Month: July 2013

The perfectly polyphagous Chrysobothris purpureovittata

/ Ted C. MacRae / 1 Comment
Chrysobothris purpureovittata on Celtis sp. | Gloss Mountains State Park, Woodward Co., Oklahoma

Chrysobothris purpureovittata Horn 1886 | Gloss Mountains State Park, Woodward Co., Oklahoma

Many species of jewels beetles in North America are known for having some degree of host specificity. This is especially true of species in the genus Chrysobothris, whose members are often restricted to a particular family, genus, or even species of host plant. There are some, however, that are not so fastidious in their choice of host plant, and perhaps the best example of such is the species Chrysobothris purpureovittata. This pretty and not uncommonly collected species has been associated with well over two dozen species of deciduous trees representing 21 genera in eleven plant families.

Chrysobothris purpureovittata

Interestingly, the extent of this species’ polyphagy has not been fully appreciated until recently. At the time of Fisher’s (1942) revision of North American species, the only recorded larval hosts were elm (Ulmus sp.) and plum (Prunus sp.). Numerous adult hosts—i.e., plants on which adults had been collected only—were recorded in subsequent years, first by Vogt (1949) in south Texas and later by Nelson et al. (1982) from other locations. However, it was not until my Missouri jewel beetle survey (MacRae 1991) and subsequent “notes papers” by me and colleagues (MacRae & Nelson 2003, MacRae 2006, Wellso & Jackman 2006) that the true diversity of larval hosts became known. A majority of the larval host records are from the Ulmaceae, including several species of hackberry (Celtis tenuifolia, C. laevigata, C. ehrenbergia, C. reticulata) and cedar elm (Ulmus crassifolia), suggesting that despite its polyphagous nature there is some preference for members of this plant family. On my recent early June trip to northwestern Oklahoma, I encountered this species at several localities as abundantly as I can ever recall, with nearly all of them beaten from hackberry.

Chrysobothris purpureovittata

Chrysobothris purpureovittata is distributed primarily in the central and south-central U.S., with records from Indiana west to Kansas and south to Mississippi and northern Mexico. A population at the western edge of its distribution (Cloudcroft, Otero Co., New Mexico) associated with mountain mahogany (Cercocarpus montanus) was recently described as a separate subspecies (C. purpureovittata cercocarpi) by Westcott & Nelson (2000)—it is distinguished from nominotypical populations by the entirely red pronotum and uniformly dark elytra.

Chrysobothris purpureovittata

REFERENCES:

Fisher, W. S. 1942. A revision of North American species of buprestid beetles belonging to the tribe Chrysobothrini. U. S. Department of Agriculture, Miscellaneous Publication 470, 1–275.

MacRae, T. C. 1991. The Buprestidae (Coleoptera) of Missouri.  Insecta Mundi 5(2):101–126.

MacRae, T. C. 2006. Distributional and biological notes on North American Buprestidae (Coleoptera), with comments on variation in Anthaxia (Haplanthaxia) viridicornis (Say) and A. (H.) viridfrons Gory. The Pan-Pacific Entomologist 82(2):166–199.

MacRae, T. C. and G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70.

Nelson, G. H., D. S. Verity & R. L. Westcott. 1982. Additional notes on the biology and distribution of Buprestidae (Coleoptera) of North America. The Coleopterists Bulletin 35(2) [1981]:129–152.

Vogt, G. H. 1949. A biologically annotated list of the Buprestidae of the Lower Rio Grande Valley, Texas. Annals of the Entomological Society of America 42(2):192–202.

Wellso, S. G. & J. A. Jackman. 2006. A new species of Anthaxia (Haplanthaxia) Reitter (Coleoptera: Buprestidae) and new North American buprestid distributional and host records. The Pan-Pacific Entomologist 82(2):262–268.

Westcott, R. L. & G. H. Nelson. 2000. Descriptions of two new species of Acmaeodera Eschscholtz, and two new subspecies of Agrilus Curtis and Chrysobothris Eschscholtz (Coleoptera: Buprestidae) in North America, with detailed notes on others. The Coleopterists Bulletin 54(3):300–312.

