Abstract
The haemocyte (blood cell) complex in insects has distinctive characteristics at various taxonomic levels. Some taxa can be recognized easily by major differences in the number and size of the haemocytes and the complexity of cell types. Others can be distinguished only with difficulty by means of cytological features of certain cell categories. Still others have revealed no distinguishing characters. The haemocyte complex is potentially useful for indicating some systematic relationships, and in some cases for distinguishing between morphologically similar species. The concept requires careful testing.