Lepidoptera

A striking mallow caterpillar

/ Ted C. MacRae / Leave a comment
Tarache delecta ("mallow caterpillar") on Hibiscus lasiocarpus | Hickman Co., Kentucky

Tarache delecta (“mallow caterpillar”) on Hibiscus lasiocarpus | Hickman Co., Kentucky

Last month while searching stands of Hibiscus lasiocarpus (hairy rose mallow) in western Kentucky, I encountered this rather large caterpillar feeding on the foliage. I presumed that something as large and striking in appearance as this should be a cinch to identify by scanning through photos on BugGuide, and not surprisingly I found photographs (here, here and here) of two very similar looking caterpillars from Oklahoma posted by Charles Schurch Lewallen. None of the photos, however, had an identification associated with them other than subfamily Acontiinae (family Noctuidae). The contributor mentioned in one of the photos that he had found nothing similar in the Wagner (2005) “bible” (a book that I do not yet own but hope to soon). Armed with this scant information (but definitive knowledge of its host plant), I searched Noctuidae of North America and settled on Tarache delecta as a good possibility. According to that site, T. delecta is the only member of the Acontiinae that feeds on plants in the genus Hibiscus. The site references Crumb (1956) for a larval description, but more useful was a plate of black & white photos that I found in Weiss (1919) and that seemed to be a good match for the species I had photographed. Weiss (1919) refers to the larva as the “mallow caterpillar” and notes that full grown larvae are 34–36 mm in length and dark purple with black spots edged with orange—consistent with the caterpillar shown here.

Apparently this species has been considered a pest of ornamental mallows. Weiss (1919) notes that the larvae feed on the upper and lower leaf surfaces usually near the margins, making large holes in the leaves and sometime devouring parts of the bracts around the buds. I will also note that, in recommending control of the caterpillars, he states that “there does not seem to be any reason why spraying with arsenate of lead should not be successful.” My, how times have changed!

REFERENCE:

Crumb, S. E. 1956. The larvae of the Phalaenidae. U. S. Department of Agriculture, Technical Bulletin 1135, 356 pp. + 10 plates [Google Books].

Wagner, D. L. 2005. Caterpillars of Eastern North America: A Guide to Identification and Natural History. Princeton University Press, Princeton, New Jersey, 512 pp. [Amazon].

Weiss, H. B. 1919. The more important insect enemies of the rose-mallow in New Jersey. New Jersey Department of Agriculture, Bureau of Statistics and Inspection Circular 25, 9 pp. + 4 plates [Google Books].

© Ted C. MacRae 2014

Southern armyworm feeding on soybean

/ Ted C. MacRae / 4 Comments
Southern armyworm (Spodoptera eridania) late-instar larva feeding on soybean.

Southern armyworm (Spodoptera eridania) late-instar larva feeding on soybean.

Here is another animated gif that I made recently, this one showing a late-instar larva of southern armyworm (Spodoptera eridania) feeding on soybean (Glycine max). This polyphagous species is widely distributed from the southern U.S. through the northern half of South America and feeds on a variety of weeds, especially pigweed (Amaranthus spp.) and pokeweed (Phytolacca americana). It also occasionally attacks vegetable, fruit, and ornamental crops; however, in recent years it has become increasingly important on cultivated soybean in Brazil and Argentina, especially in regions where cotton is also cultivated. As a result, they have become one of the insects that I deal with regularly in my own research. More information on this and other armyworm species that affect soybean can be found in my earlier post, Quick Guide to Armyworms on Soybean.

