The Humidity Behaviour of the Mealworm Beetle, Tenebrio Molitor L

Abstract

1. The mechanism of the reaction of Tenebrio molitor towards humidity has been analysed into its component behaviour elements. An estimate has been made of the quantitative importance of each type of behaviour. 2. In a gradient of humidity from 94 to 100 % R.H. the beetle rarely comes to rest in the moister region but 80 % of its time in the drier region is spent motionless. In different uniform humidities this differential activity is still evident but very much reduced. 3. The reaction is intensified somewhat by "virtual inactivity"--restricted movement confined to a small area--which is shown only in the drier part of the gradient. 4. Animals approaching regions of high humidity show turning movements which have both an undirected component (klino-kinesis) and a directed component involving movements of the antennae (klino-taxis). 5. Tropo-taxis does not occur. There are no circus movements after unilateral amputation of the antennae.