Mississippi

A polypipin’ we will go!

/ Ted C. MacRae / 10 Comments

A polypipin’ we will go, a polypipin’ we will go
Heigh ho, the dairy-o, a polypipin’ we will go
A polypipin’ we will go, a polypipin’ we will go
We’ll catch a tiger beetle and put him in a vial
And then we’ll let him go (not!)

Okay, maybe my adaptation of the popular children’s song A Hunting We Will Go isn’t the best, but if you want to collect tiger beetles in the genus Tetracha then you’ve got to try the method that my friend Kent Fothergill has dubbed “polypipin’.”

The author polypipin’ in a soybean field in Starkville, Mississippi, September 2013. Photo by Lisa G. Ruschke.

What exactly is polypipin’? Well, it’s when you look for stuff under polypipe—a big plastic tube with holes in it that some farmers use to irrigate their crops. The tube is laid across one end of their field, and when water is pumped into it the water leaks out of the holes along the length of the tube and runs down the furrows between the rows. This is a popular method of irrigation in the Mississippi Delta because the terrain is flat and the equipment costs are much lower than center pivot irrigation systems. Of course, the tube also provides excellent cover for insects and other small critters that live in and around agricultural fields, and these include tiger beetles in the genus Tetracha.

Tetracha carolina under polypipe in a soybean field in Starkville, Mississippi

Tetracha carolina under polypipe in a soybean field in Starkville, Mississippi

I wish I could take the credit, but it was Kent who had the great idea to use polypipin’ as a way to survey for T. carolina (Carolina metallic tiger beetle) in the Mississippi Lowlands (“bootheel”) in southeast Missouri. This is a common species across the southern tier of the United States, but prior to this survey the occurrence of this species in Missouri was not well understood. While a number of specimens had been collected in the bootheel over the years prior to the survey, some regarded Missouri records of the species to be a result of vagrants migrating into the state rather than residents (Pearson et al. 2006). Tiger beetles in the genus Tetracha are nocturnal and take refuge during the day, so they are not often encountered unless one goes at at night with a flashlight. Kent was interested in determining the status of this species in Missouri and had noticed their tendency to take refuge under polypipe—where they could be easily found during the day by simply lifting up the pipe. Rather than give up on sleep, Kent and colleagues surveyed agricultural fields throughout the bootheel by looking under polypipe and demonstrated not only that T. carolina is well established in and a resident of the bootheel, but that it is actually quite abundant and may reside even further north in Missouri than just the bootheel (Fothergill et al. 2011).

Adults are amazingly calm if the polypipe is lifted carefully so as not to disturb them.

Adults are amazingly calm if the polypipe is lifted carefully so as not to disturb them.

I don’t know what it is, but there is just something really fun about polypipin’. Being an agricultural entomologist by day, I have ample opportunity to do a little polypipin’ of my own as I travel across the southern U.S. looking at soybean fields, including this past September when I found myself in fields with polypipe in Arkansas and Mississippi. These photos were taken in Starkville, Mississippi near the Mississippi State University campus, and as has happened in every other case where I’ve looked, I found adults of T. carolina quite abundant underneath the polypipe. Some were found simply resting on the soil surface beneath the pipe, but a great many were observed to have dug burrows under the pipe for added shelter.

Adults often construct burrows underneath the polypipe for additional refuge.

Adults often construct burrows underneath the polypipe for additional refuge.

Polypipin’ works as a survey tool for T. carolina because of that species’ propensity for agricultural fields and other moist, treeless habitats. I’ve not yet found T. virginica (Virginia metallic tiger beetle) under polypipe, but that species is more fond of forested rather than treeless habitats. Perhaps an agricultural field next to forest with polypipe laid on the side adjacent to the forest might produce this species. At any rate, polypipin’ might offer a tool to better define the entire northern distributional limit of T. carolina—all one has to do is look.