Copyright © Ted C. MacRae 2013

Relaxed comment moderation policy

/ Ted C. MacRae / 6 Comments

During the first few years of writing this blog, I maintained an open comment policy with few restrictions on who could comment. In November 2011, however, I began experiencing a flood of spam comments, and as a result I had to implement a new comment policy that included comment moderation for new commenters and the requirement for all commenters to include their name (shown publicly) and e-mail address (not shown publicly). My hope was that the change would end the hundreds of spam comments I was getting each day while minimizing the inconvenience to those leaving valid comments.

Fortunately, the spate of spam has abated, and I think now I can relax the comment requirements. I think such measures do much to inhibit comments, as many people simply find it easier to leave comments at links on outreach sites (e.g. Facebook) rather than the post itself if they have to enter extra information in addition to the comment itself. Remote comments such as this are, of course, appreciated, but my greatest pleasure is in seeing and partaking in the conversations that develop on-site in the direct comments. I also realize that many people simply are not comfortable divulging their name and providing their e-mail address, no matter how secure the site is proclaimed to be. As a result, beginning today I have removed all comment moderation and the requirement to include name and e-mail address when leaving a comment. This means that anonymous comments are once again welcome. By eliminating as many barriers as possible to free, open communication, it is my hope that readers will not only find leaving comments here easy, but also feel comfortable doing so.

Copyright © Ted C. MacRae 2013

The ever-increasing diversity of Oklahoma beetles

/ Ted C. MacRae / 8 Comments

My idea to return to Oklahoma’s Gloss Mountains this spring actually began taking shape during last year’s fall visit to the area, when I found a single Chrysobothris octocola adult on a dead mesquite (Prosopis glandulosa) branch. While common across the southwestern U.S. in association with this plant, its occurrence in the Gloss Mountains represented a northeastern range extension and new state record for Oklahoma! On that same trip I also collected an interesting beetle in the family Rhipiphoridae representing the species Toposcopus wrightii—also not previously recorded in the literature from Oklahoma. Combined with finding Acmaeodera macra here the previous year, it was becoming clear to me that area held good potential for other more typically southwestern species of wood boring beetles. Although I had by then visited the area several times, most of these visits were more focused on tiger beetles rather than wood boring beetles. If I could find such interesting species of wood boring beetles when I wasn’t focused on them, imagine what I might find if I timed a visit in late spring when such species should be at their peak of adult activity.

Chrysobothris quadrilineata | Gloss Mountains State Park, Major Co., Oklahoma

Chrysobothris quadrilineata | Gloss Mountains State Park, Major Co., Oklahoma (new state record).

Of course, success came quickly during this early June visit. I immediately found C. octocola common on the mesquite and would collect a nice series of voucher specimens before the day was over, and the second species I encountered, also on mesquite, was the longhorned beetle Plionoma suturalis—another new state record! I spent a bit of time working the mesquite, and when I had collected a sufficient series of both species, I turned my attention to the eastern red-cedars (Juniperus virginiana) in the area. Actually, I had had my eye on the red-cedars since last fall, when I noticed that nearly every tree had dead branches mixed in amongst the living branches. Closer examination revealed the workings of jewel beetle larvae in all of these dead branches, and a few larvae typical of the genus Chrysobothris were cut from one of the branches. A common species in the Great Plains associated with Juniperus is C. ignicollis, but these larvae looked rather big to represent that species, so I bundled up some dead branches and brought them back home for rearing but forgot to check on them before I left on this trip. At any rate, I walked up to one of the red-cedars, placed my beating sheet under a dead branch, gave the branch a whack with the handle of my net, and onto the sheet fell a rather robust Chrysobothris that I didn’t immediately recognize. I knew it wasn’t C. ignicollis, a much smaller species that I have collected on numerous occasions, so I thought maybe it could be C. texana, another western Juniperus-associate that I’ve collected less commonly. Still, the robust body and broad, distinct elytral and pronotal ridges had me second guessing that identification (especially after I found some individuals that looked more like what I remembered C. texana looking like). Over the next two days I beat hundreds (literally!) of dead juniper branches, finding many C. ignicollis but every now and then getting also one of these big, robust individuals.

Chrysobothris quadrilineata

Adults were beaten from dead branches on live Juniperus virginiana (new adult host).

