The Temperature and Humidity Relations of the Cockroach

Abstract

Previous studies in this series (Gunn, 1933, 1934) have dealt with certain aspects of the physiology of the common black beetle, Blatta orientalis. The present paper is a comparison of that and two other exotic native species of cockroaches. The smallest of the three, Blatella germanica, is found in hotel kitchens, hospitals and public houses, and most rarely in private houses. Development from hatching to the last moult occupies 3 months at 23 ° C. (Zabinski, 1929). Blatta orientalis is very common in similar places and also in older houses of the poorer class. Its development occupies 1 year at 23° C. (Zabinski, 1929). Periplaneta americana, the largest species, seems to be found only in the tropical houses in Zoological and Botanical Gardens. The duration of its life cycle appears to be unknown. No reasons have hitherto been given for the existing distribution of these three species. In this paper some contributory reasons are put forward.In the experiments here described, adult males only were used. P. americana was obtained from a dealer and the other species were caught locally. All animals were kept a few days before use, and were fed on carrot and water in an oven at 25° C.