REFERENCE:

Fothergill, K., C. B. Cross, K. V. Tindall, T. C. MacRae and C. R. Brown. 2011.Tetracha carolina L. (Coleoptera: Cicindelidae) associated with polypipe irrigation systems in southeastern Missouri agricultural lands. CICINDELA 43(3):45–58 [pdf].

Pearson, D. L., C. B. Knisley & C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp. [Oxford description].

Copyright © Ted C. MacRae 2013

T.G.I.Flyday: Soybean nodule fly

/ Ted C. MacRae / 3 Comments

I’ve been walking the rows of soybean fields for many years now, and while it might seem that I would have very quickly seen all there was to see in terms of insects associated with the crop, this is not the case. The major players are almost always present—lepidopteran caterpillars such as velvetbean caterpillar (Anticarsia gemmatalis) and soybean looper (Chrysodeixis includens), and stink bugs such as southern green stink bug (Nezara viridula), red-banded stink bug (Piezodorus guildinii) and brown stink bugs (Euschistus spp.). However, numerous other insects can be found at one time or another—some of great importance from the perspective of the farmer producer but others with very little impact on the crop. During a tour of soybean fields in Mississippi this past September, I saw a large number of “signal flies”¹ (family Platystomatidae) on the foliage of the soybean plants that I presumed to represent the soybean nodule fly, Rivellia quadrifasciata.²

¹ I originally learned these to be “picture-winged flies”—a name now more commonly used to refer to members of the family Ulidiidae—which I learned as “Otitidae”!

² This species can be separated with certainty from the closely related and largely sympatric species R. colei only by examination of male genitalia (Namba 1956). Rivellia quadrifasciata is more common and widespread than R. colei and is the species cited in literature in association with soybean.

Rivellia quadrifasciata (soybean nodule fly) | Stoneville, Mississipi

Rivellia quadrifasciata (soybean nodule fly) | Stoneville, Mississipi

Rivellia quadrifasciata is widely distributed in the eastern U.S. where it originally fed probably on tick trefoil, Desmodium spp. (Foote et al. 1987), but has since adapted to soybean, Glycines max (Eastman & Wuensche 1977), and black locust, Robinia pseudoacacia (McMichael et al. 1990). Despite its relatively recent adaptation to soybean as a favored host plant, the species does not appear to cause much economic damage to the crop. The small, white, maggot-like larvae live in the soil and feed on the Rhizobium nodules of the roots that are used by the plant for nitrogen-fixation. Soybean, of course, is famous for its compensatory abilities and can withstand considerable nodule injury without yield impact, and as a result losses from this insect are considered minor (Heatherly & Hodges 1998).

Signal flies wave their wings constantly.

The wings of signal flies are almost always in constant motion.

Of more interest from a natural history perspective, these flies—like other members of the Platystomatidae—are almost always seen with their wings in a constant “waving” motion as they walk about on the host leaves. This seems clearly an intraspecific “signaling” behavior (and the source of the family’s common name), with the pattern of markings on the wings and the particular sequence of movements of the wings combining to provide species-specific signals for mate recruitment. Some Asian members of the family are famous for the remarkably elongated eye stalks of the males, which aid in intraspecific male-to-male combat behaviors that provide selection pressure for even more elongate eye stalks. Sadly, our North American species exhibit no such modifications of the head, but their strangely tubular mouthparts do give them the appearance of wearing a “gas mask.”

gas mask

The strangely tubular mouthparts give adults the appearance of wearing a “gas mask.”

Information on the biology of adult platystomatids is limited, but a wide range of adult foods, e.g. nectar, honeydew, plant sap, bird droppings, and carrion, have been reported for this species, and R. quadrifasciata males have been observed to feed females globules of liquid during mating.

REFERENCES:

Eastman, C. E. & A. L. Wuensche. 1977. A new insect damaging nodule of soybeans: Rivellia quadrifasciata (Macquarl). Journal of the Georgia Entomological Society 12:190–199.

