entomology

Friday Beetle Blogging: The Eyed Elater

Alaus1Alaus oculatus (Elateridae) – The Eyed Elater
Illinois

One of North America’s largest beetles, the eyed elater is more than an inch long.  Alaus oculatus is widespread in the deciduous forests of eastern North America where their larvae are predators of wood-boring beetles.  Other species of Alaus occur in the south and west.  This individual was attracted to a pheromone trap intended to bring in longhorn beetles as part of a University of Illinois study on beetle pheromones, a ready demonstration of how predators may exploit the chemical signaling of their prey.

This particular beetle has been around the block already, apparently. Many of the hairs have worn off and both antennae are missing segments. Still, a striking insect.

Alaus2

photo details: Canon 100mm f2.8 macro lens on a Canon EOS 50D
ISO 100, f/11, 1/160 sec (top) 1/125 sec (bottom), indirect strobe in a white box

The Phantom Ant of the Florida Dunes

phantasma1

Paratrechina Nylanderia phantasma
Archbold Biological Station, Florida

Here’s an ant I almost didn’t notice.  Paratrechina Nylanderia phantasma is one of the least known insects in North America, active at night and restricted to a particular type of sandy soil in Florida.  Workers are only a couple millimeters long and the color of sand.  In the field they appear as ghostly little shapes skirting across the ground, scarcely visible even to those looking for them.

Incidentally, N. phantasma was named and described by James Trager, a frequent commentator here at Myrmecos Blog. Perhaps, if we’re really nice to him, James will tell us something more about this little ant.

[update 1/12/10, taxonomic change to Nylanderia]

photo details: Canon MP-E 65mm 1-5x macro lens on a Canon EOS 50D
ISO 100, 1/250 sec, f13, flash diffused through tracing paper

A Guide to the Insect Field Guides of North America

Eli

The summer insect season is upon us here in temperate North America, and with it comes the need for good identification guides.

Before I begin, a cautionary note.  We have so many species on our continent that were we to create a bird-type guide that listed all the insects, with their ranges and identifying characteristics, the full set would span at least 30 volumes.   Any book small enough to carry into the field necessarily omits more than 95% of the relevant animals.  Insect guides are understandably neurotic and overwhelmed compared to the corresponding bird and plant guides, and it’s worth remembering that guides represent the author’s judgment about which species are the most likely to be encountered.  With no guarantee, of course, that the mysterious bug in your hand is common.  Proper identification to species normally requires examination of a preserved specimen under high magnification with reference to the original taxonomic literature.

Having said all that though, let’s throw caution to the wind.  Here is my completely biased opinion* of the most prominent North American insect guides.

Kaufman1Kaufman Field Guide to Insects of North America.  The Kaufman guide was only published in the last couple years, but in that short period has become the first book I consult.   The reason is simple. This guide, written by Eric Eaton and Kenn Kaufman, makes no bones about being strictly an identification tool.  The pages are packed with stylized photos, stripped from their habitats and laid out next to each other for easier identification.  By skimping on the amount of text provided for each species, Eaton & Kaufman cover a broader array of species than competing guides- more than twice the number as the NWF guide, in fact.  An insect is more likely to show up in the pages of this guide than any other. Of course, the lack of accompanying biological detail is frustrating, but that’s the price of achieving both the smallest size and the greatest coverage. Highly recommended.

nwf1National Wildlife Federation Field Guide to Insects and Spiders of North America. This handsome volume, authored by Art Evans, stands out for the depth of information provided for the illustrated species.  The photographs- many taken by the author- depict animals in their habitat, and the guide is among the most aesthetically pleasing books on the market.  The inevitable trade-off of providing more text per species is that fewer species are covered.  The NWF guide is not as likely to lead the reader to an identified insect as is the Kaufman guide, but the natural history detail in the text is much more satisfying for those insects that are included. Highly recommended.

