthosoma brunneum, Eburia quadrigeminata, and Elaphidion mucronatum). I've not done much bait trapping in the fall haven't thought to try it for Megacyllene (thinking M. decora would be nice to get in bait). Out west I'd love to encounter M. robusta and M. snowi sometime!

  2. Good to hear from you, Ted.

    I've been getting ones and twos of robusta and antennata every Fall, but set my mind to try trapping for the former this year.

    I'll keep you apprised.

    Thanks for your comment.

    Best wishes, ...

  3. Delbert, I got my traps out today. Six in all - hoping to encounter this species again! I have gotten only one in 6 years of effort and it resides at TCMC... I hope you get lots! This year I am trying cran/grape juice instead of a molasses mix. It worked well on our great plains trip this summer, so maybe it'll be the trick for robusta! Let us know how you do!

  4. Hey Paul, thanks for your comment.

    My prior attempts using brown sugar haven't been productive. Ted's recipe sounds like a good one, especially with the addition of beer (alcohol).

    My traps will be deployed later this week. I have three localities I want to work.

    Thanks for the encouragement and good luck to you too.

    Best wishes, ...

  5. Delbert, great success on your trapping! I am using a two chambered trap that can go for a month or more between checks. The first chamber that is open to the environment has anti freeze in it. There is a screen port from that chamber that goes in to the second chamber with the bait. The specimens stay cleaner, and I like them! Bad thing is I don't know if I'm getting anything or not... Ill check my traps later in the month! Take care, paul

  6. Hey, Paul.

    I'm familiar with your double-chamber trap style. Good suggestion though, as I still have Megacyllene snowi snowi to set traps for this week. The locality isn't local as the others, so I won't be able to check them as frequently. Hopefully, I can make it a Megacyllene hat trick.

    Since I am able to check my robusta traps fairly often, I haven't had any issues rinsing any of the bait from the beetles.

    So much for it being a rare species, eh?

    Thanks for your interest and comment. Keep me apprised of your trap efforts.

    Best wishes, ...

  7. Delbert, I got snowi in one of my bait traps up by Prescott last fall. We also raised a bunch from infested roots of NM locust from the Hualapais. The bait trap specimen was caught with a brown sugar bait in a two chamber trap. The robusta specimen from the Preserve was in a yellow bucket of fermenting molasses.

  8. Thanks, Paul,

    hmmm, "Yellow bucket" ???? Think that makes a difference? I know they work well trapping bups.

    My concern now is I hope I'm not too late for snowi. I won't get a chance to get to my locality until at least thurs ... erghhh ...

  9. Delbert, I ordered some yellow buckets to use for bait trapping (before I knew about the 2-chambered traps. I figured the color could do nothing but enhance their effectiveness!

  10. I had known about using yellow bowls as a technique for collecting bups - which I will have to try one of these summers.

    Thanks for your comment, Paul.

  11. Any M.robusta flying in the Sulphur Springs Valley yet? Too early?
    Was thinking about checking it out this season, I'm primarily there for tiger beetles in the monsoon.
    Aaron Chambers

    1. Aaron, sorry, missed your earlier comments.

      I haven't checked on the M. robusta this year although NOW is when they are active. From my experience, beginning of October is best.