Foote, B. A., B. D. Bowker & B. A. McMichael. 1987. Host plants for North American species of Rivellia (Diptera, Platystomatidae). Entomological News 98:135–139 [Biodiversity Heritage].

Heatherly & Hodges. 1998. Soybean Production in the Midsouth. CRC Press LLC, Boca Raton, Florida, 416 pp. [Google Books].

McMichael,  B. A., B. A. Foote & B. D. Bowker, B. D. 1990. Biology of Rivellia melliginis (Diptera: Platystomatidae), a consumer of the nitrogen-fixing root nodules of black locust (Leguminosae). Annals of the Entomological Society of America 83(5):967–974 [abstract].

Namba, R. 1956. A revision of the flies of the genus Rivellia (Otitidae, Diptera) of America north of Mexico. Proceedings of the U.S. National Museum 106:21–84 [Biodiversity Heritage].

Copyright Ted C. MacRae 2013

Quick Guide to Armyworms on Soybean

/ Ted C. MacRae / 5 Comments

Throughout the soybean growing areas of the southern U.S. and South America, lepidopteran caterpillars are the most important pest complex affecting the crop. Millions of pounds of insecticides are sprayed on the crop each year in an effort to minimize their impact—a practice that is not always successful and entails significant exposure risks to the environment and farm workers alike. A variety of lepidopteran species occur in soybeans, and proper identification is essential to ensure adequate control and avoiding unnecessary applications. While the most important and commonly encountered species are velvetbean caterpillar (Anticarsia gemmatalis) and soybean looper (Chrysodeixis includens), others include soybean podworms (Helicoverpa zea in the U.S.; H. gelotopoeon and—now—H. armigera in Brazil and Argentina), sunflower looper (Rachiplusia nu), bean shoot moth (Crocidosema aporema), and armyworms of the genus Spodoptera. The last group contains several species that can affect soybean, and while they have traditionally been considered minor pests of the crop a number of species have increased in importance during the past few years.

I have been conducting soybean field trials in both the U.S. and South America for many years now and have had an opportunity to photograph most of the species known to occur on soybean in these regions. Identification of armyworm larvae can be rather difficult due to their similarity of appearance, lack of distinctive morphological differences (e.g. number of prolegs), and intraspecific variability in coloration. Conclusive identification is not always possible, especially with younger larvae; however, the different species do exhibit subtle characters that can usually allow for fairly reliable identification of large larvae. Considering the dearth of direct comparative resources—either in print or online—I offer this quick guide to the six armyworm species that I’ve encountered in soybean.

Spodoptera frugiperda (fall armyworm) | Jerseyville, Illinois

Spodoptera frugiperda (fall armyworm) | Jerseyville, Illinois

Spodoptera frugiperda (fall armyworm). This is not the most important armyworm pest of soybean, in contrast to its great importance in other crops such as corn and cotton. It is, however, the most widely distributed of the species, occurring in both the southern U.S. and throughout soybean growing areas of Brazil and Argentina. When problems do occur on soybean they are usually a result of larvae moving from grassy weeds to small soybean plants in late-planted or double-crop fields. Larvae can damage all stages of soybean, from seedlings (cutting them off at ground level) to later stages by feeding primarily on foliage and even pods. Larvae are somewhat variable in coloration but are distinctive among armyworms by virtue of the pinaculae (sclerotized tubercles) visible over the dorsum, each bearing a single stout seta. Four pinaculae are present on each of the abdominal segments, with those on the eighth abdominal segment forming a square, and larvae also exhibit a pronounced inverted, white, Y-shaped mark on the head.

Spodoptera exigua (beet armyworm) | Stoneville, Mississippi

Spodoptera exigua (beet armyworm) | Stoneville, Mississippi

Spodoptera exigua (beet armyworm). This species is better known as a pest of vegetables but will occasionally damage soybean in the southern U.S. In soybean larvae prefer to feed on foliage of seedling plants but will, if present during reproductive stages, also feed on blossoms and small pods. Late-instar larvae can be rather variable in appearance, but most tend to be green above and pinkish or yellowish below with a white stripe along the side. Larvae can be confused with Spodoptera eridania (southern armyworm) because of a dark spot that might be present on the side, but in southern armyworm the spot is on the first abdominal segment while in beet armyworm (when present) it is on the mesothorax.