After returning home, I checked my heavily annotated copy of Fisher (1942) and quickly determined the robust specimens as representing C. quadrilineata—a rather uncommon species and one that I’d never collected before. Described by LeConte in 1860 from New Mexico and recorded early in the 20th century from Arizona, Nevada and California, it has in more recent years been found to occupy a rather wide distribution across the western U.S., including Texas (Barr & Westcott 1976), Colorado, Oregon, South Dakota (Nelson et al. 1982), and Utah (Nelson 1987). Notice one state that is not in that list—Oklahoma! That’s right, another new state record! I later found photographs of this species on BugGuide taken in the very same area a year earlier (7 June 2012).

Chrysobothris quadrilineata

Adults also emerged from dead J. virginiana branches collected Sept. 2012 (first reported larval host).

When I returned home, I also checked the rearing cans and found several adults had emerged from the branches I collected last September. The only host associations that have been recorded for this species are adults collected on Juniperus californica (Linsley & Ross 1940) and J. pachyphloea [= J. deppeana] (Barr & Westcott 1976). Thus, J. virginiana not only represents a new host record for the species but is also the first known larval host. Considering how broadly distributed across the western U.S. this species is, it seems likely that it utilizes a number of Juniperus spp. throughout its range.

REFERENCES:

Barr, W. F. & R. L. Westcott. 1976. Taxonomic, biological and distributional notes of North American Chrysobothris, with description of a new species from California (Coleoptera: Buprestidae).  The Pan-Pacific Entomologist 52(2):138–153.

Fisher, W. S. 1942. A revision of North American species of buprestid beetles belonging to the tribe Chrysobothrini. U. S. Department of Agriculture, Miscellaneous Publication 470, 1–275.

Linsley, E. G. & E. S. Ross. 1940. Records of some Coleoptera from the San Jacinto Mountains, California.  The Pan-Pacific Entomologist 16(2):75–76.

Nelson, G. H. 1987. Additional notes on the biology and distribution of Buprestidae (Coleoptera) in North America, II.   The Coleopterists Bulletin 41(1):57–65.

Nelson, G. H., D. S. Verity & R. L. Westcott. 1982. Additional notes on the biology and distribution of Buprestidae (Coleoptera) of North America.  The Coleopterists Bulletin 35(2) [1981]:129–152.

Copyright © Ted C. MacRae 2013

Registration is now open for my ESA Webinar

/ Ted C. MacRae / 6 Comments

Just released from ESA (Entomological Society of America):

Approaching the Unapproachable: Tips and Tricks for Field Photography of Wary Insects presented by Ted MacRae.  Learn valuable field photography techniques from Ted MacRae, Senior Research Entomologist at Monsanto Company.  Ted specializes in photographing tiger beetles in their natural habitats. These colorful beetles are fast runners and powerful fliers, making them among the more difficult insects to approach. Ted will describe some of the techniques that he uses to obtain close-up and macro photographs of these beautiful beetles and also techniques for field photography of other insects as well.

There’s no cost and you learn right from your desktop, laptop, or smart-phone.  This 60 minute webinar takes place August 8 at 2 PM  Eastern Time (US Time) and will be a great investment of your time.

Register for the live Webinar, August 8th at 2 PM Eastern Time (US Time).

Unable to attend, an archive of the presentation will be available at http://www.entsoc.org/students/esa-webinar-series for ESA members only.

Make a list of your pressing questions on this topic, as we’ll allow plenty of time for you to participate in the Q & A portion of the session. You may also send in questions prior to the event and this will assure you that the presenter will address your queries.

After registering you will receive a confirmation email containing information about joining the Webinar.

System Requirements
PC-based attendees
Required: Windows® 7, Vista, XP or 2003 Server

Macintosh®-based attendees
Required: Mac OS® X 10.5 or newer

Where do BitB readers come from (and why I like Facebook better than Twitter and Google+)?

