Feeding and Nutrition of the Milkweed Bug, Oncopeltus Fasciatus (Dallas)1

Feeding behavior of fifth-instar nymphs was studied utilizing a photographic technique with exposures on color film made, usually, at 60-second intervals. On the natural diet of milkweed seed, feeding occurred in cycles averaging about 22 hours, separated by inactive intervals of 2 to 6 hours. Feeding activities occupied about 75% of each major feeding cycle. No feeding was done during the 48 hours preceding the imaginal (final) ecdysis. Intensity of feeding and characteristics of feeding behavior were markedly influenced by the presence or absence of the milkweed seed coat. The seed coat factors important to normal feeding have not been identified, but are presumed to be chemotactic in nature. The apparent deficiencies of a purified diet developed in earlier work were shown not to be nutritional; instead, they were related to a failure of this diet to meet the feeding requirements of the bug.