Spodoptera ornithogalli (yellowstriped armyworm) | Jerseyville, Illinois

Spodoptera ornithogalli (yellow-striped armyworm) | Jerseyville, Illinois

Spodoptera ornithogalli (yellow-striped armyworm). This species is widely distributed throughout North and South America, but its status as an occasional pest of soybean is limited practically to the southeastern U.S. It is often encountered in soybean in low numbers but can reach pest status in double-crop fields with small plants that have been planted after wheat (similar to fall armyworm). Compared to other species in the genus the larvae are rather uniform in appearance, exhibiting paired, black, triangular spots along the back of each abdominal segment with thin to prominent yellow stripes running lengthwise adjacent to and not interrupted by the spots. Larvae oftentimes have an almost black velvety appearance with distinctly contrasting bright yellow stripes.

Spodoptera eridania (southern armyworm) | Jerseyville, Illinois

Spodoptera eridania (southern armyworm) | Jerseyville, Illinois

Spodoptera eridania (southern armyworm) | Union City, Tennessee

Spodoptera eridania (southern armyworm) | Union City, Tennessee

Spodoptera eridania (southern armyworm). This species is, like fall armyworm, widely distributed from the southern U.S. through Brazil and Argentina. In the U.S. it occurs only sporadically on soybean, usually causing “hot spots” of damage by groups of many larvae hatching from a single egg mass and skeletonizing the nearby foliage before dispersing as they grow larger. In Brazil and Argentina this species has emerged during recent years as one of the most important armyworm pests of soybean, especially in regions where cotton is also grown. Larvae can be somewhat variable in appearance and, in South America, can be easily confused with those of the black armyworm (S. cosmioides), both of which often exhibit prominent black markings on first and eighth abdominal segments and a subspiracular light-colored line along the length of the thorax and abdomen. Southern armyworm, however, rarely exhibits an additional black marking on top of the mesothoracic segment. Additionally, when the subspiracular line is present it is interrupted by the black marking on the first abdominal segment and is less distinct in front of the spot than behind, and if the line is not present then the black spots on top of the first abdominal segment are larger than those on top of the eighth abdominal segment.

Spodoptera cosmioides (black armyworm) | Acevedo (Buenos Aires Prov.), Argentina

Spodoptera cosmioides (black armyworm) | Acevedo (Buenos Aires Prov.), Argentina

Spodoptera cosmioides (black armyworm) | Chaco Prov., Argentina

Spodoptera cosmioides (black armyworm) | Saenz Peña (Chaco Prov.), Argentina

Spodoptera cosmioides (black armyworm) | Acevedo (Buenos Aires Prov.), Argentina

Spodoptera cosmioides (black armyworm) | Acevedo (Buenos Aires Prov.), Argentina

Spodoptera cosmioides (black armyworm). No accepted English common name exists for this strictly South American species that was previously considered a synonym of the North and Central American species Spodoptera latifascia. In Brazil it has been referred to by such names as “lagarta preta” (black caterpillar) and “lagarta da vagem” (pod caterpillar). The latter name has also been applied to other soybean pests, including southern armyworm, so to me “black armyworm” seems the most appropriate English name to adopt. Like southern armyworm, this species is a sometimes pest of cotton and in recent years has become increasingly important in soybean throughout Brazil and northern Argentina. Larvae often resemble and can be easily confused with those of southern armyworm; however, there is almost always a dark spot on top of the mesothoracic segment that is lacking in southern armyworm. Additionally, the light-colored subspiracular line, when present, is not interrupted by the black spot on the first abdominal segment and is equally distinct in front of and behind the spot. When the line is not present the black spots on top of the first abdominal segment are smaller than than those on top of the eighth abdominal segment.