/ Ted C. MacRae / 14 Comments

I’m not obsessed with blog stats, but every now and then it’s interesting to take a look and see what information I can glean from them. One of the stats provided by WordPress is “Referrers”—which sites readers came from. This is good information to know, as it can help guide decisions on which sites to put effort into as a referral site. It was precisely this stat that caused me to leave Google+ some months ago. I tried G+ for a time as an alternative to Facebook, cross-posting links to new posts and occasionally posting separate photos to maintain a consistent level of activity. But after several months I decided the interactions I was having on G+ weren’t very satisfying—no conversations about the subjects like what happens on Facebook, just brief comments of the “Nice shot” variety. Moreover, my WordPress Referrer stats showed virtually no traffic coming from G+. This was puzzling, as I found myself continually being added to G+ circles (thousands eventually, which in itself seemed very “spammish” to me), but since there was no automatic mechanism for linking new posts on G+ (like there is for Facebook and Twitter), I decided the tiny amount of traffic it drove was not worth the effort. I stopped posting to G+ (yet continued to be added to circles, which made me even more suspicious and eventually led me to deleting my G+ account altogether).

As my involvement with G+ waned, I became more involved with Twitter. I get Twitter—really, I do, although I had trouble getting it at first. It’s quick, it’s fun… it’s a great way to keep tabs on a lot of people who like to post links to things I am interested in. Nevertheless, I still find myself having trouble staying consistently involved with Twitter. My problem is the 140-character limit—again, I’m more interested in conversation than quips, and in this regard Facebook is a much less limiting—and thus more enjoyable—venue for interacting with like-minded individuals. I also find Twitter to be rather clumsy when it comes to sharing photos compared to Facebook’s more elegant (Google+ inspired?) model. If I can’t converse on Twitter the way I’d like to, then all I really have left to use Twitter for is to provide links to new posts on BitB. A few hundred followers may be modest, but one would still think it enough to drive a fairly good amount of traffic to the blog. Curiously, recent review of Referrer stats show this not to be the case. Over the past 30 days, only 43 visitors have come to BitB from Twitter—less than 1.5 per day! WordPress enables automatic linking of new posts on Twitter, so it doesn’t really take any effort on my part to maintain the account, but I still have to wonder if such little return warrants even this amount of effort.

Of course, search engines—primarily Google—reign supreme in driving traffic to BitB, with the past 30 days yielding 6,180 visits. But among non-search engine sites, where do most of my readers come from? Facebook! In the past 30 days, 232 visitors have clicked on a link to BitB through Facebook—either on my own page or that of somebody else who liked a post on BitB and provided a link to it. Considering how much fun I have on Facebook aside from providing links to posts on BitB—whether it be quick photos of experiences as they happen, enjoying photographs of other expert insect macrophotographers, or involvement in multi-party conversations about the finer points of insect taxonomy—the fact that it also drives a large amount of traffic to BitB almost seems like a bonus. People like to make fun of Facebook, and the recent exodus of many bug bloggers to Twitter and G+ cannot be ignored, but for me Facebook continues to be the supreme medium for online interaction.

I realize this a one-case study and don’t intend to generalize my experience to others. It does, however, raise some interesting questions. Why are Facebook users so much more likely to click on my links that Twitter or G+ users? What prompted thousands of G+ users to add me to their circles but almost none of them to actually click through to my content? Is my experience typical? Any insight on these questions would be appreciated.

I should also mention another significant referrer for BitB—Alex Wild. Combined stats from his Myrmecos and Compound Eye blogs over the past 30 days resulted in a cool 99 BitB referrals. While this is not quite at the same level as Facebook, it is remarkable for an individual blogger to be the source of so much traffic for my blog. I doubt Alex himself is responsible for all of these visits (although I’m sure he checks in from time to time), rather it is likely that a portion of the enormous reader base he has uses his sites as jumping off points for other bug blogs they like. No other bug blogger, and not even WordPress Reader or Blogger themselves, comes close to sending as much traffic to BitB as does Alex Wild. So, Alex… thank you!

Copyright © Ted C. MacRae 2013

“Rare jewel beetles discovered in Mexico by team of scientists!”

