Tag Archives: Carpenter ant

If I were to use Ted MacRae’s new Revised Key to Formicidae of North America, this could be a hybrid between Formica meganigra (big black ant) and Formica rubra (red ant). Note the black head and gaster and the curious red thingy between – not a feature found in the revised key.

Formica ulkei

I decided to look into this further, so I contacted the trusty AlbertaBugs hotline and submitted my picture for scrutiny. Among those who responded was the indefagatable indefegatable indafegable intrepid James Glasier, a MSc. Candidate for Conservation Biology at the University of Alberta. His answer?

…its hard to tell, its great picture but without seeing the head straight on I can’t say for sure. The colour (head and thorax red, gaster black), the lack of erect seta on the thorax, and the sharp petiole, suggests that it is Formica aserva.  They often have a gaster that have an underlying “red” colour.  However, it could be an ant from the Formica ‘rufa’ group as well, but around here they usually have more erect setae and have some sort of black infuscation on their thorax and head.

OK, some hesitation here. Others thought it a  Camponotus species, the big Carpenter ant –  but James wouldn’t stand for it! Said the myrmercological master:

Though Camponotus is similar, they have a mesosomal profile that is evenly convex which separates the genus Camponotus from Formica and Lasius.  This specimen has a mesosomal profile interrupted at the metanotal groove (at about the middle of the thorax you can see there is a pinched area where the posterior part of the thorax looks lower) so it would it would then either Lasius or Formica.  Lasius are stout little ants, usually brown, orange,or yellow, and around here are not bicoloured, so this ant is not a Lasius because of the colour, but it also has longer legs and thorax compared to what a Lasius would have, so it is therefore a Formica.  And like I said in my previous email, it looks to me like Formica aserva because of the lack of erect setae on its back and the colouration.

Was I fazed by this talk of “mesosomal” and “metanotal“? It was but a moment for me to peruse my trusty volume of Wikipedia, arm myself with scissors and then proceed to cut-out and paste this helpful image:

Ant Anatomy

Formica ulkei, cropped from original image

There we go, all explained. Yet the mystery remained – we were still off the mark. Did I quake at the indecisiveness of it all? No! Boldly, I emailed a second image featuring a head shot of the ant, her formidable mandibles open in a threatening display of anty…threateningness.

James didn’t falter. The head-shot, though indistinct, told him all he needed to know. (Read it and weep, ye that would revise the Formicidae!)

That is Formica ulkei, the head shot makes it clearer.  The back of the head has the classic concave shape, plus its darker on the back of the head instead of the front.  In a completely different Formica group then I first thought.  Formica ulkei is in the Formica “exsectoides” group.

Thank you, James!

Our mystery ant has been identified, and all is well with world…

N.B. James has indicated that it should read “Formica ‘exsecta’ group“, as ‘exsectoides’ is the species name (as can be seen at Alex’s site below).

Late Addition: Alex Wild has photographs of Formica exsectoides at Myrmecos.net

(Formica ulkei Emery, photographed in Elk Island National Park, 26 April, 2010. Nikon D80 with Tamron 90mm macro lens mounted on Kenko Pro 1.4x tele-extender. Nikon R1 unit with 2 diffused flashes.)

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