“…Judging from considerable work which has been done by many workers in the past few years on the effects of malathion, lead arsenate and glyodin on crop pests and beneficial insects, it became increasingly apparent that malathion gives outstanding control, of various aphids, pear psylla and other potential pests soon after the spray was practised, and at the same time destroys many beneficial species (BARTLETT, 1955;HENNEBERRY, TAYLOR, SMITH and McCLELLAN, 1961;TANEICHI, 1958,1959;HUKUSIMA, 1960NOMURA, 1954;PIELOU and DOWNING, 1960). In contrast to these instances, lead arsenate or glyodin not only tended to keep the pest populations at a low level, but did not show a detrimental effect against some of the beneficial organisms though neither the program gave satisfaction in every case (CLANCY and McALISTER, 1956;GARMAN, 1954GARMAN, , 1959MACPHEE, 1953;MACPHEE andSANFORD, 1954, 1956;MORGAN, ANDERSON and SWALES, 1958;STULZ, 1955).…”