I fear no weevil…

Megabaris quadriguttatus (Klug, 1829) | Corrientes Province, Argentina

…especially when they are as colorful as these! I found this mating pair ~60 km south of Corrientes, Argentina feeding on flowers of what I presume to be the goldenrod species Solidago chilensis (family Asteraceae). Here, as in North America, goldenrod blooms in profusion along the roadsides during late summer and fall wherever moisture is to be found, and also as in North America goldenrod here is an insect magnet. During my week exploring Corrientes and Chaco Provinces, I learned to stop whenever I spotted a stand of the distinctive yellow blossoms. I found several stands and was treated to a variety of beetles, flies, and other insects that I’ll show over the coming days, with these being among the most striking that I found.

Weevils themselves may not be anything to be afraid of; however, their taxonomy is downright terrifying (and this coming from a beetle man!). With more than 40,000 described species worldwide (and who knows how many still awaiting description), the family Curculionidae (“true” weevils) may be the largest in the animal kingdom. I don’t know why, given the distinctive and striking coloration of these individuals, but I punted early and asked my friend Henry Hespenheide (a buprestid man, but knows a thing or two about weevils) if he knew what these were. Henry must have also been scared, because he went straight to the top and forwarded the photos to weevil heavy-hitters Charles O’Brien and Jens Prena, both of whom quickly replied back with an ID of Megadaris quadriguttatus (Klug, 1829). The state of weevil bionomics seems to be as incomplete as their taxonomy, as I was unable to find even the most basic information about the distribution and biology of this species (keep in mind I’m in Argentina right now with no access to libraries). As far as I can tell this is a strictly Neotropical genus.

Of course, had I checked Curculionidae de Argentina I might have noticed the photo of this species right there on the front page. Fear does strange things to one’s confidence.

Copyright © Ted C. MacRae 2012

Sugarcane Weevil in Brazil

Sphenophorus levis (sugarcane weevil) | Conchal, Brazil.

Brazil is one of the world’s top producers of sugarcane, and they have the Middle East to thank for it.  While the U.S. was responding to the 1973 OPEC oil embargo by building bigger and bigger SUVs, Brazil aggressively developed an alternative fuels industry based on sugarcane for ethanol production.  Today, about half of Brazil’s sugarcane is milled for ethanol, yet despite this enough raw sugar is produced from the remaining sugarcane crop to rival India as the world’s top producer.

The large acreage devoted to sugarcane and tropical climate in which it is grown make Brazil’s crop especially vulnerable to infestation by insect pests—and there are many!  One of the most important is Sphenophorus levis (sugarcane weevil, or “bicudo da cana-de-açúcar”).  Larvae bore in the roots and crown of the plant, reducing biomass accumulation and longevity.  This feature of the insect’s biology also makes the larvae extraordinarily difficult to control, since they are largely protected from chemical applications by surrounding plant tissues.  This adult beetle was captured in a field trap placed in a sugarcane field in Conchal, approximately 175 km N of São Paulo.  The traps consist of split sugarcane stalks buried under debris within crop rows—adults are attracted to the cut surface of the stalks, where they congregate in numbers.  Traps are used not only to monitor beetle occurrence and abundance in fields, but also to provide a source of insects for laboratory rearing and evaluation of control test agents.

Copyright © Ted C. MacRae 2011

Bichos Argentinos #7 – Naupactus xanthographus

Naupactus xanthographus (South American fruit tree weevil) | Buenos Aires, Argentina

This weevil (family Curculionidae) was one of just a few beetle species that I encountered earlier this month in Buenos Aires, Argentina at La Reserva Ecológica Costanera Sur.  Weevils are, of course, one of the most taxonomically diverse and difficult groups of Coleoptera, making species IDs based purely on photographs quite challenging.  Nevertheless, I am reasonably confident that this individual represents Naupactus xanthographus, or the South American fruit tree weevil.  This name, it seems, has also been applied to a variety of other weevils photographed in South America and posted on the web, but the images I found at a few seemingly more authoratative sites give me confidence that this is the true N. xanthographus.  The narrow form suggests this individual is a male.

The genus, known collectively as “white-fringed weevils” is a large genus of exclusively Neotropical species - several of which have been introduced to North America (e.g., N. cervinus, Fuller rose beetle, and N. leucoloma) and which were, until recently, placed in a separate genus Graphognathus (Lanteri and Marvaldi 1995) (apparently the reduced humeri and lack of metathoracic wings were deemed insufficient for generic distinction).  In South America some of the species have become pests as well, with N. xanthographus becoming a problem for growers of grapes and other fruits and, thus, earning the names “burrito de la vid” (Chile) and “mulita de la vid” (Argentina) (both roughly translating to “grapevine little donkey”).

This was not an easy photograph to get – I found the weevil clinging to the underside of a leaf above my head.  It was impossible to photograph it in situ, so I moved it to a low twig away from other foliage where I could get the black background I desired.  Once moved, however, the weevil just never… stopped… crawling.  Snapping shots of an actively crawling insect is a crap shoot at best – not only are focus and framing more difficult to nail, but subjects photographed while moving almost always have one or two “bum” legs (lifted or cocked out of position).  A number of attempts were required to get a photo I was happy with (save for the slightly clipped antennal tip).  In such situations, I’ve found it best to track the beetle as it moves and as soon as the center focus point of the lens flashes take the shot.  This at least gives the best chance for nailing the focus, and then it’s simply a numbers game to get a shot with good framing and composition and all the body parts well placed.  Of course, I could’ve zoomed out and just cropped to perfection, but this feels a little like cheating – I’d rather put in the time and practice perfecting my game out in the field as much as possible.  An occasional clipped antenna, tarsus, etc. now will lead to better results down the line.

