Comment: Re:I don't miss fire ants (Score 3, Informative) 250
Fire ants do interbreed.
http://www.caes.uga.edu/commodities/fieldcrops/forages/events/FC13/03/ANR-1248%20Fire%20ants%20and%20cattle.pdf
http://www.al.com/sports/index.ssf/2012/07/fire_ants_joes_outdoor_office.html
http://books.google.com/books?id=vxt5BqOKEAIC&pg=PA510&lpg=PA510&dq=fire+ants+interbreed&source=bl&ots=8eWZaSkLp_&sig=uJHTanPl1LV7mhieoReC1eX0plc&hl=en&sa=X&ei=dwiYUdimJ-rI0gHttIGwBQ&ved=0CEwQ6AEwAQ#v=onepage&q=fire%20ants%20interbreed&f=false
Also, they do bite before stinging.
http://en.wikipedia.org/wiki/Fire_ants
Different plant "species", such as of pine, do interbreed as well. The distinction of species vs. sub-species is often blurred in the wild.