Comparison between malathion spraying and lindane‐whitewash mixture for controlling Ephestia elutella (Hübn.) in warehouses

SUMMARY Provisional estimates of the total numbers of adult Ephestia elutella emerging from warehouse rooms of about 4000 cu.ft. were between 228,300 and 509,300 in ‘moderately infested’ rooms and 1,670,000 in a ‘heavily infested’ room. Moths caught on commercial fly‐papers are a useful index to the emergence date of adult E. elutella. A trial in a Liverpool warehouse in 1958 showed that lindane in a commercial whitewash mixture, applied to walls and ceilings to produce an initial deposit of 40 mg. γ‐BHC/sq.ft., will remain effective against E. elutella between May and December. To obtain this deposit it was necessary to apply over twice this dosage. Very few active moths were seen and a negligible larval migration took place from trap bags which had been the only foodstuffs stored there. Observations over the same period in a warehouse which had been treated commercially at a heavy dosage, in December 1957, showed similar results. Cage tests in the laboratory and in the field indicated that malathion water‐dispersible powder, applied at an initial deposit of 162 mg. malathion/sq.ft., would theoretically be as satisfactory as lindane‐whitewash mixture. In warehouses, however, the former was not so effective as the latter, probably because of the marked fumigant effect of gamma‐BHC. There were indications that lindane‐whitewash mixtures alone might control infestations of endemic E. elutella in fully loaded rooms.