/ Ted C. MacRae / 2 Comments

I hope you’ll excuse the hyperbolic title, but such has been my impression with some of the headlines I’ve seen recently in the popular media regarding newly described insect taxa in various parts of the world. The “discovery” of new species in far away, tropical lands sounds exciting and ground-breaking to many people, who envision teams of scientists wearing pith helmets and cargo shorts machete-slashing their way through miles of virgin forest before stumbling into a secret biodiversity hot-spot, their weeks of toil and sweat finally paying off by becoming the first white men to lay eyes upon a bounty of strange, exotic, never-before-seen creatures. In reality, new species of insects are not at all hard to find—in fact, depending on where you go it can be downright easy. Admittedly the chances are greater in the tropics, where many areas remain little explored, but even in well-studied North America new species turn up regularly. This includes popularly collected beetles in the very well-studied eastern U.S., where I’ve already described one new jewel beetle (family Buprestidae) and one new longhorned beetle (family Cerambycidae) from right here in my home state of Missouri (MacRae 2000, 2003) and am in the process of describing another new jewel beetle. No, finding new species is easy—recognizing them as such is the hard part. That’s not to say that new species cannot be recognized when first encountered, but I suspect that a majority of new insect species aren’t actually “discovered” until they’ve been brought back from the field, curated, and sat in a cabinet for years or decades—unrecognized for what they really are due to resemblance to known species until somebody comes along and examines them more critically.

Such is the case with two jewel beetle species that Chuck Bellamy and I describe in a paper just published in The Pan-Pacific Entomologist (MacRae & Bellamy 2013). I joined Chuck on several trips to Mexico in 1992 and again from 2004–2006 to explore the tropical thorn woodlands in the southern states of Oaxaca, Puebla, Guerrero and Michoacán. Jewel beetle diversity is high in these still relatively intact woodlands, with a number of new species already having been described from the area in recent years, and all-told we collected well over 100 species. At least a dozen or more of these look to be new, and considering that the Mexican jewel beetle fauna as a whole includes more than 800 known species the actual number could greatly exceed 1,000. The two described in this most recent paper resemble the common, widespread species Actenodes calcaratus. This big, beautiful jewel occurs from the southwestern U.S. through Mexico and Central America to northern South America, developing as larvae in dead wood of a variety of fabaceous hosts. We collected several of what we thought was this species during our trips, but a number of subtle but consistent differences in punctation and surface sculpturing emerged as we began comparing them more critically against A. calcaratus from other locations. The coup de grâce, however, was the coloration of the male face—normal bronze in A. calcaratus (Fig. 5) and similar to the female (Fig. 6), but flash-green in male A. scabrosus (Fig. 2) and green-violaceous in male A. michoacanus (Fig. 8). It’s quite remarkable that both of these species differ from their more widespread relative by subtle morphological characters but such striking sexually dimorphic facial coloration, and we subsequently found a similar situation with another species in the genus (A. undulatus) that otherwise bears little resemblance to A. calcaratus.

Figs. 1–9. Actenodes spp. 1–3. Actenodes scabrosus. 1–2. Male holotype. 1. Dorsal habitus. 2. Frontal view. 3. Female paratype (Guerrero). 4–6. A. calcaratus. 4–5. Male (MEXICO, Guerrero, Hwy 95, 5 km S Milpillas, 7.vii.1992, "big dead tree", G. H. Nelson [FSCA]). 4. Dorsal habitus. 5. Frontal view. 6. Female (MEXICO, Hwy 95, 2 km S Milpillas, 6.vii.1992, on Acacia farnesiana, G. H. Nelson [FSCA]), frontal view. 7–9. A. michoacanus. 7–8. Male holotype. 7. Dorsal view. 8. Frontal view. 9. Female paratype, frontal view. All scale bars = 5 mm.

Figs. 1–9. Actenodes spp. 1–3. Actenodes scabrosus. 1–2. Male holotype. 1. Dorsal habitus. 2. Frontal view. 3. Female paratype (Guerrero). 4–6. A. calcaratus. 4–5. Male (MEXICO, Guerrero, Hwy 95, 5 km S Milpillas, 7.vii.1992, “big dead tree”, G. H. Nelson [FSCA]). 4. Dorsal habitus. 5. Frontal view. 6. Female (MEXICO, Hwy 95, 2 km S Milpillas, 6.vii.1992, on Acacia farnesiana, G. H. Nelson [FSCA]), frontal view. 7–9. A. michoacanus. 7–8. Male holotype. 7. Dorsal view. 8. Frontal view. 9. Female paratype, frontal view. All scale bars = 5 mm.

In the case of both of these new species, the first specimens were actually collected more than 40 years ago but remained “hidden” among specimens of A. calcaratus until we examined the collections containing them more closely. While it might seem that the striking male facial coloration both of these species exhibit should have resulted in their quick recognition as undescribed species, even seemingly obvious characters such as this can be overlooked when an otherwise great resemblance to a common, widespread species prevents their critical examination.

