Chlorpyrifos, the active ingredient of LORSBAN^® slid DURSBAN^® insecticides, has a wide spectrum of insecticidal activity. It is considered to be a residual insecticide when applied to a field aquatic environment, incorporated into the soil, or incorporated into plastic. However. when chlorpyrifos is used as a foliar insecticide it has a relatively short period of effective residuality (1). This reduces much of its value as a broad spectrum foliar insecticide.

The loss of chlorpyrifos prior to and after deposition on foliage is due to volatility and degradation. In warmer cotton belt areas, however, loss by volatility is much greater than loss by degredation (2).

Effort began, therefore, in 1981 to increase the residuality of LORSM^® 4E insecticides using vegetable oils and other relatively non-volatile products as carriers. This objective of increasing residuality would, therefore, correspondently increase the efficacy of insect pests on cotton