Like many other lepidopteran caterpillars that feed on foliage, late-instar larvae become “feeding machines” that remain active both day and night as they try to cram as much nutrition into their expanding bag of a body as possible in preparation for an adult life focused solely on finding mates and laying eggs. Large larvae actively feeding during the day can be rather conspicuous, and as a result they often secrete themselves on the undersides of the leaves while feeding to make themselves less visible to predators. As they feed, however, a “window” opens up that gradually eliminates their cover. Rather than remaining in the same spot and feeding until they are completely exposed, however, larvae will move when the feeding hole reaches a certain size and find another place to conceal themselves before resuming feeding. Different caterpillar species have different exposure tolerances, and as a result, this combines with slight differences also in preferred tissue types to create recognizable differences in the damage patterns resulting from feeding by different species.

For those interested, making these animated gifs is really simple and allows those of us without expensive macro-video gear to simulate short videos of insect behavior. I make my animated gifs at GIFMaker.me—all you do is take a series of photos, touch them up in photo editing software (I use Photoshop Elements to adjust levels, color and sharpness), upload them to the site in the sequence desired, and click “Create Now”. It couldn’t be easier! You don’t even need a “real” camera—I took the photos for this gif with my iPhone using the “burst” function to take a rapid sequence of photos (all you do is hold your finger down on the shutter button for the desired length of time).

© Ted C. MacRae

A time of reckoning

/ Ted C. MacRae / 11 Comments

The sun shall be turned to darkness and the moon to blood, before the day of the Lord comes, the great and magnificent day.

A "super moon" watches over a parasitized hornworm caterpillar.

A “super moon” watches over a parasitized hornworm caterpillar.

I’m not normally one to quote Bible passages, but this line from Acts 2:20 seems appropriately ominous for the predicament of this poor hornworm caterpillar. The white objects on its back are the cocoons of tiny parasitic wasps in the family Braconidae who spent their entire lives inside the body of the growing caterpillar slowly eating away the inner tissues of the caterpillar, eventually consuming all but the most essential of its internal organs before exiting the skin and spinning their tiny, silken cocoons. Inside the cocoons the tiny grubs transformed into adult wasps, chewed their way out through the tip of the cocoon, and flew off to mate and find more hornworm caterpillars to parasitize. Its unwelcome guests now gone, this poor caterpillar has nothing to do but to sit and await its inevitable demise (which I suspect the caterpillar will not regard as such a “great and magnificent day”).

I found this caterpillar resting on a vine climbing a tree along the Mississippi River in southeast Missouri after setting up an ultraviolet light nearby and noticing the softly glowing cocoons. I was going to photograph it in situ, but I’ve learned that choice of background can have a dramatic effect on insect photographs, and the jumble of weeds and tree bark that would have comprised the background had I photographed the caterpillar where it sat seemed decidedly boring. I looked up and saw the blood red moon (a so called “super moon”) rising above the river in the eastern sky and decided to give it a try. The above photograph is actually a composite of two photographs—one of the caterpillar taken with flash and fairly normal camera settings, and another of the moon itself with aperture, shutter speed, and ISO all adjusted for very low light conditions (at least to the extent possible without a tripod). While this may not qualify in some people’s minds as a “real” photograph, it is nevertheless a true representation of what I actually saw, as I also made a number of attempts to capture both the insect and the moon in a single exposure. Since it is impossible to have both the insect (very close) and the moon (very far) in focus at the same time, the resulting photograph has a different, though still striking, effect, as shown in the photograph below:

IMG_6919_enh_1080x720

A more surrealistic version of the above photograph, with both caterpillar and moon captured in a single exposure.

This second photograph is actually much harder to take, as the moon does not appear in the viewfinder as the small, discrete, fuzzy-edged object resulting in the image, but rather as a large, blinding light that is difficult to place within the composition and know exactly where it will end up (at least, without a lot of trial and error). Add to that the fact that my camera image and histogram display panel is, at the moment, not functional, forcing me to “guess” if I had the right settings (in a situation where I’m well outside of my ‘normal’ settings for flash macrophotography). I’m a little surprised that I ended up with any usable photographs at all!

I’ve tried this type of photography with the sun as well—those interested to see how those photographs turned can find them at Sunset for another great collecting trip and Under Blood Red Skies.

