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Семейство Cerambycidae |
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Plectrodera scalator (Fabricius, 1792) |
Adults of this species are found most often on cottonwood. |
Large, robust size and a distinctive checkered pattern of black and white makes these beetles among the most recognizable longhorned beetles in North America. |
One of the more impressive insects that we found during our visit to Sand Hills
State Park in south-central Kansas last June was Plectrodera scalator, the
cottonwood borer. Large and robust (in fact, the only larger species in the
family are the prionid root borers and their kin), their striking checkered
pattern of white pubescence on a glossy black body makes them perhaps the most
recognizable of all North American longhorned beetles (Linsley & Chemsak 1984).
The very robust body of this individual, along with the relatively shorter
antennae (only about as long as the body) identify it as a femaleЧmales are
generally smaller and less robust with the body slightly tapering and the
antennae distinctly longer than the body.
The white coloration on the body of these beetles is not a cuticular pigment
(which is rather rare in beetles and is most often associated with species found
in white sand habitats, e.g., certain tiger beetles), but instead a result of
dense mats of microscopic white setae. The patterns formed by these mats are
apparently as unique to each individual as fingerprints are to humans (Yanega
1996), making these beetles at once immediately recognizable as a species yet
distinctive as individuals.
These are said to be common beetles in their range across the eastern two-thirds
of the country, especially so in the Great Plains where their favored host,
cottonwood (Populus deltoides), is especially abundant. Despite this, I have
encountered this species only a handful of times in more than 3o years of
searching. I know they're out there, even in my home state of Missouri where I
recorded 154 specimens collected in the state and deposited in various
collections (MacRae 1994). It was not until around 2000 that I even saw my first
ones (on a cottonwood tree in a homeowner's yard just across the Mississippi
River in Illinois), and in fact this one was actually found by Mary Liz Jameson,
who had accompanied us to the field that day. It makes me wonder if their
coloration, so strikingly conspicuous when isolated against a clean, blue sky
background, might actually afford some type of cryptic protection against the
normal backdrop of foliage and branches on which they are normally foundЧa
phenomenon that I call "conspicuous crypsis" and which I have noted for other
longhorned beetles (e.g., Acanthocinus nodosus). Perhaps, with this species at
least, I have not yet set my search image to notice them.
REFERENCES:
Linsley, E. G. and J. A. Chemsak. 1984. The Cerambycidae of North America, Part
VII, No. 1: Taxonomy and classification of the subfamily Lamiinae, tribes
Parmenini through Acanthoderini. University of California Publications in
Entomology 102:xi + 1-258. [preview]
MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera:
Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4)
(1993):223-252. [pdf]
Yanega, D. 1996. Field Guide to Northeastern Longhorned Beetles (Coleoptera:
Cerambycidae). Illinois Natural History Survey Manual 6, x + 174 pp. [preview]
Web-site
"Beetles In The Bush"
Posted on January 21, 2016 by Ted C. MacRae
Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by
avocation. Areas of expertise in the latter include worldwide jewel beetles
(Buprestidae) and North American longhorned beetles (Cerambycidae). More recent
work has focused on North American tiger beetles (Cicindelidae) and their
distribution, ecology, and conservation.
Ted C. MacRae is an agricultural research entomologist with "an inordinate
fondness for beetles." Primary expertise includes taxonomy and host
associations of wood-boring beetles, with more recent interest also in tiger
beetle survey and conservation. He is currently serving as Managing Editor of
the The Pan-Pacific Entomologist, Layout Editor for the journal Cicindela and
Newsletter Editor for the Webster Groves Nature Study Society.
Очерк о привлекательном усаче вызвал многочисленные отклики читателей - посетителей сайта
"Beetles In The Bush".
Вот самый обширный и интересный комментарий:
Robert Wrigley says:
Hi Ted. My first experience with the beautiful Cottonwood Borer was on 23 July
2003, on the Arkansas bank of the Red River, 9 miles south of Foreman, along
Highway 41. On a 90-degree day, I and two companions were hunting for insects
when we found literally hundreds of individuals of this species feeding and
mating in cottonwood and willow saplings (with mature forest nearby on higher
ground). Most beetles were at eye level, and so collecting was like picking
plums in an orchard. They were so preoccupied that few flew away. They must
have emerged recently from the sandy soil, since the bodies were fresh,
without scratch marks, and with every individual sporting its own distinctive
pattern of white and black. It was one of the most-exciting experiences I have
had in my 25 years of studying and collecting insects. I have picked up
occasion specimens in other states, but nothing like that day along the Red
River. I returned there several more times and found the diversity of insect
life at this spot marvellous, if the river was not in flood stage.
Night-lighting along the sandy shore brought out an entirely different fauna
(tiger beetles and ground beetles in particular). Thank you for highlighting
the Cottonwood Borer.
Robert Wrigley
Posted on February 29, 2016