Spodoptera albula

Spodoptera albula (gray-streaked armyworm) | Saenz Peña (Chaco Prov.), Argentina

Spodoptera albula (unbarred or gray-streaked armyworm). While known to occur in extreme southern U.S., this species has been cited as a pest of soybean only in Brazil, although its importance has not matched that of southern or black armyworm. Like most armyworms it is polyphagous, but this species seems to prefer amaranth (Amaranthus spp.). Larvae of this species can be distinguished from other South American armyworms that feed on soybean by the trapezoidal black marking on the mesothorax (usually semicircular to slightly trapezoidal in black armyworm), the black marking on the first abdominal segment not larger than that on the sixth abdominal segment, both of which are smaller than those on the seventh and eight abdominal segments, the white-only rather than white and orange dorsolateral stripe, and the triangular black markings on the abdominal segments each with a small white spot in the middle or at the apex of the marking.

Copyright © Ted C. MacRae 2013

Teeny, tiny, timid tot of a toad

/ Ted C. MacRae / 9 Comments

I’ve been traveling across the southeastern U.S. for the past couple of weeks, during which time I had a chance to go polypipin’ at several of my destinations! For those of you who don’t know what polypipin’ is, it’s when you look for stuff under polypipe. What is polypipe? It’s a big tube of plastic with holes in it that farmers lay across one end of their field and then pump water into. The water leaks out of the holes and runs down the furrows between the rows, irrigating the crops. This is a popular method of irrigation in the Mississippi Delta because the super flat terrain allows the fields to be easily graded for such at much lower cost than the center pivot irrigation systems that are more often used in the rolling terrain of the Midwest and other areas. An unexpected side benefit of polypipe irrigation (at least for naturalist nerds like me) is that insects and all other manner of critters find the ground under polypipe to be a great place to hide. In a stroke of genius, friend and colleague Kent Fothergill used polypipin’ to confirm that Tetracha carolina (Carolina metallic tiger beetle), was not only a resident of the Mississippi Lowlands in southeast Missouri (there was some question as to whether the few existing records from that area represented vagrant individuals), but well established and abundant throughout the region (Fothergill et al. 2011). Ever since then I’ve gone polypipin’ whenever the opportunity presented itself, usually with good results.

Teeny tiny toad

Juvenile toad, but which one? | Starkville, Mississippi

This little toad was photographed in Starkville, Mississippi, where I had visited a soybean field and found polypipe stretched all along the north end of the field. He was clearly annoyed at being suddenly exposed to daylight when I lifted up the polypipe and immediately hopped over to the edge that was still contacting the ground and tried to crawl back in, but I can be persistent and finally ‘persuaded’ him to come back out and pose for this one shot before I felt sorry for him and let him finish his escape. This was one of the tiniest toads I’ve ever seen—no more than 2.5 cm snout to butt, and not being as well-versed in herps as I am in hexapods I didn’t really know what kind of toad he represented. Apparently there are a few different species in Mississippi, but the most common is Fowler’s toad (Bufo fowleri). Its size surely suggests it is a juvenile, which can be notoriously difficult to identify due to their still undeveloped cranial ridges and coloration. Considering the agricultural setting and location in northeastern Mississippi I think this is probably the most likely choice.

REFERENCE:

Fothergill, K., C. B. Cross, K. V. Tindall, T. C. MacRae and C. R. Brown. 2011. Tetracha carolina L. (Coleoptera: Cicindelidae) associated with polypipe irrigation systems in southeastern Missouri agricultural lands. CICINDELA 43(3):45–58.

