Ant behavior: October 2011 Archives

I was in Corcovado National Park in Costa Rica where I took this photo (sorry about the quality) of what I think is Camponotus sericeiventris. As you can see, the ant is walking over a sticky, black substance with no apparent problem. The whole trunk of the tree was covered in this substance - is it anything to do with the ants?

Many thanks

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Thank you for contacting AntBlog and including an image. We contacted an expert on the ants of Costa Rica, Dr. John T. Longino, to address your question. Here is what Dr. Longino had to say:

"Your ant is indeed Camponotus sericeiventris. I've often seen tree trunks with black, sticky, oozy areas, and ants often seem to be attracted to them. I have always surmised that these are tree infections, a result of wounds and/or pathogens, and that the tree sap is oozing out and evaporating, making a sweet exudate that ants might like. I doubt that the ants are the cause of the exudate.

From the look of your image, the area looks wet but not super sticky. Ants have no problem walking over wet surfaces. Also, if a sticky surface gets a "skin" of moisture or dryness, that would make it easy for an insect to walk over. We might touch a surface and break that thin surface layer, contacting the sticky material below. So a surface that seems sticky to us might not be to an insect.

By the way, I did my graduate work in Corcovado, back in early 1980's, and developed my love of ants there."

John "Jack" Longino (guest expert), Corrie Moreau & the AntAsk Team


I would like to know if there is any sense to make out of the strange behavior I witnessed an ant making in my house.

I live in Long Island, NY and I guess the type of ant was a regular black carpenter ant. The first thing that struck me odd was that it had a very narrow thorax, almost like it was pinched in...But that might be 100% normal and I've just never looked that hard at an ant before.

The second thing that struck me odd was that it was standing still and seemed to be jittering its legs while they were planted on the floor, almost like wobbling them. I thought maybe it was neurological damage? Poison? I don't know.

I decided to get some cookie crumbs and a plastic cup so I can try to feed it and observe it for a little while. It did eat a bit which made me feel better. The next strange behavior I saw was that it started grooming the hell out of itself, almost manically as if it was on speed, then it proceed to bite at the bottom tip of it's abdomen. It was freaky; I thought maybe it was pregnant and ready to pop out some eggs or something. I don't think it was, though. It was really weird. I hope he wasn't sick or poisoned. I named him Mercury. I got grossed out from lying on the kitchen floor to watch all this and let it go off into the sunset...


Cheryl Cusimano


Hi Cheryl,

The ant you found was very likely a carpenter ant, but without a more thorough description or any photographic cues, this might be hard to confirm. The "narrow thorax" you observed could have been either the petiole of an ant (the small segment joining the mesosoma and gaster that gives all ants and many other hymenopterans the appearance of having a "waist") or the constricted petiolar segment of a parasitoid wasp. Ensign wasps (family Evaniidae), for example, superficially resemble black carpenter ants and are familiar (if less common) interlopers in domestic settings given their predatory association with cockroaches.

The jittering movement is likewise difficult to explain without further observation. If the insect was indeed an ensign wasp, you might compare this behavior with descriptions of the wasp's peculiar bobbing movements, which involve jerking its abdomen up and down like a hatchet.

The meticulous grooming behavior you observed is characteristic of almost all insects, especially after a meal. Whether this particular individual was an ant or a wasp, obsessive self-grooming would not be unexpected following close inspection of foreign objects like cookie crumbs or plastic cups.

Hope this helps,

Alexandra Westrich & the AntAsk Team

I heard of a study wherein ants were sprayed with a chemical that dead ants usually gave off and their nest-mates carried them off as if they were still dead even though they were still alive. Have you heard of this study and if so do you know where I can find it?


Hi Jon,

Thanks for your great question! The story is true. Researchers can capture the smell of a dead ant (or any insect) by dipping it in organic solvents (usually hexane) for a couple of minutes. The solvent can then be applied to another object or individual. The ants perceive this experimentally treated object or individual as dead and dispose it to the colony's dump sites. This behavior makes a lot of sense, because a dead and rotting individual would present a threat to the colony as disease could spread easily.

There are some great studies on this behavior (called necrophoresis):

Blum MS (1970) The Chemical Basis of Insect Sociality. In: Beroza M, editor. Chemicals Controlling Insect Behavior. New York: Academic; pp. 61-94.

Choe DW, Millar JG, Rust MK (2009) Chemical signals associated with life inhibit necrophoresis in Argentine ants. PNAS 106:8251-8255.

Gordon DH (1983) Dependence of necrophoric response to oleic acid on social context in the ant, Pogonomyrmex badius. J Chem Ecol. 9:105-111.

Haskins CP, Haskins EF (1974) Notes on necrophoric behavior in the archaic ant Myrmecia vindex (Formicidae: Myrmeciinae) Psyche 81:258-267.

Howard DF, Tschinkel WR (1976) Aspects of necrophoric behavior in the red imported fire ant, Solenopsis invicta. Behaviour 56:157-180.

Visscher PK (1983) The honey bee way of death: Necrophoric behaviour in Apis mellifera colonies. Anim Behav. 31:1070-1076.

Wilson EO, Durlach NI, Roth LM (1958) Chemical releasers of necrophoric behavior in ants. Psyche 65:108-114.

All the best,
Steffi Kautz & the AntAsk Team

Science Project (Sam, Utah)

Dear Ant Ask Team,

I am a fifth grader at Cherry Hill Elementary in Utah. I need an ant expert to answer some questions about ants for a school project. If you have time, will you be able to answer the following questions?

How do ants detect food, even if it's far away?
How do ants smell and how far can they?
What do ants like to eat?
Do the ants' antennae help them detect food?
What are the differences between ants with different jobs in a colony in reference to finding food?
Thanks for your help,



Dear Sam,

These are some very interesting questions! Although the answers vary depending on which of the more than 12,000 described species of ant we're talking about, here are some general answers to get you started:

1) Most often ants use the power of social cooperation to find food that's far away. Because they cannot "smell" the food in large distances away from the nest, they send "patroller" ants out of the nest to find food and then tell the rest of the colony where it is. As more and more ants find the source of food, they leave pheromone trails (see Iain Couzin's website for a really cool video of this) behind, which other ants can easily detect and follow to the food. Pretty cool!

2) Of course, it depends on factors like wind, or what they're smelling, but one study found that 6 cm was the maximum distance a harvester ant could respond to an alarm pheromone in still air. For Weaver ants (here's a cool article about their social behavior), that distance was more like 10 cm.

Here is a previous post with a more detailed response about how ants use chemicals called "pheromones" to communicate.

3) This is a tough one! Ants eat a wide variety of food, and have a number of interesting ways of getting it. For most ants, the most digestible food is probably sugar water, and so this is often what they are fed in a lab. In fact, leafcutter ants like this sugar water so much, that they actually use a specific fungi to digest leafs in the forest for them, and then eat the sugar water that the fungus produces! Just like miniature farmers.

4) Yes. The antennae help the ants follow trails of pheromones to get to food, as well as help the ants distinguish the food once they get there.

5) The Gordon Lab does a lot of work on the jobs of ants and how they change over time. Here is an interesting video that might give you a better idea of this:

I hope these answers help you with your Science project!

Max Winston & the AntAsk Team

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