SOUND EFFECTS ON INSECTS

Press, Volume CII, Issue 30302, 30 November 1963, Page 7

SOUND EFFECTS ON INSECTS

'T'HE Winchmore irrigation research station intends to test soon the effectiveness in repelling insects of an instrument producing ultrasonic waves. It was developed in Canada. The unit consists of a battery and a coil out of a Model T Ford. The effect is to produce a spark and, at the same time, a high-frequency sound not detected by the human ear. Mr P. B. Harris, a scientific officer at the station, understands that the sound is in the same frequency as the cry of the bat and it is be-

lieved that insects may have developed a responsiveness to the bat’s call which causes them to avoid it. Mr Harris said that the equipment would be used in conjunction with a light trap to see if the sound produced resulted in a reduction in the number of insects attracted to the trap.

Mr J. M. Kelsey, the officer in charge of the Lincoln substation of the entomology division of the Department of Scientific and Industrial Research, said this week that it was very unlikely that insects in Canterbury would show any susceptibility to the bat’s chatter. There were two native bats in New Zealand but they were fairly rare, and it was likely that insects in this province had not been subject to bat’s sounds for generations. It was nevertheless true that insects were susceptible to sound, though the sound to which they were responsive varied from species to species.

In at least two cities in the United States the usefulness of such sounds had been shown in keeping starlings and pigeons away from monuments and public buildings, but there seemed to be some hitch in the technique and the method seemed always to be dropped. Now. use of a material extruded like toothpaste, was preferred, and if birds once got it on them they kept away. Since early September the irrigation research station has been using a light trap made at the Invermay Research Station. It has been operating between 7 p.m. and midnight daily to record the flights of night-flying insects. So far the main catches were of porina, on October 20 and 23. On the first of these days some 18,500 were caught in the trap and on October 23 another 5000. The first catch was probably greater than recorded, because the trap was full to overflowing. Commenting on these catches, the superintendent of the station (Mr W. R. Lobb) said that if short residue in-

secticides were to be used this sort of work would give information about the time] they should be applied to con-; trol the larval form of the pest. The observations at Winchmore would indicate that if flights occurred as early as this, application times for insesticides might have to be much earlier than had previously been recommended. Mr Harris said this week that cut worms and grass grubs were coming into the trap now. The station is also using an insectocutor with a black

light not visible to the human eye which attracts day-flying insects. This equipment, of Australian design, incorporates a high voltage electric grid which electrocutes the insects, rendering them almost unrecognisable. It is believed to sweep an acre. Insect work at the station will be discussed with farmers attending a field day on the station on December 11.