Copyright © Ted C. MacRae 2013

The Texas Prick

/ Ted C. MacRae / 47 Comments

Recently my friend Kent Fothergill launched a series of posts ranting about discussing the difficulties associated with common names. The inaugural post featured the insect I show here, Dectes texanus, a member of the family Cerambycidae (longhorned beetles) that has gained attention in recent years as an occasional pest of soybeans, especially in the upper Mississippi Delta (Tindall et al. 2010). As is usual, when an otherwise obscure little insect suddenly begins costing somebody money people feel compelled to give it a common name. Rather than the uninspired “soybean stem borer” or ironically Latin-ish “Dectes stem borer” monikers that seem to have taken hold for this species, Kent jokingly suggested that if people were serious about common names, this insect should actually be called the “Texas prick” as a direct translation of the scientific name.¹

¹ Actually, I couldn’t find any reference to the word “Dectes” as a Latin word or “prick” as its English translation. Rather, my copy of Brown (1956) lists dectes as a Greek word meaning “biter.” I think this must be what LeConte (1852) had in mind when he first coined the genus name, since he mentions among the characters that define the genus several features of the mandibles. If that is the case, then to be accurate the alternate common name for this beetle should be the “Texas biter.” However, that name causes nothing like the snicker that “Texas prick” elicits, and since common names are bound by no rules whatsoever, I choose levity over accuracy and stick with Kent’s proposed name.

Dectes texanus (dectes stem borer) | Washington Co., Mississippi

Dectes texanus | Washington Co., Mississippi

Being the pedantic, anal retentive, taxonomist-type that I am, it may surprise you to learn that I actually don’t have a problem with common names. To be honest, however, I will admit that this is a fairly recent change-of-mind for me—for many years I was a die-hard “scientific-names-only” type of guy. I not only thought common names were useless (for all the reasons listed by everybody who opposes them), but I even refused to learn them—my geek passive aggression, I guess. In the years since I started this blog, however, I’ve not only grown less oppositional in my stance, but have actually learned to embrace common names for what they are—comfortable names that don’t intimidate the taxonomically disinclined. Labels is all they are, and if one common name can refer to several species or several common names refer to one species, it’s not the end of the world. Common names aren’t meant to replace scientific names—how could they? Scientific names fulfill a special set of needs for a select group of people (i.e., to reflect phylogeny), and despite its flaws the Linnaean system of nomenclature that has been in use for the past several hundred years has served this purpose better than any other system devised. The reason for this is because genus and species names also provide a convenient and relatively easily memorizable system of labels that allow scientists to actually talk about organisms in a way that makes sense. This is an advantage that the Linnaean system has over any numerical phylogenetic system, no matter how much more precisely the latter can indicate phylogeny. For scientists, scientific names, in effect, serve a dual purpose. Non-taxonomists, however, don’t need dual purpose names—they just want easy-to-say and easy-to-remember labels, and if common names engage more people in a discussion about nature and its inhabitants then I’m all for it.

a.k.a. ''The Texas Prick''

Accepted common name: Dectes stem borer; BitB common name: ”Texas Prick”

This is not to say that I will ever give up scientific names. I love scientific names, and it is my goal in life to know as many of them as possible—even synonyms (I know, sick!). I also think that scientific names are not as scary as some people believe. Boa constrictor, for example (yes, that is both its common and scientific name), or gorilla (Gorilla gorilla)… or Dectes stem borer! To help bridge the gap, I have taken to mentioning, as a matter of practice, both the scientific name and—when one exists—the common name for the insects and other organisms featured on this blog. This applies not only at the species level, but families and other higher taxa also (e.g., “jewel beetles, family Buprestidae”). It is my way of talking science in a way that welcomes the interested lay person. Considering the increasingly anti-science din in our country by creationists, climate change denialists, knee-jerk GM critics, etc., I think the more we can get scientists and non-scientists comfortable talking to each other the better off we will be.