REFERENCES:

MacRae, T. C. 2000. Review of the genus Purpuricenus Dejean (Coleoptera: Cerambycidae) in North America. The Pan-Pacific Entomologist 76(3):137–169.

MacRae, T. C. 2003. Agrilus (s. str.) betulanigrae MacRae (Coleoptera: Buprestidae: Agrilini), a new species from North America, with comments on subgeneric placement and a key to the otiosus species-group in North America. Zootaxa 380:1–9.

MacRae, T. C. & C. L. Bellamy. 2013. Two new species of Actenodes Dejean (Coleoptera: Buprestidae) from southern Mexico, with distributional and biological notes on Buprestidae from Mexico and Central America. The Pan-Pacific Entomologist 89(2):102–119.

Copyright © Ted C. MacRae 2013

Observation and Bias in Biology

/ Kent / 11 Comments

The following is a guest post by my friend Kent Fothergill. Read more of Kent’s musings at his blog, biologistsoup.

Observation is a key activity in scientific inquiry. People who work with insects can make many interesting observations from collected insects: distribution, phenology, etc. Observations can be documented and analyzed later from photographs. A collection of photographs can also yield information about: associations with other species, behavior, while providing the same information as collected specimens – as such photography is a new tool changing entomology. Of course, most observations are made using only human senses without photographic or specimen documentation, but all observations can be subject to biases.

Observer biases are our evolutionary legacy. Our brains evolved to process and interpret data based on patterns observed in previously processed data. Because of the vast amount of data flowing in from our five senses and our limited ability to focus on data, our brains let most data be background. Even the subset of data that we focus our attention on is filtered, who hasn’t taken a photograph and found something much more interesting in the photograph than the original subject (e.g., these mites on harvestmen)? All data, even the data subset we are focused on can be misinterpreted. When teaching scientific methods, my students always enjoyed the optical illusion exercises to demonstrate why objective analyses and accurate measurement are important.

Remember, that the brain also compares incoming data to previous data. This allows pattern recognition. Recently, Ted and I were blacklighting along the Mississippi River in Southeast Missouri. We found a pair of Elaphidion mucronatum (spiny oak borer) a very common insect in Southeast Missouri. So common that many would move on to other more interesting subjects at that point. The insects were in a mate guarding situation.  Because I had a name for the behavior, my brain put my observation in the mate guarding category. At this point I would have moved on, except Ted wished to document the subject with his camera rig, which meant I would do what any friend should: watch the insects while Ted ran to vehicle to get his camera so he would be able to photograph them. While Ted was gone things got interesting. The male was positioned above the female, who was more or less caged between his legs. The pair was moving in unison on the tree trunk with very little actual contact between the pair. This was interesting, but when the female E. mucronatum suddenly shot out from under the male ending up 10’ vertical below him on the side of the tree trunk I was stunned. The male covered this distance with amazing speed and recaptured the female. After a couple minutes the female again shot out from under went down a few feet and doubled back ending out of sight above the male. At this point the male remained motionless for a brief period. When Ted came back with his camera, I took my eyes off of the male to tell him about what I had seen, and the male had vacated the area. Later, on the very same tree, we saw a mate guarding pair (presumably the same individuals) coming down towards us.

I have viewed many mate guarding insects. Mate guarding is a male insect using its body to prevent other males from mating with this female. Evolutionary biologists will explain mate guarding behavior in terms of enhanced male reproductive success, and that is why mate guarding persists. I never questioned this explanation, but should have. The E. mucronatum observation caused me to see mate guarding in a new way and realize that mate guarding involves a male and female component – I know this seems obvious, but I had my own cultural bias to overcome in this regard. I had never considered that mate guarding could involve non-willing females.

Based on a 10 minute observation of a very common insect my new understanding of mate guarding now recognizes that mate guarding influences female fitness also. Mate guarding persists when it creates a change in fitness in the male and female such that there is a positive net change in fitness for reproductive output for all individuals involved. In the case I witnessed, there may actually be a reproductive cost for the female and that is why she tried to avoid/escape the mate guarding. I have much more to learn about mate guarding.

Science is a way of objectively seeing the world and testing what you have seen to approach truth. This observation of E. mucronatum was also a mirror that showed my cultural bias and how that bias influenced my interpretation of my observations. For me, this observation could be a watershed event.