© Ted C. MacRae 2014

Not all soybean caterpillars are ‘ugly’!

/ Ted C. MacRae / 4 Comments

Although photographs of beetles dominate this site (they are my true love, after all), I am nevertheless an agricultural entomologist by day and, as such, find occasion to post photos of the insects I encounter in my area of expertise—soybean. I think by and large those soybean insects—especially the caterpillars—don’t generate as much interest as the beetles that I feature. I guess this is understandable—caterpillars of the agricultural pest variety seem generally unable to compete with the visual and behavioral charisma exhibited by jewel beetles, tiger beetles, tortoise beetles, etc. Here, however, is an example of a soybean caterpillar that is as beautiful as any beetle you will find—the larva of the silver-spotted skipper, Epargyreus clarus (Lepidoptera: Hesperiidae). Not only are the colors to die for, but that comically big head makes for a truly laughable frontal portrait!

Epargyreus clarus (silver-spotted skipper) late-instar larva on soybean | Baton Rouge, Louisiana

Epargyreus clarus (silver-spotted skipper) late-instar larva on soybean | Baton Rouge, Louisiana

This particular individual was found last September in a soybean field near Baton Rouge, Louisiana (amazingly, this is the first insect I have featured from Louisiana). Silver-spotted skippers feed on a wide variety of plants in the family Fabaceae (of which soybean is a member), but their occurrence on soybean rarely reaches levels that cause any economic impact. Normally the caterpillars hide during the day in a silken nest constructed by folding over a leaflet or tying adjacent leaflets together, emerging only at night to feed.

What a pretty face!

What a pretty face!

I suppose the orange spots on the head are intended to serve as false eye spots—for some reason the larger the eyes the more a potential predator seems to take pause before deciding to eat something. The actual eyes can be seen along the outer edge of the orange spot as a row of simple ocelli—incapable of forming sharp images and serving as little more than light and motion detectors. I can’t even begin to speculate on the function of the curious asperate/rugose texture of the head!

Copyright © Ted C. MacRae 2014

Best of BitB 2013

/ Ted C. MacRae / 14 Comments

Welcome to the 6th Annual “Best of BitB”, where I pick my favorite photographs from the past year. Like last year, 2013 was another year of heavy travel. For work I did my annual tour of soybean field sites throughout Argentina during late February and early March, then cranked it up for my own field season with frequent travel to sites in Illinois and Tennessee from May to October. In the meantime I spent a week at company meetings in Las Vegas in August, toured field sites across the southeastern U.S. for two weeks in September, visited Argentina again in October to finalize research plans for their upcoming season, and finished off the travel year by attending the Entomological Society of America (ESA) Meetings in Austin, Texas during November. On top of all this, I managed to slip in two of the best insect collecting trips I’ve had in years, with 10 days in northwestern Oklahoma in early June and another 10 days in California, Nevada, Utah, and Colorado during late August, and I got to play “visiting scientist” during short trips to Montana State University in late July and the Illinois Natural History Survey in late October! Of course, during my brief interludes at home I wasn’t sitting still, giving entomology seminars to several local nature societies and hosting two ESA webinars on insect photography. Needless to say, come December I was more than ready to spend some quite time at home (well, except for hiking most weekends) and am happy to report that I’ve successfully become reacquainted with my family and office mates. It’s a peripatetic life—and I wouldn’t have it any other way!

Okay, let’s get down to business. Here are my favorite BitB photographs from 2013. This year was less about learning new techniques as it was about refining the techniques I’ve found most useful for the style I’ve chosen as a photographer, i.e., hand-held, in situ field shots that (hopefully) excel at both natural history and aesthetic beauty. Links to original posts are provided for each photo selection, and I welcome any comments you may have regarding which (if any) is your favorite and why—such feedback will be helpful for me as I continue to hone my craft. If you’re interested, here are my previous years’ picks for 2008, 2009, 2010, 2011, and 2012. Once again, thank you for your readership, and I hope to see you in 2014!

