We saw this insect on February 24th at the Fuente de Piedra lake in Andalucia, Spain. It had 6 front legs but not hind legs, and was dragging itself along the sandy path leaving a furrow behind. 3-4cm long. Black with red bars across its back. The only thing in our insect book which it resembles is the African driver ant, but these do not have the red markings and are not supposed to be in Spain.
I'm from Spain and I've seen this insect before. It's not a queen ant. it's a type of beetle called "meloe majalis" also known in Spain as "escarabajo aceitero" which means oil beetle. It's quite a weird but common insect in the south of Spain. Hope this helps you.