Retention of Food Residues in the Midgut by Nymphs of the Milkweed Bug, Oncopeltus fasciatus Dall.

Abstract

DURING experiments on the nutrition of Oncopeltus fasciatus, in the course of which both nymphs and adults ingested solutions containing a fine suspension of Chinese black, it was noticed that only the adults voided black fæces, and that newly moulted adults voided a particularly thick black mass within two days of ecdysis. In a confirmatory experiment, the insects were reared from the egg on milkweed seed and a water-suspension of Chinese black, and their excreta were collected on the filter paper shown in Fig. 1. By the time the first adults had appeared, only watery material had been excreted, whereas three days later, when nearly all had moulted, black fæcal masses were evident.