A Gaggle of Groupies

There are over 200 species of army ants - ants that don't have a permanent home.  Army ants take or kill almost anything in their path.  After being in an area for a couple of weeks, there is nothing left to eat so they move on.  There can be as many as 20 million ants in one colony - plenty of workers to help with the relocation.  And they take everything (food, eggs, larvae, pupae) with them to the new territory.  During the stationary period the queen lays her eggs - up to 120,000 at a time.  Army ants have a lifespan of only 3 to 13 months, so in order to keep the colony going, laying eggs is a constant and only occupation of the queen.

Safari ants  Photo by Mehmet Karatay  Source:  Wikipedia

The ants almost create their own ecosystem, because the ants have groupies that live with and/or follow their trail.  As dangerous as it is for some insects to be in the path of the ant army, there are other insects and insect larvae that actually share the ants' nest.  How do they do this?  In my 'Mimicry Masters' post, I discussed how some species look like other species for their own benefit.  Some army ant groupies take mimicry to a whole new level, as these intruders can look, smell, act and even sound like their ant host species so that the ants don't think they're intruders.

Some species of adult staphylinid beetles have evolved to look like ants, but they are also capable of mimicking the chemical signature of their host.  The beetle has a glandular secretion that actually attracts the ant.  The ant will 'adopt' the beetle and obligingly carry it right into the nest.  The beetles then have access to the ants' food.  On rare occasions when there is no food, the beetles will eat ant eggs and/or larvae.  Staphylinid beetles have been observed grooming worker ants, so perhaps there is a reciprocal relationship.  Or maybe the beetles are just establishing 'friends' they hope will turn a blind eye to the occasion ant 'snack'.  Staphylinid beetle larvae also may occupy the ant nest.  They mimic the scent of ant larvae so that worker ants will groom them.

Staphylinid beetle  Source:  bugguide.net

The larvae of the Mountain Alcon Blue butterfly go a step further.  Not only can they reproduce the scent of the ant larvae so that workers will feed them, but they're also capable of making a pulsing sound that the ant queen makes and subsequently get the 'royal treatment' from their red ant hosts.

There are other groupies that don't inhabit the ant's nest, but follow the progress of army ants on the move.  Army ants may kill everything in their path but don't necessarily eat everything they've killed.  There are species of flies that take advantage of anything dead the army has killed, but don't take with them.  Certain species of birds also find an easy meal of those insects that are trying to escape the army.  Not a nice surprise to successfully avoid the ants only to be eaten by an (are you ready for this?) antbird!  Yes, it's true some birds that follow the ants are actually called antbirds, and in fact depend entirely on the ants for their food.  Cuckoos, and migrating thrushes, vireos and warblers also benefit from the fleeing insects the ants stir up.  Other birds only take advantage of the opportunity when the army goes through their territory.

Immaculate Antbird  Source:  Wikipedia

Parasitic wasps, snakes and many other creatures have also been associated with army ants.  In fact, over 300 species have been noted to either depend on army ants entirely or partially for their existence.  Army arts could be considered a keystone species.

Even though army ants are terribly destructive, there are creatures that depend on them.  And areas that have been stripped of 'ant food' are quickly inhabited again by creatures looking for a new home, or perhaps fleeing their old home as the army invades.  Another reason for making sure that the entire ant ecosystem can survive.  For a video about army ants, click here.