In view of the promising results obtained with insecticidal smokes against the common furniture beetle, Anobium punctatum (Deg.), a field trial was conducted to study the effect of deposits from lindane/dieldrin smoke on adults of the death-watch beetle, Xestobium rufovillosum (Deg.), emerging from infested roof timbers of a college chapel in Cambridge, England, in 1963. Quantitative determination of the insecticidal deposits was made and methods were devised for studying the effect of the treatment on the numbers of beetles emerging subsequently in order to assess the long-term value of annual treatments for reducing the population. Beetles collected from an untreated building were used for comparison.

Fewer males were found than in preceding years and it is postulated that some may have been prevented by the insecticides from emerging. The normal sequence of beetles dropping from roofing timbers—males predominating first, then females—did not occur. Both sexes dropped nearly uniformly, a fact suggesting, particularly in the case of the females, that the insecticides had caused them to drop before their normal time. Mating was considerably reduced. Examination of females showed no signs of their having laid eggs, this being attributed to the action of the insecticide deposits. Beetles obtained from an untreated building and placed on wood surfaces which had been exposed to the smoke treatment were affected but laid some eggs, of which a small proportion hatched; larval boring into such surfaces was, however, completely prevented.

From these results it was inferred that the deposits from the treatment with lindane/dieldrin smoke prevented emerging adults from causing reinfestation of the roofing timbers and it is argued that, provided that this can be achieved annually by a succession of treatments, the beetle population should ultimately be eliminated or, at least, greatly reduced. Other possible effects which might result from annual smoke treatments are accumulation of the insecticide deposits with a consequent increase in toxicity of the timber surfaces and sorption of the deposits by the timber to a point where they might exert a toxic effect on larvae or pupae beneath the surface.