Tremex columba, female ovipositing | Sam A. Baker State Park, Missouri

Tremex columba female drilling for oviposition into hardwood trunk | Sam A. Baker State Park, Missouri

From Ovipositing Pigeon Horntail (posted 6 Jan). I like this photo for the combination of vibrant, contrasting colors between the wasp and moss-covered wood and the visualization it provides of the remarkable depth to which this wasp will insert its ovipositor into solid wood!

Eurhinus cf. adonis on Solidago chilensis | Chaco Province, Argentina

Eurhinus cf. adonis on Solidago chilensis flowers | Chaco Province, Argentina

From Giving me the weevil eye! (posted 28 Apr). While a little soft, the color combination is pleasing and the pose taken by the beetle almost comically inquisitive.

Helicoverpa gelotopeon feeding on soybean pod | Buenos Aires Prov., Argentina

Helicoverpa gelotopeon feeding on soybean pod | Buenos Aires Prov., Argentina

From Bollworms rising! (posted 30 Mar). This is the first photo of an economic pest that has made one of my “Best of BitB” lists. The two holes in the soybean pod, one with the caterpillar and its head still completely inserted, visualizes how the feeding habits of these insects can so dramatically affect yield of the crop.

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

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

From “Blue-sky” tips and tricks (posted 1 July). Insects with a lot of delicate detail and long, thin appendages are especially difficult to photograph against the sky due to wind movement. See how I dealt with the antennae of this delicate lacewing without resorting to the standard black background typical of full-flash macrophotography.

Cicindela scutellaris lecontei x s. unicolor

Cicindela scutellaris lecontei x s. unicolor intergrade | Holly Ridge Natural Area, Stoddard Co., Missouri

From The Festive Tiger Beetle in Southeast Missouri (posted 25 Oct). I like this photo a lot more now than I did when I first took it. Its shadowy feel and the beetle “peering” from behind a leaf edge give a sense of this beetle’s attempts to hide and then checking to see if the “coast is clear”

Batyle suturalis on paperflower (Psilostrophe villosa) | Alabaster Caverns State Park, Woodward Co., Oklahoma

Batyle suturalis on Psilostrophe villosa flowers | Alabaster Caverns State Park, Woodward Co., Oklahoma

From Tips for photographing shiny beetles on yellow flowers (posted 10 Aug). “Bug on a flower” photos are a dime a dozen, but shiny beetles on yellow flowers with natural sky background can be quite difficult to take. All of the techniques for dealing with the problems posed by such a photo came together nicely in this photo.

Agrilus walsinghami | Davis Creek Regional Park, Washoe Co., Nevada

Agrilus walsinghami | Davis Creek Regional Park, Washoe Co., Nevada

From Sunset for another great collecting trip (posted 1 Sep). This photo is not without its problems, with a little blurring of the backlit fuzz on the plant, but the placement of the sun behind the subject’s head and resulting color combination make it my favorite in my first attempts at achieving a “sun-in-the-sky” background with a true insect macrophotograph.

A tiny male mates with the ginormous female.

Pyrota bilineata on Chrysothamnus viscidflorus | San Juan Co., Utah

From Midget male meloid mates with mega mama (posted 8 Nov). Another blue-sky-background photograph with good color contrast, its real selling point is the natural history depicted. with some of the most extreme size dimorphism among mating insects that I’ve ever seen.

Phymata sp.

Phymata sp. on Croton eleagnifolium foliage | Austin, Texas

From ESA Insect Macrophotography Workshop (posted 13 Nov). The oddly sculpted and chiseled body parts of ambush bugs makes them look like they were assembled from robots. Contrasting the body against a blue sky gives a more unconventional view of these odd beasts than the typical top-down-while-sitting-on-a-flower view.

Fourth attempt - holding detached pad up against sky for cleaner background.