REFERENCE:

Lanteri, A. A. and A. E. Marvaldi. 1995. Graphognathus Buchanan a new synonym of Naupactus Dejean and systematics of the N. leucoloma species group (Coleoptera: Curculionidae). Coleopterists Bulletin 49(3): 206-228.

Brazil Bugs #3 – Gorgulho Enorme!

The second night at the hotel on the outskirts of Campinas (São Paulo, Brazil), I found this enormous weevil laying on the ground underneath some windows.  It was dead but completely relaxed and in perfect shape.  I wondered if it had been attracted to lights in the window the previous evening and flown there as its “last hurrah.”  This beast of a weevil – measuring a good 30mm from the tip of the snout to the apex of the elytra – immediately brought to my mind giant palm weevils of the genus Rhynchophorus (Coleoptera: Curculionidae).  I looked around and saw palm trees everywhere, so I figured that must be what it was.  I picked up one of the dead fronds from under a nearby palm tree and placed the weevil on the stem for a few photographs.  Given it’s freshness, it was quite easy to place in a lifelike pose, and I placed the stick in various positions to get a few different backgrounds.  As I was shooting, I noticed another, smaller, weevil on the ground near where I had found the first one – also dead and fresh.  Considering that Rhynchophorus often reaches pest status on palms, this further confirmed the ID in my mind.

Once back in the hotel room I smugly entered “giant palm weevil” into Google to bring up some images and confirm my ID (and also make sure my photos were at least on par with published images).  When the images came up, I saw immediately that my weevil was not a giant palm weevil at all.  While the South American species (R. palmarum) is black, the pronotum and elytra are much smoother and distinctly striate.  I don’t know if this weevil is a member of the same subfamily (Rhychophorinae) as the giant palm weevils, but it certainly not a member of that genus.  Still, considering its large size and distinctive appearance, I remained confident that an ID would come quickly.  Sadly, this has not proven to be the case – no search term I’ve tried involving the term “giant black weevil Brazil” or its many variations brings up anything remotely similar.  So, after spending much more time trying to identify this beetle than I should have, I leave it in the hands of my readers in the hopes that one of you will recognize it and provide a name.  Only when we have a name will it be possible to know something more about how this beetle lives (and if my placing it on a dead palm frond was a truly artificial setup).

Photo Details: Canon 50D w/ 100mm macro lens (ISO 100, 1/200 sec, f/16-18), Canon MT-24EX flash w/ oversized DIY concave diffuser. Typical post-processing (levels, minor cropping, unsharp mask).

Update 01/24/11: Thanks to Henry Hespenheide (via Facebook) and Art Evans, who clued me in to the genus Homalinotus (subfamily Cholinae).  I found a key to the 21 known species of this exclusively Neotropical genus (Vaurie 1973) and consider this individual to represent H. coriaceus – broca do cacho do coqueiro (black coconut bunch weevil).  This species breeds in the stems of old leaves of several native palms; however, it has adapted to the introduced coconut palm and apparently become a limiting factor in the commercial production of coconuts.  Thus, I can breathe easy now knowing that my photographs of this individual on the stem of a dead palm frond represent an entirely natural setting.

REFERENCE:

Vaurie, P.  1973.  The weevil genera Homalinotus and Ozopherus of the Neotropical Cholinae (Coleoptera, Curculionidae).  Bulletin of the American Museum of Natural History 152(1):1–49.

Copyright © Ted C. MacRae 2011

Two ladies from Ontario

What do bugs and snakes/lizards/frogs/turtles have in common? Yes, they’re both ectothermic, but that is the scientist’s answer. Most folks would say they’re just creepy – girls especially! Well, two ladies from Ontario are proving the latter notion wrong by hosting three blog carnivals that cater to these cold-blooded critters: House of Herps, An Inordinate Fondness, and The Moth and Me.

Most people approach their first blog carnival hosting gig with some trepidation, but the Geek in Question at Fall to Climb has embraced the challenge by volunteering to host two blog carnivals simultaneously.  What chutzpah!  Clearly, she was up to the task – for issue #3 of An Inordinate Fondness, she introduces us to technical terms such as OMGSHINY and Coleappetite™ in Discovery Zone, with thirteen stories of beetley discovery. She then shows off her “slammer” talent in House of Herps #5: Slime Poetry - deftly pairing poems with prose.  I would love to see her do this live!

Seabrooke Leckie’s passion for moths is obvious – she is the founder of The Moth and Me and co-author of the soon-to-be-published Peterson Field Guide to Moths of Northeastern North America. Issue #10 of TMaM, Down to the letter, comes home to mama at the Marvelous in Nature – its 24 contributions almost enough to complete the alphabet! Recite your ABCs in lepidopterous fashion with this fine array of contributions.

Copyright © Ted C. MacRae 2010

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