Abstract
The shape of plasmatocytes in heat-fixed blood of sixth instar larvae of E. rockburnei was compared with that of the same cells in the two other species of the "declarata group", E. campestris and E. declarata. The data show that the shape, represented as the length/width ratio of mature, fusiform plasmatocytes, can serve to distinguish between populations of all three species. It suggests too that E. rockburnei is more closely related to E. declarata than to E. campestris.