Audiospectrographic Analysis of Sounds of Hemiptera and Homoptera1

Abstract

Audiospectrographs of sounds of 11 species of Hemiptera from the families Cydnidae, Pentatomidae, Reduviidae, Phymatidae, and Corixidae, and 13 species of Homoptera from the families Cercopidae, Cicadellidae, Membracidae, and Fulgoridae are presented and discussed. These sounds can be grouped as common sounds, courtship sounds, or disturbance sounds, depending on the circumstances under which they are produced. Hemiptera produce noises by moving a movable scraper over a stationary file, while Homoptera produce noises by vibrating tergal abdominal timbals. Phymatids and reduviids appear to use fewer teeth per stridulation than the total number present on the file. Also, three different patterns of head movement associated with sound production are found among the five subfamilies of Reduviidae recorded. In general, sounds produced by Hemiptera are much more uniform than the irregular series of ticks and trills produced by Homoptera. No positive evidence of function for any of these sounds has yet been presented, although many authors have linked sound production and courtship in several families of Hemiptera and Homoptera. Because they are such soft sounds, it is not likely that they function as the primary mechanism of species congregation as is the case in loud-singing insects, but rather that they function at a secondary level after congregation has occured in response to other stimuli. These soft noises probably arose in conjunction with moving visual cues in the courtship behavior of Hemiptera and Homoptera, and became functional in disturbance situations only after they became relatively intense. Species which occur in the same sound environment produce sounds which differ primarily in number of tooth-strikes or timbal-vibrations per pulse, in timbalvibration rate, in number of pulses per phrase, and in pulse rate. Special equipment has been constructed to reduce background noise and to amplify the soft sounds produced by these animals while observing them at the same time. Changes made in the tape recorder circuits and a transistor amplifier designed especially for recording soft sounds between 0.3 and 12 kcps. are described. The next logical step to be taken in the analysis of these sounds is to establish a predictable response to some naturally produced sounds, and then to proceed to analyze experimentally its function and its means of transmission and reception.