The moral(s) of this story:

  1. Life is short: enjoy time in the field with friends.
  2. Pay attention. There are new and wonderful things to observe even in the common and mundane.
  3. Be aware of the biases that can keep you from the truth.
  4. Have fun out there!

Copyright © Kent Fothergill 2013

“Blue-sky” tips and tricks

/ Ted C. MacRae / 4 Comments

For the past two years I’ve been working to refine my “blue-sky” technique for insect macrophotographs. This refers to careful balancing of camera and flash settings to achieve full-flash illumination of the subject while still allowing enough ambient illumination from the sky to produce a natural looking blue background. The use of flash, of course, is almost a necessity in insect macrophotography, as it’s nearly impossible to take hand-held photographs of insects, especially small ones, using only ambient light—there just isn’t enough of it to adequately illuminate the subject while using fast shutter speeds to prevent motion blur and high aperture settings to achieve acceptable depth-of-field. Flash illumination, however, has a drawback (actually several, but let’s focus on one)—if there isn’t something else close enough behind the subject to reflect light from the flash, the background will be jet black. In some cases this is perfectly fine, and it is almost always preferred over a cluttered background of jumbled branches and foliage. However, it usually doesn’t work well with darkly colored insects, and to me it gives the undesirable impression that the photo was taken at night. I suppose I could carry around colored cards to place behind the subjects that I photograph, but as a photographer who prides himself on the ability to take in situ field photographs of insects in their native habitats, something about the ‘artificiality’ of colored cards prevents me from resorting to them. A leaf placed behind the subject may be an acceptable alternative, but is usually possible only with quite small subjects (due to the size of the leaf needed) and is virtually impossible in dry, western habitats.

cf. Eremochrysa punctinervis | Gloss Mountains, Major Co., Oklahoma

cf. Eremochrysa punctinervis | Gloss Mountains, Major Co., Oklahoma

It’s hard to recommend specific camera settings for blue sky background, as they must be determined experimentally in each situation. The above photo of what I take to be Eremochrysa punctinervis (a green lacewing in the family Chrysopidae—identification via Frank & Slosser 1996) was taken with a 100mm macro lens set at f/16 and with ISO bumped up slightly to 320 (I normally use ISO 100–200) and shutter speed decreased slightly to 1/160 sec (I normally use 1/200 to 1/250 sec). The higher ISO makes the camera sensor more sensitive to light and the slower shutter speed allows more time for ambient light to reach the sensor. When aimed at the brightest part of the sky (next to but not right at the sun), these settings allowed sufficient light to register this beautiful shade of blue on the camera sensor. The ambient light alone is still not sufficient to illuminate the subject—if the photograph had been taken with these settings but without flash, the background would still be blue, but the subject and branch on which it is sitting would be nearly black! Only a flash pulse occurring while the shutter is open can provide enough light to fully illuminate the subject when the aperture setting is that high. In essence, the photo combines two exposures—a flash-illuminated subject and an ambient-illuminated sky.

Eremochrysa punctinervis | Gloss Mountains, Major Co., Oklahoma

Same photo before cloning out antennal shadowing

One problem that can be encountered when using this technique is the effect of wind. Holding the subject up against the sky exposes it to even the slightest of breezes, which can cause movement of delicate body parts such as the long antennae of this subject. What looks like blurring of the antennae is actually shading of the sky by the antennae as they fluttered in the wind. The antennae themselves were “frozen” by the very short flash pulse—much shorter than the 1/160 sec exposure, but they blocked enough light from the sky during the 1/160 sec exposure to darken the part of the background over which they moved. In the case of the finished photo shown at the beginning of the post, it was a relatively simple matter to use Photoshop’s cloning tool to remove the shadowing. Nevertheless, even more desirable is to avoid the need for such post-processing manipulations to begin with—waiting for a pause in the wind or moving to a more protected location would have obviated the need for PS cleanup.

REFERENCE:

Frank, W. A. & J. E. Slosser. 1996. An Illustrated Guide to the Predaceous Insects of the Northern Texas Rolling Plains. Texas Agricultural Experiment Station, Cotton DVD, Publication #MP-1718, 24 pp.

Copyright © Ted C. MacRae 2013