A Study of the Processes of Digestion in Certain Insects

Several aspects of the processes of digestion in the insects Blattella germanica, Periplaneta americana, and Tenebrio molitor are reported. In Blattella starved for 2 days, a meal of coloured starch reaches the midgut within 10 minutes and the rectum within 5 hours. The pH of the gut contents on a starch diet is approximately 4.5 in the crop, 6.0 in the midgut, and 8.0 in the hindgut. A protein diet raises the pH of the crop to about 6.0, but does not change that of the other regions. There is a gradient of decreasing redox potential from the crop to the hindgut where the Eh approximates - 0.1 V. at pH 8.0.