Hi -- I was visiting Guarulhos in Brazil recently, and I found these ants in a tree or bush interacting with other insects. I suppose they are Camponotus atriceps or Camponotus mus and the insects probably a kind of cicada. I have to send the picture to a outdoor photography magazine and I need the Latin name, at least the genus. The picture was taken at the gardens of the Cesar Palace Hotel near to the international airport. One of the photos is of what looks like to be the nest. Can you get to me information about the other insect or the plant?
Javier Castosa, Madrid, Spain
First, the bad news. I am sorry to say I cannot identify the plant in the pictures.
On the other hand, from the perspective of the AskAnt Team, you are really fortunate to have traveled to Brazil, one of the most ant-rich places in the world, where even an urban hotel garden can reveal fascinating aspects of ant behavior. The ants in your pictures are a species common both in the wild savannas and in gardens of that part of Brazil, namely Camponotus rufipes. (C. atriceps is a litttle smaller, and much shinier, and C. mus is considerably smaller with whiter hairs). When their nest is disturbed, C. rufipes can be very aggressive, delivering a strong bite into which they may squirt caustic formic acid. I had one draw blood from my finger one time, when I was doing field work in Brazil! It is one of the few ants that can do this.
The ants in your lovely pictures are associated with two types of sap-feeding insects, scale insects (round and featureless, Hemiptera: Coccidae) and planthoppers (colorful and cicada-like, Hemiptera: Fulgoroidea). Both of these animals excrete excess sugar and water from their plant sap diet in the form of honeydew (melaza in Spanish). Like many ants, C. rufipes is fond of sugar, and lingers around the honeydew "factory" to gather this waste product as it is produced by the sap-feeding bugs. you could say that one insect's garbage is another insect's treasure! The honeydew bugs in this relationship are sometimes referred to as ant-cattle. The ants also defend the bugs from parasites, predators, and competing ants.
This ant is known to make a nest of cut grass, a picture of which can be seen at the link in the next paragraph. Out in the savanna, this ant may nest in low, wet areas, and its nests may be suspended among grass stalks above the saturated ground, looking something like birds' nests. As your second picture shows, the ants also use bits of grass to build structures covering their "cattle", an additional way to shelter them from enemies. Partly chewed and glued-together plant fibers used by ants for construction are referred to as carton.
Here's a post about C. rufipes at one of our favorite blogs: http://myrmecos.net/2012/06/13/answer-to-the-monday-night-mystery-camponotus-rufipes/. Another post at the myrmecos blog lists this ant as the 48th most published ant species (among over 12,000 species to choose from). Your intention to publish these photos in an outdoor magazine will make them just a little bit more well-published.
James C. Trager & the AskAnt Team