As I go I think about  something I read once,  about a certain kind of ant - a
 stink ant  that lives on the floor of the West African  forest.  This ant goes
 about its ant business on the ground in an unremarkable way.  It does not know
 the curious and bizarre fate nature has in store for it.  For in these forests
 there is a  particular type of  arboreal fungus  that flourishes at the top of
 the great forest trees.   At certain times this fungus  releases  its millions
 of spores into the air.  They blow here and there,  driven by softest breezes,
 eventually coming to rest somewhere on the ground.  Some of these spores fall,
 by the law of averages, onto animals and reptiles and some on crawling insects.
 They  are quite  harmless except  for one species:  our stink ant.  This minute
 fungus  spore falls on  the stink ant and is absorbed into its ant system.  It
 drives the  ant mad.  Remember the stink ant's habitat is  the ground, but the
 lethal poison of the fungus spore  engenders in it the sudden desire to climb.
 So the stink ant,  for the first and last time in its life,  leaves the ground
 and begins to ascend.  It climbs  up and up,  higher and higher,  until it can
 climb no more. There, at the very top of the tree. It sinks its mandibles into
 the ultimate twig and abruptly dies. Inside the dead ant the fungus peacefully
 grows,  nourished  by  the  ant  meat,  warmed by top of the tree.  The ant is
 consumed and a new fungus is born.<br>
<cite>  "The New Confessions", William Boyd
</cite>