 The posterior to the eyes are convex , where it converges towards the occiput ( the back of the head ) and forms a collar seen in several Aphaenogaster species . The ants have large , triangular mandibles with three apical teeth and a flat clypeus . The eyes are large with 400 facets , but workers from small incipient colonies only have 200 facets . Workers from incipient also differ from workers living in mature colonies , notably in size , body shape and coloration . The average length is 5 @.@ 56 – 6 @.@ 5 millimetres ( 0 @.@ 219 – 0 @.@ 256 in ) ; the head is 1 @.@ 52 – 1 @.@ 69 millimetres ( 0 @.@ 060 – 0 @.@ 067 in ) long and 0 @.@ 98 – 1 @.@ 12 millimetres ( 0 @.@ 039 – 0 @.@ 044 in ) wide . The epinotal spines ( spines found on the first abdominal segment that protect the pedicel ) are much shorter . Hair is also less noticeable on the workers . 