Moneilema armata on Opuntia macrorhiza | Alabaster Caverns State Park, Woodward Co., Oklahoma

From Q: How do you photograph cactus beetles? (posted 24 Nov). Photographing cactus beetles requires patience, persistence, long forceps, and strong forearms. Natural sky provides a much more pleasing background than a clutter of cactus pads and jutting spines.

I hope you’ve enjoyed this 2013 version of “Best of BitB” and look forward to seeing everyone in 2014.

Copyright © Ted C. MacRae 2013

Party on a pin oak

/ Ted C. MacRae / 9 Comments

In September 2012 while collecting in western Oklahoma (Weatherford) I came across this interesting scene. It had been exceedingly dry in the area, and because of this few insects were out and about in the small city park that I stopped by to check for the presence of tiger beetles. I had nearly completed my circuit of the park when I came upon a moderate-sized pin oak (Quercus palustris) tree and noticed something on the lower trunk:

Six insect species representing five families in four orders share a sap flow.

Six insect species representing five families in four orders share a sap flow on the trunk of a pin oak.

No less than six insect species representing four orders were seen all huddled together at a darkly stained sap flow. This could be the result of slime flux, a bacterial disease that usually affects deciduous hardwoods that are under stress and results in darkly stained weeps on the trunk that are known to be attractive to a variety of insects. At the center sat a green June beetle (Cotinis nitida) and three bumble flower beetles (Euphoria inda)—all in the family Scarabaeidae (subfamily Cetoniinae). Covering the scarab beetles were half a dozen Texas Tawny Emperor (Asterocampa clyton texana) butterflies (family Nymphalidae, or Brushfooted Butterflies), and milling around the perimeter was a velvet ant (Dasymutilla creusa, I believe) in the family Mutillidae, an apparent flesh fly (family Sarcophagidae), and a true ant (family Formicidae). I guess this would be the equivalent to a watering hole in Africa with a lion, a hyena, a baboon, three vervet monkeys and six zebras all crouched shoulder-to-shoulder at its edge.

Euphoria sepulchralis feeds on a sap flow higher up on the trunk.

Euphoria sepulchralis feeds on a sap flow higher up on the trunk.

Further up on the trunk, yet another species of scarab beetle, a dark flower scarab (Euphoria sepulchralis) was found feeding on a smaller sap ooze. Unlike the diverse aggregation of insects on the lower ooze, this guy had managed to keep the ooze all to himself.

Cotinus nitidus | Weatherford, Oklahoma

Cotinis nitida | Weatherford, Oklahoma

Green June beetles, especially, are known for their feeding on sap oozes. The beetles are actually attracted to the odors caused by fermentation of the sap rather than the sap itself. It has been reported that the presence of alcohol in fermenting sap can affect the behaviour of insects that feed upon it, causing them to act “stupid and lethargic.” I did not see any such behavior, but I did notice that the insects were not at all skittish and loath to leave the sap.

Copyright © Ted C. MacRae 2013

One-shot Wednesday: Hawk moths suck!

/ Ted C. MacRae / 9 Comments
Hyles lineata nectaring at flowers of Ericameria nauseosa | San Juan Co., Utah

Hyles lineata nectaring at flowers of Ericameria nauseosa | San Juan Co., Utah

I admit it—I give short shrift to Lepidoptera compared to other groups of insects. This is not because I don’t think they deserve attention; they are a stunning group with an amazing suite of adaptations to life on earth. It’s just that they already receive a lot of attention from others, while so many other equally amazing groups of insects remain almost completely unknown and under-appreciated due to the sole fact that they are smaller and less conspicuous. I’m not anti-Lepidoptera; I’m just pro-other Insecta. Every now and then, however, I must give Lepidoptera their due, and since today is Wednesday it’s a good day to feature a hawk moth that I got but a single photograph of on my late August Great Basin collecting trip.