The insect featured in this post was found and photographed in a field of cultivated soybeans in northeastern Mississippi. It’s identification as Dectes texanus (other than its association with soybean) is based on the face being only slightly protruding and the relatively large lower lobe of the eye. There is one other species in the genus, D. sayi, also broadly distributed in the U.S. but distinguished from D. texanus by its distinctly more protruding face and small lower eye lobe (giving the impression of “tall cheeks”). This species, too, is known to bore in the stems of soybean but is much happier doing so in common ragweed (Ambrosia artemisiifolia) (Piper 1978). The species name—sayi—was given to honor the 19th century entomologist Thomas Say, regarded by many as the ‘Father of American entomology.’ This species also has been called “soybean stem borer” by some, which doesn’t do much to alleviate concerns about common names referring to multiple species. I am reluctant, however, for reasons of respect, to use the common name for D. sayi that results if one uses the same rationale used by Kent in coining his common name for D. texanus…

REFERENCES:

Brown, R. W. 1956. Composition of Scientific Words. Smithsonian Institution Press, Washington, D.C., 882 pp.

LeConte, J. L. 1852. An attempt to classify the longicorn Coleoptera of the part of America north of Mexico. Journal of the Academy of Natural Sciences Philadelphia (series 2) 2(1):99–112.

Piper, G. L. 1978. Biology and immature stages of Dectes sayi Dillon and Dillon (Coleoptera: Cerambycidae). The Coleopterists Bulletin 32(4):299–306.

Tindall K. V., S. Stewart, F. Musser, G. Lorenz, W. Bailey, J. House, R. Henry, D. Hastings, M. Wallace & K. Fothergill. 2010. Distribution of the long-horned beetle, Dectes texanus, in soybeans of Missouri, Western Tennessee, Mississippi, and Arkansas. Journal of Insect Science 10:178 available online: insectscience.org/10.178.

Copyright © Ted C. MacRae 2013

Crazy Eyes

/ Ted C. MacRae / 70 Comments

Spissistilus festinus | Stoneville, Mississippi

Spissistilus festinus (three-cornered alfalfa hopper) is one of the few truly economic pests in the otherwise bizarre and innocuous family Membracidae (treehoppers).  Its common name alludes to one of the crops it affects, but my encounters with this species are most often in soybean (I am, after all, a soybean entomologist).  Damage in this crop is caused by both adults and nymphs, whose piercing/sucking mouthparts cause girdling and breakage of the stem—often just a few inches above the soil.  This individual was seen during my travels last week in a soybean field in Stoneville, Mississippi, where numbers throughout the season were especially high this year.  Although I have seen innumerable S. festinus adults, I have never noticed their crazy, zig-zag patterned red and white eyes until I managed this closeup face shot (click on photo for best view).

This slightly cropped photo was taken with a 100mm macro lens and full extension tube set, resulting in slightly more than 2X magnification.  One of the lessons I took from was the need to pay more attention to background and value contrast.  By placing the subject a few inches in front of the dark green soybean foliage I was able to achieve a much more pleasing background than the typical black background one gets with full flash photos at high magnification.  Although both the subject and the background are green, there is still sufficient difference in shade to create contrast between them.  Light-green is one of the more difficult colors to work with when full flash is used with high shutter speeds and small apertures to maximize crispness and detail (in this case, 1/250 sec and f/16).  However, increasing ISO to 400 and lowering flash exposure compensation to -2/3 can reduce the amount of flash needed to illuminate the subject with such settings, making it easier to achieve a properly exposed and true-colored subject.

Copyright © Ted C. MacRae 2011

Tracking Tetraopes texanus with Terry

/ Ted C. MacRae / 12 Comments

Last month I traveled to Starkville, Mississippi to meet with an academic cooperator at Mississippi State University.  While arranging the trip, I contacted Terry Schiefer (no, not the fashion jewelry designer, but curator at the Mississippi Entomological Museum) to let him know I would be visiting.  Considering that late May should be pretty good insect collecting in that area, I wanted to see if he might be interested in doing a little beetle collecting after I finished up with my meetings.  Terry also specializes in Coleoptera and shares with me an interest in the taxonomy and faunistics of Cerambycidae and Cicindelinae.  I first met Terry some 13 years ago during my previous visit to MSU; I remember ogling at an impressive series of Aegomorphus morrisii, a spectacular species of longhorn beetle that was known at that time by precious few specimens and that he had recently found in Mississippi.  We hadn’t seen each other since but managed to keep in contact with occasional correspondence during the course of our longhorn studies.

