The studies reported indicate that cypermethrin (NRDC 149) has considerable potential as an insecticide for wood preservatives. Cypermethrin appears to be about twice as effective as permethrin. The effectiveness of cypermethrin compared with g-HCH varies depending on the insect species, the phase of the life cycle and size of larva: for example, against mature Anobium larvae cypermethrin is approximately equal to g-HCH in effectiveness, but against egg larvae it is four times more effective. Against emergence of Anobium adults an organic solvent formulation containing 0.1% cypermethrin was more effective at 16 months than the g-HCH solution which was ten times stronger. Against mature Hylotrupes larvae it is approximately four times more active than g-HCH but as a surface spray against Lyctus a concentration of cypermethrin fifty times less than that used commercially for g-HCH spray treatments prevented infestation. Bioassay tests with a range of wood-boring insects reveal broad spectrum activity and considerable resistance to standardised accelerated evaporative ageing. In emulsion formulation cypermethrin at 0.1% prevented emergence of Anobium adults for 5 years, and was effective against attack by termites. A 0.01% emulsion formulation prevented infestation by Lyctus. In organic solvent formulation 0.1% cypermethrin gave an acceptable level of mortality against both Anobium and Hylotrupes larvae and prevented emergence of Anobium adults at 26 months.

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