Fig. 4

Different stages in the digestion of blood meals in Culicoides biting midges. The numbers 2–6 indicate the respective stages of blood meal digestion for Culicoides females. Stage 2: undigested (engorged abdomen showing intense dark-brown or fresh red tones) Stage 3: early digestion (engorged abdomen showing first signs of digestion with abundant dark blood). Stage 4: advanced digestion (abdomen showing advanced digestion but visible blood remains). Stage 5: pregravid (abdomen showing early egg formation mixed with a reddish tegument). Stage 6: gravid (engorged abdomen showing egg formation with no sign of blood). The upper row of images shows whole specimens of Culicoides and the lower row of images shows two different forms of the abdomens at the respective stage. Stage 1 (not shown) is the nulliparous stage