Me & Terry Schiefer | Noxubee National Wildlife Refuge, May 2011.

Terry was more than happy to go beetle collecting with me, and among the possibilities that he mentioned when I arrived at the museum was nearby Noxubee National Wildlife Refuge.  I had done a little collecting there on my last visit, but I was especially intrigued when he mentioned the local population of an uncommon milkweed beetle species, Tetraopes texanus, that he had reported in one of the refuge’s prairie remnants (Schiefer 1998).  I have only seen this species once, up here in in east-central Missouri and which I reported as the species’ northernmost known population (MacRae 1994).  My more recent attempts to find this species have not been successful, so I was excited at the chance to see this longhorned species once again.

We arrived at the prairie with plenty of daylight to spare and began walking through the area where Asclepias viridis (its presumed host in Mississippi; in Missouri I found it on Asclepias viridiflora) was growing.  Typically milkweed beetles are quite approachable, having nothing to fear from predators by virtue of the cardiac glycosides that they sequester in their bodies from their milkweed foodplants and advertise so conspicuously with their bright red and black coloration.  Thus, we were looking for beetles sitting brazenly on the plants, but none were seen.  Eventually, Terry saw one in flight, and then I saw one in flight as well.  For some time, this was the only way we were seeing the beetles, and only by slowing down and scanning the prairie vegetation more carefully and deliberately did we begin to see the adults sitting on vegetation.  Interestingly, very few of them were seen actually sitting on milkweed plants.  Rather, they were on all manner of other plants, and they were very quick to take flight on our approach.  This was playing havoc with my desire to get field photographs of the beetles, especially field photographs on the host.  I decided that any photograph—host plant or not—was better than none, so I began attempting some shots.  My first one didn’t work out so well:


Finally I was able to get one of the beetle sitting on a plant, but the dorsal characters can’t be seen, nor is there anything about the photo that allows the species to be distinguished as T. texanus (the abruptly attenuate last antennomere distinguishes it from similar-appearing species):


Progress—more of the dorsal surface can be seen in the photo below, and the beetle is actually sitting on a milkweed plant.  However, the antennal tips are still frustratingly out of focus.  Note the completely divided upper and lower lobes of the eye—Tetraopes beetles give new meaning to the term “four-eyes”:


I chased beetle after beetle in flight, endlessly zigzagging across the prairie in what had to be a spectacle to any unknown observer.  Eventually, we found a beetle sitting on its host plant, and it remained calm during my deliberate approach.  I circled around for a good view of the dorsal surface and snapped off an apparent winner—everything in focus, good composition… but arghh, the antennal tips were clipped!


I kept at it and was about to back off a bit on the magnification and switch to landscape mode so I could get the full antennae in the frame when the beetle turned in a most fortuitous manner—nicely positioning its distinctive antennal tip right in front of a bright green leaf for contrast.  My friends, I present Tetraopes texanus on its presumed host plant, Asclepias viridis!


Terry and I were both puzzled by the flighty, nervous behavior that the beetles were exhibiting.  Neither of us had seen such behavior with milkweed beetles before, and I’m not sure I can offer any explanation for such.  I’d be interested in hearing any ideas you might have.

My thanks to Terry for showing me a few of his favorite spots (allowing me to collect a few choice species of longhorns), and to my co-worker/colleague Jeff Haines for indulging my desire mix a little beetle collecting into the business trip.  I hope they enjoyed it as much as I did.

REFERENCES:

MacRae, T.C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) occurring in Missouri. Insecta Mundi 7(4) (1993):223–252.

Schiefer, T.L. 1998. Disjunct distribution of Cerambycidae (Coleoptera) in the black belt prairie and Jackson prairie in Mississippi and Alabama. The Coleopterists Bulletin 52(3):278–284.

Copyright © Ted C. MacRae 2011