Carminic acid, found in the hemolymph of the cochineal scale (Dactylopius coccus, Homoptera: Dactylopiidae) is already known to have antifeedant properties to ants, but insecticidal properties have not previously been reported. This and other insect dyes are usually found in homopteran species that also have a woolly body covering. This coincidence suggests that the insect dyes may also have photoactivated toxic properties, and that the white woolly covering could act as a natural sunscreen. The photoactive properties of carminic acid were compared with cyanosine, a synthetic red dye known as a photoactive insecticide, using wingless fruit flies as a model system. Carminic acid was insecticidal to fruit flies within 48 h in both lighted and darkened conditions; exposure to light increased its toxicity by 24%. At 48 h exposure in lighted conditions, the toxicity of carminic acid and cyanosine were very similar, causing ~70% mortality to flies ingesting bait containing 0.4% dye. Carminic acid is already accepted by U.S. FDA as a natural food coloring, suggesting that it could be tested as a substitute for cyanosine in an organically acceptable baited spray for controlling economically important Tephritid flies.