nas1National Audubon Society Field Guide to Insects and Spiders. Decades out of date, riddled with creative misidentifications, and arranged in an utterly nonsensical manner, this book will provide hours of surreal amusement.  Some bugs are included with the beetles.  There are moths in the wasps, and flies in the bees, except for the ones placed with the ticks.  Or spiders.  In the book’s defense, the faux-leather binding is flexible and durable in the field, perhaps the most field-worthy of the lot, so you’ll be able to abuse this book for years and still be able to misidentify your insects just as easily as when it was new.  My advice?  Don’t bother.  Not recommended.

peterson1Peterson’s A Field Guide to Insects.  Peterson’s is the grandaddy of insect guides, now several decades past the original printing and slipping out of date, and digestable only by the already entomologically literate.  The vocabulary is technical, some of the characters arcane, and the illustrations are based on preserved specimens rather than live insects.  Non-specialists may lack the technical chops to properly use this guide. Or is it another sign that today’s kids just aren’t as smart as they used to be?  But I digress. For the persistent naturalist, the Peterson’s Guide offers the best hope for identifying rare and unusual insects short of consulting the original taxonomic monographs.  It’s a rigorous, professional, and satisfying guide.  If you’ve already passed Ent 101, that is.  Recommended only for more advanced users.

*disclaimer: The Kaufman and the NWF guide both licensed images from myrmecos.net in exchange for fistfuls of cash.

These are a few of my favorite stings…

…well, not really.  But an exchange I had at Photo Synthesis with Andrew Bleiman of Zooillogix got me thinking about all the different insects that have charmingly envenomated me at one time or another.

Myrmecia piliventris, Australia
Myrmecia piliventris, Australia

So I’m starting a meme called Things That Have Stung Me.  The rules are simple:

  1. List all the things that have stung you.
  2. Bites don’t count.
  3. Pass the meme to 3 or more other bloggers you suspect have also been well-zinged.

Here are mine.

Things that have stung me: (more…)

The stench of the living

humile29

It has long been known that ants recognize their deceased nestmates using the smell of fatty acids that accumulate as the body decomposes.  The chemical signature of deadness helps ants remove the corpses from their midst, keeping a clean and sanitary nest. Indeed, this classic tale of ants and oleic acid is one of E. O. Wilson’s favorite stories.

But it turns out that the story is even richer than previously supposed.  A study by Dong-Hwan Choe et al published in yesterday’s PNAS note that Argentine ants (Linepithema humile) carry away the dead even before the fatty acids appear.  It seems that the ants not only recognize the scent of death, they also pick the scent of life.  (Apparently, life smells of “dolichodial” and “iridomyrmecin”.)  Here’s the abstract:

Abstract: One of the most conspicuous and stereotyped activities of social insects such as ants and honey bees is necrophoresis, the removal of dead colony members from the nest. Previous researchers suggested that decomposition products such as fatty acids trigger necrophoric behavior by ant workers. However, fatty acids elicit both foraging and necrophoric responses, depending on the current nest activities (e.g., feeding or nest maintenance). Furthermore, workers often carry even freshly killed workers (dead for <1 h) to refuse piles before significant decomposition has a chance to occur. Here, we show that the cuticular chemistry of Argentine ant workers, Linepithema humile, undergoes rapid changes after death. When the workers are alive or freshly killed, relatively large amounts of 2 characteristic ant-produced compounds, dolichodial and iridomyrmecin, are present on the ants’ cuticle. However, these compounds disappear from the cuticle within about 1 h after death. We demonstrate how this phenomenon supports an alternative mechanism of ant necrophoresis in which the precise recognition and rapid removal of dead nestmates are elicited by the disappearance of these chemical signals associated with life.

Source: Dong-Hwan Choe, Jocelyn G. Millar, and Michael K. Rust. 2009. Chemical signals associated with life inhibit necrophoresis in Argentine ants. PNAS 2009 : 0901270106v1-pnas.0901270106.