How To Tell The Difference Between the Japanese Pavement Ant And The Common Pavement Ant


Urban ant collectors across temperate North America are undoubtedly familiar with the pavement ant Tetramorium caespitum*. This small brown insect is as common as dirt along sidewalks.

The pavement ant is not native here. Rather, it is a European species that proliferates in the novel habitats where Americans added cement and paving stone to previously uncapped, pavement-free soils. Since we love our sidewalks and our asphalt, we have created a lot of ant habitat and a lot of pavement ants.


Identification of the pavement ant in North America was straightforward until recently. Tetramorium caespitum is a small, blocky, brown ant with a squareish head, a two-segmented waist, a series of lengthwise ridges on the head, two nubbin-like spines on the propodeum, and an antennal socket with a distinct ridge as described here.

This diagnosis failed in the 1980s when an extremely similar species was introduced to St. Louis. The newcomer, the Japanese pavement ant Tetramorium tsushimae, is so similar in appearance to its European congener that correct identification even under high magnification involves measuring several body parts on a sample of workers and performing statistical analyses. On average, the new introduction is slightly smaller and with slightly larger propodeal spines. Your chances of nailing the ID based on a single worker aren’t great.

Tetramorium tsushimae
There is one easy identification trick that works pretty well at low magnification in the field, though. The trick is worth learning, because Tetramorium tsushimae appears to be more aggressively invasive than the common pavement ant and may become more common as it spreads from Missouri and Illinois.

Here’s the trick:

Colonies of the Japanese pavement ant usually host a great deal more color variation in the workers.

While older T. tsushimae are uniformly dark, the same as their European counterparts, younger workers are strongly bicolored, with a light thorax, giving colonies a more varied appearance. This difference should be visible in the photograph above.

Now that you can spot the difference, keep an eye out for T. tsushimae. It could show up many places where T. caespitum is currently king.

*sometimes called “Tetramorium sp. E.”, for reasons too lengthy to discuss here.

source: Steiner, Florian M., Birgit C. Schlick-Steiner, James C. Trager, Karl Moder, Matthias Sanetra, Erhard Christian, and Christian Stauffer. 2006. Tetramorium tsushimae, a New Invasive Ant in North America. Biological Invasions 8(2):117-123.


Public Talk, University of Kentucky: How The Digital Photography Revolution Is Good For Entomology



For those of you in Lexington, I’ll be giving a talk this Thursday on two of my favorite subjects: entomology and photography. Here are the details:

How The Digital Photography Revolution Is Good For Entomology

Alex Wild

Thursday, April 24, 2014
3:30 pm
Cameron Williams Auditorium
Plant Sciences Building
University of Kentucky

update: video of the talk will be posted here:

Wednesday Afternoon Mystery


Owing to a magical combination of travel and norovirus, I missed the Monday Mystery. To make it up to you, here’s an ant for you to identify:

I won’t award any points for our belated ant challenge, but you should feel free to bask smugly in the knowledge of your myrmecological acumen.


The Midwestern Ant Season Begins With Prenolepis Mating Flights

Prenolepis imparis

At noon, winged ants amass at the nest entrance in my front yard.

As a sign of how prolonged the 2013-14 winter has been, the Prenolepis imparis  winter ant mating flights did not occur here in Urbana until yesterday. That’s April 10th. The last time I photographed Prenolepis flights was in 2012- the same colony- and the ants flew a whole month earlier, on March 12.

I took a break from the email backlog (sorry! I know some of you are waiting on things from me, but it’s been a busy, busy month) to shoot the action. I hope you enjoy this batch of photos.

Prenolepis imparis

The queens and males climb nearby grass blades and some clumsily take to the air. Several queens are divebombed by incoming males- I presume from other colonies- and mate near their natal nest.

Continue reading →

Sorry Guys: No More Free Images for Scientific Papers


Dear scientists,

Owing to a series of recent incidents where my photographs have been used in technical papers without my consent, without credit, and released under Creative Commons licenses, I am sorry to announce I am ending my policy of free use of photographs for scientific papers.

Future use of my work will require a paid licensing agreement, the same as for most professional uses of copyrighted content. There are two exceptions. First, if I have photographed captive animals in your laboratory, those laboratories are allowed use of the associated images without additional permission, as long as those uses don’t involve releasing the images under a Creative Commons license. Second, use of the photographs as primary data should be considered fair use and is allowable.

Use of my images in presentations and classroom lectures is still allowable if credit is given, but please be aware that uploads of presentation slides to the internet requires a photo credit be given next to the image to prevent the appearance of being orphaned.

I regret having to tighten my policy, but my photo business has been my primary source of income for the past few years, and I cannot continue to afford producing and hosting natural history images for the myrmecological community to use if my guidelines are routinely sidestepped.

Thanks for understanding,


Little Fire Ants Conquer Hawaii


Among the smallest but most damaging pest insects is the little fire ant Wasmannia auropunctata, a Neotropical species that has been tearing across the Pacific region. The Maui Invasive Species Committee has assembled a nice short documentary on recent problems in Hawaii:


Answer to the Monday Mystery


As commenter Jenna B picked within minutes, Monday’s mystery flower was Theobroma cacao- the magical plant that so generously provides the world with chocolate- and it is pollinated by midges in the family Ceratopogonidae. In particular, the cacao pollinators are found in the large genus Forcipomyia. Here is one feeding not on a cacao nectary but from the hemolymph of a caterpillar.

Biting midge

Forcipomyia sp. (Belize)

So. Ten points to Jenna.

This brings us to the end of the month, and I am pleased to report we have a two way, ten point tie for March between Jenna B and Dave Almquist.

Congrats, Jenna & Dave! Email me for your loot.

Monday Night Mystery: Flower Power


Tonight’s challenge is more botanical than our usual fare. Here, for your consideration, is a flower:


1. What species is this? (4 points)
2. What insect (Family or genus) pollinates this plant? (6 points)

To earn points, be the first person to correctly answer each question. The cumulative points winner for the month of March will win their choice of:

1) A guest post here on Myrmecos
2) Any 8×10 print from my insect photography galleries
3) A myrmecos t-shirt

Good luck!