Hyles lineata is not a particularly rare insect—in fact, it is one of the most common and widespread species of hawk moth (family Sphingidae) in North America. What is hard to come by, however, is a good shot of an adult nectaring at a flower. While such shots abound, most feature busy backgrounds and blurred wings. My photo is no different. However, I am a coleopterist, and when I took this shot there were also longhorned beetles present on the same flowers—it could be considered remarkable that I even diverted my attention long enough to attempt a shot. Of course, hawk moths are amazing creatures that have independently arrived at the same flight abilities and feeding habits as the equally amazing but taxonomically distant hummingbirds with their ability to hover motionless while sipping nectar and beating their wings at blinding frequencies. With little time to practice and even less to optimize settings, I’m amazed that I even got an adequate photograph before the moth zipped off to another bush. Yes, hawk moths suck, and that is amazing!

Copyright © Ted C. MacRae 2013

Hooray for iStock—I finally have an ID for my photo

/ Ted C. MacRae / 16 Comments

I was all set to make a “One-Shot Wednesday” post today, but sometimes big news strikes and plans must change. The news today was in the form of a random tweet by Alex Wild:

iStock-caption_Wild-20131120

The link in the tweet led me to the following photo on iStock by Getty:

bedbug has captured worm

I was stunned—the photo depicted a scene almost identical to one that I had photographed back in September while visiting soybean fields in Louisiana. For two months I sat on the photo with no idea what I was looking at, but now thanks to Alex I have my answer! Compare the above photo with mine below, and you’ll see that everything matches perfectly—I had photographed a “bedbug” that had captured a “worm”!

Podisus maculiventris preying on Chrysodeixis includens larva

bedbug captures a worm

I considered myself to be fortunate, because there was not just one but two different subjects in the photo, and both of them matched perfectly with the subjects shown in the iStock photo. Gotta love the internet—nowadays names for even the most hard-to-identify bugs are just a click away if you know where to look!

</snark>

Of course, the aggressor in both photos is not a “bedbug” [sic for “bed bug”] (order Hemiptera, family Cimicidae) but a stink bug (family Pentatomidae), specifically Podisus maculiventris, or “spined soldier bug”—perhaps the most common predatory stink bug in North Amerca and ranging from Mexico and parts of the West Indies north through the U.S. into Canada. It is a well-known predator of crop pests and, as such, has been imported to several other countries as part of classical biological control efforts. As for the “worm,” in my photo it is a late-instar larva of Chrysodeixis includens, or “soybean looper, and while I haven’t been able to identify the exact species in the iStock photo it is definitely a lepidopteran caterpillar that appears to related to if not in the same family as the soybean looper (Noctuidae). Now, I concede that “worm” is sometimes used for lepidopteran larvae, but one must also concede that in it’s broadest sense “worm” can refer to members of several disparate phyla such as Nematoda (roundworms), Platyhelminthes (flatworms), or Annelida (segmented worms).

This case, of course, just screams for application of the Taxonomy Fail Index (TFI), which scales the amount of error in a taxonomic identification in absolute time against the error of misidentifying a human with a chimpanzee—our closest taxonomic relative. For example, when TFI = 1 the error is of the same magnitude as mistaking a human for a chimp, while  TFI > 1 is a more egregious error and TFI < 1 a more forgivable one. In the case shown here, one must go back to the common ancestor that eventually gave rise to all of the worm phyla and noctuid moths (~937.5 mya). In addition, since there are two subjects in the photo, one must also go back to the divergence of the main hemipteran groups that contain bed bugs and stink bugs (mid-Triassic, ~227.5 mya). This results a whopping 1.165 billion total years of divergence between the identifications assigned to the subjects in the iStock photo and their actual identity. Assuming that chimps and humans diverged approximately 7.5 mya, this gives a TFI for the iStock photo of 155! I haven’t searched thoroughly to determine whether this is a record for the highest TFI in a single photo, but surely it is a strong contender!

Copyright © Ted C. MacRae 2013