Leafcutting ants of the genus Atta have perhaps the most complex caste systems of all the social insects. Mature colonies contain millions of workers of varying shapes and sizes. Here are two sisters from opposing ends of the spectrum.
photo details: Canon MP-E 65mm 1-5x macro lens on a Canon EOS 20D
ISO 100, f/13, 1/250 sec, flash diffused through tracing paper