The Humidity Behaviour of the Mealworm Beetle, Tenebrio Molitor L. I. the Reaction to Differences of Humidity

HUMIDITY is well known to be a factor of great importance in the lives of many insects and other terrestrial arthropods. Apart, however, from the pioneer work of Shelford (1913) and his school on the rather complex stimulus of "evaporating power of the air", there has been, until recently, little detailed and exact study of the behaviour of animals towards humidity as a stimulus. The recently developed methods of Gunn & Kennedy (1936) now make such study possible. By means of these methods, humidity behaviour has been examined in the wood-louse, Porcellio scaber, by Gunn (1937); in the locust, Locusta migratoria, by Kennedy (1937); in the mosquitoes, Anopheles gambiae and A.funestus, by De Meillon (1937); in the mosquito, Culexfatigans, by Thomson (1938) and in the cockroach, Blatta orientalis, by Gunn & Cosway (1938). The work described below deals with the reactions of the adult mealworm beetle, Tenebrio molitor L., towards humidity. This beetle lives in flour, bran and similar products and is moderately resistant to desiccation. It loses about 4% of its weight per day in dry air at 25° C. and dies in 8-9 days. Its resistance to desiccation is therefore less than that of its. larva, which was investigated by Buxton (1930).