Lacquers containing dieldrin, malathion, or diazinon as controls for the German cockroach.

The effect of residues of dieldrin, malathion, and diazinon formulated in lacquer was compared with the effect of residues of solutions and emulsions for control of Blattella germanica (L.). Short exposure to enameled plywood treated with lacquer containing dieldrin was less effective against normal cockroaches than residues from solutions in acetone or deodorized kerosene or from emulsion formulations. All formulations were ineffective against dieldrin-resistant cockroaches. A colony increased from 300 to more than 5000 in a room where dieldrin had been applied in lacquer as a barrier around the baseboard and to all resting places and harborages. Residues of malathion in lacquer were less effective against normal male cockroaches than residues from a kerosene solution applied to enameled or unpainted plywood when the insects were exposed for 3 hr or continuously to treatments aged 1 week or 3 months; in some tests, an emulsion formulation was more effective than the lacquer, but in others it was less so. All formulations were less effective on enameled plywood than on unpainted plywood. Residues of diazinon in lacquer were less effective on unpainted plywood panels than residues of solutions in acetone or deodorized kerosene or with emulsion formulations when exposure was limited to 15 min, but when exposures were as long as 30 min or were continuous on panels aged 6-8 weeks, the lacquer was more effective than the solutions.